Each autumn in early modern India, certain men drifted out of the central provinces to take up their craft. Known as ‘Thuggees’, these men were said to be inspired by a bloodthirsty goddess and would attach themselves to a caravan on the road, posing as a merchant glad of the company or a cook looking for work. Days passed, sometimes weeks. The Thuggee played his part and earned the trust of the men he travelled with, and he waited. Then one night, with the camp asleep, he rose from his blanket, strangled his companions with a scarf, knifed each one in the stomach to be sure, and vanished with the caravan’s money. The perfect crime.

The modern vexillology movement works the same way. Give or take the strangling. In 2006 a pamphlet went out to the members of the North American Vexillological Association, enthusiasts who study flags. It was called Good Flag, Bad Flag, by Ted Kaye, and it laid down five principles of good design. Keep it simple, simple enough that a child could draw it from memory. Use meaningful symbolism. Hold to two or three colors that contrast and come from a standard set. No lettering, no seals. And be distinctive, or be deliberately related to flags you share something with. Like most pamphlets from fringe outfits, it sold nothing and lay dormant.

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Then in 2015 the radio host Roman Mars built a TED talk on it, ‘Why city flags may be the worst-designed thing you’ve never noticed’. Millions watched. It remains one of the most watched TED talks ever produced. American flags were wrong, Mars said. Seals on plain fields, that isn’t what a flag is for. Others were too busy. Age was no defense. A flag could have flown for a century and still stand condemned as badly designed.

His favorite target, and Kaye’s, was Milwaukee. Milwaukee’s flag, adopted in 1954, is an utterly mad chaos of city skyline, a ship, a stalk of barley, and various texts and numbers. In the middle, big as a sun, sits a gear. Tucked inside it is a Native American in a war bonnet, lifted more or less from the Milwaukee Braves logo of the day. But if that wasn’t enough, your eye continues to roam across the flag and finds a church, the county stadium, a factory, a lamp, a few houses, a flock of gulls. And just when you thought you had been overstimulated enough, you squint and realize there is a picture of another flag on it. Milwaukee put a flag on its flag.

The flag obsessives began their campaign in Milwaukee, and the city began to trust the thugs in disguise. In 2016 the city government ran a design contest, a thousand-odd entries, and crowned a winner: ‘Sunrise Over the Lake’, by a local designer named Robert Lenz. A golden sun comes up over a blue field, the blue for the lake and the rivers, three thin lines for the city's three founders. It ticks every single one of Kaye’s boxes. But hang on, could it not also be Tulsa’s flag? No, it could be Reno’s. In fact it is so similar to Reno’s that both cities believe the other stole their design.

And the city never adopted it. The council picked the fight up in 2018, dropped it, raised it again in 2024, and kept finding reasons to wait, among them that the original contest hadn’t been inclusive enough. The 1954 design is still the official flag of Milwaukee. Meanwhile the sunrise spread across the city on its own, on t-shirts and stickers and bike frames and beer cans, with no legal standing at all. So upset were the thugs that they have insisted unilaterally that their design, while not official, is the ‘Milwaukee People’s Flag’.

That is the pattern wherever the redesigners get their way. NAVA grade flags like schoolwork, F to A+, and they now sort municipal flag changes into before 2015 and after, a vexillological BC and AD. Pull up the twenty cities they rate highest and they are the same flag. Navy, near enough every one, carrying white and a single hit of gold. A sun or a star. Often a wavy line where a lake or a river should be, now and then a triangle standing in for a mountain. Tulsa, Reno, Topeka, St George. Twenty different American towns, indistinguishable. One flag drawn twenty ways.

Which is the joke. Kaye’s fifth principle, the one the movement hurries past on the way to the part about the child, says ‘be distinctive’. Do not duplicate other flags. By the rubric these people carry into council chambers, their own redesigns fail. They have built a continent of flags so well behaved you cannot tell them apart, and they call it a job well done.

The twenty flags they rate worst are ugly. They are also, every one of them, unique. Belle Glade, Florida, painted an entire landscape into an oval. Nitro, West Virginia, kept a small red figure and a name left over from the explosives plant that built the town. Hideous, the lot of them, and not one you could mistake for anywhere else.

The movement’s base is r/vexillology, half a million of them looking in each week, a fresh municipality in the crosshairs every time. A man watches the talk one evening and by midnight has drawn a new flag for some town of three thousand in Iowa he has never set foot in. The forum encourages him. The design gets refined.

And then they move like the Thuggee. Not marching on anything, just drifting in. A flag nerd turns up at a council meeting wearing the face of a concerned citizen, and somewhere between the sanitation budget and the painting of the municipal fences, asks to speak on the matter of the flag. Nobody else has come. Nobody ever does. He runs through Kaye’s pamphlet from memory, explains in patient detail why the town’s flag is wrong, and the council, who have a budget to pass, defer to the helpful expert and wave through a consultation and a contest. What harm could it do? The town of three thousand never knew what hit it. Milwaukee, which is not a town of three thousand, is where the thing became a decade of trench warfare but in most of these places, the old flag is strangled in the night before anyone can realise.

A fair point cuts the other way, and it should be made before someone makes it for me. Plenty of the old flags were not like Milwaukee. But most did commit the flag obsessive’s greatest held sins, a ‘seal on a bedsheet’ (SOB), illegible from afar and identical to four hundred other city seals on four hundred other navy bedsheets. The flag thugs are right about them in theory: an SOB is never full of character but neither is the minimalist sunrise.

Paul Skallas, who writes as the Lindy Man, calls the instinct ‘refinement culture’. He claims that our civilization has lost its nerve for making new things and instead sands the character off old ones, then calls the sawdust left on the floor progress. Once you are told about refinement culture, it is hard to miss. The car badges that all went flat and wordless within about three years of each other. Every new film in the cinema being an already exhausted intellectual property. And of course the old fashion houses that swapped their idiosyncratic and romantic logos for the same anonymous sans font.

James Scott wrote the book on it, more or less. Seeing Like a State is about taking a tangled reality and making it clean and legible from above, then finding the clean version holds none of what made the thing worth having.

Which brings us back to the Thuggee sneaking through the camp at night, because there is something about them I left out. The strangling cult, the goddess, the scripture that blessed the killings, much of it may never have existed as imperial Britain described it. The more recent histories tell us that the thuggee was a colonial construction, to cover up good old fashioned banditry scattered across central India. Tidied up by an administration into a single category with a scary backstory so it could be cataloged and stamped out. The British did to highway robbery exactly what the refiners do to flags. They took something various and local and difficult, and made it simple enough to draw from memory. Twenty cities, one flag. Stand a man from Tulsa in front of the winning twenty and he could not find his own.

Ned Donovan is a policeman. You can follow him on Twitter.

In the TV miniseries Lessons in Chemistry, chemist Elizabeth Zott presents her research on de novo nucleotide synthesis to a panel of suited and bespectacled colleagues. ‘Unlike the amino study group’, says Zott, ‘we are starting with the basic assumption that DNA, not protein, is the basic foundation of life’. The panel scoffs at this apparently ridiculous claim. The head of her department dismisses DNA as a ‘dead end’ and Zott’s method for making it from scratch as ‘nothing more than a party trick’. Zott’s proposal is rejected.

Zott was a fictional character, but the scientific debate was real. The fact that DNA encodes genetic information is now taught in biology classrooms worldwide, but until the late 1940s it was a fringe idea. Most scientists instead believed genes were made of protein. James Watson and Francis Crick are now household names for discovering DNA’s double helix structure, but the importance of that discovery rested on earlier work establishing that DNA, not protein, carries genetic information. The scientists who made this more fundamental discovery have often been overlooked.

The organisms that enabled this discovery were similarly unexpected: bacteria. At the time, few scientists, even microbiologists, thought that bacteria could offer anything of value to genetics. Many doubted they even had genes! Those primitive blobs swimming under microscope lenses were thought to be nothing more than tiny bags of enzymes – a totally different kind of life. So it came as a surprise when the pivotal discovery of modern genetics emerged not from a geneticist but a microbiologist.

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What parents pass on

Evolution by natural selection requires that organisms inherit characteristics from their parents. Heredity wasn’t a new idea when Darwin published On the Origin of Species in 1859. Farmers had exploited it for centuries, selectively breeding livestock and crops for desirable traits. But neither Darwin nor anybody else at the time could explain how traits were passed down from parents to offspring.

Inheritance was full of mysterious patterns: skin color tended to be a blend of the parents’, eye color could differ from either, and sex only matched one. How could such variation be explained? There were plenty of theories – including Darwin’s own provisional hypothesis of ‘pangenesis’, in which every cell in the body shed tiny particles called ‘gemmules’ that traveled to the reproductive organs and were passed to offspring – but nobody had persuasive evidence to support one over another.

Nobody, that is, except a little-known Austrian monk named Gregor Mendel. Mendel’s experiments with pea plants showed that inheritance depended on discrete factors transmitted from parents to offspring. Some traits, such as peas being wrinkled rather than smooth, could disappear and then pop up again in later generations – an impossibility if traits were a simple blend of both parents. Mendel’s work went unnoticed in his lifetime, but in 1900 three botanists independently rediscovered and confirmed his findings. By 1909 these factors had been given a name: genes. But the original meaning differed significantly from today’s. Wilhelm Johansen, who coined the term, explicitly rejected the idea that genes were physical particles, instead conceptualizing them as a chemical or physiological process.

The geneticist Thomas Hunt Morgan hypothesized that genes might either be a ‘chemical molecule’ or a ‘fluctuating amount of something’, but concluded: ‘I see at present no way of deciding’. By 1933, the confusion hadn’t resolved. Morgan wrote in his Nobel Prize lecture: ‘There is no consensus of opinion amongst geneticists as to what the genes are – whether they are real or purely fictitious’.

A common thread was the assumption that genetic information must be encoded in protein, not DNA. Proteins are made from long chains of simpler molecules called amino acids, joined in sequence like beads on a string. With 20 different amino acids for each position, like letters in an alphabet, even short protein sequences can produce an astronomical number of combinations. Meanwhile, the alphabet of DNA has only four ‘letters’, made from the four simpler molecules called nucleotides that join in sequence to make strands of DNA. Today, a four-letter alphabet may seem luxurious compared to the binary language of computers (1 and 0), but while information theory would eventually come to influence biologists’ thinking, this would not take hold for a few decades more.

Further, the best evidence suggested that the four letters of DNA were present in equal proportion in every organism, and arranged in repeated blocks. Such a monotonous molecule could be structural, but surely not informational. The physicist-turned-biologist Max Delbrück spoke for many at the time when he derided DNA as ‘so stupid a substance’.

For decades, geneticists remained stuck. To establish causality, they needed to show that a chemical induced predictable and hereditary changes in cells. The dream experiment would be to isolate and purify either DNA or protein from one organism, introduce it into another, and observe a heritable change. But living things could not take up genetic material from their environment – or so they thought. That assumption would be overturned by experiments with bacteria.

An unlikely answer

For much of the early twentieth century the study of bacterial variation and heredity was hopelessly confused. As late as 1942, the biologist Julian Huxley excluded bacteria from his theory uniting Mendelian genetics with Darwinian natural selection on the grounds that ‘they have no genes’. It seemed unlikely that bacteria had anything to offer genetics.

Then, in 1928, the British bacteriologist Frederick Griffith published a paper that shocked researchers around the world. Griffith was studying pneumococci, the bacteria responsible for pneumonia, and a promising new treatment called ‘serum therapy’ in which antibody-rich serum from patients who survived an infection could be used to treat others. But subtle differences between pneumococci rendered serum from one infection ineffective against others, so scientists categorized pneumococci into ‘serotypes’ (I, II, III, and IV). A pneumococcus’s type was fixed and inherited: it was genetic. The bacteria also differed in their colony shapes. Some produced smooth (‘S’) dome-shaped colonies, while others were rough (‘R’) and irregular. The S form was virulent and deadly, thanks to a slippery coat that protected it against our immune cells. But the R form, lacking this coat, rarely caused disease.

In his experiment, Griffith combined two bacterial strains that should have been harmless when mixed: live type I bacteria of the rough form, which didn’t cause disease, and heat-killed type II bacteria of the smooth form, which had once been virulent but were now inert. Injected into mice separately, neither was harmful. But together, the mixture proved unexpectedly deadly. Even more surprising, when Griffith isolated bacteria from the dead mice, he recovered live type II smooth pneumococci. Somehow, by coming into contact with the remains of the virulent dead bacteria, the harmless live bacteria had been ‘transformed’ to match the dead ones. And this change was not temporary: the transformed bacteria continued to produce descendants of the same type as they multiplied. It was heritable.

Immunologists were initially skeptical of Griffith’s work. Perhaps some small fraction of the virulent pneumococci hadn’t really been killed? But soon the experiment was confirmed independently by labs around the world.

Among those struck by Griffith’s experiment was Oswald Avery at The Rockefeller Institute. For 20 years, Avery had studied the immunology of pneumococci. After reading Griffith’s paper, he assigned trainees to investigate transformation. One was JL Alloway, who showed that transformation could also be brought about in vitro with chemical extracts from the killed smooth cells. By dissolving living cells and filtering out cellular fragments, Alloway extracted the ‘thick syrupy precipitate’ that contained whatever it was that was causing bacteria to change serotype. This mixture became known as the ‘transforming principle’.

Solving the puzzle

Avery had shown that the transforming principle caused hereditary changes. That meant it contained genes. If he could isolate the component responsible for transformation and determine its chemical composition, he’d finally have an answer to the long-sought question of what genes were made of.

But on the precipice of a major scientific breakthrough, progress suddenly stopped. Avery was diagnosed with Graves’ disease, a thyroid condition that exhausted him and gave him a tremor that made it difficult to perform experiments. After having his thyroid surgically removed he spent months recovering; when he finally returned to work, he shifted his research focus to newly discovered antibiotics.

When Avery came back to the question of the transforming principle eight years later, the field was largely unchanged. Why no other group swooped in during his absence remains a mystery. Perhaps geneticists were uninterested in working with bacteria, or bacteriologists had prioritized practical research into vaccines and antibiotics.

Whatever the reason, Avery began by refining the method to extract the transforming material with the help of scientists Colin MacLeod and Maclyn MacCarty. Their new process required vast quantities of bacterial culture: 75 liters of broth teeming with bacteria to obtain just 10 to 25 milligrams of transforming principle. They adapted a steam-driven kitchen cream separator to separate bacterial cells from the broth. Obviously, the device was not intended for handling pathogenic bacteria. Tiny gaps in the seals meant that its use filled the room with an invisible mist of potentially lethal pneumococci. Avery’s team had to construct a vessel that could contain and sterilize the machine before opening. The cake of bacteria it collected had to be handled with towels soaked in germicide, and the recovering Avery left the lab whenever it was being used.

Through this effort, the team purified a substance that had rich transforming activity. It contained a mixture of polysaccharides, proteins, RNA, and DNA. Next, they needed to work out which of these was responsible for transformation. Adding enzymes that inactivated proteins or polysaccharides did not stop the bacteria from transforming. But when they added an enzyme that destroyed DNA, transformation no longer occurred. That meant the transforming principle, and therefore the gene, was DNA.

The mood in the lab was electric. But Avery knew it would be an uphill battle to convince others that DNA, not protein, was the genetic material. Opponents would argue that minute traces of protein remained and these were what accounted for the transforming activity. Since it was impossible to prove a negative (that the samples were protein-free), Avery aimed to gather as much evidence as he could: chemical composition, enzyme inactivation, centrifugation, electrophoresis, and ultraviolet absorption. Every result converged on DNA.

In a letter Avery wrote to his brother, he overflowed with excitement about the implications of his discovery. ‘It touches genetics, enzyme chemistry, cell metabolism and carbohydrate synthesis, etc.’ But in his public addresses, he was cautious to a fault. ‘It’s lots of fun to blow bubbles – but it’s wiser to prick them yourself before someone else tries to’.

Avery, MacLeod, and McCarty’s paper was published in 1944. Reflecting Avery’s caution, the word ‘gene’ does not appear in the title, summary, or conclusion, and the paper ends by acknowledging that minute amounts of contaminants nevertheless could be the true source of the transforming activity. But the conclusion was unmistakeable: genes were made of DNA. The response to the paper was mixed: many praised Avery’s work, while some critics argued that contamination by protein could explain the results. But the burden of proof now rested on them to identify such a protein, and nobody was able to do so.

The molecule that changed everything

Avery’s experiment not only settled the question of the physical nature of genes, but also made it possible to ask a hundred more. How does DNA encode genetic information? Do other living organisms also use DNA, or just pneumococci? What is DNA’s molecular structure, and how does it replicate itself?

Hundreds of papers would be published on the nature of DNA over the following decades. Their authors are among the most celebrated scientists of the twentieth century, including the Nobel laureates Joshua Lederberg, who studied how bacteria can exchange DNA; Alfred Hershey and Martha Chase, who demonstrated that DNA, not protein, is transferred from bacteriophages to bacteria during viral infection; and of course Watson and Crick, who discovered the double helix structure of DNA.

Avery however never received a Nobel Prize, despite having been nominated 38 times. The Nobel committee, unaccustomed to Avery’s ‘restraint and self-criticism bordering on the neurotic’, as described by his protégé René Dubos, perhaps decided it best to wait for further confirmation. But Avery was already 65 when he published his DNA work, and died 11 years later; Nobels are not awarded posthumously. Avery’s work has received less notice than that of other geneticists, in large part because he never received science’s top prize. Nevertheless, it is the foundation upon which the last 75 years of genetic and biomedical research has been built.

DNA now dominates all facets of biomedical research. But perhaps the most important consequence of Avery’s investigations has been the recognition that all living things on Earth – from deep-sea algae to high-flying birds, sharks to iridescent beetles, disease-causing bacteria to humans – store their genes in the same way: in the twisting strands of DNA.

Kevin Blake is scientific editor at Washington University in St Louis.

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What explains recessions? Are they the product of boom-bust cycles? Do they follow cyclical or semi-cyclical patterns? Or are they best viewed by policymakers as being due to surprises changes in the global economy, which economists call ‘shocks’. These are the questions addressed in Tyler Goodspeed’s Recession: The Real Reasons Economies Shrink and What to Do About It.

Economists usually communicate new arguments and data in journal articles. In contrast, Recession is published by Basic Books, an imprint of Hachette, the third-largest publisher in the world. The book is rich with both historical anecdotes and biographical sketches of key players such as Irving Fisher and FA Hayek. Despite this, Goodspeed’s book is a serious, data-rich work.

At first glance, Goodspeed’s target is the popular understanding of a boom-and-bust cycle. Consider his vivid account of the crisis of 1873. Both popular and scholarly histories have attributed this recession to railway mania and the collapse of the Northern Pacific Railroad. Goodspeed instead points out the devastating role of a surprise that had nothing to do with economics or economic policy: the great grasshopper plagues of 1873-1876, during which a single locust swarm covered an area larger than California and devastated the very regions the railroad was supposed to open to European settlers.

Goodspeed’s first message is that macroeconomic events are not morality plays, nor always under policymaker control or influence. Jay Cooke’s vision of a railway connecting the Pacific northwest was not inherently flawed or hubristic. Nor were other nineteenth-century business busts such as the 1857 New York banking crisis associated with the collapse of Ohio Life. Instead these panics were, like that of 1873, each associated with an idiosyncratic confluence of factors.

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The intuitive account of recessions: payback for good times

Goodspeed is not just interested in confronting the kinds of explanations for mania, crashes, and panics seen either in history books or in journalist accounts. He wants to see if the data supports theoretical accounts of recessions that locate the cause of the downturn in the preceding expansion. His antagonists are two celebrated Austrians: first Friedrich Hayek, introduced early in the book as a prospective restaurant dishwasher as a young man in New York and whose prominent account of business cycles rivaled Keynes’s in the 1930s; and second, Joseph Schumpeter, who saw in recessions the opportunity to sort out the mistakes and misallocations of the boom. Goodspeed’s main goal in the 200 or so pages of the book is to ask whether the data supports these theories, or their modern variants, or whether it is consistent with a much simpler story.

The short answer is no, and this is Goodspeed’s second main message. The spine of the book is data on quarterly output for the UK and US. The UK data comes from the work of Steve Broadberry and coauthors. The US data stems from the National Bureau of Economic Research but Goodspeed has extended it back to 1700 and applied a consistent methodology to provide a continuous business cycle series for both countries.

Goodspeed shows that British and American expansions do not resemble Dorian Gray, looking beautiful but hiding an inevitable accumulation of malinvestments (objectively bad investments that are destined to fail) and distorted decisions (mistaken economic decisions taken on the basis of bad regulation or flawed prices) that make a correction inevitable. If they did so, he argues, one would expect that as expansions get longer they get more and more likely to end. In his data, however, the relationship between the age of an expansion and the probability of death is essentially zero. Nor do measures of increased investment during the boom correlate with the severity of a downturn. Nor do longer expansions have longer recessions after them.

This is why recessions remain essentially unpredictable. Any perceived regularity is likely to be a statistical illusion. Goodspeed shows that attempts to forecast recessions such as inversions of the yield curve (where long-dated government bonds have lower interest rates than short-dated ones) or the Sahm rule (which says a recession is likely underway if the unemployment rate spikes high above its recent lows for three months) are overfitted to US data and don’t work for the UK. The same proved to be true of the Phillips Curve, a strong correlation between unemployment and inflation that existed in British data between 1860 and 1960, which broke down after governments attempted to target it and fine tune the economy in the 1960s.

On top of all this, he finds no evidence that recessions are corrective. Reallocations tend to happen more aggressively during expansions not contractions, contrary to the arguments that Joseph Schumpeter famously made. Similarly, he finds that contrary to common belief recessions tend not to be contagious but rather are mostly patriotic, usually confined to a single country like the modest 2001 downturn in the US (which did not spread to the UK).

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Nothing new under the sun

The blurb provided by Niall Ferguson on the hardcover of the book proclaims that it is ‘truly revolutionary’. I would say that Goodspeed’s account is highly consistent with at least one strand of research in macroeconomics.

As Goodspeed makes very clear, his account of recessions has a direct antecedent in Milton Friedman’s so-called plucking model, which is not so much a model as an empirical observation that the path of the economy could just as well be described as a straight trend upwards, which sees negative deviations from the trends and recoveries back to the trend. In Friedman’s view, there is no special reason to see faster-growth periods as artificial booms or bubbles. The goal for policy makers, if Friedman’s model is true, is neither to burst bubbles nor to prevent booms from getting going, but simply to limit or prevent negative shocks and ameliorate their consequences.

Goodspeed’s historical case studies are also consistent with a much derided tradition in macroeconomics, known as real business-cycle theory, associated with economist Ed Prescott, who won the Nobel Prize in 2004 and died in 2022. In real business-cycle theory, the economy ticks along its regular path until it is hit by what real business-cycle theorists call ‘technology shocks’. Former US Treasury Secretary and Harvard President Larry Summers objected to these models because technology shocks were undefined. Goodspeed’s narrative accounts provide compelling examples of how shocks broadly understood can account for much business cycle behavior.

I recall being distinctly unimpressed by this emphasis on shocks as an undergraduate. Nonetheless, it is clear that until recent times, most economic fluctuations were caused by exogenous factors such as the climate. What Goodspeed emphasizes is that exogenous shocks have played an important role even into modern times.

For example, recent research has demonstrated the role of bank failures in explaining the depth of the Great Depression. Goodspeed notes that huge locust plagues like those of 1873 ravaged western and central states. By late 1931, one in six farms in this region was underwater. So while contemporaries blamed land speculation and irrational land booms, it is clear that exogenous shocks to the real economy lay behind part of the severe banking distress of the early 1930s. Again, Goodspeed notes that this wasn’t The Cause of the Great Depression. There was no one cause, ‘but rather a succession of overlapping and interacting shocks, often highly region-specific’.

Predicting such events is a fool’s errand. Rather, Goodspeed argues we should imagine several dice being rolled as if in a game of chance. A roll of one is a negative shock: a war or a coal-strike or a climatic shock. A recession might occur if we simultaneously roll three ones.

If you’re in a hole, stop digging

Not all shocks are necessarily exogenous in nature. Chapter 7, entitled ‘Firefighters and Arsonists’, notes that while policymakers can play a vital role in smoothing shocks and responding to a crisis, they have often themselves acted as arsonists.

The actions of the Federal Reserve during the Great Depression are a famous example. Wary of speculative finance, the Fed allowed the money supply to fall precipitously and failed to halt the banking collapse. The shock here was hardly exogenous to the economy itself but the type of unforced error that is sadly not unusual in the historical record.

Similarly, conventional accounts at the time of the Great Recession of 2008 emphasized financial malfeasance in the housing market with subprime mortgages being repackaged to unsuspecting lenders. But why should these issues in the banking sector produce a worldwide recession? Moralizing accounts that emphasize the greed of bankers can be politically and emotionally satisfying but they don’t explain the scale of the downturn. The vast majority of the homes built during the bubble between 2002-2006 turned out to be entirely consistent with subsequent demand.

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Goodspeed sees the 2008 recession as caused by a confluence of largely independent and to a degree avoidable shocks. There was a negative supply shock that saw the price of gasoline reach $5.86 per gallon in 2026 prices (at time of writing still an all-time real terms high). As a result, fertilizer prices also spiked. This energy-shock-induced slowdown began before distress in financial markets resulted in the collapse of Lehman Brothers. But this shock itself would not be nearly enough to explain what then happened.

Rather, as monetary economists such as Robert Hetzel and Scott Sumner have argued, monetary authorities then responded to this shock to prices by tightening policy at precisely the wrong time. In Spring and Summer 2008, the Fed failed to decisively lower interest rates in the face of declining economic activity. Goodspeed highlights the particular errors made by Alistair Darling in failing to agree to a US proposal to bail out Lehmans on the grounds that this would be importing the US contagion. Regardless of the rights or wrongs of that particular decision, Goodspeed’s account is consistent with those who see the crisis of 2008 as at least partly caused by a departure from the standard monetary policy procedures during the Great Moderation.

Prepared to get schooled in my Austrian perspective

It is worth asking how adherents of either FA Hayek’s Austrian business cycle theory, which says, effectively, that the bust is punishment for an unsustainable boom, or Hyman Minsky’s financial instability hypothesis, which says that highly financialized economies are inherently unstable, would react to his arguments.

The Austrians might challenge whether Goodspeed’s empirical tests map onto the theoretical objects they are meant to be testing. For example, Goodspeed’s data show that longer expansions don’t predict deeper or longer recessions. But the Austrian claim is subtler: it is comfortable with a short expansion generating more malinvestment than a long, sound-money expansion, if the short expansion is driven by massive credit inflation. The Austrian story is fundamentally microeconomic: it predicts distortions in specific investment decisions and the accumulation of these decisions across the economy produces macro-level effects. This is hard to test with Goodspeed’s data and without firm-level data on investment and capital decisions, it seems like the two views risk talking past each other.

The Minskyites would say that Goodspeed had proven them right. Goodspeed acknowledges that recoveries from a financial crisis or credit crunch tend to be slower. But it isn’t apparent from his framework or Friedman’s plucking model why this should be the case. If financial recessions are qualitatively different from other types of recession, this suggests that the state of the financial system at the time of the shock matters, meaning that Minsky’s concerns about financial fragility cannot be dismissed.

The data that Goodspeed has assembled is impressive but it covers just two countries. The experience of a broad set of countries might reveal still more of a role for financial overextension or capital market distortions. These responses notwithstanding, Goodspeed does pose important challenges for adherents of either Hayek or Minsky. If the empirical data Goodspeed offers is not an adequate test, then it becomes incumbent on them to at least propose tests which would offer a fair hearing for their theories. If they cannot do that, their theories risk becoming more metaphysics than economics.

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An end to boom and bust?

So, does Goodspeed’s book succeed in smiting the myth of the boom-bust cycle? Without doubt, he lays to rest many suppositions or beliefs many have about business cycles. The book is a great read and packs a lot of analysis into its 200 pages. The datawork of the book is itself an important contribution. While I don’t see Recession as the final word on this topic, readers will update their priors about the extent to which shocks to the economy such as the 2026 US-Iran conflict have been the key drivers of many economic downturns. In contrast, plausible and intuitive accounts that both non-specialists and specialists alike have offered for an endogenous business cycle, where booms sow the seeds of eventual busts, struggle to find support in his data.

Personally, Recession strengthened my prior beliefs that policymakers simply don’t have enough information to even distinguish between a robust expansion and a speculative bubble in real time, let alone the tools to safely tame any bubbles that they did find. Rule-based monetary policy, which allows market participants to form stable expectations about what its response will be, while still allowing flexibility in the event of shocks, might be the best we can hope for. Here Goodspeed’s advice is sensible: policymakers should first do no harm before thinking that they have the ability to entirely tame the business cycle.

Mark Koyama is professor of political economy at the Hamilton School, University of Florida.

I recently visited Washington DC, for the first time since I was a boy. Visiting Washington in person is like seeing the Mona Lisa: one has experienced it so many times in reproduction that it is almost eerie to see the real thing. I found the experience fascinating, and I have tried to write down a few of my thoughts and impressions.

Each of the monumental buildings of Washington sits on its own city block, with a border of lawn separating it from the street, like a great roast turkey sitting alone on a silver dish. This quality of distinctness and separateness is a common aspiration of nineteenth-century design, but it was hard for Europeans to achieve amidst their dense and historically layered cities. In London, tremendous monumental buildings are piled up along crowded narrow streets and chaotic traffic islands, like the British Museum on Great Russell Street and the Palace of Westminster on Parliament Square. Not so in Washington, where every grand building rests calmly at the end of a long perspective. This certainly does give the city dignity, though perhaps it loses something of vitality at the same time.

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The buildings themselves are distinctive too. For one thing, most of them are faced in marble. Marble was used extensively for monuments in ancient Rome, but it has not been the dominant building stone in any great city of Europe since then, and in fact very few of Europe’s major buildings feature much exterior marble. Indeed I believe there is only one significant marble structure in London, the Marble Arch, whose material was so distinctive the building was named for it. In every European city the dominant building stone is limestone, or sandstone if limestone is unavailable, or granite if neither is. But because Washington was built so late in history, when transport costs had fallen, the Americans could access the wonderful building marbles of Georgia and Vermont, and create the world’s first marble city since antiquity.

Marble is favored by sculptors because of a feature called subsurface scattering. What this means is that marble is slightly translucent: sunlight not only illumines its surface, but a millimeter or so of its depth, creating a softly luminous quality in certain lights. Human flesh also has this feature, whence arises the special appeal of marble for sculptors of the human figure. I had read about subsurface scattering before, but I had never engaged seriously with the idea and slightly suspected it of being a pious canard. But in Washington, I became a believer. The monuments of Washington do seem to glow softly in the brilliant southern light: this does give them a sensuous quality, which becomes almost overwhelming when a whole city is built this way. I am not sure I am a good enough photographer to capture this effect, but I think you can see something of it in the contrast between the colonnade of the Jefferson Monument (Vermont marble) and the Church of the Madeleine in Paris (Lutetian limestone).

Washington’s monuments are stylistically unusual, too. For monumental architecture, the Americans traditionally favored the neoclassical style, drawn from Greco-Roman antiquity. Many people think of neoclassicism as, so to speak, the official style of Western civilization. There is an element of truth in this, but quite a limited one. When Europeans began to draw on ancient precedents in the Renaissance, they did so loosely and freely, and each country did so in its own way, such that French, German, Spanish and Italian Renaissance styles are highly distinct from each other. These national renaissance traditions continued in various forms for over three centuries. There was then a brief period of international neoclassicism in the late eighteenth and early nineteenth centuries, after which European architects mostly returned to their national idioms.

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The upshot of this is that the quantum of strictly neoclassical architecture in most European cities is actually very small. The most iconic form of classical architecture is the detached portico (the temple front with columns and a gable). I have had a go at counting detached porticos in the old city of Rome, in some sense the ‘world capital’ of classical architecture. I have found only two unambiguous examples, on the Pantheon and the Temple of Portunus, both of them survivors from antiquity. In Washington, by contrast, there are detached porticos in front of most major buildings, including, starting from the top, the Capitol, the White House, the Supreme Court, the Jefferson Monument, the National Gallery, and the Treasury Building.

This leads me to the curious idea that what Americans think of as traditional European architecture – marble neoclassicism – is actually characteristic of Washington in a way that it is not, and has never been, characteristic of any city of post-antique Europe. In the late nineteenth and early twentieth centuries, American thinkers worried that their architects were copying European precedents rather than developing a national style of their own. But perhaps, in their fervor to emulate European antiquity, they had developed an American national style after all.

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I find longhaul flights extremely tedious, so I distract myself by watching films. Returning from Washington I watched Dune: Part One and Dune: Part Two, in which families of aristocratic spacemen compete to rule a Middle Eastern-themed planet called Arrakis. I enjoyed this very much, and I was fascinated by the architecture of the sets. There was something of the Sumerians, something of Boullée’s neoclassicism, a dash of Brazilian modernism, elements from Hindu temple architecture, lots of Islamic motifs, and maybe something of the Mayans, but all pared back, horizontal, massive and monochrome, blended together very harmoniously, plausibly futuristic and ancient at the same time.

The designer of all this seems to be one Patrice Vermette, who has no historical or architectural training at all, having studied communications at Concordia University in Montreal. The star of Dune, an actor called Timothee Chalamet, recently generated something of a rumpus by criticizing the fustiness of opera and ballet. I find it pleasing that among his colleagues he has a historicist designer of some genius, who can draw upon a wide range of fusty sources with virtuosity.

Samuel Hughes is an editor at Works in Progress.

A few days after Sasse’s interview, in April 2026, Revolution Medicines announced Phase 3 trial results for daraxonrasib showing the drug had roughly doubled survival in patients with metastatic pancreatic cancer compared to standard chemotherapy. For a disease where median survival has long been measured in months and where little had changed for decades, that result represents a genuine turning point.

But the significance extends beyond pancreatic cancer. Daraxonrasib is among the first drugs in an emerging generation designed to target RAS, a protein implicated in roughly a quarter of all human cancers and long considered beyond reach, in all its mutant forms. And it belongs to a broader class of medicines, molecular glues, that are beginning to show what becomes possible when drugs no longer depend on finding a ready-made pocket in their target. Several compounds in this class are now in clinical development, each probing a different protein that previous generations of drugs could not touch.

Pancreatic cancer: a tough nut to crack

Pancreatic cancer has the highest mortality rate of all major cancers. Although its five-year survival rate has improved from roughly 4 percent in the mid-1990s to around 13 percent today, it remains among the deadliest of all cancer types.

Survival is so poor partially because pancreatic cancer is typically diagnosed late: the pancreas sits deep in the abdomen, symptoms are vague and late to appear, and by the time most patients are diagnosed, the cancer has already spread. This feature has earned pancreatic cancer the name ‘silent killer’. Metastatic cases, where the tumor has already spread to other organs, represent more than half of all new diagnoses. For these patients in particular there has been minimal improvement in outcomes over recent decades, with just 2 to 3 percent still alive five years after their diagnosis.

For decades, no fundamentally new and effective treatments for metastatic cancer emerged. That changed in 2011, when a wave of innovation began transforming the field. At the heart of this renaissance are immunotherapies: drugs that harness the body’s own immune system to fight cancer. Among them are checkpoint inhibitors, which work by releasing the natural brakes on immune activity, and CAR-T therapies, a new class of anti-cancer wonder treatments which engineer a patient’s own immune cells into precision cancer-fighting weapons.

These treatments have redrawn the boundaries of what is possible in oncology. In metastatic melanoma (the most serious type of skin cancer), immunotherapy has produced results once thought unimaginable: from only 25 percent survival after one year twenty years ago to 50 percent survival after 10 years now. Unfortunately, metastatic pancreatic cancer is particularly good at protecting itself against immune attack and has thus remained beyond the reach of this newer wave of drugs.

Pancreatic tumors build a shield around themselves to evade immune attack. They are surrounded by a dense, scar-like layer of tissue that physically blocks a patient’s immune cells from entering the tumor. As a result, checkpoint inhibitors, which work by reactivating immune responses, often have little effect. CAR-T therapies also struggle to penetrate this physical barrier. Even when immune cells do manage to get inside, the tumor creates a hostile environment that weakens them. It does this by attracting suppressive immune cells, including regulatory T cells, myeloid-derived suppressor cells, and tumor-associated macrophages, and by releasing molecules that dampen immune function.

There is a further problem that compounds this. Immunotherapy tends to work best against genetically ‘noisy’ tumors: cancers with many mutations that generate abnormal surface proteins, known as neoantigens, which help the immune system recognise the cell as foreign. Melanoma is a classic example. Driven by UV-induced DNA damage, it often carries a heavy mutational burden and is therefore more susceptible to immune attack. Pancreatic tumors, by contrast, are comparatively quiet. They contain fewer mutations, and can remain largely hidden from immune surveillance.

Yet despite these disadvantages, pancreatic cancer has one feature that should, in theory, make it highly targetable: KRAS mutations, which are found in more than 90 percent of cases. A mutation this common, and so central to the cancer’s biology, ought to be a gift to drug developers: a clear and identifiable target around which therapies could be designed. In practice, however, it proved far more difficult.

Targeting RAS

The genomic revolution promised, among other things, that we would crack cancer. When the Human Genome Project concluded in 2003, the optimism was intoxicating. If cancer was fundamentally a disease of mutated DNA, then sequencing that DNA would tell us exactly what to target and how. What researchers hoped is that we would be able to find the broken gene, design a drug to block its protein, and shut the cancer down. Precision medicine, we were told, would transform oncology by swapping the bluntness of the old chemotherapy approaches into something more like a guided missile.

More than twenty years later, the progress has been mediocre. Two problems have stood in the way of realizing the genomic promise. The first is evolution: tumors have genomes that can change rapidly, and under the selective pressure of a targeted drug, resistant clones can emerge and allow the cancer to adapt around the treatment. The second problem is even more fundamental: many of the mutations that drive cancer produce proteins that simply cannot be targeted by conventional drugs.

RAS is one such example. RAS is a molecular switch. In its normal state, it cycles between an active ‘on’ position and an inactive ‘off’ position. When a cell receives a signal to grow or divide, RAS flips on, relays the message downstream through a cascade of other proteins, and then switches itself off again. It is, under normal circumstances, a tightly regulated relay station.

Cancer hijacks this system through mutations, which are small but catastrophic in their effect: they lock RAS permanently in the ‘on’ position. Cells receive a continuous, unrelenting instruction to proliferate, regardless of what the rest of the body is telling them.

For over two decades, RAS carried one of the most dispiriting labels in drug discovery: undruggable. This was not for want of understanding. RAS is in fact one of the most studied proteins in cancer biology, mutated in roughly 25 percent of all human cancers, and in over 90 percent of pancreatic cancers. In lung adenocarcinoma and colorectal cancer, the figure sits between 30 and 45 percent. The problem lies in the fundamental geometry of the protein.

Most cancer drugs are small molecules or compounds precisely shaped to slip into a pocket or groove on a target protein, jamming its function the way a foreign key might get stuck in a lock. This approach depends entirely on the protein offering a suitable cavity to exploit. But RAS’s surface is unusually smooth and chemically inhospitable, presenting none of the clear binding sites that drug designers look for.

In 2013 researchers demonstrated that small molecules could, in fact, bind to a specific mutant version of RAS called G12C. This particular mutation creates a small pocket that does not exist in the normal protein. The biochemist Kevan Shokat at the University of California, San Francisco, showed that certain compounds could lock into this pocket and trap K-Ras in its inactive state.

From that insight emerged the first generation of RAS drugs: sotorasib and adagrasib, both of which bind to and ‘switch off’ the G12C-mutated RAS protein. Sotorasib received FDA approval in 2021 for RAS G12C-mutated non-small-cell lung cancer. It was also, for pancreatic cancer patients, largely useless. The G12C mutation is common in lung cancer but rare in pancreatic cancer, accounting for only around 1 percent of cases. The vast majority of pancreatic tumors carry a different RAS mutation entirely, that does not form such a cavity in the protein.

Molecular glue

Molecular glues entered cancer medicine before they had a name. In the late 1990s, thalidomide, a drug infamous for causing birth defects decades earlier, showed unexpected activity against multiple myeloma. Its analogue lenalidomide was approved for multiple myeloma in 2006 and became one of the defining drugs in the disease. Only later, beginning with the identification of cereblon as thalidomide’s target in 2010, did scientists realise that these drugs worked as molecular glues.

Molecular glues take a different approach from most small molecule drugs. Rather than binding a pocket, they create new connections between proteins. A molecular glue binds to the surface of one protein and, in doing so, alters that surface’s chemistry just enough that a second protein is now attracted to it. The two proteins, which might never normally interact, are held together by the glue acting as a chemical intermediary, for example by adding new contact points, or bridging surfaces that would otherwise repel or ignore each other. Because this strategy doesn’t depend on finding a pre-existing cavity, it opens up proteins that have long been considered beyond reach.

After the mechanism of molecular glues was understood, scientists started to think about targeting RAS. But progress required more than understanding molecular glues in principle. Scientists had to recognise that Cyclophilin A, a protein that is common in human cells but with no prior connection to cancer, could serve as a bridging partner, and that a small molecule might hold it against RAS. Seeing whether that was even possible required advances in cryo-electron microscopy, a technique can capture the fleeting, multi-protein assemblies that a molecular glue would need to stabilise. Only once the interface between RAS and Cyclophilin A was mapped precisely enough could a bridging compound be designed.

Daraxonrasib is that compound. It binds Cyclophilin A first, and the two form a combined unit whose reshaped surface fits snugly against the active form of RAS, locking the three components together. Cyclophilin A then simply takes up space, blocking RAS from making contact with its downstream partners.

In the Phase 3 trial, patients treated with daraxonrasib experienced a median overall survival of 13.2 months, roughly twice as long as those who received standard chemotherapy: just a prolonging of survival, not a cure. But for a disease that was otherwise so untreatable, doubling survival with a daily pill rather than intravenous chemotherapy is, by the standards of pancreatic cancer, a genuine advance.

The limits of targeted therapy

Daraxonrasib’s clinical success has been real, but resistance inevitably emerges. Analysis of patients treated with the drug has already revealed the tumor’s counter-moves. Some cancers acquire mutations at positions on the RAS protein itself, such as Y64, that physically prevent the molecular glue from forming the complex with Cyclophilin A. Still others amplify copies of KRAS itself, or activate parallel signaling pathways, rerouting growth signals through channels the drug cannot reach.

Because resistance to any single agent is essentially guaranteed, the future lies in combinations: hitting multiple vulnerabilities simultaneously, or switching strategies as the tumor evolves. But doing that well requires being able to test new approaches quickly and in small, targeted patient populations. This sits uneasily with a regulatory framework built around several rounds of trials in multiple patients. Matching the right drug to the right mutation in the right patient, in something close to real time, will require that framework to change. One important idea is making small-scale Phase I investigator initiated trials much easier to carry out.

The broader lesson of this era, though, is one of optimism. As well as RAS, the cancer field has scored another win against a previously ‘undruggable’ target, PI3Kα, another commonly mutated protein in cancer. Inavolisib, which both inhibits and destroys the mutant form of the protein, roughly doubled progression-free survival in PIK3CA-mutated advanced breast cancer when added to standard treatment. The assumption that certain targets are simply beyond reach has repeatedly turned out to be wrong.

For the mothers of the baby boom, pediatrician Benjamin Spock’s child care handbook was a practical, confidence-boosting essential. Originally published in 1946 as The Common Sense Book of Baby and Child Care, Dr Spock’s baby book sold more than 500,000 copies in its first six months. By the time the second edition came out in 1957, with the simplified title Baby and Child Care, Dr Spock was selling a million copies a year. My mother, who was 24 when I arrived in 1960, still remembers the book’s reassuring tone.

‘You know more than you think you do’, the author told readers. ‘We know for a fact’, he wrote with medical authority, ‘that the natural loving care that kindly parents give to their children is a hundred times more valuable than their knowing how to pin a diaper on just right’.

Dr Spock went on to provide detailed instructions on the practical intricacies of parenthood, including diapers. Buy at least two dozen, he counseled, more if you aren’t washing them daily. Six dozen would cover all contingencies. With a diagram, he showed how to fold a diaper and explained how to position it on a boy versus a girl. ‘When you put in the pin’, he advised, ‘slip two fingers of the other hand between the baby and the diaper to prevent sticking him’. The book covered when to change the diapers and what to do with the dirties.

You want a covered pail partially filled with water to put used diapers in as soon as removed. If it contains soap or detergent, this helps in removing stains. Be sure the soap is well dissolved, to prevent lumps of soap from remaining in the diapers later. When you remove a soiled diaper, scrape the movement off into the toilet with a knife, or rinse it by holding it in the toilet while you flush it (hold tight).

You wash the diapers with mild soap or mild detergent in [the] washing machine or washtub (dissolve the soap well first), and rinse 2 or 3 or 4 times. The number of rinsings depends on how soon the water gets clear and on how delicate the baby’s skin is. If your baby’s skin isn’t sensitive, 2 rinsings may be enough.

On this subject, the 1957 edition contains two telling differences from the original. In 1946, Dr Spock recommended the knife method to those without flush toilets. And starting with the second edition, he advised new parents to buy an automatic washer and dryer if they could possibly afford them. ‘They save hours of work each week, and precious energy’, he wrote. ‘Energy’ in this case referred not to electricity or gas but to maternal stamina.

Disposable diapers did exist, but they accounted for a mere one percent of US diaper changes. They were expensive, specialty products and not that great. ‘The full-sized ones are rather bulky’, noted Dr Spock. ‘The small ones that fit into a waterproof cover do not absorb as much urine as a cloth diaper and do not retain a bowel movement as well’. Disposables were mostly used for travel, when washing diapers wasn’t an option.

But even as the second edition of Baby and Child Care was hitting bookstores and supermarket racks, change was afoot. After buying Charmin Paper Company in 1957, Procter & Gamble began looking for ideas for new paper products.

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Motivated by the less pleasant aspects of spending time with his new grandchild, the company’s director of exploratory development, Victor Mills, suggested disposable diapers. After analyzing existing products and conducting consumer research, P&G created a dedicated diaper research group.

The research this group conducted, like that of its successors and competitors, wasn’t glamorous. It didn’t advance basic science. It wasn’t even an obvious route to profit. (One percent of the market!) It was a high-stakes gamble that required solving difficult engineering problems. How that happened represents the kind of hidden progress that leads to everyday abundance.

P&G’s first design flopped. Tested in the extreme heat of a Dallas summer, the pleated absorbent pad with plastic pants made babies miserable and left them with heat rashes. Starting over, the group had a one piece diaper ready for testing in March 1959. With an improved rayon moisture barrier between the baby and the absorbent tissue wadding, the new diaper was softer and more comfortable. An initial test of 37,000 hand-assembled prototypes went well, with about two thirds of the parents deeming the disposables as good or better than cloth. The next step was mass production.

Designing one well-functioning disposable was hard enough. Turning out hundreds a minute was practically impossible. ‘I think it was the most complex production operation the company had ever faced’, an engineer recalled.

There was no standard equipment. We had to design the entire production line from the ground up. It seemed a simple task to take three sheets of material – plastic back sheet, absorbent wadding, and water repellent top sheet – fold them in a zigzag pattern and glue them together. But glue applicators dripped glue. The wadding generated dust. Together they formed sticky balls and smears which fouled the equipment. The machinery could run only a few minutes before having to be shut down and cleaned.

Eventually, the diaper team mastered the process. In December 1961, Pampers went on the market in Peoria, Illinois. Once again, the test failed.

This time mothers liked the diapers. But the price was way too high for a single use item: ten cents a diaper, equivalent to about one dollar today. By contrast, diaper delivery services, which served about five percent of the market, charged no more than five cents a diaper. Home laundry costs ran to one or two cents.

Lowering the price of a diaper required much larger volumes. Aiming at about six cents a diaper, P&G engineers spent several years developing what Harvard Business School’s Michael E. Porter described as ‘a highly sophisticated block-long, continuous-process machine that could assemble diapers at speeds of up to a remarkable 400 a minute’. After successfully testing Pampers at 5.5 cents each, P&G began a national rollout in 1966. By 1973, disposables accounted for 42 percent of the US diaper market.

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A noteworthy success was in Puerto Rico, which Pampers entered in 1972. Although incomes were significantly lower than in the continental US, the island’s poverty actually favored disposables. Many families lacked easy access to washing machines, and line drying diapers was tough in the humid climate. ‘Puerto Rico became one of the most successful Pampers markets’, records Oscar Schisgall in Eyes on Tomorrow, a corporate history of P&G. Disposable diapers turned out to be a particular boon to poor families.

The success of Pampers drew competitors into the growing market. ‘Any diaper maker that carved out a modest market share against Procter & Gamble could expect sales to triple as a result of sheer market growth’, write business historians Thomas Heinrich and Bob Batchelor in Kotex, Kleenex, Huggies, a history of Kimberly-Clark. But there was a catch. The bulky diapers took up so much space on shelves that stores rarely stocked more than two brands, plus maybe a discounted private label. Second place meant profits, third place disaster.

Most entrants gave up within a few years. Scott Paper abandoned the market in 1971. International Paper exited in 1972. Union Carbide left in 1977. Johnson & Johnson held on until 1981. J&J was adept at marketing baby products but couldn’t get its machines to turn out diapers fast enough to keep prices competitive.

Kimberly-Clark was the exception. The company that had introduced the world to Kleenex tissues and Kotex feminine pads, both completely new concepts in the 1920s, created a disposable diaper called Kimbies. It featured tape fasteners and an unusual triangular fold. Buyers liked the tape fasteners, which Pampers soon copied, but complained that the weirdly folded diapers leaked. After a disastrous switch in the glue affixing the cover lining to the pad, Kimbies began losing shelf space to J&J. In 1975, the company decided the only way to survive in the diaper business was to start over with a better design.

The new diapers, introduced as Kleenex Huggies in December 1977, were elasticized along the edge of the crotch to prevent leaks. Manufacturing them was a complicated process requiring custom-designed machines. Heinrich and Batchelor write:

A tissue machine combined layers of absorbent padding into sheets of varying thickness to form the wings and the crotch section, which was 15 percent thicker than the edges. Once the sheet had been cut into individual hourglass shapes, the latter received an elastic band at the crotch section and were combined with the cover and backing sheet to form the diaper.

Huggies had tapes that could be refastened without tearing the plastic cover, an annoyance I remember from my days as a teenage babysitter. Like P&G’s premium Luvs, which included similar features, Huggies cost about 30 percent more than regular disposables. But consumers were willing to pay more for higher quality diapers.

‘At a time of rampant inflation, declining real wages, and economic uncertainty, consumers flocked from Johnson & Johnson’s moderately priced diapers to the Huggies and Luvs premium brands’, write Heinrich and Batchelor. As Huggies expanded nationally, J&J sales cratered.

The following decade saw fierce competition between the two remaining diaper giants, with Huggies eventually becoming the market leader. In the mid-1980s, P&G and Kimberly-Clark replaced paper wadding with superabsorbent polymers (SAPs) that trap water like particles in a net. As manufacturers learned how to work with these wonder materials, disposable diapers got thinner and better.

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‘In the early eighties’, wrote Malcolm Gladwell in a 2001 New Yorker feature, ‘they were three times bulkier than they are now, thicker and substantially wider in the crotch. But in the mid-eighties Huggies and Procter & Gamble’s Pampers were reduced in bulk by fifty percent; in the mid-nineties they shrank by a third or so; in the next few years they may shrink still more’.

As diapers got slimmer, they took up less space in trucks and on shelves. Shipping costs dropped, allowing fewer factories farther apart. More shelf space permitted greater variety. ‘We cut the cost of trucking in half’, Ralph Drayer, P&G’s former logistics chief, told Gladwell. ‘We cut the cost of storage in half. We cut handling in half, and we cut the cost of the store shelf in half, which is probably the most expensive space in the whole chain’.

In 1987, Huggies got an unexpected boost from a cameo in the Coen Brothers farce Raising Arizona. It starred Nicolas Cage as a convenience store robber who marries Holly Hunter’s police photographer after she takes his mug shot. Needing diapers for the baby they’ve swiped from a family of quintuplets, Cage’s character hits a convenience store, grabbing a huge package of Huggies and waving a pistol (unloaded). ‘Wake up, son!’, he drawls to the young clerk, who looks up from perusing Juggs magazine. ‘I’ll be taking these Huggies and [shrug], uh whatever cash you got’. The filmmakers picked Huggies, Ethan Coen told a journalist, because ‘it sounded funnier than any other brand name’.

Meanwhile, Kimberly-Clark was secretly working on a product that would shock competitors: disposable training pants for toddlers. It wasn’t a new idea, but the execution was tricky, requiring enough side elasticity to allow little hands to pull up their britches without adult help. What Heinrich and Batchelor describe as ‘an innovative synthetic fabric’ was the key. Huggies Pull-Ups Training Pants debuted in 1989, completely blindsiding Procter & Gamble. ‘Huggies Pull-Ups in fact reigned unchallenged for the next three years, capturing 9 percent of the diaper market and generating more than $200 million in annual sales for Kimberly-Clark,’ write Heinrich and Batchelor.[ref 1] In 1992, a smaller competitor, Drypers, finally introduced a rival product.

By this time, disposable diapers had become a nursery necessity, commanding some 95 percent of the diaper market in the United States, Canada, Japan, and most of Europe. (The UK and Netherlands lagged by about a decade.) It was time for a backlash.

In the late 1980s and early 1990s, US environmentalists proposed restrictions on disposable diapers. Florida, Pennsylvania, and Vermont considered outright bans, while bills elsewhere would have exempted only disposables whose materials were biodegradable. New Hampshire’s legislature considered a ten cent tax on every diaper. In California, a 1990 bill supported by the Sierra Club would have required a package label declaring that ‘single-use disposable diapers pose significant environmental problems and costs when disposed. The state of California recommends that you consider reusable diapers for your daily diaper needs’. New York legislators proposed a similarly reproachful label.

None of these laws passed. In part, they failed because their environmental claims were disputed. Research by William Rathje, a University of Arizona archaeologist who spent decades analyzing the contents of landfills, found that disposable diapers made up less than two percent of US trash.

Others pointed to the complexities of measuring environmental harms across the entire diaper lifecycle, which would include water needed for irrigating cotton fields and washing dirty diapers. There were ‘too many ambiguities’ to declare disposables an environmental no-no, said Allen Hershkowitz of the Natural Resources Defense Council, which remained neutral on the issue.

Nonsense, responded green critics. Hershkowitz wasn’t a reliable source, Fred Munson of Greenpeace told the Los Angeles Times. ‘He has a kid and uses disposables’, said Munson, ‘and I personally think he is trying to placate his conscience’.

It was a petty ad hominem, but it contained a truth. Punitive bans, warning labels, and diaper taxes were doomed not because of wonky arguments about landfill contents and lifecycle analysis but because normal people love disposable diapers. Few parents would willingly return to diaper pails and daily loads of diaper laundry. Threaten their Huggies and you’re likely to find yourself out of office.

‘As a mother’, wrote humorist Erma Bombeck in a 1990 syndicated column. ‘I’d rather do away with foam cups and have hot coffee poured into both my hands than do away with disposable diapers’.

Virginia Postrel is a contributing editor and author at Works in Progress.

To overcome these problems, researchers have long experimented with vessels that could transport drugs to their destination while shielding them from the body’s defense system. These include nanoparticles, which are tiny structures made from metals, polymers or lipids that are about a thousandth of the width of a single human hair; liposomes, which are fatty spherical pouches whose walls are made from the same material as cell membranes; and nanobots, hypothetical miniature machines that could perform tasks at the molecular or cellular level.

But all of these face challenges. The liver and spleen intercept a large fraction of nanoparticles before they ever reach the target (though they still show promise for certain breast and lung cancers, as they can more easily permeate blood vessels). Liposomes face a similar problem: macrophages in the liver recognize and engulf most of them on the journey. Working nanobots are still a distant prospect. And most are blocked from reaching the brain. These are some of the barriers that microbubbles may be able to cross.

Boy in the bubble

Microbubbles are just what they sound like: tiny gas-filled bubbles. Scientists have engineered them further, to be coated with a protective outer shell and made capable of carrying drugs or genetic material to cells in the body. They are microscopic, roughly the width of spider silk, but still hundreds or thousands of times larger than nanoparticles or liposomes. This means they’re too large to leave the bloodstream. Instead, microbubbles deliver drugs by bursting on command.

As they burst open, they briefly force open biological barriers that are otherwise impenetrable, such as the blood-brain barrier, allowing treatments to pass through. The force of their bursts can even be the treatment itself, as they could also be used to break apart kidney stones.

Microbubbles were first developed to help radiologists read scans. In the late 1960s, doctors at the University of Rochester were using ultrasound to take pictures of heart structures when they made an accidental discovery. When they injected saline into a vein near the heart, their ultrasound image lit up with a cloud of bright signals. The flashes had been created by tiny air bubbles, formed by the rush of fluid from the injection: sound waves passed through blood and tissue fairly smoothly, but once they encountered gas, the change in density reflected the waves back to the sensor.

That discovery became a standard technique for spotting structural defects in the heart: if bubbles crossed from one chamber to the other on the scan, it indicated a hole. But the bubbles were short-lived and inconsistent in size, so researchers began experimenting with other injectable substances, including blood and medical dyes, to produce stronger, more stable signals. These efforts to engineer reliable contrast agents for ultrasound imaging mark the beginning of what we now call medical microbubbles.

Over the following decades, researchers moved from experimenting with whatever was at hand to deliberately designing microbubbles from scratch, giving them thin shells of lipids, proteins, or polymers to control their size and keep them stable long enough to be clinically useful.

One approach to create a protective shell was to use albumin, which is familiar as the protein in egg whites but is also the most common protein in the bloodstream, where it is used to ferry molecules through the body. Since the body already produces it in large quantities, it doesn’t provoke an immune response and can be used medically. It also has useful structural properties: it unfolds and hardens into a shell sturdy enough to survive circulation, but is brittle enough that it can fall apart when hit by focused sound waves. Albunex, an albumin-coated and air-filled microsphere, was approved by the FDA in the early 1990s for use in cardiac ultrasounds, specifically to make the inner walls of the heart’s left ventricle visible on a scan. Unlike air bubbles, these albumin-coated microbubbles were stable with refrigeration for at least two years.

Researchers also found they could make even sturdier shells through sonication: blasting a protein-rich liquid with high-energy sound waves. The intense energy causes the protein molecules to assemble spontaneously with their water-repelling sides facing inward toward the gas, and their water-loving sides facing out, and as they do, the acoustic energy chemically cross-links them in place, forming a rigid shell. Unfortunately, air inside dissolves readily into the surrounding blood, causing the bubbles to collapse within seconds. Scientists found they could dramatically extend bubble lifetime by replacing the air with heavier, less soluble gases, such as perfluorocarbons and sulfur hexafluoride, which linger inside the shell long enough to be clinically useful. These second-generation microbubbles can persist in the bloodstream for several minutes, and can meaningfully enhance ultrasound images of the heart and liver.

Microbubbles, being bubbles, have many other interesting properties beyond reflecting sound and carrying material: they can expand, contract and burst.

This behavior, known as cavitation, was already familiar to physicists: when a bubble collapses, it generates a brief pressure pulse that can push on surrounding material. Lawrence Crum, a researcher from the University of Washington, had shown this in larger bubbles, but the question was whether the same forces could be harnessed usefully in living tissue.

A group at Stanford found that they could. At lower intensities, cavitation didn’t destroy cells. Instead, it temporarily loosened the walls of blood vessels and punched small, reversible pores in cell membranes, in a process called sonoporation. This opened a new possibility for drug delivery, especially in the brain, where the blood-brain barrier tightly regulates what can enter. Sonoporation offered a way to open that barrier temporarily and locally, letting drugs through without permanently disrupting it.

Bubbles also move with what surrounds them: wind, water, blood. In the bloodstream, that would usually mean being swept along by the current, with no control over where they end up. Scientists from Northwestern hypothesized that by steering the bubbles, they could control the drugs. They eventually cracked it in the early 1980s by attaching magnetic nanoparticles to microbubble shells made of albumin and treating rats with tail tumors by injecting microbubbles into a nearby artery and using a magnet to capture the bubbles at the tumor site.

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A microbubble future

Microbubbles have been used in diagnostics since the 1990s, but haven’t yet been approved for delivering medical treatments. Part of the reason comes down to how they’re tested. Imaging microbubbles, which are already in clinical use, are relatively straightforward to evaluate. Therapeutic bubbles are harder, because their success depends on both whether the bubbles reach their target and whether the treatment they carry actually works. The external ultrasound system adds another layer of complexity, as researchers need to make sure the ultrasound pulses are working correctly and reliably too. Imaging bubbles also had a head start: they were developed first, and built up a safety record in thousands of patients through large multicenter trials in the 1990s, while therapeutic microbubbles are still catching up.

But researchers are exploring their use across a wide range of conditions: dissolving blood clots in stroke patients, delivering chemotherapy directly to tumors, opening the blood-brain barrier for brain cancer treatments, and even targeting genetic material like mRNA to specific tissues.

Microbubbles are different from many other delivery platforms because they can be steered. But some use cases are more promising than others: treatments where the target is physically accessible, such as a tumor with a clear boundary or a clot in a vessel, are better suited to microbubbles than diffuse conditions where the problem is spread across many tissues.

Brain cancer is likely one promising area: microbubbles can open the blood-brain barrier and early trials in glioblastoma patients have shown the approach is feasible with manageable side effects such as passing headaches. In one small pilot trial, the cavitation effect from bursting bubbles was used to oxygenate tumors, which are otherwise harder to treat with radiation.

Pancreatic cancer is another: in a small 2016 pilot trial, patients treated with microbubble-delivered gemcitabine survived on average eight months longer than the control group, and tolerated more treatment cycles. These are small trials, and results like these need to be replicated at scale.

The same idea is likely to extend beyond cancer. To treat ischemic strokes, doctors currently deliver a clot-dissolving protein called tPA intravenously, but because it circulates through the whole body, it also interferes with healthy clotting elsewhere. Microbubbles could release tPA directly at the clot site, avoiding that tradeoff. Similarly, they also offer a way to deliver chemotherapy drugs like doxorubicin and gemcitabine directly to tumors, sparing the heart, liver, and bone marrow from the damage that comes with high systemic doses. And for mRNA therapies, including vaccines like those developed against Covid-19, current delivery systems distribute the vaccines across many tissues, wasting much of it.

Kidney stones are another option, as a physical object that could be broken apart with microbubbles. Researchers have proposed equipping microbubbles with chemical tags that bind specifically to the mineral in most kidney stones, then triggering cavitation with an ultrasound pulse to burst them from inside. Focused ultrasound devices for kidney stones have already received FDA clearance, which suggests regulators are comfortable with the broader approach.

Most drug delivery is systemic: drugs circulate through the entire body, and only a fraction reaches the intended site; the rest is either wasted or can cause off-target side effects. Microbubbles, on the other hand, could carry a therapy through the bloodstream and release it precisely where it’s needed, guided by an external ultrasound pulse. It turns out that to solve some of medicine’s unsolved problems, you sometimes need to think very, very small, and then burst through.

Ambika Grover is an undergraduate at Harvard University.

The Ogallala Aquifer sits under eight states and 111.8 million acres of US farmland. A windmill can lift only a few gallons per minute, useful for drinking water but useless for agricultural purposes. In the 1940s, electrification reached the Great Plains and a Colorado farmer invented center pivot irrigation, a sprinkler line on wheels that rotated around a central wellhead. The 1949 version could lift thousands of gallons per minute and irrigate 40 acres.

Since then the aquifer has lost 286.4 million acre-feet of water, comparable to draining Lake Erie entirely. The parts of it beneath arid states have seen much bigger drops. Large parts of Western Kansas have lost 50 percent of their aquifer depth. Texan wells are down as much as 265 feet. On current trajectories, the water there will be gone in 20–30 years.

Before center pivot irrigation, everyone could use as much of the Ogallala Aquifer as they were physically able to extract without any risk of depletion. An incredible invention created a tragedy of the commons. The southern Great Plains will have to ration water use by some mechanism, probably water charges, or face the total end of irrigated farming.

This is only one example of a common historical story. Fish catch sizes were limited until radar, sonar, and diesel engines; the North Sea Cod population collapsed a few decades after their invention. The telegraph led to the extinction of the passenger pigeon by letting hunters easily communicate about the whereabouts of the flocks. Chlorofluorocarbons almost killed the ozone layer. Technologies can collide with common-pool resources and drive them into extreme scarcity.

The Roadgallala aquifer

This is about to happen again. Road transport, especially the private car, is the dominant mode of transport in every country around the world. None of these countries charge at the point of use for the bulk of their road networks. When traffic gets slow enough – ten miles per hour in Tokyo and eight in Paris – people switch to other modes of transport because they can’t do much else when they are stuck behind the wheel.

This constraint is about to be lifted. Self-driving cars are not a hypothetical future but a familiar part of the urban background in San Francisco. I have driven in them several times and the novelty of seeing a steering wheel turn itself has pretty much worn off. During 2026, Waymo service will expand to Dallas, Houston, San Antonio, Orlando, and Miami, joining Atlanta, Austin, Los Angeles, San Francisco, and Phoenix.

Right now, self driving is a premium experience, more expensive than a human driver, in part because Waymo uses new cars, and in part because there are still relatively few Waymos on the road, spreading operational overheads thickly on a small fleet. Over time, Waymo and its competitors will become cheaper than human-driven taxis.

You make driving fun

Self-driving cars need not look like traditional cars inside. Normal cars are heavy and bulky, in large part due to safety requirements. Despite sharing the road with human drivers, Waymos already have 80 percent fewer accidents. When self-driving cars become 90 percent of the cars on the road, they will be able to platoon and join up into little trains, saving the space usually spent on gaps between vehicles and doubling road capacities.

They can be more comfortable as well. The Volkswagen GEN.TRAVEL has seats that fold out into flat beds, with passenger restraints for safe sleeping while moving and lighting designed to generate natural circadian rhythms. The Volvo 360c offers a first-class private cabin with a classic Volvo touch: a special safety blanket that acts like a seatbelt, usually loose and comfortable but tightening instantly on impact. In theory it can be an entertainment space or a mobile office too. Simpler, working versions of this idea, like the Amazon Zoox, are already driving around Las Vegas and San Francisco.

With imagination, you can see how a wide range of functions could be performed in a car: working, sleeping, eating, and even socializing, effectively bringing back the bar cars once enjoyed by New York commuters to Connecticut. I already buy cans of beer for long train rides with my friends. Train lines created entirely new seaside resorts like Atlantic City in the US, and Heringsdorf, Ahlbeck, and Bansin in Germany. Just imagine the trips people would make with the ability to effectively travel business class in their cars, driving overnight.

Our gridlocked future

Autonomous vehicles are the centrifugal water pump of the roads. Just like the Ogalalla Aquifer, most roads are currently free at the point of use. And just like the Ogalalla Aquifer, they will be overused if we do not charge for the privilege of drawing on them. Anyone who needs to get where they’re going quickly will be stuck in traffic with all the people enjoying a beer, working from a mobile office, or having a nap. There will be total gridlock.

Though taxes on fuel and registering cars are universal across the developed world, imposing charges at the point of use has been trickier. It took New York City 60 years to impose congestion pricing, and it was almost revoked several times along the way. London’s congestion charge has survived, but attempts to extend it out of the very inner core have not. Dutch voters destroyed per-mile charges, the Kilometerheffing, in 2010. Hong Kongers rejected such a scheme in the 1980s, despite an effective trial.

These attempts failed for a range of reasons. But a major one is that they aimed to change the rules of the game for everyone at the same time, creating a lot of people who lost out under the policy while giving them nothing in exchange.

Tax doesn’t have to be taxing

There are two tricks to making new levies politically durable. First, a quid pro quo: drivers are much happier to pay if they get something in exchange, usually infrastructure. Second, grandfathering: drivers don’t like the price of anything they have already accounted for, including road access, to change, but they don’t mind high prices on new things. Fuel taxes are an example of a quid pro quo: in most developed countries, they entirely cover the cost of road construction and maintenance. Tolls, which are usually charged on new tunnels, roads, lanes, or bridges, are an example of both.

The Harris County Toll Road Authority, created by referendum in 1983 to fund the construction of two new roads, now manages 128 miles of roads around Houston, Texas. Voters have continually opted to expand it. Forty-three percent of the lanes added to California highways between 2018 and 2023 have restricted access, whether by requiring vehicles to carry multiple passengers or charging a toll.

Nearly all of France’s motorway system was funded by tolls, as are Japan’s and Austria’s. Voters accept these charges because they both generate a quid pro quo, new infrastructure in exchange for new money, and they keep old infrastructure free.

Voters will even tolerate variably priced toll lanes. Colorado added dynamic tolling, calculated by an algorithm to balance supply and demand, to a congested stretch of a major highway. The state’s Department of Transportation says that throughput there has gone up by 20 percent. The I-4 near Orlando has two express lanes that run for 21 miles. They range from $0.50 to $3.00 per three-mile segment. Cars on these segments go eight miles per hour faster than on the regular lanes during the evening peak. These Lexus Lanes have faced grumbling, but no serious opposition.

One simple trick to make road pricing popular

Grandfathering can work not just by location – new bridge, new tax; old network, no tax – but by vehicle type, if that new vehicle type is not currently being used by most drivers and voters. This is exactly what the UK government did in late 2025, despite being one of the country’s most unpopular governments ever, by imposing a charge of £0.03 per mile on electric vehicles. The new charge was possible because only 5.2 percent of the market is electric.

This shows the path for other countries: imposing a charge that falls only on autonomous vehicles. Since current drivers will not face any unexpected charges, they will tolerate the new tax. If governments want to charge the tax at a high rate, they should give autonomous vehicle owners and users something in return, most likely new road infrastructure. This needs to happen now. When AVs are dominant, users will balk at a big change.

If governments follow these rules, they can charge variable surge prices in busier locations and at busier times, clearing the market so roads flow, as surge pricing already does for Ubers and Lyfts, and as variable pricing does on Singaporean expressways. And if they wish, governments can dispense with gantries and numberplate cameras and use location trackers. Voters are comfortable with location tracking that they opt for themselves, as in ride shares or many of their apps.

If we continue to treat our roads as a common-pool resource, we will drain them like the Ogallala Aquifer. The good news is that if we act quickly, before autonomous vehicles become dominant, we can prevent this surprisingly easily.

Ben Southwood is an editor at Works in Progress.

By late January 1945, the end of World War II finally seemed in sight. American business leaders began thinking about introducing products delayed by the war. The most anticipated was nylon stockings, which debuted in 1939 only to have the new fiber diverted to military applications. Another was television, which had entranced visitors at the 1939 World’s Fair. But the new medium was a much tougher sell than high-tech hosiery.

‘Television presents a vicious triangle’, JJ Nance, a Zenith Radio Corp executive explained to Wall Street analysts. Television shows were far more expensive to make than radio programs. Producers needed advertising revenue to cover the costs. But advertisers demanded large audiences. ‘We can’t get a mass audience’, Nance said, ‘until we have provided the American peo­ple with assured continuous entertainment, pleasing enough to stimulate the buying of receivers by the million’. Hence the vicious triangle: attracting viewers required programs, which required advertising, which required viewers...

It’s a dilemma every new technology platform faces – only more so. To catch on, television needed to sell hardware, create content, and find revenue. Few contemporary platforms have to do all three. Most build on an installed base of hardware. Social media gets its content free from users. In theory, TV might have paid for programming with a license fee on sets, like the tax that still funds the BBC. But Americans, accustomed to free, ad-supported radio programming over public airwaves, fiercely resisted any such suggestion.

Yet just a decade after Nance’s speech, two thirds of American homes had a TV set, including 78 percent of those in cities. As early as 1948, public housing officials were already debating whether tenants in subsidized apartments should be allowed sets and antennas. Television was one of the most quickly adopted technologies in history.

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To escape the vicious triangle, broadcasters exploited ready-made productions, complete with their own stages, fan bases, and well-established stars: sports. Showcasing athletic competition was the new medium’s killer app. ‘For the next few years, at least, sports coverage will be far and away the most important single element in television programming’, the sports manager for Chicago’s WGN station wrote in 1948. ‘It’s a safe bet that up to 50 per cent of television hours, both live shows and films, will be in the field of athletics’.

The postwar rematch between heavyweight boxers Joe Louis and Billy Conn in June 1946 was an early success. Broadcast from New York’s Yankee Stadium, the fight reached north to Connecticut and south to Washington, DC. Fans ‘saw everything that went on in that 24-foot square, and they saw it in much better detail than most of the 45,266 persons who paid their way’, enthused a New Jersey sports reporter, putting the TV audience at about 100,000. ‘You could hear the roar of the crowd; the count of the referee; the ring of the bell’, he wrote. A Brooklyn bar owner who crammed in 150 fans to watch his television said he’d turned away at least 500 more.

Bars were critical to television’s early success. ‘More people see television sets in bars than would ordinarily see them in showrooms’, said the director of a Chicago station. ‘The bars are helping sell sets to private homes’. Although some bartenders complained that sports fans contented themselves with a single beer rather than multiple cocktails, most reported that television brought in more customers, ultimately raising sales. Sometimes a bar would place a large magnifying glass in front of the screen to make the broadcast more visible at a distance.

TV’s early appeal can strain the twenty-first-century imagination. Broadcasts were in blurry black and white, with pictures plagued by shadows, snow, and jitters. Screens were tiny, typically about 52 square inches, and a basic set cost around $325 (about $4,400 in today’s dollars). An exceptionally well-capitalized bar might splurge on the UST Tavern Tele-Symphonic, featuring a 25” x 19” screen, at a cost of $1,995, or nearly $30,000 today. But those were rare luxuries.

With their one-on-one action and limited ring size, boxing and wrestling were well suited to the small screen. New wrestling fans, particularly women, were a common trope in newspaper reports. ‘A lot of frail women are enjoying the sight of Danny MacShane cracking a man’s head into a steel post and having his head cracked in turn’, observed a sports columnist. Wrestling might or might not be a sport, but it was definitely entertainment.

Amid widespread fears of ‘juvenile delinquency’, television promised to keep kids out of trouble. ‘There’s no juvenile delinquency here’, proclaimed an ad for TV sets, portraying a family seated around their living room console. The tavern connection contradicted that wholesome image. Minors weren’t supposed to enter bars, but young sports fans often peered in the windows.

In response, churches, Boys Clubs, youth centers, and YMCAs began buying their own sets. On a summer evening in 1948, a Methodist church outside Philadelphia attracted a crowd of 125, mostly teenagers, to watch a baseball game between the Philadelphia Phillies and the Cincinnati Reds. Pastors around the country reported that TV was drawing in the kids. ‘Our church set is used primarily for hockey games, prize fights, and other sports events’, said a Presbyterian minister in Chicago. ‘We’re sorry we didn’t think of it before’.

Sports were so perfect for television that many feared the new medium would devastate ticket sales. ‘It’s inevitable that sports attendance will crash to a national calamity’, declared a columnist, reporting that boxing authorities in the nation’s capital were lobbying for legislation requiring broadcasters to cover match expenses. Football coach Rip Engle, then at Brown University and soon to move to Penn State, foresaw a shakeout. ‘I won’t be surprised if there are only ten college football teams left in a few years’, he said in 1949. ‘That’s what’s going to happen if games involving the big schools are widely televised’. Others predicted the death of minor league baseball. Why turn out for the local farm team when the big leagues were on TV?

Nonsense, said optimists. Veteran sports columnist Ed Danforth cited history and initial results. Baseball owners were always against change. ‘Look how they resisted the avalanche of money night baseball brought them’, he wrote. He ticked off the televised events of 1947 – the World Series, the Notre Dame–Army football game, the Joe Louis–Jersey Joe Walcott fight, the Sugar Bowl featuring the University of Georgia’s undefeated football team – and noted that they all set attendance records. ‘Big events played to capacity, whether they were televised or not’, he wrote. Television was ‘publicity for these sports and publicity that was PAID for at the source’. Television, he predicted, would only increase the popularity of sports.

Eight decades later it’s safe to say he was right. In 2024, US sports events attracted a staggering 292 million in-person fans, reports sports-marketing firm Two Circles. Far from shrinking to a handful of teams, college football games endure as a major cultural experience, and sell the most tickets of any US sport. At the same time, sports continue to support television in its many forms. Whether viewed on an enormous flat screen or a palm-sized phone, sports offer a compelling form of visual entertainment, with real stakes and unknown outcomes. And they still draw fans to bars.

Virginia Postrel is a contributing editor and author at Works in Progress.

When How Asia Works appeared in 2013, the prevailing mood was one of considerable optimism. China seemed a triumph of economic development. Between 1990 and 2013, China averaged a real annual growth rate of ten percent. It added almost half a billion urban residents and quintupled its manufacturing output. And other Asian economies were moving along comparable trajectories, if less spectacularly. Growth in India and parts of sub-Saharan Africa lent further weight to the idea that the developing world was at last catching up.

How Asia Works was Studwell’s theory of what drove this growth: land reform, export discipline, and states willing to impose hard constraints on capital. Beneath Studwell’s specific prescriptions lay a bolder claim: that countries were not condemned by geography, history, or culture to particular economic outcome, and a relatively small number of well-chosen policies could make an enormous difference. Tyler Cowen called it the best treatment of Asian industrial policy available. Noah Smith named it his favorite book on development. Bill Gates made the agriculture team at his foundation read it.

But a decade on, China’s growth has decelerated from over ten percent per year to around five. The rest of East Asia has settled into the one-to-three-percent range typical of mature economies. South and Southeast Asia continue to grow, but less spectacularly. And Africa, which once seemed poised to follow the same path, has not grown at all in per capita terms. Against this backdrop comes Studwell’s sequel, How Africa Works.

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Against Afro-pessimism

How Africa Works opens with an account of the continent’s historical constraints. Studwell responds to what can be called the Afro-pessimist view: that postcolonial Africa was at least as wealthy as East Asia at independence, and that the subsequent divergence was a story of misgovernment. This widely held position, he argues, is premised on a mistaken reading of the limited quantitative evidence, driven by mismeasurement and temporary commodity booms at the moment national accounts were first assembled. The supposedly high incomes per person in Africa don’t match, for example, with the fact that life expectancy was two years lower than in South Asia and between 6 and 20 years lower than the level of countries in East and Southeast Asia.

What Africa inherited at independence was considerably worse than what most other regions had to work with. Population densities were less than 25 percent of those in East and South Asia, driven by limited arable land, disease burdens, the enslavement and export of 12.5 million people, and even the abundance of crop-destroying elephants. This blunted incentives to build states capable of projecting authority over territory.

Colonial and postcolonial land policy concentrated wealth among large holders rather than diffusing it broadly. Ethnic and linguistic fragmentation locked post-independence politics into patronage networks. And on top of all that, Africa entered sovereignty as the world’s least educated region. Africans who attended school did so for half as much time as South Asians, the second least educated population in the world. Out of a population of 15 million, what is now the Democratic Republic of Congo had just 30 university graduates when Belgium departed in 1960.

But Studwell thinks that the essential preconditions for growth – literacy, governance, and especially population density – are gradually falling into place across much of Africa. Today, Africa is about where east Asia was in the 1960s and. What is needed, according to Studwell, is the disciplined application of the three-part model that already worked in Asia: redistributing agricultural land to smallholders, who farm more intensively and whose rising incomes create domestic demand; channeling state support toward manufacturers that must compete in international markets, rather than sheltering them behind tariffs indefinitely; and directing credit toward investment by suppressing consumption.

Studwell illustrates the argument with four African cases: Mauritius, Rwanda, Botswana, and Ethiopia, countries that have either begun this process, or, in the case of Mauritius, more or less finished it.

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The Asian model in Africa

The usefulness of the Asian model in Africa seems to hold up best for agriculture. Across the continent, governments often subsidized large farmers who were not necessarily more productive. In Ghana, for example, the Savannah Zone Agricultural Productivity Improvement Project was meant to benefit smallholders in the region, but only farmers with over 40 hectares and a tractor were eligible for subsidies.

Consolidation resulted in much more land held at medium-scale by urban elites, rather than by smallholders who had scaled up through accumulated expertise. But these farms weren’t necessarily more productive. Among medium-scale farmers in Zambia, only 11 percent of such farms were cultivated, compared to 91 percent of smallholder land.

When smallholder farmers did receive tenure security, training, and market access, they achieved remarkable successes. In Ethiopia, crop production more than doubled between 2004 and 2014, for example, and continued to grow during periods of crisis afterwards. Extreme poverty fell by over 25 percentage points between 2000 and 2015.

Beyond agriculture, the link between the East Asian model and Africa’s successes is harder to trace. Botswana is one of the richest countries in Africa, but didn’t start that way. It managed its diamond wealth with unusual discipline, by partnering with an experienced foreign firm, De Beers, on favorable terms, building reserves, investing in education and infrastructure, and maintaining a frugal bureaucracy. In negotiating with De Beers, the government was able to secure two thirds of the profits of diamond extraction. The returns were remarkable, as life expectancy rose from 48 to 65 in barely twenty-five years.

These are impressive achievements, especially given the country’s poor starting position. But Botswana neither supported smallholder agriculture nor created a manufacturing base. It devalued its currency to help beef exporters, not to spur industry. The government preferentially leased grazing land and directed subsidies to large farms. The result was a rapid concentration of livestock ownership: by the 1990s, five percent of the population owned half of all cattle, and nearly half of rural households owned none. Manufacturing subsidies were tied to headcount rather than exports, in a system that rewarded loyalty more than efficiency. It is telling that Studwell himself describes the country as a ‘gatekeeping state’ that managed wealth without knowing how to grow it.

Rwanda fits awkwardly too. It adopted something of the rhetoric of the Singaporean developmental state, attracted substantial foreign aid, and made itself, by the standards of the region, relatively easy to do business in. But with energy costs roughly five times those of neighboring Ethiopia, and a remote, landlocked position that gives access only to an extremely impoverished regional market, most of the resulting growth has come through tourism and services rather than manufacturing.

Mauritius comes closer to validating the model, given that it actually pursued export-oriented manufacturing and achieved real industrialization. But it did so at an early stage of development, as a small island economy. It never progressed far beyond basic manufacturing, pivoting instead to tourism and offshore finance, which happen to be precisely the sectors that Studwell, in How Asia Works, is most dismissive of.

The most compelling case, however, is Ethiopia. In 1991 it was by many reckonings the poorest country in the world. Under Meles Zenawi, the government consciously modeled its approach on the East Asian experience: devaluing the currency to support manufacturing, directing resources toward smallholders, channeling development finance into productive investment, and building, with some success, an administration oriented around growth rather than corruption.

In agriculture, the government expanded fertilizer distribution almost a thousandfold between 1995 and 1999. While droughts historically led to famines with death tolls in the hundreds of thousands, increased food reserves all but eradicated this concern.

But even in Ethiopia, the manufacturing story is thin. While massive industrial projects, including one of the largest dams in the world, reduced Ethiopia’s electricity cost to among the lowest on the continent, the results are limited. The successes he highlights are in low-value-added sectors like cement. Whether one looks at manufacturing as a share of output or at manufacturing value added per capita, there is little evidence that any large African country is genuinely following the East Asian path. The highest rate of manufacturing as a share of output for any African country with a population in excess of 10 million is Zimbabwe at 16 percent, compared with China’s 25 percent with 80 times the population.

‘It is likely that manufacturing – or its absence – will be the single biggest divider between African economic success stories and the nations that are left behind,’ Studwell writes at the end of chapter nine. But he spends remarkably little time in the book interrogating the extent to which that manufacturing growth is actually happening.

New headwinds to export-oriented manufacturing

Studwell contends that export-oriented manufacturing is the fastest route to broad-based growth, as it allows countries to build capacity on a scale that domestic demand could never absorb. Poor countries have an enormous pool of cheap labour, and that advantage can offset the productivity gaps, infrastructural deficiencies, and institutional weaknesses that would otherwise make competition with technologically advanced and better capitalized rivals impossible. This process tends to begin in the simplest industries. But expertise in one area of production generates spillovers into related ones, and the act of making simple goods builds the capabilities required to attempt more complex ones.

Even if Studwell’s view was once true, manufacturing-led growth has empirically become much harder. The evidence for this is visible in what economists have called premature deindustrialization, the phenomenon whereby poor countries are beginning to deindustrialize at substantially lower levels of manufacturing output, and substantially lower per capita incomes, than the West and other mature economies did.

If Studwell is right, African countries must now do to China what China did to the United States, Japan, and Europe. It is not obvious that the conditions for this are in place. While labor costs in Africa are between a half and a tenth of Chinese levels, this is far smaller than the fiftyfold difference between Chinese and American wages in 2000. All this must happen in competition with a country that has, by most measures, among the best logistics infrastructure in the world, very high labor productivity, and an industrial ecosystem without parallel.

China remains by far the world’s largest textile exporter, comparable to its position in 2008, even as it has become the largest exporter of smartphones, semiconductors, and electric motors and batteries. Even where countries like Bangladesh have found niches, they have often struggled to move into more complex manufacturing the way the East Asian countries once did.

Nor is China the only headwind. The pace of globalization has slowed, and poor countries may not be able to compete on labor costs alone, as manufacturing now generates far fewer jobs per unit of output than it did in the 1960s. Automation is eroding the advantages that cheap labor once conferred. In America, manufacturing output roughly quintupled between 1960 and 2015, while employment fell by nearly a third. The implication is that wage competition may no longer provide the foothold it once did.

Several of these difficulties may be reinforcing one another, and addressing them would require a degree of generosity from wealthy countries that is not obviously forthcoming. The current American posture – sweeping tariffs and sharp cuts to foreign aid – is closer to the inverse of what the East Asian model would seem to require than to anything that might help it along.

The wrong kind of development

Africa’s starting endowment was uniquely difficult. Studwell’s considerable achievement is to show that this need not be fatal: that a state genuinely focused on development can exist in the African context, and that the obstacles, formidable as they are, are not insuperable.

But the development he charts is rarely of the kind he wants. He is dismissive of the services-led growth that Rwanda has pursued, insisting that countries need to focus singularly on manufacturing, without recognizing that the path may be much harder than before. While countries continue to deindustrialize earlier than before, services offer viable, if unspectacular, alternatives, and India’s experience suggests that a services-oriented economy can sustain growth well above the African average, even if well below China’s.

The book is most persuasive as a historical and agricultural diagnosis.The account of colonial land policy, resource extraction, and patronage politics is careful, and the case for smallholder agriculture is the strongest thing in it. But the manufacturing argument is much thinner. Studwell never quite confronts the possibility that the East Asian path is considerably more difficult to follow today than when it was first travelled. That the honest answer to his book’s central question may be that nobody knows is not a failure of the argument so much as a reflection of the moment. But a book more willing to acknowledge this would have served its subject better.

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Saarthak Gupta is an analyst and quantitative researcher.

I recently published a long piece on urban government in the nineteenth century. I have always been interested in nineteenth-century architecture and urbanism, but I wanted to get into the details. I knew the Victorians built gigantic cities very quickly, and that the resulting urbanism was usually a lot better than what we have managed since 1945. But I wanted to study the institutional mechanics behind this. How were the streets planned? Who paid for the pumping stations? Who operated the trams?

Doing so has affected my opinions quite a lot. Here are a few examples:

1. It made me more pro-planning

Living in 2020s Britain, it is easy to become sceptical about planning. Our planning system enormously constricts housing supply, impoverishing the country. The housing and industrial buildings that do get built are often distributed around the country according to political imperatives rather than economic logic. It is natural to think that some sort of Hayekian emergent order would be preferable.

In the nineteenth century, however, we see planning performing its true function, solving the collective action problems inherent in urban life. Planned street networks turn out to be straightforwardly better than unplanned ones: the most planned street networks of the nineteenth century are some of the most successful systems in the history of the world. Urban transit systems also manifestly work better when they are planned by a single authority, and most nineteenth-century governments unified transit ownership accordingly (of which more below).

There is also the interesting fact that most nineteenth-century people voluntarily paid premiums to live in ‘covenanted’ neighbourhoods, which had forms of private-sector development control. This shows that they valued protection from disruptive development by their neighbours more than they valued the development rights foregone thereby.

Covenanting wasn’t very effective, but its prevalence reveals that there was genuine and broad demand for development control before the state started providing it. That doesn’t necessarily mean that such development control was morally good – maximising economic value need not realise the morally best outcome. Nor does it mean that the degree of development control we have today is value-maximising, even in the narrow economic sense. But it does mean that some level of development control has genuine popular support, and is not an extraneous state imposition.

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2. It made me care less about public or private ownership

I was aware that a lot of nineteenth-century infrastructure was built by private companies, and also that the Victorians were great infrastructure builders. In Britain, Parliament famously granted compulsory purchase powers for 9,500 miles of railways in 1846, 67 times longer than the catastrophic HS2 railway it is trying to build today. In America, most cities had superb public transport in the nineteenth century, actually much better than they do now. This suggested to me that private ownership worked a lot better than public ownership has.

Closer inspection reveals that the public/private distinction was not as important as I thought. Some nineteenth-century infrastructure was owned by private companies, but other infrastructure was owned by municipalities. Intracity transport and utilities in Germany were normally owned by municipal companies called Stadtwerke, and by the early twentieth century this was increasingly true in England too; in France they were also owned by the state, though operated by private concessionaires. There is no clear evidence that these systems were worse than the private franchises that predominated in the USA, and indeed the German Stadtwerke were often seen as world-leading.

The real differences seem to be elsewhere. Nineteenth-century urban infrastructure was funded almost entirely by user fees, not subsidies. It was far less price-controlled than modern infrastructure, so it was generally profitable to supply, and suppliers raced to meet rising demand. If they were particularly incompetent, they went bankrupt. This was true even if they were municipalities: if a city went bankrupt in the nineteenth-century, that was its problem, not the national government’s. These features generated a set of benign incentives that were surprisingly similar across both the public and private sectors, leading both to operate infrastructure fairly efficiently.

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3. It made me more interested in monopolies

We are all familiar with the idea that monopolies are bad, and no doubt they have some serious disadvantages. Because monopolies are not under competitive pressure, their incentives to be efficient are weaker, and because they almost never go bankrupt, they are not subject to selection effects. They may also have opportunities to exploit their market position to charge higher prices than is socially optimal.

Interestingly, however, the hugely successful urban infrastructure of the nineteenth century was nearly all operated by monopolies. A given city would usually have a single company operating its trams, another one operating its gas, another its water, and so on. Governments encouraged and sometimes explicitly required this. One justification for this was that infrastructure has so many positive spillover effects that monopolistic pricing was in fact efficient in this case: you want infrastructure to be more profitable to supply than it is in a competitive market, because it is just so good to have more of it. Another justification was that it led to a better coordinated network, rather than the chaotic duplication that occurred in competitive markets.

Some countries even found ways of partly replicating the pro-efficiency incentives and selection effects of competitive pressure. Under the French concession system, virtually all urban infrastructure was owned by the municipalities but operated by private companies. Municipalities awarded time-limited concessions to whichever company offered the best deal. This clever system, which still exists today, got many of the advantages of competition while preserving the advantages of infrastructure monopolization.

Samuel Hughes is an editor at Works in Progress. Follow him on Twitter.

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The problem with buses is that they are slow. For example, buses in New York City and San Francisco crawl along at a paltry eight miles per hour, only about double walking speeds in the fastest countries. There are lots of ways to speed up buses, including bus lanes and busways, congestion pricing, transit-priority signals, and all-door boarding. But one of the most powerful solutions requires no new infrastructure or controversial charges and has minimal cost: optimizing where buses stop.

Buses in some cities, particularly those in the US, stop far more frequently than those in continental Europe. Frequent stopping makes service slower, less reliable, and more expensive to operate. This makes buses less competitive with other modes, reducing ridership. This is why, despite having fewer bus stops, European buses have a higher share of total trips than American ones.

Bus stop balancing involves strategically increasing the distance between stops from 700–800 feet (roughly 210–240 meters; there are 3.2 feet in a meter), common in older American cities or in London, to 1,300 feet, closer to the typical spacing in Western Europe, such as in Hanover, Germany. Unlike many transit improvements, stop balancing can be implemented quickly, cheaply, and independently by transit agencies. By removing signs and updating schedules, transit agencies can deliver faster service, better reliability, and more service with the same resources.

American bus stops are too close together, driving low bus ridership

American bus stops are often significantly closer together than European ones. The mean stop spacing in the United States is around 313 meters, which is about five stops per mile. However, in older, larger American cities, stops are placed even closer. In Chicago, Philadelphia, and San Francisco, the mean spacing drops down to 223 meters, 214 meters, and 248 meters respectively, meaning as many as eight stops per mile. By contrast, in Europe it’s more common to see spacings of 300 to 450 meters, roughly four stops per mile. An additional 500 feet takes between 1.5 and 2.5 minutes to walk at the average pace of 2.5 to 4 miles per hour.

Frequent stopping is part of a strategy that maximizes coverage – giving everyone some access to the bus – even at the expense of overall ridership, which is largely a function of how useful the bus is relative to other transport options. In England, where 28 percent of all bus passengers are on concessionary fares for age or disability, Prime Minister Margaret Thatcher is supposed to have said, ‘If a man finds himself a passenger on a bus having attained the age of 26, he can count himself a failure in life’. This pattern, of only those without good alternative options riding the bus, is especially pronounced in the US. But close stop spacing creates problems.

Close stop spacing slows buses down. When a bus stops, it loses time as passengers get on and off the bus (dwell time). The bus also needs to decelerate and accelerate; it may need to kneel (hydraulically lower itself to the floor and back up again to let strollers, wheelchairs, and mobility vehicles on); it may need to leave traffic and return into traffic; and it may miss a light cycle (non-dwell time). Buses spend about 20 percent of their time stopping then starting again.

Slow buses make transit less competitive with driving and reduce the number of places riders can get to in a given amount of time, making the network less useful.

Labor is transit agencies’ largest cost. For example, close to 70 percent of the 2026 operating budget of Washington DC’s transit system will go toward labor and associated fringe benefits and overhead. Drivers are paid by the hour. Thus, slow buses increase the cost of running services, reducing the amount of service that agencies can run.

Close stop spacing also creates lower quality bus stops. In the US, the sheer number of bus stops means that agencies can’t invest meaningfully in each one. This results in many stops being ‘little more than a pole with a sign’, lacking basic amenities like shelters, benches, or real-time arrival information. Uneven and cracked sidewalks and a lack of shelter or seating present a particular challenge for elderly and disabled riders.

By contrast, a bus stop in a French city like Marseille will have shelters and seating by default. Higher quality stops in the city also include real time arrival information, better lighting for safety, level boarding platforms, curb extensions that prevent illegal parking at bus stops, and improved pedestrian infrastructure leading to the stops. Marseille is not a particularly wealthy French city, but because it has wider stop spacing and fewer stops, it can invest more money into each one.

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Stop balancing addresses these issues and more

Many of the solutions to these problems require money – running more buses, improving stop amenities, or upgrading signals – or the political will to take away street space for busways and transit lanes. But stop balancing can have a meaningful impact on these issues for a fraction of the price.

Bus stop balancing saves riders’ time. Riders save between 12 and 24 seconds per stop removed. San Francisco saw a 4.4 to 14 percent increase in travel speeds (depending on the trip) by decreasing spacing from six stops per mile to two and a half. Vancouver’s transit operator ran a stop-balancing pilot that removed a quarter of stops and saved passengers five minutes on average and ten minutes on the busiest trips. Portland saw a six percent increase in bus speeds from a project which increased average stop spacing by just 90 feet.

Limited stop services – aggressive forms of stop consolidation, effectively express buses – can see even more impressive savings. Los Angeles saw operating speeds increase by 29 percent and ridership by 33 percent on its Wilshire/Whittier Metro Rapid corridor. Washington DC pursued a limited stop service on its Georgia Avenue Line that increased speeds by 22 percent in the base and 26 percent in the peak. Colombia’s Bus Rapid Transit, based on this idea, is famous worldwide.

Because stop balancing speeds up buses it can actually increase the access of the transit network.

Access may be thought of in terms of the number of access points to the system, for example the number of bus stops or metro stations. But planners also think about access in terms of where the system can take you. This idea can be visualized as isochrones – shape maps that show the distance one can travel in a set time. By speeding buses up, stop balancing actually increases the number of destinations reachable within a given timeframe.

Stop balancing need not even reduce the number of access points much. Many North American bus stops have overlapping ‘walksheds’ (the areas within walkable distance of them) and are competing with each other. The combination of many stops and a street grid means that many riders have two or more stops that they can use, so that closing one only requires a marginally longer walk to the next.

A McGill study found that even substantial stop consolidation only reduced system coverage by one percent. A different study modeled a stop balancing proposal for San Luis Obispo, and found that even a 44 percent reduction in stops would have only a 13 percent reduction in coverage area. New York’s transit authority increased the distance between stops on a local route from ten to seven stops per mile (a 42 percent increase in distance between stops) but estimated that the average walking distance went up by only 12 percent.

Buses that move more quickly can traverse their routes more times per day. That means that achieving the same frequency requires fewer drivers as the speed of the journey goes up. Because labor is the largest expense of running a service, faster buses are cheaper to run.

You can determine the peak number of vehicles (and therefore the number of operators on a route) by dividing the time needed for a full round trip (including the layover) by the desired interval between every bus.

Layover varies by operating company but is usually a fifth of round trip travel time, subject to a minimum for short routes (something like ten minutes).

In Vancouver, stop balancing on one route saved the transit operator $700,000 CAD (about $500,000) in annual operating costs owing to peak vehicle savings. They estimate they will save a further $3.5 million each year by cutting stops across their 25 most frequent routes. In the study from McGill on Montreal’s operator, stop balancing had the potential to ‘save a bus’ (reduce the total buses needed each day by one) on 44 routes.

These savings can be reinvested to improve service frequency on those routes or elsewhere in the system. Or they can prevent a bus service from having to reduce frequency when facing budget cuts.

Beyond speed, stop balancing improves reliability. Each potential stopping point introduces uncertainty. When stops are closer together, this uncertainty multiplies by spreading passengers out between locations, making it difficult for agencies to provide accurate schedules.

Vancouver found that stop balancing improved the reliability of Line 2, especially on the slowest trips. This helps passengers plan their journeys and agencies maintain more accurate schedules, reducing the need for excess recovery time at the end of routes. If agencies want to maximize the benefit of stop balancing on reliability, they can incorporate passenger boarding variability into their stop consolidation program, as McGill University did in their proposal for Montreal’s Bus Network.

For passengers, improved reliability may be even more valuable than speed. Studies show that waiting time feels two to three times longer to passengers than in-vehicle time, and unpredictable waits feel longer still. By making bus arrival times more predictable, stop balancing directly addresses one of the most frustrating aspects of bus travel. Operators tend to favor these changes as well, describing stop balancing as helpful for staying on schedule.

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With fewer stops per mile, European agencies can create high-quality waiting environments that are prominently displayed on transit maps similar to rail stations. This enhances the visibility and permanence of the bus network, potentially supporting development along transit corridors. With stop balancing, North American agencies could do the same.

Bus stop balancing is a rare example of a transit reform that is at once fast, cheap, and effective. Fewer, better-placed stops can improve the speed and reliability of buses, while freeing up resources to improve the stops that remain. In practice, that can mean the difference between a service people tolerate and one they’re happy to use.

Nithin Vejendla is a transit planner.

In the summer of 1760, a French military officer named Nicolas Husson was brewing his Eau Médicinale, a medicinal draught that would eventually find its way across the Atlantic to Benjamin Franklin’s Philadelphia doorstep. Franklin, tormented by gout and desperate for relief, had heard whispers of this mysterious European remedy. He could not have known that he was importing one of humanity’s oldest medicines, recorded as a poison roughly around 1500 BC, and that it would, more than two centuries after Franklin’s death, prevent heart attacks in American patients.

Colchicine is extracted from the autumn crocus, a purple flower native to Europe, and its story spans three millennia of medical history. Today, it stands as one of the few substances that can claim both ancient pedigree and modern FDA approval, having navigated the treacherous waters of contemporary pharmaceutical regulation to emerge as a treatment for gout, rare genetic diseases, and cardiovascular conditions.

The origin story

The earliest surviving reference to colchinine appears in the late fourth century BC, when botanist Theophrastus wrote of a deadly plant called ephemeron, meaning ‘one-day killer’. By the first century AD, Dioscorides had given it the name that stuck: kolchikon (‘plant from Colchis’) and later called colchicum, warning it ‘kills by choking, similar to mushrooms’. For the next 1,500 years, Western medicine treated colchicum strictly as poison. Medieval herbalists warned against its use; renaissance physician John Gerard declared its roots ‘very hurtfull to the stomacke’.

This reputation began to shift in the late eighteenth century, when French army officer Nicolas Husson created a wildly popular secret gout remedy called Eau Médicinale. Selling for the equivalent of 22 shillings per tiny bottle, then a fortune, the mysterious potion baffled Europe’s chemists, who guessed its active ingredient might be everything from white hellebore to digitalis to tobacco.

In 1814, Englishman John Want finally solved the puzzle through a combination of scholarly research, chemical analysis, and possibly industrial espionage, reportedly obtaining information through a nursemaid who had previously worked for Husson. Want identified colchicum as the secret ingredient and published his findings in medical journals, sparking a revolution in gout treatment. The plant physicians had avoided for nearly two millennia had suddenly become their most effective remedy for gouty attacks.

In medicine, as in chemistry, dosage makes the poison. Colchicine binds to an essential protein that forms the skeleton of cells – tubulin – and prevents the formation of microtubules, which make up the scaffolding that enables everything from cell division to the movement of cells toward sites of injury. By disrupting this process, colchicine causes cascading effects. Neutrophils, which are the body’s first-line inflammatory responders, find themselves unable to move, to attach to the walls of blood vessels, or to release critical signals that help in wound repair and inflammation control.

What makes colchicine compelling as a drug is that it accumulates specifically in neutrophils, which are less able to pump the drug out as they have limited quantities of a protein, P-glycoprotein. This makes the drug able to reduce inflammation at doses that have minimal side effects, even though its ‘therapeutic window’, the dose range at which it can be safely used, is narrow.

The same mechanism it uses to halt inflammation also explains the drug’s most notorious side effect: by blocking microtubules, colchicine interferes with cell division, which disrupts rapidly dividing tissues in the gut and bone marrow. The gut relies on constant cell renewal to maintain its protective lining, so when this process is disrupted, it suffers intestinal inflammation and damage. Hence the legendary diarrhea that has plagued colchicine users for millennia.

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The clinical renaissance

Despite centuries of use, rigorous clinical evidence for colchicine remained scarce until recent decades. The modern renaissance began in the 1970s, when doctors discovered that daily colchicine could almost entirely prevent the recurrent fever and inflammatory attacks of Familial Mediterranean Fever, a rare inherited autoinflammatory disease, and help prevent secondary amyloidosis, an often fatal complication of the disease where abnormal proteins accumulate in vital organs. This finding established that colchicine was not just an old gout remedy but also a precise anti-inflammatory drug.

The pivotal moment was the AGREE trial, published in 2010, the first modern randomized controlled trial of colchicine in acute gout attacks. The study revealed that a low-dose regimen – 1.8 milligrams total over one hour – was nearly as effective as the traditional high-dose regimen of 4.8 milligrams over six hours in aborting gout attacks, while producing far fewer toxic side effects.

More surprisingly, colchicine has found new life in cardiology. Reasoning that the drug’s anti-inflammatory properties might benefit patients with pericarditis (inflammation of the lining around the heart), Italian researchers conducted a series of landmark trials beginning in 2005. The ICAP trial, published in the New England Journal of Medicine in 2013, showed that adding colchicine to conventional therapy halved the rate of pericarditis recurrence, from 37 to 16 percent. The drug’s impact on pericarditis is an example of successful drug repurposing: finding new uses for established drugs.

The cardiovascular applications expanded further as researchers investigated colchicine’s potential benefits in treating patients with coronary disease. The LoDoCo2 and COLCOT trials demonstrated that a daily 0.5 milligram dose could reduce cardiovascular events, such as heart attacks and strokes, by around 30 percent in patients with stable coronary disease and by around 23 percent after myocardial infarction.

The cost of compliance

Despite its eventual success, colchicine’s drug’s regulatory journey has also become a cautionary tale about the unintended consequences of pharmaceutical policy.

For decades, colchicine existed in a regulatory gray area: widely used but never formally approved under modern FDA standards. It was available from multiple generic manufacturers at remarkably low cost, often mere pennies per pill.

This changed with the FDA’s Unapproved Drugs Initiative, launched in 2006 to bring older, unapproved drugs into compliance with contemporary standards of safety and efficacy. The initiative offered companies a period of market exclusivity, in return for conducting rigorous studies to confirm their effects and thus secure FDA approval for these legacy drugs. Philadelphia-based URL Pharma identified colchicine as a prime opportunity: the drug was widely prescribed, particularly by rheumatologists, and its safety risks at higher doses were well-documented. This suggested that a modern approval could both improve patient care and prove commercially valuable.

URL Pharma, through its subsidiary Mutual Pharmaceutical, conducted the required studies, including absorption and metabolism tests and the AGREE trial in acute gout. Based on these data, the FDA officially approved colchicine for the first time in July 2009, under the brand name Colcrys. The approval covered two indications: the treatment of acute gout flares and the prophylaxis of Familial Mediterranean Fever. Notably, because  FMF qualified as a rare disease, Colcrys was granted seven years of orphan exclusivity, an extended period to reward the development of drugs for rare diseases, and FMF patients faced the $4.85‑a‑pill brand until 2016, even after cheaper generics began reentering the gout market. Meanwhile, the data on gout, not a rare disease, earned URL only a three-year term for that usage.

Critically, upon approval, the FDA ordered all other manufacturers to cease marketing unapproved colchicine tablets, effective October 2010. URL Pharma had secured a complete monopoly on oral colchicine in the United States.

The regulatory victory came with a cost to patients. Overnight, colchicine prices soared from approximately ten cents per tablet to five dollars, transforming an affordable generic into a luxury medication.

The pricing strategy sparked fierce political backlash. In 2011, Senator Sherrod Brown of Ohio, along with Senator Herb Kohl of Wisconsin and Representative Henry Waxman of California, publicly accused URL Pharma of price gouging and exploiting the Unapproved Drugs Initiative. If three million gout patients required daily therapy at the new pricing, the annual cost would approach eleven billion dollars. This was wildly disproportionate to the tens of millions URL Pharma had spent on clinical trials to secure approval for a drug that had been in continuous use for millennia.

URL Pharma defended the pricing by pointing to patient assistance programs and emphasizing the value of ensuring a uniform, FDA-vetted product with updated safety guidelines. The company noted that the approval process had led to important safety improvements, including clearer warnings about drug interactions and revised dosing guidelines for people with kidney problems, changes that could prevent potentially fatal complications. The FDA and rheumatology experts acknowledged these safety benefits, though many questioned whether they justified the price increase.

The controversy intensified when lawmakers discovered that over twenty generic manufacturers had been producing colchicine before the Colcrys approval, and had all been forced to cease production. The Unapproved Drugs Initiative, originally conceived as a program to improve drug safety and quality, was increasingly criticized as a mechanism that allowed companies to game the system, improving drug regulation at the expense of patient access.

Despite its controversies, Colcrys quickly became a lucrative product, with annual sales reaching approximately $430 million in 2011. This success attracted attention from Takeda Pharmaceutical, Japan’s largest drugmaker, which agreed to acquire URL Pharma for $800 million dollars upfront in April 2012. For Takeda, the acquisition offered immediate revenue boost and strategic synergy with its existing gout portfolio that included Uloric, a drug for chronic gout management. The deal allowed Takeda to offer a complete suite of gout therapies: Uloric to lower uric acid levels and Colcrys to prevent acute flares.

The monopoly eventually eroded as competitors found ways to challenge Colcrys’s exclusivity. In 2014, Hikma Pharmaceuticals obtained FDA approval for a colchicine capsule called Mitigare, relying on published literature rather than conducting new trials. In response, Takeda sued both the FDA and Hikma, unsuccessfully, arguing that the approval violated Colcrys’s exclusivity rights. By 2015, the temporary exclusivity had run out, and generic colchicine tablets returned to the US market, though prices remained several times higher than the pre-2009 generic cost.

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The future

The Colcrys episode had lasting implications for pharmaceutical policy. The pricing controversy, along with similar cases involving other drugs brought under the Unapproved Drugs Initiative, led to growing criticism of the program. In late 2020, the Department of Health and Human Services announced it was ending the initiative altogether, partly due to the cost inflation seen with colchicine and other drugs. The program had achieved its stated goal of improving drug safety and quality, but at a cost that many deemed unacceptable.

There are likely many more long-standing generic drugs that could be repurposed, but at the moment, there is little incentive to invest in the research and trials needed to discover them. Many of the problems with Colcrys could have been avoided with different policy designs, such as shorter exclusivity periods, prizes, or vouchers.

Colchicine’s evolution from a crude plant extract to a precision anti-inflammatory drug is not an unusual one, as various ancient herbs have been refined and improved with better tools and understanding. But its story shows how specific policy decisions can change the calculus for investment and pricing, resulting in unintended consequences that affect the lives of millions of patients.

Alex Kesin is a biotech writer. Follow him on Twitter.

Soap is an ancient innovation: a Sumerian text from around 2200 BC gives a basic recipe for making soap. But early soap was mostly used to wash clothes, and sometimes for bathing. For kitchen dishes and eating utensils, people made do with cheaper and more readily available materials.

Sand has been used to scour dishes for thousands of years. It’s easy to find and great for physically scrubbing food detritus off of wooden or metal dishes. Many other natural abrasive substances have been used too. In India, traditional dishwashing materials ranged from jute fiber to rice husk to eggshells. In England, the horsetail plant, Equisetum hyemale has been known as ‘scouring rush’ or ‘pewterwort’, and John Gerard’s 1597 botanical reference book explains that the plant’s roughness ‘is not unknowen to women, who scowre their pewter and wooden things of the kitchen therewith’.

When scouring with physical abrasives was not enough to remove grease, the women described by Gerard could turn to the chemical properties of ash. Wood ash contains potassium carbonate. When it’s leached in water, it creates lye, an alkaline solution of potassium hydroxide, which can be combined with an oil or fat to form soap. In essence, washing a greasy dish with ash and water creates soap on a micro scale. The use of wood fires to heat homes and cook food meant that ash was available in abundance.

That would change in the early modern period, when households started switching from wood to coal. In London, the shift began around 1570 and was almost complete by 1600, making wood ash more scarce. Without ash to cut the grease, Londoners began using ready-made soap to wash dishes.

Soap introduced a new requirement: hot water. Hot water is helpful when washing with ash, but not needed when scouring with sand. In fact, Ruth Goodman, in her book The Domestic Revolution, reports that for sand-scouring, cool water actually works better. The soaps available at the time, by contrast, only worked effectively when activated by hot water. So the new soap-and-hot-water dishwashing regime was both prompted by the switch to coal and fueled by it.

In the mid-nineteenth century, inventors made the first steps towards mechanizing dishwashing. In the United States, the first dishwasher patent was granted in 1850. This dishwasher (or ‘table furniture cleaning machine’, as its inventor called it) was a large tub with a rotatable dish rack in one half and a paddle wheel in the other half. The user would load the dishes, heat up some water separately, pour the hot water into the machine, and then crank the paddle wheel with one hand to throw water onto the dishes, while their other hand (or an assistant) spun the dish rack. This was an awkward process, and probably also ineffective – the water splashed onto dishes with the little scoop wouldn’t have enough power to replace scrubbing.

In the next patent for a dishwasher, granted 13 years later in 1863, inventors Gilbert Richards and Levi Alexander proposed a stationary dish rack around the edges of a tub, with curved paddles attached to a vertical shaft in the middle. The operation would be similar: heat water, pour it into the tub, hand-crank the paddles to splash water onto the dishes.

Richards and Alexander must have realized that this process couldn’t fully replace scrubbing, because their patented machine also had a little side compartment where the operator could scrub one dish at a time using a completely separate mechanism: with one hand, holding the dish up to the revolving sponge-arms; with the other, cranking the handle to spin the sponges.

Their design was the beginning of a flurry of new dishwasher patents. Between 1863 and 1888, the US Patent Office granted more than 60 patents for dishwasher designs and improvements. Many of the designs were remixes of the same key elements: dish racks, tubs of water, various hand-cranked mechanisms for splashing the water up onto the dishes. Some designs involved submerging the entire dish rack, and spinning it around underwater to clean the dishes. Others expanded on the ‘revolving sponge’ idea: for example, a machine that sandwiched a plate between two brushes, and dipped the whole plate-and-brush sandwich underwater while the brushes rotated in opposite directions. Still others invoked centrifugal force, conveyor belts, or springs.

None of those designs caught on. Instead, the first commercially successful dishwasher, created and sold by Josephine Garis Cochrane, used jets of pressurized water to clean the dishes. Although Cochrane was not the first to propose using water jets, she was granted seven US patents for various other dishwasher designs and improvements. Her first patent, in 1886, covered the idea of using two separate water systems: one for soapy water, and one for clean hot water to rinse away the soap. A small lever on the outside of the machine controlled whether it was in washing mode or rinsing mode, engaging the appropriate pump and channeling water to return to the appropriate tank to be reused.

Unlike previous dishwasher inventors, Cochrane manufactured her machine at scale and built a company. She established her factory near Chicago, and traveled throughout the Midwest to demonstrate and sell the machines. The 1893 Chicago World’s Fair was a great showcase for her dishwashers: they were on display in the Machinery Hall and in the Women’s Building, and they were in use behind the scenes at the fairground’s restaurants. They were also installed in many of the hotels that Chicago built for World’s Fair visitors.

In fact, although Cochrane had imagined her dishwasher as an aid to women managing households, she found that restaurants and hotels were her core customers. The dishwashers were expensive for a household: we have records listing them for $350 in 1911 (equivalent to about $12,000 today). Restaurants and hotels, with their industrial quantities of dishes to wash, benefited more from the purchase.

Access to utilities was also a factor. Cochrane’s first patent described a machine that the user pours hot water into, but by 1903 her dishwasher received its hot water from a hot-water-supply pipe. Similarly, the first design was powered by hand, but by 1894 the machine was ‘driven by an engine or any other suitable motor or power’. These changes made the machines easier to operate and more effective, but were also prohibitively expensive for many households. When Cochrane was selling her dishwashers around the turn of the century, fewer than ten percent of American homes had electricity, and even fewer would have had electricity, piped hot water, and the money for the up-front cost of a dishwasher. With all of these barriers to adoption, the dishwasher didn’t become a common appliance during Cochrane’s lifetime.

But by 1925, electricity had reached more than half of American homes, and by the 1960s it was close to universal. Over the following decades, dishwashers were widely adopted. They’re still not nearly as ubiquitous as electricity, but the share of homes with dishwashers has grown from about 7 percent in 1960 to about 73 percent in 2020.

Alongside other household appliances and cultural shifts, dishwash­ers have allowed Americans, especially American women, to spend significantly less time on housework. In 1965 (when 14 percent of families had dishwashers), the average married American woman did 34 hours of housework per week, while the average married man did 5. For comparison, in 2010 (when 70 percent of families had dishwashers), the average married man did 10 hours of housework per week, and the average married woman did 18. This certainly shows shifting gender dynamics, but it also shows that a typical married couple spends 11 fewer hours per week on housework than they did in 1965.

In addition to saving time, modern dishwashers save water and energy. Studies collected by a group of California utilities companies found that washing dishes by hand uses about three times as much energy, and seven times as much water, compared to washing them in a dishwasher. Environmentalists now aim to convince more people to buy dishwashers, use them regularly, and trust them enough to load the dishes without pre-rinsing.

This is a case where resource efficiency happily goes hand-in-hand with domestic ease: we don’t have to gather horsetail for scouring, we don’t have to heat water over a coal fire, and we don’t even have to rinse our dishes before we load the dishwasher.

Erin Braid is a writer and researcher.

Charles Darwin saw evidence of evolution in all the animals and plants he studied. He boxed, bottled, and pressed thousands of specimens: mockingbirds and iguanas from the Galápagos, corals from the Indian Ocean, lichens and seaweeds from Tierra del Fuego, and even the skull of an extinct giant sloth from Argentina. He turned the gardens and greenhouses at Down House into personal laboratories for breeding pigeons, fertilizing orchids, and dissecting barnacles.

But one form of life was conspicuously absent from Darwin’s work: microorganisms.

Darwin might be impressed at how these invisible creatures have come to reinforce and shape his theory. Over the past four decades, scientists have used microbes to reproduce evolution under laboratory conditions and test hypotheses about how natural selection works, in evolution experiments that have led to surprising new discoveries.

Natural selection is driven by a few basic processes: births, deaths, mutation, selection, and competition. Individuals better adapted to their environment tend to survive and reproduce more successfully than their competitors, passing their advantageous traits down to their offspring. Over generations, beneficial traits increase in frequency in the population until traits that were once found in just a few are shared by many.

In the large organisms Darwin studied, natural selection happens over many thousands of years. This is because these species’ reproductive cycles are long and those with the most adaptive genes do not have many more children than those with the least. More time between generations means more time is needed for genes to spread through a population. However, in species with shorter generation times, it can progress much more quickly.

For example, elephants have a generation time of 20 to 30 years, while the fruit fly grows from egg to adult in a mere ten days. Tens of generations of fruit flies can pass in a month or two, and one elephant takes up as much space in a lab as millions of fruit flies. Geneticists have a long and successful history using flies to study natural selection, but large-scale evolutionary changes, such as the origin of new functions and new species, typically require thousands of generations. Even with fruit flies, experiments attempting to capture this spread of evolutionary time could take centuries.

William Dallinger, a minister and amateur scientist, hypothesized in 1880 that microorganisms might make evolution experiments possible. A population of E. coli can experience seven to ten generations overnight. An individual E. coli bacterium is about 100 times smaller than the width of a human hair, and half a cup of broth can hold billions of them. Larger populations contain more genetic diversity than smaller ones, thanks to random mutations during the DNA replication process. They are therefore more likely to include at least one individual with mutations that make them better able to survive a changing environment.

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Dallinger tested his hypothesis by growing water-dwelling microbes called flagellates in a custom-built copper incubator, exposing them to progressively hotter and hotter water. After much trial and error, his evolved flagellates were thriving at temperatures lethal to ordinary ones (and when they were put back into lukewarm water, they died). Today’s evolution experiments operate on similar principles.

The longest-running and most celebrated of modern evolution experiments is the appropriately named Long-Term Evolution Experiment (LTEE). Started by Richard Lenski in 1988 at the University of California, Irvine, and continuing in the hands of Jeffrey Barrick at the University of Texas at Austin, the LTEE has been running nearly continuously for 80,000 generations of E. coli over nearly 40 years. This is equivalent to two million years of human evolution.

The experiment began when 12 genetically identical populations of E. coli were grown in liquid medium. Every day since then, one percent of the previous day’s culture has been transferred into fresh medium. The medium is a dilute sugary solution limited in glucose, which E. coli uses as its primary carbon source. After about seven generations the glucose runs out and the bacteria stop growing until the next day, when they are transferred into fresh medium. Like Dallinger’s warm water, glucose-limited media is a selective pressure on the microbes, spurring the evolution of adaptations that compensate for a lack of their preferred food source.

Every 75 days (about 500 generations), a portion of LTEE’s cloudy soup of bacteria is stored in a minus-80-degree-centigrade freezer. These remain as frozen fossil records that can be used for direct comparison to their descendants.

The LTEE has shed light on many unanswered questions about the dynamics of evolution, and experimentally validated long-running speculations. Do species improve indefinitely in a constant environment or will they stop at some maximum level? By comparing evolved E. coli with their ancestors, LTEE found that the rate of adaptation to the environment slows over time, but doesn’t plateau. Even after tens of thousands of generations in a stable laboratory environment, natural selection seems to be able to continuously eke out improvements.

Another major finding was that not all replicate populations follow the same evolutionary trajectory. In one replicate, named Ara-2, the population diverged into two coexisting lineages: one that rapidly consumes glucose and afnother that feeds on a byproduct of glucose metabolism called acetate. From a single population came a community of two.

But the most surprising finding was the observation that after about 31,000 generations, a different replicate, Ara-3, gained the ability to grow on citrate. Natural E. coli can’t metabolize citrate—in fact, it’s one of the defining features of the species—so the emergence of a strain which thrives on this carbon source could represent an entirely new species.

Simple, long-running experiments like the LTEE show what can be learned about evolution if given enough time. Other scientists, such as Roy Kishony, at Technion-Israel Institute of Technology, further accelerate the rate of evolution in their experiments by combining the intense selective pressure of antibiotics with cleverly designed experimental apparatuses. Kishony’s group has designed many selection devices, often with elaborate names like ‘morbidostat,’ but the most well-known is the Microbial Evolution and Growth Arena (MEGA) plate.

The MEGA plate is a two-by-four-foot rectangular petri dish that is divided into nine bands of gelatinous nutrient agar. The outermost bands have no antibiotics; the next inward has an antibiotic concentration barely high enough to kill E. coli; the bands inward have ten times that concentration, then a hundred times; and the middle band has the same antibiotic concentrated to 1,000 times. Spread over the top of each layer of agar, the bacteria can swim in.

At the start of the experiment, a drop of E. coli is placed on the outermost band. The bacteria multiply and spread right up to the boundary with the first antibiotic concentration band, but no further. The starting E. coli isn’t antibiotic resistant, and neither are most of its descendants. But thanks to random mutation a select few are, and these are able to cross the barrier and fan out into the next band. The descendants of these mutants themselves spread and mutate, crossing bands—or getting stuck behind them—until some reach the band that’s 1,000 times more concentrated than the first. The whole process takes just ten to twelve days, and can be recorded by a camera mounted above the plate to track the spread of each lineage.

We already knew that higher levels of resistance usually come at the cost of slower growth. With the MEGA plate, this evolutionary trade-off has immediate consequences: more-resistant but slower-growing strains get boxed in and trapped behind less-resistant but faster-moving ones. This is one reason why evolution may not always favor the most antibiotic-resistant bacteria.

No individuals in the initial population of E. coli could jump directly from the antibiotic-free agar to 1,000-times-concentration antibiotics. Adaptation to such a different environment is possible, but requires several specific mutations in multiple genes and these are extremely unlikely to occur together by chance under normal conditions. But when evolution is steered in that direction by a gradual gradient of intermediate concentrations, the E. coli reliably get there in a matter of days.

Evolution experiments are easily adaptable to new technologies. Whole-genome sequencing, for example, has been an enormously powerful tool for evolutionary biologists because it enabled them to connect changes in phenotype (observable characteristics, like antibiotic resistance) with genotype (underlying genetic mutations). New technologies can not only be used with future experiments, but also the frozen stocks from previous generations. Whole-genome sequencing may not have been feasible when the LTEE began, but 20 years later the researchers are able to sequence the genomes of the initial frozen E. coli generations just as easily as they could the latest generation. Whatever the next great technological revolution in biology may be, freezer shelves full of bacteria stand ready to be studied in a whole new light.

Today, labs around the world are running evolution experiments of all shapes and sizes, each using microbes to understand a specific facet of evolution. Some study predation by mixing predator and prey species, and observing how each adapts to the other. Other groups have studied starvation by growing bacteria for long periods of time without the addition of any nutrients, nor the removal of dead cells. And by selecting yeasts for increased size, others have directed the evolution of macroscopic multicellularity from single-celled ancestors.

Evolution by its nature takes time. With microbes we’ve been able to condense it down to more manageable timescales, but even 80,000 generations is a blip on the evolutionary clock. As these experiments continue to run, the more we’re sure to learn from them.

Kevin Blake is scientific editor at Washington University in St Louis.

But what makes this Nobel win so remarkable, and so pleasantly surprising, is that Mokyr’s work is not the kind that is often published by economics journals, or even many economic history journals anymore. Over the past few decades, journal editors and peer-reviewers have increasingly insisted that papers must present large datasets that have been treated using complex statistical methods in order to make even the mildest claims about what caused what. Although Mokyr is a master of such methods – he was one of the early pioneers of economic history’s quantitative turn – the work for which he has won the prize is firmly and necessarily qualitative.

Mokyr’s is the economic history that gets written up in books – his classics are The Lever of Riches, The Gifts of Athena, The Enlightened Economy, and A Culture of Growth – and in readable papers shorn of unnecessary formulae. His is history accessible to the layman, though rigorously applying the insights of economics. The prize is a clear signal from the economics profession that it doesn’t just value the application of fancy statistical methods; its highest prize can go to works of history.

Whereas most of the public, and even many historians, think of the causes of modern economic growth – the beginnings of the Industrial Revolution – as being rooted in material factors, like conquest, colonialism, or coal, Mokyr tirelessly argued that it was rooted in ideas, in the intellectual entrepreneurship of figures like Francis Bacon and Isaac Newton, and in the uniquely precocious accumulation in eighteenth-century Britain of useful, often mechanically actionable knowledge. Britain, he argued, through its scientific and literary societies, and its penchant for publications and sharing ideas, was the site of a world-changing Industrial Enlightenment – the place where progress was thought possible, and then became real. Indeed, this publication – Works in Progress – was itself founded on the principle that Mokyr identified, that airing and sharing useful knowledge, and of the idea of progress, are what makes all the difference.

One of Mokyr’s big early insights, first appearing in Lever of Riches, was that many inventions could not be predicted by economic factors. Society could enjoy remarkable productivity improvements from simply increasing the size of the market, leading to division of labour and specialization – what he labelled ‘micro-inventions’ – in the vein popularised by Adam Smith. But this could not explain an invention that appeared out of the blue, like Montgolfier’s hot air balloon in the 1780s – what he called a ‘macro-invention’, not for the magnitude of its impact, but for its novelty. Macro-inventions often required further development to make them important, but the original breakthrough could not be predicted by looking at changes in prices or the availability of resources. It ultimately came down to advances in our understanding of the world. Mokyr put the Scientific Revolution – and the factors that contributed to it – on the economist’s map.

Mokyr also looked at the relationship between different kinds of knowledge. A scientist might know, through observation, that the air has a weight. A craftsman might know, through long training and experience with glass, how to make a long glass tube. Each could not get far alone. But combining them, by creating means to ensure that scientists and craftsmen talked with one another and collaborated – through connecting their propositional and prescriptive knowledge, their heads and hands – very quickly led to the invention of thermometers, barometers, and much more besides, in an ever expanding field of knowledge. What Mokyr taught economists is that it’s not knowledge per se that makes the difference, but the way it is organized. Much of his later work has shown just how deep a pool Britain’s scientists could draw on, of skilled artisans.

In a way, Mokyr himself has practised what he preached. As editor of Princeton University Press’s book series on the Economic History of the Western World, Mokyr has for decades provided an all-important space for economists and historians to write the kinds of research that would never have been publishable in economics journals – including of explanations of the Industrial Revolution that are the polar opposite to his own. He helped keep the connection between history and economics alive.

Mokyr’s case for the primacy of knowledge and ideas was not an easy one to make to economists. They are naturally drawn to data that can be counted, and not to narrative, often no matter how well evidenced. But it appears that Mokyr’s persistence, elevated by his infectious, irrepressible sprightliness, has paid off. His prize is a long overdue recognition of the history in economic history, and a remarkable testament to the power of ideas to persuade.

Anton Howes is a historian. He writes Age of Invention.

Toronto has one of the world’s great commercial downtowns. Two metro lines, eight suburban heavy railways, an extensive bus system, a highway, and North America’s greatest surviving tram network all converge on a tiny area by the shores of Lake Ontario. Hundreds of thousands of commuters pour into the downtown every day, filling the great towers that line its nineteenth-century streets.

As with many downtowns, this causes congestion. Streets and pavements are thronged at peak times. Bicycles, pedestrians, cars, trams and buses compete for scarce space. As with all traditional radial transport systems, there is an enormous concentration of movement in a tiny area. Pedestrians make slow progress across the urban fabric, stopping every block for a minute or two to wait to cross the road.

In the early twentieth century, Toronto’s businesses developed a novel response to this. They began to create pedestrian tunnels from their offices to the metro stations so that their employees could flow in smoothly, avoiding the congested streets (and, in winter, the cold). Shops quickly started to be added. After a few businesses had done this, a ‘network effect’ emerged whereby other businesses started to add their own tunnels to the system, benefiting from the existing tunnels while also making them more useful. It became routine for downtown developers to tie new office blocks into the network. Over many decades, a sort of ‘pedestrian metro’ emerged.

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Known as the Path, the network today stretches for more than 30 kilometers, linking nearly all central metro and railway stations with many of the major office buildings. Although the Path forms a unified network, it is not in unified ownership: it is divided into some 35 chunks, each of which is still owned and managed separately by descendants of whichever business originally contributed it. Many branches of the Path thus terminate in the lobbies of office buildings, with the curious result that these grand spaces function as metro entrances for the general public. The municipal authorities play only a limited regulatory role.

The Path is unlike the gloomy and malodorous underpasses with which most of us are familiar. It is expensively decorated and feels like a high-end shopping mall, which in a way it is. It is extremely clean and closely policed by dozens of private security teams. Until recently, it was thronged with shoppers: this use suffered in the pandemic and has not wholly recovered, but the Path is still used for its original commuting purpose by hundreds of thousands of people every weekday.

Urbanists are normally sceptical about pedestrian tunnels, fearing that they kill off street life. This is a reasonable concern and may often be a decisive reason to avoid them. But in a downtown like Toronto’s, human density is so enormous that this worry seems exaggerated. The pavements of Toronto are still busy, even on weekends, despite hundreds of thousands of pedestrians going underground. The carriageways are still congested with vehicles. It is facile to see this as a simple trade-off between walking and driving. The Path frees up space for bicycles, buses and trams as well as cars. It complements the metro and railway system by shaving off five minutes from the station-to-office walk. The Path may well be substantially net positive for a radial system of public and active transport.

The Path is also interesting for what it tells us about transport economics. It is exceptionally unusual in forming an integrated network without having been developed by a single body. The equivalent would be a railway that was created piecemeal by uncoordinated landowners, with each adding small chunks until it stretched from one city terminus to another – a thing which, to my knowledge, has never happened.

There are at least two reasons for the Path’s distinctive economics. First, pedestrian tunnels are clearly exceptionally valuable to individual landowners, such that they are prepared to bear the entire cost of providing transport infrastructure from which other landowners could subsequently benefit. It wasn’t necessary for the whole network to exist in order for the first landowners to get started: in downtown Toronto, pedestrian tunnels are so good that there was no first-mover problem. This is generally untrue of transport infrastructure: for example, any given stretch of a railway is virtually useless until the entire railway is finished, which is why public authorities usually have to plan entire railways from the start.

Second, pedestrian tunnels have an extremely high upper limit on how many people they can take. As a famous 2003 advert illustrated, a human travelling in a vehicle requires space for their vehicle as well as themselves. A human travelling by foot does not, and is thus much more spatially efficient. This means that additional chunks can be added to the Path without normally creating ‘pedestrian jams’ in the existing stretches: there is nearly always space for more people. This is often untrue for roads and railways, where planners constantly worry that adding additional branches will cause congestion on central trunks.

This means the Path’s model isn’t easily replicable for other transport modes: roads and railways really do need unified planning. But it isn’t clear why pedestrian metros should be impossible in other cities. In fact, to some extent, they do exist. Montreal has a similar system, while Tokyo, Osaka, Seoul, Hong Kong, Singapore and Houston have systems that resemble the Path in some respects. A few European cities also make considerable use of pedestrian tunnels, including Helsinki, Stockholm and Munich.

Overall, though, the list of pedestrian metros is short. It would be interesting to investigate why this is. Why aren’t there pedestrian metros in Manhattan, Boston, Shanghai, Vancouver, Paris and the City of London? Is there some reason why the economics are different? Is the soil already too full of tunnels and utilities? Or are there regulatory constraints that might, in principle, be fixable?

Downtowns were one of the great triumphs of nineteenth-century urbanism. Where they have not been destroyed by cars and modernism and civic mismanagement, they remain enormously valuable urban forms today. But they present, and have always presented, unique and interesting transport problems. Maybe pedestrian metros have a role to play in solving them.

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Samuel is an editor at Works in Progress. He focuses on urbanism and cities. He has previously written The beauty of concrete, Making architecture easy, Against the survival of the prettiest, and In praise of pastiche for Works in Progress.

The supply and demand of electricity must match exactly at every moment. There is no slack in the system: an electricity grid is a unique market with no inventories at all. If demand exceeds supply even briefly, the frequency of the grid drops, causing equipment to shut off and risking widespread blackouts. If supply overshoots demand, the grid becomes unstable in the other direction, forcing operators to quickly scale back production. Since electricity can’t be stored within the grid itself, the system has been built to maintain balance second by second, under all conditions.

To make this work, electricity systems rely on layers of complex rules and processes. Power plants are scheduled hours or days in advance based on forecasts. Others are paid just to stay running in case demand spikes or another plant fails. Some are required to operate even when uneconomic, in order to meet reliability rules. Prices are often fixed or averaged across large regions, so they don’t reflect real-time local conditions. These tools keep the system running, but at a high cost.

Much of the infrastructure – plants, power lines, and reserves – exists only to cover rare events and sits underused most of the time. The cost of this redundancy is passed on to consumers. This complexity also means electricity markets are less efficient than they could be. Prices and investment don’t reliably reflect scarcity, location, or flexibility. The result is an expensive, inefficient grid that is struggling to keep pace with demand and the transition to renewable energy sources.

Batteries offer a way out of this structural bind, giving producers, consumers, and distributors a way of keeping inventories for the first time ever, meaning that their value goes well beyond simply storing excess solar or wind.

They can respond in milliseconds, shift between consuming and supplying power as needed, and are controlled entirely through software. This flexibility allows them to take on a wide range of roles within the system: stabilizing frequency, supporting local distribution networks, reducing peak demand, and easing pressure on transmission lines. Because they require no fuel, emit no local pollution, and can be deployed close to where electricity is used, they can often replace several types of traditional infrastructure at once. Rather than being single-purpose assets, batteries adapt in real time to whatever role is most valuable at that moment.

The just-in-time energy supply chain

Thermal power stations, whether coal‑fired, nuclear, or combined‑cycle gas (a type of plant that uses both gas and steam turbines to improve efficiency and reduce emissions), are fundamentally large heat engines. Like any big piece of industrial equipment, they must be started up slowly. This can involve up to 20 hours of careful temperature ramp‑up to avoid cracking boilers, warping turbine rotors, or shocking reactor vessels.

Once online, they can be surprisingly brittle. In deep freezes, for example, the screens that filter debris from incoming cooling water can clog with slushy ice, restricting flow and forcing plants offline just when electricity demand spikes. At the other end of the spectrum, heat waves can shrink water supplies, raise ambient temperatures, and potentially trigger overheating and shutdown.

Even in good weather, large units are routinely pulled offline for weeks-long shutdowns to inspect and repair critical components. Technicians may need to replace corroded metal tubes that transfer heat from exhaust steam to cooling water, or to examine turbine blades for hairline cracks or deformation. These procedures are essential to prevent catastrophic failure, but they take time, specialized crews, and careful planning.

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Decarbonization is adding further complexity. Utility wind and solar are already reshaping the supply curve. Renewables are expected to provide 25 percent of all US generation this year. Solar generation is set to increase by a third in 2025 alone, followed by nearly a further fifth in 2026. The resulting volatility is evident. The North American Electric Reliability Corporation, an industry body that promotes supply reliability, warned in its 2025 Summer Reliability Assessment the growing fleet of ‘intermittent renewable resources drives a risk of emergency conditions in the evening hours when solar generation ramps down and loads remain elevated’. Between January and mid-May of this year, California’s energy system operator had to curtail 2.4 terawatt hours of wind and solar output, only slightly less than total curtailment for all of 2023.

Maintaining any kind of complex process or system becomes increasingly difficult as inventory falls. Even Toyota, famous for relying on a ‘just-in-time’ model of minimal inventories, operates with some buffers and has weeks of finished goods sitting on dealer lots.

Until recently, the only substantial physical buffer in the grid was pumped-storage hydropower. It works by using surplus electricity to pump water uphill from a lower reservoir to an upper one; when electricity is needed, the water is released back down through turbines, generating power. This is efficient, scalable, and dispatchable on demand, but it’s geographically limited. Viable sites require two large reservoirs at different elevations, close enough together to manage efficiently, and with sufficient water. Even with these constraints, pumped-storage still provides 96 percent of all utility-scale energy storage in the US.

Demand-side flexibility could, in theory, compensate for rigid supply, but utilities have only minimal leverage over when customers actually consume power. Customers simply expect electricity to be available on demand. If a Toyota dealership runs out of parts, it loses sales and disappoints a handful of prospective customers, but a shortfall in the electricity supply risks cascading blackouts.

The combination of expensive storage and inflexible demand creates two problems.

First, inflexible power plants have to match demand perfectly over a wide range of conditions because there is no storage buffer and customers don’t want to change behavior.

To cover these risks, system operators must build and maintain capacity well above peak demand. The North American Electric Reliability Corporation estimates that PJM Interconnection, the largest US power grid, maintains a reserve margin of 24.7 percent. That means it has to hold roughly 125 gigawatts of generation to cover a 100 gigawatt peak. This excess capacity is mostly idle, but still needs to be financed, maintained, and staffed, pushing up system costs, which are in turn borne by billpayers. When these reserves are powered by fossil fuels, this also means higher emissions from plants running inefficiently or idling just to stay warm.

Second, it is shockingly easy to have an outage on a normal day, even with many plants on standby. If there are even slight perturbations, there may not be enough time to bring more units online, resulting in outages. This is a rough description of how the 1965 Northeast blackout, the 1977 New York City blackout, the 2003 Northeast blackout, and the 1999 Southern Brazil blackout all went.

Collapsing the cost of reliability

Electricity markets have developed some partial fixes. System operators now plan which power plants need to run a day ahead, based on demand forecasts. They also pay certain plants to stay ready on short notice or to adjust their output quickly if needed.

This has led to the emergence of a market for ancillary services, which are the grid’s insurance policy. Ancillary services are fast-acting capacity that can be brought online in under ten minutes to prevent swings in frequency and plug capacity gaps before slower acting generation comes online. In practice, this has usually involved paying for modern, fast-start gas turbines to remain on standby.

Utility-scale batteries’ millisecond response allows them to deliver frequency regulation, back up other power sources within minutes, or restart the system after an outage. In December 2017, a coal generator in Victoria, Australia tripped offline, causing 560 megawatts of generation to vanish in an instant. Hornsdale Power Reserve, a major Australian battery storage system, injected 7.3 megawatts within milliseconds to stabilize grid frequency. This bought time while slower conventional generators could ramp up, preventing an outage.

Once even a few gigawatts of storage come online, batteries quickly dominate the ancillary market and cut prices dramatically. In Texas, for example, in the space of a year, the price of ancillary services dropped from $3.74 per megawatt hour to $0.98, while the cost of maintaining the emergency reserve fell from $76.77 to $9.62 per megawatt hour. In California, ancillary service costs in 2024 were roughly one-third lower than in 2023. This is because a system with abundant fast storage no longer needs to commit gas units days in advance or pay plants to stay warm.

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Ending overbuilding

As well as slashing the cost of reliability, batteries can reduce the need for surplus power plants built to cover short-lived peaks in demand. Batteries are already cheaper than new gas turbines per kilowatt, and are better suited to handling the daily rise and fall of electricity use. At 10 percent capacity factor, a gas turbine produces for $250 per megawatt hour, versus about half that for a modern battery. Their ability to charge during low-demand hours and discharge during peaks allows the rest of the system – thermal plants and renewables – to run more efficiently and predictably.

On hot days, the gap between average and peak demand is significant. On 17 July, Texas grid operator ERCOT’s total load was 1,608 gigawatt hours. That is an average of 67 gigawatts, but peak demand reached 79 gigawatts, 18 percent higher. Over the preceding 30 days, the average daily peak was 20 percent above the average load. Batteries can fill much of this gap – the ERCOT record is seven gigawatts out of 70 – reducing the need to keep additional thermal plants online just to meet brief surges.

Today’s batteries already manage daily fluctuations well. Between June and September, solar provided 25 percent of total power needs in Texas during midday hours, while batteries discharged in the evening. During this period, real-time wholesale prices averaged just $28, compared with $97 the year before. Between 6 and 9pm, when battery discharge is strongest, wholesale prices were $80 in 2024 versus $332 in 2023.

Along with overbuilding plants and reliability, another major constraint on electricity grids is inefficient and expensive power lines. In markets with locational pricing, it’s common to see large price differences between market points just 50 miles apart because of limits on how much power the lines can carry. Investment from utilities in new distribution infrastructure now significantly exceeds new investment in generation. But extra batteries are almost always cheaper than extra transmission.

Transmission and distribution lines are built to handle rare peak loads and provide redundancy in the case of outages, so they are heavily unused. Their average capacity factor is often under 50 percent, and in some cases close to 10 percent.

Batteries help solve this in two ways.

When placed on the demand side – closer to homes or businesses – they can charge during off-peak hours and discharge during peaks, letting local demand temporarily exceed what the power line could otherwise deliver. For example, a connection for a residential street that is rated for five megawatts might see six megawatts of demand on hot summer afternoons, as air conditioning systems power up. Without storage, the only solution is upgrading the wires and transformers. But installing one megawatt battery means the grid only needs to supply five megawatts, even as demand grows.

They also reduce the need for redundant circuits: a battery on a line can act as its own backup, so other lines don’t need to be oversized to cover for it. That means existing infrastructure can support much more load without upgrades. Since transmission and distribution costs are mostly fixed, spreading those costs over more delivered energy helps reduce overall system costs, and the batteries also narrow price gaps between congested parts of the grid.

The same logic applies to power plants. The transformers, substations, and other infrastructure required to connect a solar farm to the grid can make up a third of the total project costs. A solar farm paired with a battery can operate with a cheaper, lower capacity connection. Batteries allow the plant to smooth output, store power during low-price hours, and sell more during peak times – all while avoiding the cost of a larger grid connection. This boosts revenue and lowers the average cost per unit of energy delivered.

One reason the value of batteries is often underestimated is that analysts focus only on time-based arbitrage – buying low and selling high across the day – without accounting for location-based price differences. These local price spreads can be much larger and more consistent, and batteries positioned well on the grid can take full advantage of them: storing up power when it is cheap in one area and releasing it when it is expensive there. The result is that the economic case for batteries is frequently stronger than it appears in simplified models.

The combined effect of simplifying market structures and using batteries to arbitrage both time and location is to commoditize daily electricity generation, turning time and location into cost numbers rather than complex planning operations.

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Batteries and their enemies

Despite rapid growth, grid-scale batteries remain unevenly deployed, in large part because policymakers did not design regulatory systems to accommodate them. In several countries, batteries are treated as a curiosity: not quite generation, not quite demand, meaning that they are effectively banned. The Netherlands, for example, taxes residential batteries on the electricity they charge with (although grid-scale batteries can apply for an exemption), which undermines their ability to reduce price spreads. In other countries, the absence of location-based pricing prevents batteries from addressing local grid bottlenecks, even when they could do so efficiently.

The deeper issue is that many electricity markets suppress or distort price signals. These include fixed retail tariffs, uniform national pricing, price caps, and minimum generation requirements. These policies protect thermal fleets by weakening or removing the price signals that would otherwise force them out of business. Fixed tariffs and uniform pricing smooth over volatility and local congestion, shielding high-cost plants from exposure. Without strong locational and real-time prices, flexible alternatives like batteries can’t demonstrate their value, meaning the system continues to fund excessive and inflexible thermal capacity by default.

Embracing the market

A more efficient electricity system depends on embracing, not resisting, price signals and the market. Prices should vary by location, as they already do in most US wholesale markets, so that investors and operators can clearly see where supply is needed most. These signs should also be extended deeper into the distribution network, even down to the neighborhood level, so batteries can respond to local bottlenecks. This would allow the grid to adapt in real time, rather than relying on slow and expensive infrastructure upgrades.

If prices reflect real conditions across time and space, there’s less need for complex mechanisms like capacity markets or day-ahead scheduling. Real-time prices would contain the information needed to guide investment and operations. Letting those prices rise and fall naturally gives generators and storage the incentives to be available when they’re most needed.

Grid connection rules should follow the same logic. Rather than requiring every new project to wait for lengthy studies and upgrades, a more flexible ‘connect and manage’ model would let generators plug in quickly and accept the financial risk for curtailment when the grid is full. With proper locational pricing, developers can judge the risk for themselves and build where the economics make sense, not just where the permitting queue allows.

Texas offers a clear example. It already uses location-based real-time prices and has added more than ten gigawatts of batteries since 2022. Even as peak demand has grown rapidly, grid reliability has improved. Short-term price spikes now last minutes, rather than hours, and the cost of reliability services has dropped sharply.

By simply making prices reflect reality, the system can grow fast, run cheaper, and respond with greater precision. Batteries push investment into flexibility, smooth demand peaks, and keep the grid stable at lower cost. They will be the foundation of a power system that can deliver abundant electricity, with reliability built in, rather than as an afterthought.

Austin Vernon is the CEO of Standard Thermal.

Ben Southwood is a founder and editor of Works in Progress.

Making paint requires combining two elements: a medium (the liquid), and a dry powdered pigment that’s dispersed in that medium. Suitable media, like acrylics, have the property of polymerizing over time, becoming a plastic film. Apart from giving paint its color and opacity, pigment gives physical stability to the film, making it dry to a hard surface. But without pigments the medium simply becomes a varnish, which is translucent and not nearly as tough as paint.

Before the invention of acrylic media in the middle of the twentieth century, the main option for a paint medium was linseed oil, which is made by crushing flax seeds. Linseed reacts slowly with oxygen and takes a week or longer to dry. In industrial applications demanding many coats this is a problem. Many pigments don’t speed up drying at all. Some, like carbon-based blacks, even slow it down further.

To make it durable, manufacturers added lead. Lead speeds up the drying time of paint, allowing subsequent coats to be made in quicker succession. It also reacts with the medium over long periods of time, creating a particularly stiff film through the creation of lead soaps. The pigment also lends paint antifungal, antimicrobial, and anti-corrosion properties.

This is why lead-based paint has been used in Asia and in Europe for thousands of years. Until the nineteenth century, basic lead carbonate was the only reliable white paint available. Even if you wanted a different color, it was typical to add basic lead carbonate to other paints to harness the metal’s useful properties.2

The problem is that lead is poisonous. Flakes of the paint are eaten by children, the dust of the paint enters adults’ lungs, and the heavy metal is absorbed through the skin. When ingested, the material causes cancers, chronic and acute toxicity, and reductions in IQ. But replacing it requires finding a material with similar properties.

Magnetic sand

Titanium was discovered in 1791, when a Cornish vicar called William Gregor noticed a ‘magnetic sand’ in a small stream. This was ilmenite, an ore which contains the element titanium. Gregor described in his first report that this ‘magnetic sand’ had a ‘great resemblance to gunpowder’.

Gregor tested the ore with various chemicals, mostly sulfuric acid, recording the many different colors produced over time. With one solution of sulfuric acid he got a blue color. When he used a yellow solution of sulfuric acid and acid-digested ore, then added a plate of iron, he got the hue of Port wine. Among the many colored precipitates and solutions released by Gregor’s chemical probing was a white powder.

Without knowing it, Gregor was demonstrating the fact that titanium is a transition metal: a type of element that dominates the world of pigments. These metals can exist in stable states with different numbers of electrons missing, resulting in different positive charges. In turn, this changes the way the metals absorb light energy, changing their color.

Initially, only the more exotically colored compounds of titanium were explored. In the 1830s, a deep green compound of titanium and potassium ferrocyanide was discovered by an obscure chemist, Elsner-Lampadius. The inventor of this pigment hoped it might replace Paris green, a highly toxic arsenic compound. In the 1890s, it was suggested by the chemist Joseph Barnes that impure titanium oxides (lacking any use as pigments) could be used as a fixative for wool dyes.

The breakthrough towards a white pigment and a substitute for lead would occur in 1909, when Peder Farup, a chemistry professor in Norway’s first technical school, tried to separate titanium from its ore. This followed a request from a government-backed committee; the new country, which had abundant iron ores of which titanium is a byproduct, was searching for uses. Farup noticed opaque red and yellow by-products: pigments.

Farup reached his next breakthrough in 1910 by mimicking the technique described by the eighteenth century Cornish vicar: digesting titanium ores with sulfuric acid. This yielded near-pure titanium dioxide, a white pigment. Though less exciting than deep green or port wine, white titanium could compete with lead white.

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Mass production began in 1916. The new pigment was not perfect. It was marketed as ‘old India ivory’ – a euphemism for its off-white hue caused by iron impurities. These impurities also resulted in a gritty and unreliable pigment. Unlike lead it was neither tough nor fast-drying. But it was stable, smooth, pure, and could be made cheaply in large quantities. Most importantly, it was not poisonous.

The new titanium pigment manufacturer at Fredrikstad, Norway was bought by the US’s National Lead Company in 1927. From the 1930s onwards, titanium dioxide factories spread around the world; as production processes improved, the pigment became cheaper. In 1920, researchers at the Societé de Produits des Terres Rares, a French company, discovered the Blumenfeld process, which still involved sulfuric acid but which produces (almost) exclusively anatase titanium dioxide, a snow-white crystalline form. In the 1930s and 1940s, new processes were developed by independent laboratories in Germany and Czechoslovakia for making synthetic rutile titanium dioxide, a different crystalline configuration of the same elements but with an even greater opacity than anatase.

This made titanium increasingly competitive with lead. In 1979 the United States banned lead pigment for residential use; in 1989, the European Economic Community banned the use of lead white paint outright. But by this time lead white was already being replaced by the cheaper and safer titanium white.

Titanium dioxide was more expensive by weight than its competitors, but its cost per area covered was lower than other pigments due to its high opacity. With titanium white, the same amount of paint goes much further and fewer layers of paint are needed.

Mass production has continued driving costs down. Lead white now costs about $72 per kilogram of pigment; titanium white prices are down to $16 per kilogram.

The discovery of titanium white is a fortunate one. New pigments are incredibly rare. YInMn blue, discovered in 2009, was the first inorganic blue pigment found for almost 200 years. We still lack good alternatives to cadmium red and cadmium yellow, the highly durable primary red and yellow pigments discovered in the nineteenth century.3 Titanium white’s combination of safety, usefulness, and cost is an achievement that will likely remain unrivaled for some time to come.

Alfie Robinson is a historian.

Many cities face the following problem. They have railway lines that go where people live. But these railway lines end at the edge of the city center, and don’t go out the other side.

For cities with this problem, the solution is through running. Terminating a train and turning it around takes a lot of space, space that is usually unavailable in a city center. This means running a railway line through the city often doubles or triples the number of trains it can handle. As a bonus, passengers who are going from one side of the city to the other can do that much more quickly, with no change.

Many cities, such as London, Paris, Munich and Milan, have used through running to turn some of their existing Victorian railway lines into metro-style services, by building tunnels under the city center. A few other cities, like Berlin, built viaducts (bridges that carry roads and railways over obstacles), while others, such as Cologne, have simply added platforms at their main stations to enable suburban trains to run through. But all of these are big cities, with over a million people, where the property value uplift or extra revenues from fares can cover the enormous costs of tunneling. But there is another option, affordable for smaller cities or large towns: the tram-train.

Karlsruhe is a small city of only 300,000 people in southwestern Germany, near the French border. The city’s main station is nearly two kilometers from the city center, following a project in the early twentieth century to build a larger station on a less cramped site. This caused great inconvenience to passengers, who had to change to the city’s tram network in order to get to the old center.

In 1957, the city took the first steps towards creating a new type of transit, the tram-train, when it took over a bankrupt suburban railway, the Albtalbahn, and extended it into the city center over the tram network.

Over the next four years the line’s gauge (the space between the rails) was converted from 1,000 millimeters to 1,435 millimeters, the standard gauge used by the tram network, and it was re-electrified at the same voltage as the tramway. The modernization of the line enabled quicker journey times – the 70 minute journey to Bad Herrenalb, the line’s terminus, was reduced to 46 minutes – but more importantly passengers who wanted to get to the city center did not need to change to a tram.

The idea of a tram that runs outside of a city’s urban area was not new: Vienna, for instance, had been operating a similar line to the neighboring spa town of Baden since 1907. Karlsruhe’s inventive step, which came later, was to extend the tram-train onto railway lines that did not just carry tram traffic. In 1979, the line was extended onto a freight railway north of the city, and in 1992 the first tram-train took over pre-existing passenger services, to the town of Bretten.

Joining the tram and train networks together was tricky. German railways are electrified at 15 kilovolts alternating current, while Karlsruhe’s trams use 750 volt direct current, which meant that the city needed to procure trams capable of using both voltages, which were (and still are) rare. The railway and the tram network used two different signaling systems, the ‘traffic lights’ that are used to control the movement of rail traffic. The trams have to use retractable steps to overcome the big gap between the 2.65 meter-wide trams and platforms which can handle 3 meter-wide trains. These steps also enable later models of the trams, whose floors are 570 millimeters above the ground, to work with both 380 and 760 millimeter-high platforms.

Overcoming these technical problems led to a much better network. Ridership of the Bretten line went up 400 percent after it was extended into the city center on tramlines, and the line now has 18,000 trips per day, up from 2,000 before the tram-train took over. Passenger numbers on the network doubled between 1985 and 1999, after several more lines had been added. The network today, which carries 170 million passengers per year, is over 660 kilometers long, longer than the combined length of Munich’s tram, metro and suburban railway networks.

Tram-trains have trade-offs. Trams are slower than trains, because they have to share road space with cars, pedestrians and bicycles. Where possible, therefore, Karlsruhe runs the tram-trains down wide roads in the suburbs where trams can run in their own lanes, and it gives signal priority to trams at road intersections. Tram-trains manage speeds about the same as the wholly tunneled Paris Metro.

The fact that trams interact with other vehicles also means that they have to be short. The Munich S-Bahn has a maximum capacity of more than 50,000 passengers per hour per direction because of its 200-meter-long trains, similar to London’s Elizabeth Line. Manchester’s Metrolink, which runs 60-meter-long units, can transport 15,000 per hour on its busiest section, while owing to its lower frequency Karlsruhe’s 75-meter-long tram-trains, as long as trams can feasibly get without causing unbearable problems for other road users, carries only 8,800.

Other models of light rail

The Karlsruhe Model involves mixed traffic: the tram-train lines also carry longer-distance trains and some freight. This caps capacity and reliability.

For this reason, some bigger cities such as Manchester, Dublin, Melbourne and Rotterdam, have converted railway lines to tram lines, with no other form of traffic allowed, enabling more frequent services. This often means the railway line needs to be closed to be converted to tram standards: in Manchester, the commuter line to the southern suburb of Altrincham was closed for six months to enable the electrification to be converted to 1,500 volt direct current from the British standard of 25 kilovolts alternating current.

In Manchester, however, the trade-off was worth it. There was no other traffic on the Altrincham Line, and the city is three times as big as Karlsruhe, so needed a more frequent service on its tram-trains: the line now runs a tram every six minutes.

Another model is the ‘tram-metro’. This is common in medium-sized German cities like Düsseldorf. It involves trams that run on the streets in the suburbs of the city, and then go into a tunnel under the city center. Although this is more expensive than running on streets, tunneled trains are never held up by traffic in the center.

Karlsruhe has, in fact, now built a tunnel for its tram-trains. The ‘Kombilösung’, or ‘combined solution’, which was completed in 2021–2022, involved building two tunnels.

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One of them was a 2.1 kilometer-long tunnel under the city center for the tram-trains, which enabled the main shopping street, the Kaiserstraße, to be fully pedestrianized, creating a three-way hybrid: a tram-train-metro. This would not have been justified with the ridership numbers of the 1990s, but by the 2020s passenger numbers had grown so much that it was viable and necessary to prevent the Kaiserstraße from being congested.

The purpose of the other tunnel was to put the city’s main east-west artery, a ten-lane road known as the Kriegsstraße, underground, and to build a boulevard on top where tram traffic can run uninterrupted by cars.

A final model of light rail worth mentioning is interurbans. Interurbans ran on streets within cities, while in suburbs and in rural areas they ran alongside roads or on dedicated rights-of-way. These systems were sometimes staggeringly expansive: at one point, it was possible to travel from Wisconsin to New York State exclusively by interurban. In the American Midwest, they were the main method of rail transport, outcompeting the commuter services offered by the American railroads. Although most of the interurban lines closed in the postwar period, a few of them are still there today: the South Shore Line still runs from Chicago to South Bend.

The case for tram-trains

Choosing between these different models of light rail is a trade off between cost, engineering difficulties, and the ability to reuse pre-existing infrastructure on the one hand, and capacity, speed and reliability on the other. But there is one specific advantage of tram-trains: their similarity in spirit to interurbans.

The key advantage of interurbans over ordinary suburban railway lines was their ability partially to solve the ‘last mile problem’. Railway stations are often awkwardly sited far away from town and city centers. Usually, this is for engineering reasons: railways are unable to navigate steep gradients, so the Victorian builders had to go where the land was flat, not where people wanted to go. Furthermore, railway lines were often optimized to link two big places together quickly, rather than adding connections to all of the smaller towns en route. Because they could travel on streets, however, interurbans could go anywhere within a town or city, with stations nearer to people’s origins and destinations.

Bringing back the interurbans would be prohibitively expensive. Even in Germany, where the average mile of new tramway costs just $32 million, a network as extensive as the motorways – 8,200 miles – would cost around $270 billion. In Britain, it would be more expensive still: tramways cost $118 million per mile, and in Australia, they come in at $165 million.

The Karlsruhe Model allows interurban-like service at much lower costs. In many cities, the suburban railway lines have already been built: they just need linking up to a tram network.

A concrete example of where tram-trains would be useful is Oxford, UK. Oxford is not big enough to justify a metro: there are only 260,000 people within ten kilometers of its center. The city’s main station is quite far from the center, like in Karlsruhe, and currently has little development around it. This means that a through-running network focused on Oxford station would fail to serve all the places people want to go to. A tram-train network, however, could enable people from the towns and cities surrounding Oxford to get directly into the center, plus direct service to the centers of the surrounding towns like Abingdon and Bicester, and possibly Reading.

Something similar could be said for many French cities. France has been undergoing a tramway renaissance: it has built 21 new tram systems since 2000. But, even though France has an extensive high-speed rail network, and excellent transit within urban areas, its suburban railway lines are operated infrequently outside Paris. For this reason, the country is planning to run its suburban trains through the center in 26 metropolitan regions. In smaller cities like Tours, this could be done by running trains onto the existing tram networks. The same goes for many of the smaller cities in the former Eastern Bloc, which often have extensive tram networks as well as suburban railway lines in need of upgrading.

The biggest opportunity, however, is perhaps in North America. Take Charlotte, North Carolina. The American model of huge low-density suburbs means Charlotte only has 380,000 people within ten kilometers of its center, even though its urban area overall has 1.4 million people, similar to Munich’s. The low density of Charlotte means a transport network like Munich’s is not viable, but the city could take its pre-existing light rail network and join it up to the extensive network of railroad lines around the city that are currently used only for moving freight.

Tram-trains are not suitable everywhere. In big cities like Munich, through running needs to use a tunnel, for reasons of speed and capacity. In some smaller cities like Utrecht, then there is no need: the main station is close to the city center, which is compact enough that it can all be reached on foot. Utrecht has therefore implemented through running simply by running trains through the main station, without needing any more infrastructure. Other cities don’t have any wide streets in the center on which to run tram-trains. These need viaducts or tunnels, or need to demolish buildings to make space. Or they will have to do without.

But in Oxford, Tours and Charlotte none of these things are true. Bring on the tram-trains!

Benedict Springbett is a writer and Bar student based in London.