When Vincent van Gogh was thirty-one years old, in the fall of 1883, he travelled to the bleak moors of northern Holland and stayed at a tavern in the village of Stuifzand. The local countryside was hardly inhabited then—“Locus Deserta Atque ob Multos Paludes Invia,” an old map called it: “A deserted and impenetrable place of many swamps”—but a few farmers and former convicts had managed to carve a living from it. They dug peat, brewed illegal gin, and placed poles across the marshes to navigate by. Any squatter who could keep his chimney smoking for a full year earned title to the land he cleared.

There is little record of what happened to van Gogh in Stuifzand—whether he got lost in the marshes or traded sketches for shots at the bar. When I visited the village, the locals mentioned him merely to illustrate an even greater national obsession: height. At the old tavern, which is now a private home, I was shown the tiny alcove where the painter probably slept. “It looks like it would fit only a child,” J. W. Drukker, the current owner, told me. Then he and his wife, Joke (a common Dutch name, they explained, pronounced “Yoh-keh”), led me down the hall, to a sequence of pencil marks on a doorjamb. “My son, he is two metres,” Joke told me, pointing to the topmost mark, six and a half feet from the floor. “His feet”—she held her hands about eighteen inches apart—“for waterskiing.” Joke herself is six feet one, with blond tresses and shoulders like a Valkyrie. Drukker is six feet two.

The Netherlands, as any European can tell you, has become a land of giants. In a century’s time, the Dutch have gone from being among the smallest people in Europe to the largest in the world. The men now average six feet one—seven inches taller than in van Gogh’s day—and the women five feet eight. The national organization of tall people, Klub Lange Mensen, has considerable lobbying power. From Rotterdam to Eindhoven, ceilings have had to be lifted, furniture redesigned, lintels raised to keep foreheads from smacking them. Many hotels now offer twenty-centimetre bed extensions, and ambulances on occasion must keep their back doors open, to allow for patients’ legs. “We will not go through the ceiling,” the pediatrician Hans van Wieringen assured me, after summarizing national height surveys that he had coördinated. “But it is possible that we will grow another ten centimetres.”

Walking along the canals of Amsterdam and Delft, I had an odd sensation of drowning—not because the crowds were so thick but because I couldn’t lift my head above them. I’m five feet ten and a half—about an inch taller than the average in the United States—but, like most men I know, I tend to round the number up. Tall men, a series of studies has shown, benefit from a significant bias. They get married sooner, get promoted quicker, and earn higher wages. According to one recent study, the average six-foot worker earns a hundred and sixty-six thousand dollars more, over a thirty-year period, than his five-foot-five-inch counterpart—about eight hundred dollars more per inch per year. Short men are unlucky in politics (only five of forty-three Presidents have been shorter than average) and unluckier in love. A survey of some six thousand adolescents in the nineteen-sixties showed that the tallest boys were the first to get dates. The only ones more successful were those who got to choose their own clothes.

Like many biases, this one has a certain basis in fact. Over the past thirty years, a new breed of “anthropometric historians” has tracked how populations around the world have changed in stature. Height, they’ve concluded, is a kind of biological shorthand: a composite code for all the factors that make up a society’s well-being. Height variations within a population are largely genetic, but height variations between populations are mostly environmental, anthropometric history suggests. If Joe is taller than Jack, it’s probably because his parents are taller. But if the average Norwegian is taller than the average Nigerian it’s because Norwegians live healthier lives. That’s why the United Nations now uses height to monitor nutrition in developing countries. In our height lies the tale of our birth and upbringing, of our social class, daily diet, and health-care coverage. In our height lies our history.

Ifirst heard of anthropometric history from John Komlos—the pope of the field, as one of his colleagues described him. Komlos, who is a professor at the University of Munich, has the look of an Old World tailor—sharp eyes, receding hairline, bottlebrush mustache—and the scholarly instincts of a born scavenger. For twenty years, he has rummaged through archives on both sides of the Atlantic, gathering hundreds of thousands of height records in search of trends that others may have missed.

In his way, Komlos was born to do such research. He stands five inches shy of six feet, and he blames much of the gap on history. His parents were Hungarian Jews who lived in Budapest during the Second World War. In 1944, when his mother was pregnant with him, the Nazis took control of the city and the Russians were poised for a counterattack. “The bombardment started almost simultaneously with my birth,” Komlos told me. (His English is perfect, aside from a few oddly flattened vowels, but he speaks with an exaggerated drawl, as if he had learned the language by watching old Westerns.) His parents managed to get to a bombed-out hospital, using fake identity papers, and to take the baby back safely to the family hideout. But there was little food, and Komlos cried incessantly. One relative told his mother to throw the baby outside, since he wasn’t going to make it anyway.

The Hungarian Communists took over the city in 1948, but Komlos’s diet improved only slightly. During the war, his father, Herbert, had spent months in a Hungarian forced-labor battalion outside Stalingrad, returning on foot when the Russians broke the German siege, in the winter of 1943. After the war, Herbert Komlos was imprisoned again, this time by the Communists. “They trumped up some charges because they said he was middle-class,” Komlos said. “He was working odd jobs at the time and had only a fourth-grade education.” When the Hungarian revolution came, in 1956, Herbert supported it. A month later, when it failed, he packed up his family and fled for America.

Biologists say that we achieve our stature in three spurts: the first in infancy, the second between the ages of six and eight, the last in adolescence. Any decent diet can send us sprouting at these ages, but take away any one of forty-five or fifty essential nutrients and the body stops growing. (“Iodine deficiency alone can knock off ten centimetres and fifteen I.Q. points,” one nutritionist told me.) Komlos was twelve years old when he left Hungary, and he had been malnourished most of his life. His first growth spurt had been cut short; his second was hardly more successful. But if heights have obsessed him over the last twenty years it’s because of what happened next, in his adolescence.

When Komlos and his parents arrived in Chicago, in the winter of 1956, America was a land of almost mythical abundance. For more than two centuries, its people had been so healthy and so prosperous that they towered above the rest of the world—about four inches above the Dutch, for example, for most of the nineteenth century. To Komlos, raised on the black bread and thin broth of Communist Hungary, Chicago’s all-you-can-eat restaurants were astonishing. “I was just amazed that these things existed,” he says. But he found the restaurants not nearly as impressive as the giants who fed there.

There is a rueful tone to his nostalgia. His father arrived with no money, no English, and no marketable skills, Komlos says. For a year, he worked in a factory, making belts, for a dollar an hour. When it was clear that he would never be promoted, he quit and started his own business, making leather watchbands at home. In Hungary, there had always been a market for handmade goods, but Chicago stores were full of cheap imports. To compete with Hong Kong, Herbert Komlos had to work sixteen hours a day while his wife worked ten, and John put in twenty-five hours on the weekend. They ate better than in the old country, but only a little. “Everyone has a story like mine, if they were born with my religion in my part of the world,” Komlos says. And those experiences are spelled out in their bodies.

Komlos now knows that he arrived in America at a pivotal point in its history. Over the next fifty years, by most indicators dear to economists, the country remained the richest in the world. But by another set of numbers—longevity and income inequality—it began to lag behind Northern Europe and Japan. It’s this shift that fascinates Komlos, and that emerges so vividly in his height data.

One evening last winter, Komlos and I were walking by the U.S.O. office at the Philadelphia airport, when he stopped to watch a batch of Coast Guard recruits who were shipping out to Cape May, New Jersey. “Look at that,” he said. “Hardly any of them is six feet tall.” Komlos had to catch an 8 p.m. red-eye to Munich, but he couldn’t resist taking this group’s measure. Standing at a discreet distance, he slowly sized up each man as if with a pair of calipers. “Amazing,” he said. “The average German soldier is a hundred and seventy-nine centimetres—about five foot ten and a half. These guys are more like me.”

For centuries, he explained, governments have kept careful records of their soldiers’ heights, providing a baseline against which modern populations are compared. (Records for women are much more scarce, but they tend to follow the same trends.) Looking down these rows of men, four abreast, Komlos could see the shadowy ranks of their ancestors lined up behind them, from West Point cadets and Citadel graduates to Union soldiers, Revolutionary War soldiers, and fighters in the French and Indian War.

If you were to stretch a string from the head of the earliest soldier in that row to the head of the most recent recruit, you might expect it to trace an ascending line. Humans are an ever-improving species, the old evolution charts tell us; each generation is smarter, sleeker, and taller than the last. Yet in Northern Europe over the past twelve hundred years human stature has followed a U-shaped curve: from a high around 800 A.D., to a low sometime in the seventeenth century, and back up again. Charlemagne was well over six feet; the soldiers who stormed the Bastille a millennium later averaged five feet and weighed a hundred pounds. “They didn’t look like Errol Flynn and Alan Hale,” the economist Robert Fogel told me. “They looked like thirteen-year-old girls.”

Fogel, who won the Nobel Prize in Economics in 1993, is the man most responsible for Komlos’s interest in height. In the fall of 1982, when Komlos was working on a Ph.D. in economics at the University of Chicago (he had earlier earned a Ph.D. in history there), Fogel gave a lecture on stature that Komlos attended. Most historians, if they thought about height at all, tended to assume that it was tied to income. The more people earn, the better they eat; the better they eat, the taller they grow. “Men grow taller and faster the wealthier their country,” the French hygienist and statistician Louis-René Villermé wrote in 1829. “In other words, misery . . . produces short people.”

Fogel knew it wasn’t that simple. In 1974, he and Stanley Engerman published an exhaustive study of slave economics entitled “Time on the Cross.” Historians had long insisted that slavery was not only inhuman; it was bad business—hungry, brutalized workers made the poorest of farmers. Fogel and Engerman found nearly the opposite to be true: Southern plantations were almost thirty-five per cent more efficient than Northern farms, their analysis showed. Slavery was a cruel and inhuman system, but more so psychologically than physically: to get the most work from their slaves, planters fed and housed them nearly as well as free Northern farmers could feed and house themselves.

“Time on the Cross” was greeted with uncommon fury in academia—one reviewer consigned it “to the outermost ring of the scholar’s hell.” Yet each point that critics blew apart left a scattering of uncomfortable facts behind it. The most dramatic example came from a graduate student of Fogel’s, Richard Steckel, who is now at Ohio State. Steckel decided to verify his mentor’s claims by looking at the slaves’ body measurements. He went through more than ten thousand slave manifests—shipboard records kept by traders in the colonies—until he had the heights of some fifty thousand slaves; then he averaged them out by age and sex. The results were startling: adult slaves, Steckel found, were nearly as tall as free whites, and three to five inches taller than the average Africans of the time.