The Next Great Migration

MALTHUS’S HIDEOUS BLASPHEMY

Between the 1940s and ’60s, scientists documented another knotty ecological phenomenon in nature, one that leading population biologists would call on to warn about the dangers posed by migration.

Aldo Leopold, a friend of Elton’s, wrote the first reports about Kaibab in 1943. He called the episode the result of an “upset” in the “balance of natural forces in the ecosystem.”

The Kaibab, an isolated thousand-square mile high-elevation plateau bounded by deep canyons in northern Arizona, had been established as a game preserve in 1906. To expand the populations of deer that hunters liked to stalk, the U.S. Forest Service endeavored to clear the Kaibab of the deer’s predators. Between 1907 and 1923, it killed 3,000 coyotes, 674 mountain lions, 120 bobcats, and 11 wolves.

The cull transformed the plateau.1 Liberated from the appetites of their predators, the deer population skyrocketed. At the beginning of the twentieth century, about four thousand deer lived in the Kaibab. By 1924, observers estimated that the deer population had grown to one hundred thousand.

But the deer population did not thrive for long. Their success planted the seeds of their demise. The deer stripped the aspen, spruce, and fir of their bark, stunting the trees’ growth and diminishing the quality of vegetation available for them to eat. They began to starve. “In nearly every case,” observers reported in 1924, “the outline of the ribs could be easily seen through the skin.” Between 1924 and 1928, nearly three-quarters of the population’s fawns perished.

Researchers arrived to check on them in 1963. They found the island crisscrossed by reindeer tracks and droppings. The initial population had grown to more than six thousand. The reindeer had trampled the lichen that sustained them nearly beyond recovery. A few years later when the researchers visited again, they found little sign of the reindeer. All that was left was their bleached skeletons.

The deer of Kaibab and St. Matthew did not sacrifice their surplus numbers by migrating off cliffs to their deaths. They did not ritually murder every other baby like the Funafuti or engage in battles that killed scores.

They just kept consuming and reproducing. If allowed to freely roam, they’d bring their outsized, ecosystem-killing appetites elsewhere.

What happened on Kaibab and St. Matthew recalled the warnings of the eighteenth-century cleric Thomas Robert Malthus. Malthus had pointed out that aiding the poor with food and clothing, as England’s Poor Laws required and which most people viewed as beneficial charity, circumvented nature’s checks on human population growth. “We cannot, in the nature of things, assist the poor, in any way,” Malthus wrote in 1798, “without enabling them to rear up to manhood a greater number of their children.” Progress against poverty, disease, and hunger would result in an exponentially growing human population, Malthus warned, whose appetites would regularly outstrip the food supply, creating a permanent state of conflict and scarcity.

Malthus was proved wrong in the centuries that followed his warning. All the things that caused death rates to fall—modernization, economic development, prosperity—also led to declining birth rates. Social scientists call the shift from high birth and death rates to low ones the “demographic transition.”2 In the United States, for example, modern sanitation and other factors drove death rates down from 25 per thousand in the seventeenth century to less than 10 per thousand a few centuries later. But catastrophic population growth was averted because birth rates fell, too: the average number of children born to white American women declined from seven in 1800 to just two by 1940. Influential thinkers condemned Malthus as an alarmist. The nineteenth-century philosopher Friedrich Engels called his theory “hideous blasphemy against nature and mankind.”

But then, after World War II, demographic trends shifted. In the United States and other prosperous countries, birth rates zoomed. The “baby boom” reversed the prediction of demographic transition theory, which suggested that people in prosperous societies tended to have smaller families. Meanwhile, in poor countries such as India, death rates fell. Chemicals such as fertilizers and antibiotics, developed during the war, circumvented the disease and famine that otherwise killed off millions. That undermined demographic transition theory, too, because there’d been no underlying economic development or modernization.

Scientists started resurrecting Malthusian concerns in a spate of popular books. The result for humans could be a slow-motion version of the collapse on the tablelands of Kaibab, they warned. The ornithologist William Vogt, who’d written the foreword to John James Audubon’s illustrated classic Birds of America, wrote a best-selling book on the topic called The Road to Survival in 1948. A book exploring similar themes written by Henry Fairfield Osborn’s son, Henry Fairfield Osborn Jr., who’d taken over the helm of the New York Zoological Society, appeared that same year.

“Every argument, every concept, every recommendation” in Vogt’s book, notes the historian Allan Chase, became “integral to the conventional wisdom of the post-Hiroshima generation of educated Americans.” The Reader’s Digest, a publication with sales second only to the Bible, reprinted a condensed version of Vogt’s book. Between 1956 and 1973, seventeen out of twenty-eight general biology textbooks included a version of Leopold’s account of the collapse of the deer in Kaibab.

Tall and angular, with piercing eyes framed by heavy brows and long sculpted sideburns, the Stanford University biologist Paul Ehrlich had grown up in New Jersey collecting butterflies and wandering around the American Museum of Natural History.

Like others of his generation, he knew about what had happened on the Kaibab and on St. Matthew Island. He had absorbed the lessons of Vogt’s and Osborn’s books, which he’d read while an undergraduate at University of Pennsylvania. Vogt had even given a lecture on campus while he was a student.

But Ehrlich studied checkerspot butterflies. They were nothing like the deer of the Kaibab. Female checkerspots laid hundreds of eggs, but in many years getting even two to survive was a stretch. If it was a little too warm, or a little too rainy, the larvae’s growth would fail to coincide with the brief blossoming of their food supply. The plantago plants the larvae fed on were not only short-lived, they also grew exclusively in outcrops of serpentine rock in the arid grasslands of the hills, a unique and scarce habitat. For a population of checkerspots to survive, a newly emerged butterfly not only had to find those special plants and lay her eggs on them, she also had to do it at the right time and under the right conditions, so that the eggs would mature into larvae and be able to feed on the plants before the plants died down for the winter. What biologists called the “phenological window”—the time between the emergence of an adult butterfly ready to mate and the death of the plants her offspring can feed on—could be measured in a matter of days.

When conditions worsened for checkerspots, their populations simply died down and vanished. Despite the wings that allow them to surmount geographic and other barriers and spread into new regions, checkerspot butterflies, Ehrlich knew, were isolated homebodies, rarely leaving their patch of mountainside, regardless of how bad conditions got. He’d conducted studies that proved it, noting what he called their “remarkable lack of wanderlust.”3

So long as his attention remained focused on butterflies, the ecological calamities of population growth predicted by Malthus—famine, environmental degradation, and collapse—did not concern Ehrlich. Then he visited South Asia.

Ehrlich landed at dusty Palam Airport in New Delhi, India, in the deep heat of the pre-monsoon season in late June 1966. It was the last stop on a year-long multicountry research trip on which he’d brought his wife, Anne, and daughter, Lisa Marie, along.

Most American visitors found the place, while dizzyingly hot and turbulent, charming and transformative. Shaggy-haired counterculture enthusiasts flocked to India to imbibe its ancient traditions of yoga, meditation, Buddhism, and more. The members of the Beatles arrived in Delhi about a week after the Ehrlichs to pick up authentic Indian classical musical instruments.

Not Ehrlich. Everywhere he looked, he saw a disaster in the making.

“The streets seemed alive with people,”⁴ he’d write later. “People eating, people washing, people sleeping. People visiting, arguing, and screaming. People thrusting their hands through the taxi window, begging. People defecating and urinating. People clinging to buses. People herding animals. People, people, people, people.” Delhi dramatically conveyed “the feel of overpopulation,” he wrote, calling the city “hellish.”

Repulsed, the Ehrlichs left Delhi and headed north to the thickly forested high-altitude valleys of Kashmir, nestled between towering Himalayas. Here they encountered yet more signs of impending ecological catastrophe. Kashmir’s high-altitude meadows had become “biologically barren,” Ehrlich wrote, “grazed to within a fraction of an inch above the ground.” He could find hardly any of the butterflies he’d hoped to study. Plus, the hotel the family stayed in was dirty; the houseboat they rented on Kashmir’s famous Dal Lake was grossly overpriced. Kashmir was a “big disappointment,” Ehrlich wrote to a friend.

For Ehrlich,⁵ the Indians had effectively trampled on their own lichen, like the reindeer of St. Matthew. If it hadn’t been for a shipment of 9 million tons of wheat from the United States the year before his visit, Ehrlich figured, India would surely have been plunged into famine already, just as the deer on Kaibab had.

In fact, the crowds and environmental damage⁶ the Ehrlichs saw had as much to do with local economic and political factors as with the growth rate of the population. India’s population had grown, but the city of Delhi had not, in fact, become especially large compared to other cities around the world. With a population of 2.8 million, Delhi was just a fraction of the size of, say, Paris, where 8 million resided. The chaos and crowding he saw resulted less from the size of the local population than from the effects of new government programs that encouraged people from the rural hinterlands to move into the city for factory jobs. The influx of newcomers had overwhelmed local housing capacity and the city’s rudimentary infrastructure.

And while Kashmir had indeed suffered environmental damage, attributing that to population growth was a stretch, too. The Ehrlichs had arrived less than a year after India and Pakistan had fought a bloody and destructive war over control of the region. Tens of thousands of troops armed with artillery and tanks had overrun Kashmir’s steep valleys, turning vast stretches into battlegrounds. So many soldiers had poached the local wildlife for food and for fur that many of the valley’s unique species had been pushed to the verge of extinction. Kashmir may have been “spoiled,” as Ehrlich pointed out, but destructive mountain warfare had been a powerful culprit in the process.

For Ehrlich, such historical particulars obscured the forest for the trees. In close-up, conditions in India may not have conformed to Malthus’s predictions, but through a wide-angle lens they did. The population grew; the quality of the environment declined. It was that simple, and it was just as Malthus and Vogt had said.

Ehrlich’s crusade to arrest the growth 7 of the human population began soon after he arrived back home from India. At first, he delivered his warnings about the risks of Kaibab-like collapse in humans to students at Stanford. Soon local clubs and NGOs started inviting him to speak to their members.

Ehrlich’s Stanford offices became a hub for scientific debate over the ecological crisis precipitated by population growth. At weekly seminars and conferences at Stanford, he gathered scientists such as the University of California ecologist Garrett Hardin, the social scientist Kingsley Davis, and others to share notes on the possibility of a human population explosion and its portents for the future.

They saw signs of impending Kaibab-like collapse all around, including in California. By 1962, more people lived in California than the state of New York. Red brake lights glared on the jammed freeways. The cities sprawled. And when the unprocessed tailpipe emissions of millions of California cars streamed into the Golden State sunshine, a toxic chemical reaction created clouds of smog, which because of their location in mountain-ringed basins, hung thickly over California’s major cities. The air grew so polluted it became opaque. People walking the streets of Los Angeles took to wearing “smogoggles” to protect their eyes.

Pollution wasn’t the only ominous sign. New research suggested that, like famine and environmental degradation, antisocial behavior might be a sign of impending Malthusian collapse, too.

In his influential study,8 the Johns Hopkins animal behavior expert John B. Calhoun built a quarter-acre enclosure behind a neighbor’s house outside Baltimore, Maryland, into which he’d released five pregnant rats. With no predators, the rat population grew into the hundreds. But Calhoun continually replenished their food supply. He would not let the rats eat themselves into Malthusian collapse.

Chaos ensued regardless. The rats’ behavior changed. Male rats banded together in aggressive groups and attacked females and young rats. They ate the bodies of the dead. Female rats neglected and even attacked their own infants. Some rats became homosexual; others hypersexual. Eventually the rats’ behaviors became so disturbed that they could no longer successfully reproduce, presaging the population’s ultimate collapse.

Ehrlich encouraged a social psychologist named Jonathan Freedman to conduct follow-up studies to see if the effect occurred in humans. Even before Freedman published his results, Ehrlich cited what he considered their foregone conclusions 9 in his own papers. He wasn’t alone. In Congress, politicians sounding alarms about human population growth offered Calhoun’s work to buttress their arguments, too. Commentators used Calhoun’s results to link antisocial behavior with crowds. “Uncontrollable aggressiveness” resulted from crowding, the zoologist and TV host Desmond Morris wrote. It had been “proved conclusively with laboratory experiments.” The journalist Tom Wolfe compared crowds of New Yorkers “running around, dodging, blinking their eyes, making a sound like a pen full of starlings or rats.” The critic and philosopher Lewis Mumford wrote of the “ugly barbarization” of humans due to “sheer physical congestion,” which had been “partly confirmed” by Calhoun’s experiments in rats. The “freedom to breed,” Hardin argued, had become “intolerable.”

Scientists started to refer to human population growth 10 not as the happy outcome of prosperity and improved health but as a silent killer that would violently erupt. Science magazine called population growth the “P-bomb,” like the A-bomb and the H-bomb. Time magazine featured the problem in a 1960 cover story titled “That Population Explosion.”

At the time, frightened American readers could take comfort in the presentation of the problem as a distant one, transpiring a world away. Time magazine suggested as much, illustrating the story with a collage of bare-breasted African women and sari-wrapped Indian women laden with infants. Americans were effectively cordoned off from such people: immigration laws had prevented their kind from penetrating U.S. borders for decades.

After refusing entry to ships full of terrified Jews and others persecuted by the Nazis, chastened political leaders in the United States, Europe, and elsewhere belatedly agreed to provide refuge to those fleeing Nazi-style persecution, signing the United Nations’ Refugee Convention in 1951. With the civil rights movement gaining momentum, pressure built to dismantle the decades-long racial quotas on the borders. Two years after the New York Times Magazine excerpted President John F. Kennedy’s inspirational essay dubbing the United States a “nation of immigrants,” Congress passed the Hart-Celler Act in 1965,11 removing race as a criterion for judging whether a migrant could enter the United States.

The Hart-Celler Act had been sold as a practical measure, to allow skilled foreigners such as my parents help the country staff newly expanded government programs such as Medicare and Medicaid, and to bolster the nation’s reputation as a welcoming nation, in contrast to the Soviet Union’s closed society. It had not been intended to actually alter the racial makeup of the nation. Most likely, its architects thought, white-skinned Europeans would continue to dominate the migrant flow, just as they had in the past. This is “not a revolutionary bill,” President Johnson said upon signing it, promising that it “will not reshape the structure of our daily lives.” “There is no danger whatsoever of an influx from the countries of Asia and Africa,” Representative Emanuel Celler reassured the nation.

He was wrong. Nine out of ten of the post-1965 newcomers hailed from Asia, Latin America, and other non-European locales. The explosive chaos described by the Malthusian ecologists emanating from countries like India could reach the shores of the United States. The population bomb would not be contained.12 Its catastrophic effects would be “compounded,” the Ehrlichs wrote, “by man’s unprecedented mobility.”

A popular movement to defuse the population bomb—and to contain its effects outside American borders—started to coalesce.

The crusading leader of the Sierra Club, David Brower, heard Ehrlich being interviewed about the population problem on a daytime talk show. Inspired, he called the publisher Ian Ballantine. Together they persuaded Ehrlich to write a popular book on the subject.

Paul and his wife, Anne, wrote it together. Anne, a French major in college, had often collaborated with him on his projects. She’d even illustrated his doctoral thesis on insecticide resistance. But when Ballantine published the book, they decided to drop her name from the byline for marketing reasons. They also changed the title from the dryly descriptive Population, Resources, and Environment, which the Ehrlichs had come up with, to the catchier The Population Bomb.

In it, Ehrlich dispensed with the scientist’s normal caution and circumspection. He warned that population growth would usher in an “utter breakdown of the capacity of the planet to support humanity” within fifteen years. By 1984, he predicted, Americans would be dying from dehydration.

Population growth was a problem that implicated everyone,13 but Ehrlich prescribed dramatically different solutions for Americans than for foreigners. While Americans needed to have their awareness raised about their reproductive habits and consumption patterns, he suggested that all Indian males with three or more children be sterilized—and recommended sending in American helicopters, doctors, vehicles, and surgical instruments to help the Indians do it. He suggested “very unpopular foreign policy positions,” such as letting some needy countries starve rather than shipping them food aid and adding antifertility drugs to their water supply.

Ehrlich was not an overt racist.¹⁴ On the contrary, he championed civil rights, and as a scientist, he vociferously objected to the concept of biologically distinct races. He had helped organize an antisegregation protest in Kansas while a postdoc, and he’d written books and papers decrying the psychologist Arthur Jensen and the Nobel Prize–winning physicist William Shockley, who argued that black people were genetically inferior and should therefore be the primary subject of population control efforts. (Unlike his writings on the population problem, Ehrlich’s book on race was condemned for an “arrogance and polemicism that rivals the worst excesses of [his] chosen opponents.”)

And yet no one who read The Population Bomb could miss that Ehrlich didn’t consider foreigners to have the same capacity for change and understanding as his own people. Throughout the book, he characterized people’s variable practices not as dynamic and responsive to changing conditions but as immutable biological features.

He bemoaned the fact of child marriage in India, noting how it extended childbearing years over decades, for example, but considered the dire policy of forced sterilization more feasible than altering that cultural practice. He considered the difference between castration and sterilization “almost impossible to explain” to people in India. He insisted that the population control achieved in Taiwan, Korea, and Japan could never succeed in poor countries. “We would be foolish in the extreme” to think anything similar could occur in “other parts of Asia, and Africa, or in Latin America,” he wrote. He disdained voluntary family planning programs, which left it up to women to decide how many children they wanted. While he himself—an educated Western male—could see the Malthusian problem posed by large families, he could not see how women, especially women who lived in poor countries—or as he sometimes called them, the “never-to-be-developed” nations—ever could.

Ehrlich’s characterizations conformed to a popular theory in his scientific discipline. During a brief period in the late 1960s and ’70s, a theory called “r/K selection” consumed population biologists.15 In effect, it imagined two kinds of places—those where the living was easy, and those where the living wasn’t—and two broad classes of creatures that inhabited them. In the easy-living places resided “r-strategists,” small, quickly maturing, highly fecund creatures, almost mindless in their pursuit of large families. Their environments did not pressure them to be particularly clever or frugal, which is why they were mostly dumb and wasteful. In the tough places resided the large-bodied “K-strategists,” whose environments required them to be clever and frugal and who tended to mature later and invest more in their few offspring. Conservation biologists used r/K selection theory to distinguish between r-strategists such as mice, compared to K-strategists such as elephants.

Controversally, in 2000 the Canadian psychologist John Philippe Rushton would explicitly apply r/K selection theory to human racial groups,¹⁶ arguing that black people were r-strategists, “Orientals” K-strategists, and white people in between. Rushton’s bias was overt: he served as the head of the eugenics research outfit the Pioneer Fund, which Harry Laughlin had led for years.

Ehrlich’s bias was not overt, but 17 his characterizations of Indians and Europeans echoed Rushton’s. In his foreword to The Population Bomb, the Sierra Club’s David Brower similarly presumed fixed r/K–like differences between people who lived in different places. “Countries are divided rather neatly into two groups,”18 Brower wrote. “Those with rapid growth rates, and those with relatively slow growth rates.” The fast growers, he wrote, were “not industrialized, tend to have inefficient agriculture, very small gross national products, high illiteracy rates and related problems.” The slow growers, presumably, were just the opposite.

Ehrlich’s fellow neo-Malthusian scientists,¹⁹ such as Kingsley Davis, explicitly called for an end to immigration. According to Davis, immigrants slowed technological progress and gave rise to “school problems, health risks, welfare burdens, race prejudice, religious conflicts and linguistic differences,” as he wrote in Scientific American. He recommended closing the state of California to newcomers from Mexico and China.

Ehrlich alluded to the invasiveness of immigration from places like India, too. Starving Indians, he warned, would flood the borders, intent on stealing American resources. “They have seen colored pictures in magazines of the miracles of Western technology,” he wrote. “They have seen automobiles and airplanes. Many have seen refrigerators, tractors, and even TV sets. Needless to say, they are not going to be happy.” Indians, he wrote, would not “starve gracefully without rocking the boat.” Most likely, they’d “attempt to overwhelm us in order to get what they consider to be their fair share.”

To prevent them from swamping the nation, muscular action would be required. “I know this all sounds very callous,”20 Ehrlich wrote, sympathizing with his readers while simultaneously priming them to accept the necessity of authoritarian measures. Drugging people and forcing surgeries on them was coercive. But it was “coercion in a good cause.”

“Remember the alternative,” he wrote.

Ehrlich’s provocative two-hundred-page book, though witty, dark, and stylishly written, generated modest interest at first. Then in early 1970, Johnny Carson called.21 Carson’s late-night talk fest The Tonight Show dominated television, bringing in more money than any other program on television at the time or since. A slot on Carson equaled a shot at stardom, as a generation of performers, including Barbra Streisand, Woody Allen, and Steve Allen, had discovered.

At age thirty-seven, on stage with the biggest name in the entertainment industry, Ehrlich “wasn’t particularly nervous,” he recalled later. He was a showman who knew how to get people’s attention and enjoyed doing so. He’d “always been a loudmouth,” he says. Ehrlich’s explanations about the Kaibab-like future that awaited and the radical interventions required to avert it were beamed into the homes of nearly 15 million people across the country.

After his first appearance on The Tonight Show, viewers sent in five thousand letters, more than any other guest had ever provoked. Sales of The Population Bomb exploded. In the first months of 1970, the book sold nearly a million copies; by the end of the year, it had sold nearly 2 million. The journalist Joyce Maynard remembers the “rush of dread” she felt 22 while reading The Population Bomb. “Not personal individual fear,” she explained, “but end-of-the-world fear, that by the time we were our parents’ age we would be sardine-packed and tethered to our gas masks in a skyless cloud of smog.”

Ehrlich became a celebrity with the stature²³ of Al Gore or Neil deGrasse Tyson today, overnight. He appeared on Carson’s show dozens of times; during one stretch, he appeared three times in as many months, chatting with Carson about a range of political issues facing the nation. “Richard Nixon would do very well on an IQ test,” he deadpanned, in a discussion about the uselessness of intelligence tests, “but would you want your daughter to marry him?” “We are quite happily destroying the only resources [our children will] ever have,” he’d point out. “But you know,” he quipped, “what did posterity ever do for us?”

Prestigious institutions showered Ehrlich with honors²⁴—an Emmy nomination, an endowed chair at Stanford, awards from the United Nations, the MacArthur Foundation, and the Royal Swedish Academy of Sciences. Entrepreneurs such as Hugh Moore, who’d made a fortune selling disposable Dixie-brand drinking cups, paid for ads in major newspapers, sent hundreds of college radio stations free radio segments featuring Ehrlich, and distributed hundreds of thousands of leaflets and brochures about The Population Bomb.

Top Hollywood directors and actors signed on²⁵ to shoot sci-fi films inspired by the famished, overcrowded future Ehrlich described. In 1972’s Z.P.G., Charlie Chaplin’s daughter, the Golden Globe–nominated actress Geraldine Chaplin, portrays a woman who rears a robot baby in a future world in which all human reproduction had been banned for thirty years; in the following year’s Soylent Green, Charlton Heston navigates a future New York City so depleted and overcrowded that people survive on cannibalistic corporate rations.

Suspicions that population control really meant controlling certain populations and not others dogged the movement from the beginning. At a conference in June 1970, a group of African American activists stormed out, accusing the assembled environmental and population control activists—Ehrlich, Hardin, and others—of being interested less in the problem of population than in problem populations. The conference agenda—which included visiting “teeming urban areas” where “a dangerous crisis²⁶ of ecological imbalance already exists,” as the organizers put it—aimed at the “systematic reduction of a specific population, namely blacks, other non-whites, the American poor and certain non-white and ethnic immigrants,” the protesters wrote in a statement.

Their critiques did not slow the population control movement’s momentum.27 For counterculture activists, the movement offered an opportunity to rile religious conservatives by touting the birth control they considered sacrilege. For business leaders who’d built their empires promoting consumerism, it offered a handy diversion from their own role in despoiling the environment. For Western NGOs and their allies in the political establishment, it offered an opportunity to promote technological quick fixes such as contraceptive devices that compared favorably to slow, Soviet-style economic development. Impoverished, rapidly growing countries such as India went along with the new population control regime, too. Their elites didn’t mind blaming their country’s poverty and hunger on the fertility of poor women, rather than, say, the oppressive caste system or widespread corruption from which they benefitted.

On one of his appearances on The Tonight Show, Ehrlich announced the founding of a new organization 28 called Zero Population Growth, aimed at averting Malthusian collapse by making abortion and sterilization more accessible. The group quickly enlisted sixty thousand members. On college campuses across the country, student activists held events in which they tossed condoms into crowds. They conducted “experiment[s] in overpopulation,” in which participants were herded together in circumscribed spaces and fed a “famine diet” of rice and tea. They affixed pins on their lapels featuring the symbol for a male with a chunk cut out of the circle to broadcast their vasectomies. They wore IUDs fashioned into earrings.

Scientists such as Vogt, Osborn, and Kingsley Davis launched international NGOs such as the Population Council, which shipped 1 million IUDs to India.29 Philanthropic groups such as the Rockefeller and Ford foundations pressured the U.S. government to demand that foreign-aid recipients crack down on the fertility of poor women as a precondition for receiving funds or food.

In June 1975 the population control movement scored a major victory.³⁰ That summer the Indian prime minister suspended the constitution and embarked on an ambitious plan to sterilize its booming populace. In states across India, men with more than three living children would be required to undergo sterilization, and pregnant women with three children would have to abort their babies. Government employees working under quotas fanned out across the country, scalpels and IUDs in hand.

John Tanton, an unassuming man³¹ with hooded gray eyes and an unblinking stare, lived on the shore of Lake Michigan in a small, quiet town called Petoskey, where he raised bees in his backyard and practiced ophthalmology.

Ehrlich’s book had “a big influence on me,” he says. He joined Ehrlich’s ZPG movement in 1969, even before Ehrlich appeared on The Tonight Show, and bought copies of The Population Bomb by the case to hand out to friends and neighbors. He and his wife were ardent conservationists and committed community activists. Tanton had founded the Petoskey chapter of the Audubon Society and together with his wife co-founded a Planned Parenthood branch. He maintained a lifelong membership in the Nature Conservancy.

But the population control movement’s emphasis on lowering the birth rate as the primary strategy for reducing population growth puzzled him. He’d seen the ecological value of other methods inside the beehives he’d been keeping since he was a teenager. Every fall, when the size of the bee colony reached its peak, the female worker bees would forcibly expel the male drone bees from the hive. They’d block the entrance to the hive, preventing the male bees from returning to its refuge. They’d drag any male bees still inside the hive to the precipice and throw them off the edge. Beekeepers such as Tanton would find the expelled drones’ famished and frozen bodies with telltale chew marks on their wings. These were victims, Tanton presumed, of a brutal but necessary form of population control, a heartless mass eviction similar to the mass suicide of the lemmings.

The more he thought about it, the more he saw parallels between the beehive and human population.32 Wasn’t the nation-state sort of like a hive, too, with its complex civilization enclosed within cozy borders? When the population of the bee colony exceeded the capacity of the hive to accommodate it, the bees took dramatic action. They evicted the dead weight and closed the borders. Didn’t their behavior, he wondered, “raise questions about the human enterprise”?

Actually, it didn’t. A honeybee is more like a cell in a body than an individual in society: it’s a component of a larger whole. Many bees can’t even feed themselves, and most play no role in reproduction. Evicting drones is nothing like deporting foreigners. It’s like sloughing off dead cells. And a beehive is not like a nation. It’s an enclosed and exclusive habitat. It’s more like a private residence.

Hardin had used a similarly misleading metaphor³³ to call for closed borders. In an influential 1974 essay, he likened the countries of the world to separate lifeboats adrift at sea. That was why, he said, wealthy nations had to close their borders to people from poor nations. Passengers from one lifeboat clambering aboard another could end up swamping it.

But nation-states are not isolated, self-contained units surrounded by impassable terrain. Except for a few remote island nations, they’re connected to each other by land or by navigable waters. Human populations share the same more or less contiguous habitat. A more apt maritime metaphor would have likened the nations of the world to different parts of a single boat, and migration to passengers moving from one part to another.

Tanton prided himself on his emotional detachment,³⁴ farsighted rationality, and moral integrity. Unlike Ehrlich, Tanton wasn’t a charming man or much of an orator. He spoke in a flat monotone, his harsh views obscured by a mild, pedantic midwestern exterior. He was more of a moralist, the kind of person who considered it his ethical duty to scold someone who dropped a cigarette butt into a creek.

He was careful, in his public pronouncements, not to be openly hateful or bigoted. But privately, he had another reason to resist immigration. Tanton considered foreigners biologically alien.

He characterized them as separate species³⁵ with distinct biological capacities: “homo contraceptivus” were those born in Europe and the United States, who generally had smaller families than did the newcomers, “homo progenitiva.” These outsiders, he claimed in private correspondence, would “bring their traditionally high fertility patterns with them.” (In fact, immigrant fertility rates conform to local ones within a generation.)

Like Madison Grant and Henry Fairfield Osborn decades earlier, Tanton characterized intelligence as a biological feature passed down unchanged from generation to generation, in which education and opportunity played little or no role. That was why “less intelligent” people, as he wrote to a colleague, should “logically have less” children than the more intelligent ones. Even political cultures lay embedded within bodies, which immigrants would drag around with them like phantom limbs. “If through mass immigration, the culture of the homeland is transplanted from Latin America to California, then my guess is we’ll see the same degree of success with governmental and social institutions that we have seen in Latin America,” he wrote in a private letter.

Such deeply rooted differences between locals and foreigners were the reason why, for Tanton, migrants had to be barred from entry into the nation. “How could³⁶ homo contraceptivus compete with homo progenitiva,” he wondered in private correspondence, “if borders aren’t controlled?”

Tanton thought the population control movement needed to do something about it. “I started writing to ZPG,” he recalls, “and saying, ‘If you’re interested in numbers of people, what difference does it make whether they’re born here or they move here?’ ”

They couldn’t see any. ZPG invited Tanton to write background papers to help the group develop positions on immigration policy. Environmentalists in the population control movement 37 shifted their focus from too many people in the world to too many people in the nation. The National Wildlife Federation resolved to support restrictions on immigration as part of its environmental platform. Top environmental thinkers such as the ecologist David Pimentel, the conservation biologist Thomas Lovejoy, the sustainable development advocate L. Hunter Lovins, the Blue Planet Prize–winning economist Herman Daly, and others served as board members or advisers to groups such as the Carrying Capacity Network, which called for an immediate moratorium on immigration into the United States.

Tanton quickly ascended³⁸ to the upper echelons of the ZPG movement. He joined the board. He became friendly with Ehrlich and Hardin. By 1975 he was president of ZPG. The group called for slashing immigration into the United States by 90 percent.

For too long, Tanton wrote in a cover article for The Ecologist magazine, environmentalists had been overly focused on reducing the birth rate, allowing the “role of international migration in perpetuating³⁹ population growth” to escape notice. The growing size of the human population “dwarfs the absorptive capacity of the few countries still willing to receive legal (and certainly illegal) immigrants,” he wrote.

The only solution was to do as the bees did: evict the surplus and close the borders.

The July 4, 1977, edition of the Washington Post landed with a thud on millions of doorsteps, with an explosive two-thousand-word exposé of India’s population control program 40 on its front page.

The reporter who’d written it had traveled through small villages across India, reporting on the front lines of the global war on out-of-control population growth. He’d visited a small village of mostly poor Muslim families about two hours south of New Delhi called Uttawar, where electrical service had been abruptly cut off in 1976. The villagers had no idea why, they told the Post reporter, until a small contingent of police officers and local politicians arrived to explain.

They’d turned the electricity off on purpose, they said. And they’d turn it back on only if the local men agreed to undergo vasectomies.

The people of Uttawar were so reluctant to get vasectomies that they managed without electricity for two months. Finally the authorities could wait no longer. At three o’clock one November morning, a booming loudspeaker awakened the sleeping villagers. A police officer announced that the village had been surrounded by armed guards equipped with gasoline. “Do not try to run,” the officer said. “We will shoot you and burn the village down. All men and boys come out quietly.”

Terrified men and boys trickled out of their homes and into a waiting line of trucks and buses, which whisked them away under the dawn sky. They hustled the boys to a local jail. The men were sent to an outdoor clinic where clinicians took a scalpel to their groins.

The Post report added to a steady trickle of tales of abuse and violence committed in the war against Malthusian catastrophe. The Indian government had deprived those without proof of sterilization of ration cards and land allotments. It paid people to snitch on neighbors who avoided the surgeries. Botched vasectomies conducted in ad hoc open-air clinics like the one in Uttawar killed over two hundred Indian men.

The violations did not stop at the Indian border. In China, seven-months-pregnant women were forced to undergo abortions. In the United States, a dozen states considered passing laws⁴¹ requiring women on welfare to undergo sterilization. African American teenagers were forcibly sterilized at federally funded family planning clinics.

Outraged feminists attacked Ehrlich as the mastermind⁴² behind the widespread human rights abuses. Groups such as Women Against Genocide showed up at Ehrlich’s public appearances, handing out leaflets titled “Bomb Ehrlich.”

Ehrlich was forced to backtrack. He blamed the excesses of his call to action on the uncertainties of the science on which it had been based. The book “had its flaws,” he allowed, but only because “science never produces certainty.” At the same time, he admitted that the book hadn’t really been rooted in science at all, despite the fact that he had long capitalized on his gravitas as a scientist and a Stanford professor to promote it. The Population Bomb, he said, had been a “propaganda piece,” aimed at galvanizing interest in environmental protection. “I was trying to get something done,”43 he said.

By the time the population control movement crashed,⁴⁴ the demographic trends that had fueled its ascent reversed themselves.

Thanks to people working together to develop and share new technology, improve education, and modernize societies, the pull of the demographic transition—by which people have fewer babies when the death rate falls—asserted itself over the postwar Malthusian blip. The U.S. birth rate had started to decline in 1955, even as millions of Americans panicked about a coming population explosion. By 1972 it had fallen below the level recommended by ZPG. Global population growth had peaked too. Demographic transition theory reestablished its authority. A 2009 Nature paper called it “one of the most solidly established and generally accepted empirical regularities in the social sciences.”

Activists concerned about the state of the environment 45 turned to less contentious ways to protect nature than railing about poor people’s reproductive habits. Those concerned about poverty turned to the incrementalist socioeconomic development programs they’d discarded earlier. While population control efforts remained an important—and highly contested—part of international development programs, the population problem faded from the headlines. Within a handful of years, writes the historian Thomas Robertson, “despite isolated pockets, population had fallen off the national agenda almost entirely.”

Quietly, out of the public eye, ecologists started to rethink the infamous raft of studies and observations that they’d trumpeted as proof of incipient Malthusian collapse. The depraved rats in their Baltimore enclosure; the lichen-killing reindeer hordes of St. Matthew; the clouds of smog above Los Angeles; the predictions of impending famine: all came to be seen in a new light.

They resurrected the work of the University of Chicago ecologist Warder Clyde Allee, who had documented the positive effects of population density,46 and even the negative effects of low population density, back in the 1930s. Allee spent his summers at the marine biological lab at Woods Hole, where he walked along the coast of Cape Cod for hours, collecting creatures he found along the shore. He had noticed how, in his glass-bottomed bucket, the snakes and starfish he collected tended to clump together tightly and how, in the eelgrass that washed up with the tide, the starfish never appeared alone but always in groups. He wondered whether there was some reason why.

In a series of what would later be hailed as “unambiguous” experiments⁴⁷ in an “impressive range of taxa and ecosystems,” Allee found that crowding actually improves the survival of individuals. A group of goldfish, he found, can survive in a liter of poisoned water for 507 minutes; a single goldfish, in contrast, can survive the same water for only 182 minutes. A clump of worms snuggled together can survive UV radiation 1.5 times longer than a single worm that slithers off on its own. Sea urchins and frogs that live close to one another lay higher densities of fertilized eggs than those spread out over long distances, and their eggs develop faster. Allee even figured out some of the mechanisms by which crowding improves life for individuals, for example by allowing aquatic creatures to benefit from the protective chemicals secreted by others, which are otherwise too diluted to have an effect.

Bringing individuals together, in other words,48 produces varying forms of social cooperation, which help individuals survive and thrive. It is why fish form schools in the sea, why birds flock, why mammals travel together in herds, and even why, Allee suspected, newcomers form neighborhoods when they settle in strange new cities. Ecologists called it the “Allee effect.” Experts from a range of fields recognize the phenomenon, too. Modern neuroscientists call it the “hive mind.”

In other words, ecologists who’d adopted the simple Malthusian calculation had left out an important part of the equation. They considered the costs of each additional human being: more mouths to feed, more cars on the road, more stress on natural resources. But they hadn’t considered the benefits.

The Allee effect shed new light on the tragedies of the Kaibab and St. Matthew Island. The collapse of the ungulate populations in these predator-free locales shocked because they’d been characterized as places of easy living where the ungulates should have thrived. But the deep canyons encircling the Kaibab tablelands and the towering cliffs and Arctic seas surrounding St. Matthew also meant that the deer and the reindeer could not move.

The reindeer had trampled their lichens not because their crowds were too dense but because they were marooned. The Kaibab and St. Matthew Island were not paradises for the ungulates, despite being predator-free. They were prisons.

New understandings about the benefits of social cooperation explained why the catastrophic effects of population growth that Ehrlich and the other Malthusian ecologists warned about failed to materialize. Ehrlich’s argument that the world would run out of nutritious food had relied heavily on Vogt’s predictions that countries such as Mexico would soon be unable to sustain their growing populations. But he hadn’t taken into account that working cooperatively together allows people to innovate more efficient agricultural and other technology. Instead of a growing population outstripping the food supply, the food supply expanded. Between 1944 and 1963, Mexico’s production of wheat grew by a factor of six.

The innovative capacity of groups of people 49 working together created new technology and collective actions that controlled environmental problems such as California smog, which the Malthusian ecologists had presumed would inexorably worsen as the state population continued to grow. Instead, catalytic converters and regulations on vehicle emissions lifted the blanket of smog over California’s valleys, even as the number of people and cars in the state continued to climb. While technology and social cooperation were no cure-all, they formed an important counterweight to the costs of population growth.

The scientific basis for Ehrlich’s claims about the social depravity of crowds had started to disintegrate almost as soon as he’d made them. In a 1971 paper that described the scientific research underlying The Population Bomb, Ehrlich had written that crowding “may increase aggressiveness in human males.” He’d cited as proof the research of Jonathan L. Freedman, the social psychologist he’d encouraged to conduct studies in humans of the social depravity Calhoun had found in rats, although at the time Freedman had yet to publish the results of his research. When he did, about a year later, he reported just the opposite, a reversal similar to Harry Shapiro’s after visiting Pitcairn Island. “Crowding does not have a generally negative effect on humans,” Freedman wrote, and “what effects it does have are mediated by other factors in the situation.” In a book based on his research, he celebrated the benefits of high-density living.

Later research even mitigated the finding of social depravity among Calhoun’s rats, jammed into their enclosures. Calhoun had later seen Allee effects, too. In one experiment, crowding had led the rats to innovate new ways of building burrows. Inspired, a National Geographic writer who’d visited Calhoun’s lab wrote one of my all-time favorite children’s books, Mrs. Frisby and the Rats of NIMH, in which a mouse family is saved by the superintelligent rats bred at the National Institute of Mental Health.

But while the social panic about out-of-control population growth diminished, deflated by demographic shifts and political scandal, the movement to make migration as difficult and deadly as possible not only persisted, it grew.

In 1979 the Michigan ophthalmologist John Tanton spun off ZPG’s immigration committee 50 into a new group aimed entirely at restricting immigration called the Federation for American Immigration Reform. He and his allies created a slew of associated organizations, all focused on cracking down on the flow of migrants into the country. Within a few years, Tanton’s antimigrant network included the Center for Immigration Studies, an anti-immigration think tank; NumbersUSA, an anti-immigration lobby group; U.S. English, a group that opposed the bilingual education that newly arrived immigrants relied on; and Social Contract Press, a publishing outfit specializing in anti-immigrant literature.

Tanton’s goal was to “make the restriction of immigration a legitimate position for thinking people.” For a while, liberal advocates were broadly sympathetic to his economic and environmental arguments against migrants. In the 1980s and ’90s, elements on both sides of the political spectrum aligned both for and against immigration, with corporate interests and their partisan allies broadly aligned in favor of immigration and labor unions and their partisan allies arguing that immigrants drove down wages and had a negative impact on the environment. Garrett Hardin and Anne Ehrlich served on the board of Tanton’s Federation for American Immigration Reform.

Like Ehrlich, who primed his readers and viewers to accept the necessity of authoritarian measures, Tanton gently helped his supporters disregard 51 those who might call his antimigrant positions “racist.” For too long, he’d tell them, environmentalists had been averse to discussing the truth about immigration because of the “seamy history” of “xenophobia and racism” that surrounded it. But those who truly cared about the planet and its people knew better. “We’re not anti-immigrant,” he’d say, “just as someone on a diet is not anti-food.” It’s just that “we have to address the finitude of resources,” and because foreigners were unfailingly fecund and backward, “we can’t do that by moving people around.”

It worked, for a while.52 Then in 1988 the Arizona Republic exposed Tanton’s private remarks describing foreigners as a lasciviously breeding subspecies. The civil rights group the Southern Poverty Law Center listed Tanton and his organizations on its damning list of hate groups. The conservative commentator and George W. Bush adviser Linda Chavez, who’d served as president of NumbersUSA, resigned in protest, decrying Tanton’s “anti-Catholic and anti-Hispanic bias.” “Any hope of significant liberal support,” the New York Times noted, “vanished.”

The gap between the two movements birthed by the population panic widened. Brower and a faction of anti-immigration activists 53 within the Sierra Club brought the growing tension to a head by proposing that the group explicitly adopt an anti-immigration policy as part of its environmental platform. “Overpopulation is a very serious problem,” Brower explained, “and overimmigration is a big part of it.” A coalition of feminist and civil rights activists objected. After a series of bitter fights that ended with Brower’s resignation from the Sierra Club board, the proposal was defeated.

The break with the mainstream environmental movement freed Tanton to reach deeper into other circles. Eco-nativists, worried about the impact of foreign peoples on the environment, flocked to the Tanton network. So did social nativists worried about the degrading effect of foreign cultures, eugenicists concerned about foreigners’ impact on the gene pool, and white supremacists worried about the diminishment of their political power. Tanton invited their leaders into his home, supported their leading thinkers, and disseminated their ideas and writings through his publishing company.

That included what Politico would later call the “bible of the alt-right,” a dystopic 1973 French novel called The Camp of the Saints 54. In the novel “swarthy hordes” of Indian migrants, described as “grotesque little beggars from the streets of Calcutta” who eat feces, invade France, force white women to work in brothels, and engage in orgies involving men, women, and children. The far-right French leader Marine Le Pen kept a dedicated copy in her desk. The former Breitbart chairman Steve Bannon considered the novel prescient and visionary. He suggested that the flow of migrants across the Mediterranean Sea would create a similarly horrific social meltdown. He called it an “almost Camp of the Saints–type invasion.”

Tanton’s organizations reconstructed the Fortress America 55 that Grant and Osborn had built. They successfully led efforts to defeat a 2007 bill that would have provided legal status to millions of people who’d crossed the border without permission; they mobilized opposition that successfully defeated the DREAM Act, which would have provided legal status to those brought to the United States without permission as children; they helped write the notorious “show-me-your-papers” law implemented in Arizona, under which the failure to show valid immigration documents became a state crime.

After the war in Syria began in 2011, a new social panic about migrants erupted,56 creating another political opening for Tanton’s network. The Trump administration tapped people from Tanton’s organizations to oversee immigration policy. The office tasked with helping immigrants whose visas and citizenship applications had been denied or delayed would be overseen by Julie Kirchner, a former executive director of the Federation for American Immigration Reform. The administration’s panel on election integrity would be led by the group’s legal counsel, Kris Kobach. The head of the organization’s polling firm, Kellyanne Conway, would become one of the president’s top advisers. The federation’s director of lobbying, Robert Law, would serve as a senior policy adviser to the Trump administration’s U.S. Citizenship and Immigration Services, where he’d recommend that the government reduce the number of refugees it admitted and end the practice of automatically granting citizenship to people born in the United States.

In 2018 thirty-two of the thirty-four representatives 57 in Congress who had earned an A-plus rating from NumbersUSA won reelection; the former Alabama senator who had been the subject of effusive press releases and awards from the organization, Jeff Sessions, ascended to the office of the attorney general. Sessions’s aide, Stephen Miller, rose to become one of President Trump’s chief policy advisers and speechwriters. He crafted the administration’s immigration policies, including a 2017 executive order banning people from several majority-Muslim countries from traveling to the United States at all.

Tanton died in the summer of 2019. By then his antimigrant ideology had reached the highest echelons of global power. In the White House and the halls of Congress, a gaseous mixture of three hundred years of outdated scientific ideas wafted freely.

Antimigrant politicians and advocates described their vision of biological inheritance as Grant and Osborn had, as if complex traits passed down unchanged from generation to generation. “You have to have the right genes,”58 Trump said. “I have great genes,” he announced. “I’m proud to have German blood,” he added. “Great stuff.” He had a “genetic gift,” he said, for business. His Treasury secretary agreed: “He’s got perfect genes.” The Trump family, one of Trump’s sons said, subscribed to the “racehorse theory” of inheritance, which “places a high value on bloodlines.”

They referred to the inferior biology of people of African descent, as Linnaeus had. “Some people,” noted Trump adviser Steve Bannon, in reference to black people shot by police, are “naturally aggressive and violent.” “Laziness is a trait in blacks,” Trump said. “Some people cannot, genetically, handle pressure,” he added. “Go out in nature,” said a Republican nominee for Illinois representative, “and you don’t find equality anywhere … I don’t believe in this doctrine of racial equality.”59

They implied that mixing biologically distinct peoples⁶⁰ disrupted the natural order, as early twentieth-century eugenicists had. “ ‘Diversity’ is not our strength,” one of President Trump’s national security officials wrote. “It’s a source of weakness, tension, and disunion.”

They argued for the restoration of a Linnaean vision of nature, in which biologically distinct peoples lived separately in geographically distinct locales. “Defined, ethnically and racially homogenous homelands” were the goal, as one white nationalist and Trump supporter put it. “We can’t restore our civilization with somebody else’s babies,” said Steve King, a Republican representative from Iowa.

Antimigrant politicians in the United States mostly refrained from discussing environmental problems of any kind. But antimigrant politicians in Europe, echoing Aldo Leopold, Garrett Hardin, and the other neo-Malthusian ecologists, openly denounced migrants for the environmental burden they supposedly exacted. The antimigrant politician Marine Le Pen planned to remake Europe as “the world’s first ecological civilization” by closing the borders to migrants. “Nomadic” people, she claimed, “do not care about the environment.” “Borders are the environment’s greatest ally,” a spokesperson from her party added. Unhinged advocates agreed. Twenty-eight-year-old Brenton Tarrant from Australia, who aimed to repel migrants fleeing climate change, took matters into his own hands. In the spring of 2019 he slaughtered fifty-one worshippers at two mosques in Christchurch, New Zealand. A twenty-one-year-old from Dallas named Patrick Crusius allegedly claimed that “if we can get rid of enough people,61 then our way of life can become more sustainable.” In the summer of 2019 he drove 650 miles southwest to the border to stop what he called a “Hispanic invasion.” He opened fire at a Walmart in El Paso, Texas, killing twenty-two in the third-deadliest mass shooting the state had ever seen.

“Let them call you racists,”62 Bannon said in a speech to an antimigrant party in France. “Let them call you xenophobes. Let them call you nativists. Wear it as a badge of honor … History is on our side.”

Antimigrant advocates like Bannon imagined a version of the past that biologists had championed for centuries. It was one in which peoples lived separately in long isolation, adapting to their distinct landscapes and differentiating from each other. It was one in which migration’s proper role was to rid ecosystems of excess individuals, and in which the movement of peoples across landscapes and biological borders presaged ecological doom. It was one in which modern migration, by bringing biologically distinct people together, disrupted the natural order.

That vision had been laid out over centuries. But when scientists finally turned their attention to probing its details, they found that most of it was wrong.