The Next Great Migration

If the fever of xenophobia evolved as a kind of immune defense, perhaps it once helped protect us. It is no longer useful for that purpose. Modern medicine provides us with the insights and technology we need to protect ourselves from pathogens, whether we shun strangers or not. Still, the vestigial impulse to suspect outsiders lingers, lodged deep in our psyches. Politicians can harness its heat simply by pointing to a border between “us” and “them.”

In Ohio, immigration officials scooped up a businessman and deported him to Jordan. He had been living in the United States for nearly forty years and had raised four daughters. He left the country with nothing more than the clothes on his back and a few hundred dollars in his pocket. In Connecticut, they picked up a couple and deported them to China. They’d lived in the United States for nearly two decades and had been running a local nail salon. They had to leave their five-year-old and fifteen-year-old sons behind. In Iowa, a teenager who’d lived there since the age of three was deported to Mexico. He was murdered shortly after arriving.

While previous administrations had captured and deported migrants living in the interior of the country before, they’d primarily targeted those who’d been convicted of crimes. In a single year, the number of migrants living in the interior who’d been arrested shot up by 40 percent. The majority had no criminal convictions at all. Their sole violation consisted of a lack of valid immigration documents

of the world’s migrants move from one developing country to another, that is, between countries where the range of available public services varies little.

Critics, noting the unsanitary and overcrowded conditions27 in the detention centers and the unwashed, sickened, and traumatized children within them, complained that the policy amounted to state-sponsored kidnapping and child abuse. But President
Trump claimed that separating parents from their children would deter migrants. “If they feel there will be separation,” he explained, “they don’t come.” The government’s own data suggest otherwise

Our bodies have evolved, in other words, to “evade substantial ‘genetic commitment’ to local ecological conditions,” write the anthropologists Jay T. Stock and J. C. K. Wells.

past, in other words, is “no less complicated than the present,” Reich notes. We weren’t migrants once in the distant past and then again in the most recent modern era, with a long defining period of stillness in between. We’ve been migrants all along.

Human migration is not exceptional. Long isolation did not differentiate our species into separate races. Feats of navigation are not the sole province of “white gods” from the West. The oceans can be crossed by canoe.

And humans aren’t the only ones who move across the landscape, leaping over continents and oceans. Plants and animals do, too.

Geographic barriers—open oceans, mountain ranges—had not barred their wanderings. Nor had a lack of modern navigation technology. Ancient migrants washed over even the remotest regions of earth, and they’d done it successfully more than once. For years, scientists had figured that ancient peoples had migrated into the forbidding Tibetan plateau 15,000 years ago. According to new DNA analyses,41 they’d also migrated there 62,000 years ago.

No freak accident

The homogenous ancestral population that commentators such as Madison Grant and others imagined never existed. Several genetically distinct groups of people migrated into the region and variously mixed and melded with one another. From what paleogeneticists can piece together, they included dark-skinned hunter-gatherers, farmers with dark eyes and fair complexions, and
another group of farmers with light hair. The western Europeans of today are hybrid descendants like the rest of us.

When our ancestors encountered them, they did what migrants do everywhere: they had babies with the locals, a process of mixing that allowed bits of their DNA to enter ours. About 2 percent of the DNA in modern-day peoples in Europe and Asia traces back to the migratory collision with Neanderthals; and around that proportion of DNA in people now living in New Guinea and Australia traces back to the Denisovans, a group of ancient humans discovered through genetic analyses. A Denisovan gene that allows people to survive at high altitude now resides in the DNA of people living in Tibet.