‘The Next Great Migration’ Review: A World in Motion

In 2009, people in Tibet began to suffer from a novel form of unpleasantness—unconnected to the torment of living under Chinese rule. There were widespread reports of “strange itchy bites,” the first time anyone in that elevated tundra on the northern side of the Himalayas “could ever remember being bit by a mosquito.”

So writes Sonia Shah, an accomplished science journalist and the author of “The Next Great Migration.” A quick search on the internet—prompted by a disbelief likely in anyone plagued by this omnipresent insect—turns up scientific papers that corroborate her story. Mosquitoes had indeed, about a decade ago, made a home in Tibet, no doubt in response to changing temperatures and patterns of forestation. Put simply: The mosquitoes had migrated. Just as people do.

Human-rights groups are inclined to assert that there’s a moral right to migrate inherent in all persons, accompanied by a right to be resettled. Ms. Shah, equally liberal in her politics, states her case differently: She asserts the existence of an irrepressible “migratory impulse” that is embedded not just in human nature but in the nature of all living things. Fish migrate. Birds migrate. War-ravaged Syrians migrate. Even coral reefs migrate: Scientists have discovered two reef species off Japan that move northward at a rate of nearly 9 miles every year.

Ms. Shah is quick to distinguish the movements of “wild species” from those of human migrants. The former are shaped by “their own biological capacities” and the “geographic features they encounter on their journeys,” such as the steepness of mountains or the swiftness of currents. By contrast, the paths taken by human migrants “are shaped primarily by abstractions.” {snip}

The statistics Ms. Shah marshals are eye-catching: Fifteen million people fled their countries in 2015, more than at any time since World War II. More people live outside their lands of birth today than at any time in recorded history. By 2045, the enlarging of deserts in sub-Saharan Africa could force 60 million people to “pick up and leave.” By 2100, rising sea levels could add an additional 180 million to their ranks. “The next great migration,” she says, “is upon us.”

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Yet she acknowledges the resistance to migrants in much of modern history, even in countries whose credo celebrates migration. In the case of the U.S., one such country, migrants came not merely from other lands but also from within national boundaries—over just a few decades, nearly six million Southern blacks, she observes, moved to the country’s industrial North. By the turn of the 20th century, “immigrants and their progeny” outnumbered those whose parents had been born in the U.S.

America’s “scientific elites” at the time, says Ms. Shah, were obsessed with the “biological menace of migration”—a eugenicist fear that a mixing of peoples would result in a rise in crime and disease. She argues that the roots of their resistance to incomers—which continues on the less-elite nativist right to this day—traces back to the 18th century, “when European naturalists first started cataloging the natural world.” Western Christian civilization came to see people and species as being “from” specific places that had been determined for them by the Creator.

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There are a few places in this thoughtful and eloquent book in which readers will take issue with Ms. Shah’s narrative. For instance, having made the perfectly good assertion that economists have “long struggled to detect” any negative economic effect of migrants on locals, she makes the overwrought claim that, in a 2015 study, George Borjas, a Harvard economist, “overturned” a near-consensus on the positive nature of migration. {snip}

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