Who We Are and How We Got Here: Ancient DNA and the New Science of the Human Past

by David Reich

Aurignacian,

Event Three was the coming of the people who made

Gravettian

Instead, his closest relatives today are the people of Sardinia, an island in the Mediterranean Sea.

Yamnaya—led

Kossinna’s ideas were embraced by the Nazis, and although he died in

The obvious candidate for dispersing most of today’s Indo-European languages is thus the Yamnaya, who depended on the technology of wagons and wheels that became widespread around five thousand years ago.

South Asian culture

The Indian subcontinent is one of the breadbaskets of the world—today it feeds a quarter of the world’s population—and it has been one of the great population centers ever since modern humans expanded

Andaman Island My research into the prehistory of India began in 2007 with a book and a letter. The book was The History and Geography of Human Genes, Luca Cavalli-Sforza’s magnum

earliest expansions of modern humans out of Africa, perhaps

India, which affected nearly every group. So between four thousand and three thousand years ago—just

which means

Zellweger syndrome, and one of my mother’s first cousins died young of Riley-Day syndrome, or familial dysautonomia, another

eight hundred years ago, and were at the crossroads of all these

the Clovis culture were the first humans south of the ice sheets,

Pottery was first invented there at least nineteen thousand years ago.1 It was the jumping-off point for the peopling of the Americas before fifteen thousand years ago. East Asia witnessed

corresponding to mutations that rose to extreme frequencies in the first

“ancestry” is not a euphemism, nor is it synonymous with “race.” Instead, the term is born of an urgent need to come up with a precise language to discuss genetic differences among people at a time when scientific developments have finally provided the tools to detect them. It is now undeniable that there are nontrivial average genetic differences across populations in multiple traits, and the race vocabulary is too ill-defined and too loaded with historical baggage to be helpful. If we continue to use it we will not be able to escape the current debate, which is mired in an argument between two indefensible positions. On the one side there are beliefs about the nature of the differences that are grounded in bigotry and have little basis in reality. On the other side there is the idea that any biological differences among populations are so modest that as a matter of social policy they can be ignored and papered over. It is time to move on from this paralyzing false dichotomy and to figure out what the genome is actually telling us.

The person who has most recently made a prominent argument that there is a genetic basis to stereotypes about differences across human populations is the New York Times journalist Nicholas Wade, who in 2014 published A Troublesome Inheritance: Genes, Race and Human History.37

The pleasure Watson takes in challenging establishment views is legendary. His obstreperousness may have been important to his success as a scientist. But now as an eighty-two-year-old man, his intellectual rigor was gone,

Writing now, I shudder to think of Watson, or of Wade, or their forebears, behind my shoulder. The history of science has revealed, again and again, the danger of trusting one’s instincts or of being led astray by one’s biases—of being too convinced that one knows the truth. From the errors of thinking that the sun revolves around the earth, that the human lineage separated from the great ape lineage tens of millions of years ago, and that the present-day human population structure is fifty thousand years old whereas in fact we know that it was forged through population mixtures largely over the last five thousand years—from

33 percent higher genetic diversity in West Africans than in Europeans.48 Whether or not this explains the dominance of West Africans in sprinting, for many biological traits—including cognitive ones—there is expected to be a higher proportion of sub-Saharan Africans with extreme genetically predicted abilities.

The real offense of racism, in the end, is to judge individuals by a supposed stereotype of their group—to ignore the fact that when applied to specific individuals, stereotypes are almost always misleading. Statements such as “You are black, you must be musical” or “You are Jewish, you must be smart” are unquestionably very harmful. Everyone is his or her own person with unique strengths and weaknesses, and should be treated as such. Suppose you are the coach of a track-and-field team, and a young person walks on and asks to try out for the hundred-meter race, in which people of West African ancestry are statistically highly overrepresented, suggesting the possibility that genetics may play a role.

in Britain, we know that beginning after forty-five hundred years ago with people who buried their dead in association with wide-mouthed Bell Beaker pots, ancient Britons harbored a blend of ancestries

Ancient DNA research also reveals pathogen evolution. When grinding up human remains, we sometimes encounter DNA from microorganisms that were in an individual’s bloodstream when he or she died and so were the likely cause of death. This approach proved that the bacterium Yersinia pestis was the cause of the fourteenth-to-seventeenth-century CE Black Death,14 the sixth-to-eighth-century CE Justinianic plague of the Roman Empire,15 and an endemic plague that was responsible for at least about 7 percent of deaths in skeletons from burials across the Eurasian steppe after around five thousand years ago.16 Ancient pathogen studies have also revealed the history and origins of ancient leprosy,17 tuberculosis,18 and, in plants, the Irish potato famine.19

He said all human graves are sacrosanct, but there are mitigating circumstances that make it permissible to open graves as long as there is potential to promote understanding, to break down barriers between people.