Who We Are and How We Got Here

shared a common ancestor as the mutations accumulate at a more or less constant rate over time. So the density of differences provides a biological stopwatch, a record of how long it has been since key events occurred in the past.

The first startling application of genetics to the study of the past involved mitochondrial DNA. This is a tiny portion of the genome only approximately 1/200,000th of it which is passed down along the maternal line from mother to daughter to granddaughter. In 1987, Allan Wilson and his colleagues sequenced a few hundred letters of mitochondrial DNA from diverse people around the world. By comparing the mutations that were different among these sequences, he and his colleagues were able to reconstruct a family tree of maternal relationships. What they found is that the deepest branch of the tree the branch that left the main trunk earliest is found today only in people of sub-Saharan African ancestry, suggesting that the ancestors of modern humans lived in Africa. In contrast, all non-Africans today descend from a later branch of the tree.2 This finding became an important part of the triumphant synthesis of archaeological and genetic and skeletal evidence that emerged in the 1980s and 1990s for the theory that modern humans descend from ancestors who lived in the last hundred thousand years or so in Africa. Based on the rate at which mutations are known to accumulate, Wilson and his colleagues estimated that the most recent African ancestor of all the branches, Mitochondrial Eve, lived sometime after 200,000 years ago.3 The best current estimate is around 160,000 years ago, although it is important to realize that like most genetic dates, this one is imprecise because of uncertainty about the true rate at which human mutations occur.4

The finding of such a recent common ancestor was exciting because it refu

simple: Who We Are . . . is mostly not a controversial book, but a wondrous one. It sheds light on the nascent field of ancient DNA, paleogenetics, which is exposing the human past by tracing population histories. Give a paleogeneticist a single genome, and they will unfurl the history of whole peoples.
India Today

"Ancient DNA is rewriting human (and Neanderthal) history. The genomes of the long dead are turning up all sorts of unexpected and controversial findings. Who We Are and How We Got Here, charts the myriad ways the study of ancient DNA is lobbing bombs into the halls of established wisdom."
The Atlantic

"A thrilling account of mapping humans through time and place. . . . Genomics and statistics have drawn back the curtain on the sort of sex and power struggles you d expect in Game of Thrones. . . . We do need a non-loaded way to talk about genetic diversity and similarities in populations. This book goes some way to starting that conversation."
Nature

In this comprehensive and provocative book, David Reich exhumes and examines fundamental questions about our origin and future using powerful evidence from human genetics. What does race mean in 2018? How alike and how unlike are we? What does identity mean? Reich s book is sobering and clear-eyed, and, in equal parts, thrilling and thought provoking. There were times that I had to stand up and clear my thoughts to continue reading this astonishing and important book.
Siddhartha Mukherjee, Pulitzer Prize-winning author of The Emperor of All Maladies
 
Reich s book reads like notes from the frontline of the 'Ancient DNA Revolution' with all the spellbinding drama and intrigue that come with such a huge transformation in our understanding of human history."
Anne Wojcicki, CEO and Co-Founder of 23andMe

In just five years, the study of ancient DNA has transformed our understanding of world prehistory. The geneticist David Reich, one of the pioneers in this field, here gives the brilliantly lucid first account of the resulting new view of human origins and of the later dispersals that went on to shape the modern world.
Colin Renfrew, Disney Professor of Archeology Emeritus, University of Cambridge
 
Reich s magisterial book gives a riveting account of human prehistory and history through the new lens provided by ancient DNA data. The story of human populations, as he shows, is ever one of widespread and repeated mixing, debunking the fiction of pure populations.
Molly Przeworski, Professor of Biological Sciences, Columbia University
 
This breathtaking book dramatically revises our understanding of the deep history of our species in our African homeland and beyond. Beautifully written, it reads like a detective novel and demonstrates a hard truth that often makes many of us uncomfortable: not only are all human beings mixed, but our intuitive understanding of the evolution of the population structure of the world around us is not to be trusted.
Henry Louis Gates Jr., University Professor, Harvard University, and Executive Producer of Finding Your Roots
 
This absorbing book will blow you away with its rich and astounding account of where we came from and why that matters. Reich tells the surprising story of how humans got to every corner of the planet, which was revealed only after he and other scientists unlocked the secrets of ancient DNA. The courageous, compassionate, and highly personal climax will transform how you think about the meaning of ancestry and race.
Daniel E. Lieberman, Professor of Human Evolutionary Biology, Harvard University, and author of The Story of the Human Body: Evolution, Health, and Disease
 
Powerful writing and extraordinary insights animate this endlessly fascinating account, by a world scientific leader, of who we modern humans are and how our ancestors arrived in the diverse corners of the world. I could not put the book down.
Robert Weinberg, Professor of Biology, Massachusetts Institute of Technology

"David Reich uses the power of modern genome analysis to show the fascinating complexity of human migration and history. By letting the data lead him, he treads a narrow path between racists and xenophobes on one side and left-wing ideologues on the other. Although many of his conclusions will be controversial, he starts a necessary conversation about what modern genome analysis can tell us about the variability of human populations."
Sir Venki Ramakrishnan, Nobel Laureate and President of the Royal Society, London


[Praise from the UK]:

"Remarkable. . . . Spectacular. . . . In making constant new discoveries about humanity, Reich and his Harvard team are now plunging into uncharted academic waters. . . . Reich s influence in this field has been immense and the output of his department monumental. . .  . Thrilling in its clarity and its scope."
The Guardian

"David Reich of Harvard Medical School is one of the leading lights in the field of ancient DNA. His team's work has cast a new perspective on human history, reconstructing the epic migrations and genetic exchanges that shaped the people of different regions worldwide."
BBC

"This is a compendious book . . . its importance cannot be overstated and neither can some of its best stories." 
Sunday Times

"Who We Are and How We Got Here provides a marvellous synthesis of the field." 
Financial Times