David Reich

David Emil Reich (born July 14, 1974) is an American geneticist known for his research into the population genetics of ancient humans, including their migrations and the mixing of populations, discovered by analysis of genome-wide patterns of mutations. He is a professor in the department of genetics at the Harvard Medical School and an associate of the Broad Institute. 

Reich was highlighted as one of Nature's 10 for his contributions to science in 2015. He received the Dan David Prize in 2017, the NAS Award in Molecular Biology, the Wiley Prize, and the Darwin–Wallace Medal in 2019. In 2021 he was awarded the Massry Prize. Reich grew up as part of a Jewish family in Washington, D.C. His parents are novelist Tova Reich (sister of Rabbi Avi Weiss) and Walter Reich, a professor at George Washington University, who served as the first director of the United States Holocaust Memorial Museum. 

David Reich started out as a sociology major as an undergraduate at Harvard College but later turned his attention to physics and medicine. After graduation, he attended the University of Oxford, originally with the intent of preparing for medical school. He was awarded a Ph.D. in zoology in 1999 for research supervised by David Goldstein. His thesis was titled "Genetic analysis of human evolutionary history with implications for gene mapping."

Reich received a BA in physics from Harvard University and a Ph.D. in zoology from St. Catherine's College at the University of Oxford. He joined Harvard Medical School in 2003. Reich is currently a geneticist and professor in the department of genetics at Harvard Medical School and an associate of the Broad Institute, whose research studies compare the modern human genome with those of chimpanzees, Neanderthals, and Denisovans.

Reich's genetics research focuses primarily on finding complex genetic patterns that cause susceptibility to common diseases among large populations rather than looking for specific genetic markers associated with relatively rare illnesses.

Reich's research team at Harvard University has produced evidence that, over a span of at least four million years, various parts of the human genome diverged gradually from those of chimpanzees. The split between the human and chimpanzee lineages may have occurred millions of years later than fossilized bones suggest, and the break may not have been as clean as previously thought. 

The genetic evidence developed by Reich's team suggests that after the two species initially separated, they may have continued interbreeding for several million years. A final genetic split transpired between 6.3 million and 5.4 million years ago.