Humans share 99.9% of the same genetic information, and are 99% similar to chimpanzees. Although humans have less genetic diversity than many other species [? ], polymorphisms in populations can nonetheless lead to differences in disease risk. Learning about the 0.1% difference between humans can be used to understand population history, trace lineages, predict disease, and analyze natural selection trends.
In this lecture, Dr. David Reich of Harvard Medical School describes three historic examples of gene flow between human populations: gene flow between Africans and Europeans due to the slave trade, Indian intermixing due to migration, and interbreeding between Neanderthals, Denisovans and modern humans of Western Eurasian decent.