David Reich — How one small tribe conquered the world 70,000 years ago

Ancient DNA analysis is fundamentally rewriting human history, revealing that modern humans are not a static lineage but the product of repeated, complex admixture events. Standard evolutionary models, which once treated Neanderthals and Denisovans as simple sister groups, fail to account for the deep, messy genetic connections uncovered by recent sequencing. Human history is characterized by a chaotic "archipelago" of small, isolated groups that frequently went extinct, with survival often determined by contingency and cultural innovation rather than innate biological superiority. Pathogens like *Yersinia pestis* have played a pivotal, often overlooked role in these population replacements, disrupting societies and enabling the spread of new groups, such as the Yamnaya in Bronze Age Europe. Genetic data now suggests that human evolution is defined by constant, profound migration and interbreeding, challenging long-held assumptions about our origins and the nature of human diversity.