David Reich – Why the Bronze Age was an inflection point in human evolution

Ancient DNA analysis reveals that natural selection has been rampant in human history, contrary to previous findings that suggested a quiescent evolutionary period. By analyzing 16,000 ancient human genomes, researchers identified thousands of genetic variants under selection, with a marked intensification during the Bronze Age. This period served as an evolutionary inflection point, forcing populations to adapt to new agricultural diets, high-density living, and emerging infectious diseases. While immune and metabolic traits show the strongest signals of adaptation, complex traits like cognitive performance also exhibit systematic shifts. Furthermore, the data challenges traditional models of human evolution, suggesting that modern humans, Neanderthals, and Denisovans share a more complex history of interbreeding and cultural exchange than previously understood. This research demonstrates that human populations possess the latent genetic variation necessary to rapidly adapt to environmental shocks within mere thousands of years.