Genetic split occurred 520-630 thousand years ago between ancestors of modern humans and Neanderthals. Common ancestral genetic variation persists largely in modern humans. Modern humans evolved new DNA changes after the split. New SARGE method identifies genome portions unique to modern humans. Unique DNA not present in shared ancestors with Neanderthals or Denisovans. Unique DNA not from interbreeding with Neanderthals or Denisovans. Analysis covered one Denisovan, two Neanderthal, and 279 modern human genomes. Non-Africans carry 1.5-2.1% Neanderthal ancestry. Individual Neanderthal DNA varies, but 40% of Neanderthal genome reconstructible from modern human populations. Unique human mutations mainly affect brain development genes. Studying these mutations reveals cognitive differences from Neanderthals. Neanderthals extinct 40,000 years ago but DNA persists in humans. Modern humans inherited much DNA from common ancestors. Interbreeding added more archaic DNA to human gene pool.