Modern humans may have interbred with Neanderthals and Denisovans

Modern humans have about 1 to 3% Neanderthal DNA and some Denisovan DNA. Australian Aborigines have the highest proportion of Denisovan DNA, at about 4 to 6%. Modern Africans lack Neanderthal and Denisovan DNA. Some modern human immune system genes - HLA-A genes - contain very high proportions of DNA from these archaic cousins. So, it appears that modern humans may have mated with Neanderthals and Denisovans as the former spread out of Africa and across Eurasia, in the process gaining important disease-resi