Non-Africans inherit 1-4% Neanderthal ancestry from admixture after out-of-Africa migration. Sub-Saharan Africans have only 0.3% Neanderthal DNA from later Eurasian back-migrations. East Asians carry 8-20% more Neanderthal DNA than Europeans due to extra admixture pulses. Oceanians derive 4-6% genome from Denisovans – mainland Asians and Africans have near-zero. Archaic DNA introgressed adaptive genes for immunity, skin pigmentation, high-altitude living, and brain function into non-Africans. Neanderthal genes purged from X chromosome and testes regions due to hybrid male infertility. No Neanderthal mtDNA or Y-chromosome in modern humans indicates Neanderthal males bred with sapiens females. Upper Paleolithic Eurasians had 4-5% Neanderthal DNA reduced to 1-2% today by purifying selection. Sub-Saharan Africans show global genetic divide from other humans lacking Neanderthal introgression. North Africans have Neanderthal DNA levels matching or exceeding Eurasians tied to indigenous ancestry. Denisovan admixture highest in Papuans and Philippine Negritos up to 40% more than other groups. Neanderthal alleles influence modern skull shape, brain morphology, cholesterol, schizophrenia risk, and eating disorders. Archaic introgression shifted consensus from Out-of-Africa replacement to assimilation model. Fossils like Oase 1 show up to 9% Neanderthal DNA in early Europeans diluted by selection.