Non-Africans carry 2-4% Neanderthal DNA. Neanderthal DNA depletes near functional genes due to Neanderthals' 40% lower fitness. Lower Neanderthal fitness explains depletion without needing harmful epistasis. Non-Africans suffer residual Neanderthal mutational load cutting fitness by at least 0.5%. This Neanderthal load was ignored in African-non-African mutation load debates. Africans lack Neanderthal admixture and thus avoid this fitness cost. Recessive deleterious mutations allow Neanderthal haplotypes to protect against recent human mutations. Neanderthal admixture fraction rises over time via heterosis if mutations recessive. Simulations confirm Neanderthal fitness 40% below humans. Neanderthal inbreeding and mutation distributions predict observed introgression patterns. Archaic admixture persists due to adaptive benefits outweighing load in some cases. Non-Africans' Neanderthal DNA adds to their mutation load versus Africans. Neanderthal-human hybridization left lasting deleterious genetic burden in Eurasians.