All modern humans trace to African ancestors. Greatest human genetic diversity exists within Africa. Non-Africans carry reduced gene pool from small migrant group out of Africa. Genetic bottleneck out of Africa occurred around 60,000 years ago. African hunter-gatherers split from non-African ancestors 130,000 years ago. West Africans diverged from other Africans around 90,000 years ago. Substantial population substructure existed in Africa before out-of-Africa migration. Ancestors of Sahulians split from Eurasians 51,000-72,000 years ago. Denisovan admixture highest in Sahulians due to early split. Possible extra out-of-Africa migration 120,000 years ago visible in some Sahulians. Neanderthal admixture occurred in Eurasians. Less genetic variation between non-Africans than within Africans due to serial founder effects. African genomes show deeper divergence times than non-African ones. Pioneers reached Australia rapidly after leaving Africa. Second migration into East Asia from West Eurasia occurred later.