Four West African populations trace 8% genetic ancestry to archaic hominin. Archaic hominin branched off human line over 600,000 years ago, predating Neanderthals by 100,000 years. Populations include Yoruba and Esan of Nigeria, Mende of Sierra Leone, and Gambians. Study provides strongest evidence yet of human-archaic intermixing in Africa. Statistical methods detect archaic DNA without fossil reference. Archaic is close evolutionary relative of humans. Intermixture occurred hundreds of thousands of years ago. Results consistent across two new statistical methods. Analyzed DNA from 405 people in 1000 Genomes Project. Evidence supports complex African evolutionary history with ghost population admixture. Modern Africans show genomic patterns of archaic introgression. Neanderthal DNA found outside Africa – Denisovan in Asia/Oceania – now archaic ghost in West Africa. Archaeological evidence of coexistence and mixing in Africa. No usable archaic DNA from African fossils yet. Findings challenge simple out-of-Africa models by revealing deep African hybridization.