Recovering signals of ghost archaic introgression in African populations [19 percent archaic DNA not found in asians or caucasians] 'While introgression from Neanderthals and Denisovans has been documented in modern humans outside Africa...Our results reveal the substantial contribution of archaic ancestry in shaping the gene pool of present-day West African populations. https://www.science.org/doi/10.1126/sciadv.aax5097