So far, there are two proven gene-flow events to Homo sapiens from non-sapiens: Homo neanderthalensis and from the Denisova hominin population. In the latter ca

So far, there are two proven gene-flow events to Homo sapiens from non-sapiens: Homo neanderthalensis and from the Denisova hominin population. In the latter case science isn't sure yet whether the Denisova hominin was a sub-species or species. http://en.wikipedia.org/wiki/Archaic_human_admixture_with_modern_Homo_sapiens http://en.wikipedia.org/wiki/Archaic_human_admixture_with_mo... We probably got some immunity-related genes from neanderthals, but probably not red hair - red hair in neanderthals is caused by a different mutation that doesn't exist in humans.