EXTINCT HUMAN ANCESTORS SURVIVE IN OUR GENES
For years, anthropologists suspected that Homo sapiens cross-bred with Neanderthals before our closest ancestor went extinct. That hypothesis proved officially true in 2010, with the first hard genetic evidence of Neanderthal DNA surviving in living humans, and in July further tests found even more evidence of cross-breeding. Moreover, it's not just Neanderthals that live on in us, but long-extinct, recently discovered Neanderthal cousins called Denisovans.
The functional role of formerly non-human gene variants remains to be determined, but their importance to a human sense of self is clearer: Homo sapiens isn't the product of some long, pure lineage, but a bit of a hominid mutt.