IGX

The story of how modern humans came to be is still complicated and murky, but there’s one thing that’s become very clear over the last decade of research: humans loved to get down, even with other species—that’s why nearly everyone whose ancestors migrated out of Africa possesses at least some lingering bits of Neanderthal DNA.

As it turns out, those experiences in interspecies mating were far from isolated one-night stands. According to a new analysis of gene ancestry data published Monday in Nature Ecology & Evolution, populations of humans and Neanderthals mated and procreated multiple times over during the 30,000 years when the two species overlapped. Our snippets of Neanderthal DNA are not the result of one-off hookups.