New genetic data suggests that, at at least two points in history, Homo sapiens were interbreeding with other species, most likely Homo neanderthalensis or heidelbergensis.
This is pretty damn interesting, because it's a reversal on previous research. A couple of years ago, I got a chance to see Svante Pääbo, an evolutionary anthropologist with the Max Planck Institute, and kind of a big deal in the world of ancient hominid genetics, talk about this very topic. He and his team studied bits and pieces of the neanderthal genome and came to the conclusion that hanky panky hadn't happened between that species and ours. And, because it was Svante Pääbo (again, kind of a big deal) everybody trusted his results. So much so, in fact, the the University of New Mexico researchers who did this new study were surprised that their data said differently.
This is a really fun moment in science, when accepted information gets legitimately challenged. And now the ball is back in Pääbo's court. Remember, his previous neanderthal analysis was based on bits and pieces of the genome. Recently, he wrapped up a rough draft sequence of the entire genome, and, as Nature points out, what he finds there will probably be the first test of this new theory. Of course, it's also possible that both groups are right, and it's really H. heidelbergensis who was knocking boots with ancient sapiens. We'll just have to wait and find out.
Nature News: Neanderthals may have interbred with humans