We are currently the only human species alive, but as recently as 24,000 years ago another one walked the earth — the Neanderthals.
These extinct humans were the closest relatives we had, and tantalizing new hints from researchers suggest that we might have been intimately close indeed. The mystery of whether Neanderthals and us had sex might be solved if the entire Neanderthal genome is reported soon as expected. The matter of why they died and we succeeded, however, remains an open question.
Maybe not nasty and brutish, but still short
First recognized in the Neander Valley in Germany in 1856, Neanderthals revealed that modern humans possess a rich and complex family tree that includes now-extinct relatives.