A mandible from the Tibetan Plateau shows the ancient humans adapted to harsh climates long before us.
On the mountainous Tibetan Plateau, small groups of nomadic herders still make a living two miles or more above sea level. Most of us would be poorly-equipped to deal with that altitude for long periods of time, but the Tibetans there have unique genetic adaptations that let their bodies function in the thin air.
Mysteriously, those genes seem to come from another species of human, the Denisovans, a little-understood group of hominins who died out tens of thousands of years ago. Until now, Denisovan remains had only been found in a single cave, at low altitude. That left the extinct species' high-altitude genes, like much else about their people, a puzzle. But the discovery of new Denisovan remains in Tibet might begin to change that.