It’s 1980, and a Buddhist monk is trekking through the mountainous terrain of the Tibetan Plateau. Eventually, at an altitude of more than 10,000 feet, he comes to the opening of a curious cave. Here, he finds what appears to be the ancient remains of a jaw. At this point in time, this individual can’t possibly understand how important his find will one day prove to be. But in reality, it’ll ultimately shed light on a special genetic trait exhibited by the Tibetan people of today.