Tibetans live in one of the least hospitable, and therefore one of the last populated areas on the planet: the Himalayan mountains. And their ability to handle the low-oxygen levels up there is not due to mere hardiness — it's coded into their genes.
One study compared indigenous Tibetans, who live at altitudes above 10,000 feet in the Himalayan highlands, with Han Chinese from Beijing, who are closely related genetically but live right around sea level elevation.
The researchers found that the Tibetans' blood was genetically predisposed to produce more of the oxygen-transporting hemoglobin protein. Still up for debate is when this mutation occurred, but some geneticists have estimated it happening as recently as 3,000 years ago(though unsurprisingly, archaeologists push that date much further back).
It's not just oral surgeons who are removing wisdom teeth (third molars) from human mouths — evolution is playing a part too.
On our evolutionary road to becoming humans, our big brains crowded our skulls and narrowed our jaws, making it difficult for the third row of molars to emerge from the gums.
And after we began cooking our food and developed agriculture thousands of years ago, our diet became softer. This switch to soft grains and starches required less strenuous chewing than our past hunter-gatherer diet. This meant our jaw muscles didn't grow as strong as they used to, keeping the wisdom teeth beneath the gums increasing the risk of painful and deadly infection.
A few thousand years ago, a mutation popped up that prevented wisdom teeth from growing at all. Now one in four people are missing at least one wisdom tooth. The people who are most likely to be missing at least one wisdom tooth are the Inuit of the northernmost regions of Greenland, Canada, and Alaska.