Science paper isn't up yet but probably will be by the time you read it. Tibetans only split from Han less than 3,000 years ago and already they've built up a whole repertoire of genetic low-oxygen adaptations.
While that may not be a surprise, the speed with which it occurred probably is. More and more, it's becoming clear that cultural choices we make (what we eat, where we live) over time affect our genes. So this leads us back to the elephant in the room of human evolution studies. There are genes which affect cognition. Why do we think these haven't been selected differentially as well?