Sasless, the key IS "aclimatize", .... those who spend a lot of time at altitude are more able to function at altitude. A great example are the Sherpas in the Himilaya's. They can do more physical work at their altitudes than any flatlanders can. I'm not about to go and climb Everest, but I do spend a fair amount of time at (Rockies) altitudes.
PR, it certainly helps to have a tiny little brain that doesn't need too much 02 as well
