Altitude living vs. longevity

It would seem obvious that high-altitude living puts more demand on the body than living in lowland areas. With less oxygen to work with, the heart would have to work harder, other problems could come up, like for example mountain dwellers that suffer from hardening arteries. Yet, my research on the issue has not showed much in terms of interesting studies or scientific papers that have focused on that hypothesis.

I've even read reports to the contrary, alleging that high-altitude living could even be desirable for the body. Has anyone come across a serious study or even some basic discussions on this issue or are there any opinions worth listening to? If the subject interests you or if you have something interesting to share about it, please leave a comment and some contact information.