At very high altitudes, the air holds less oxygen. Recent research has revealed how people living 13,000 feet above sea level in the mountains of Tibet have adapted to their
oxygen-poor environment. The Tibetan population, as a consequence of living at high
altitude for thousands of years, has developed several characteristics that allow them to
survive and thrive in this type of environment. These characteristics enable Tibetans to
tolerate hypoxia, or low oxygen levels. For example, compared to lowland peoples,
Tibetans have greater lung capacity, the ability to generate a higher maximum heart rate
when exercising, and a higher density of capillaries in their muscles. Scientists have
identified many other adaptive traits as well. Some of these adaptations are linked with
specific genes, thus allowing the traits to be passed from one generation to the next.