By Justin Boggs

Previous evidence suggests that living at higher altitudes leads to longer life spans for humans. Scientists at Harvard Medical School wanted to know why.

In a study released this week of mice, evidence found restricting oxygen flow led to significantly longer lifespans. Researchers placed mice into two chambers. One set of mice was in a chamber with normal oxygen levels; another set was in a section with an oxygen level equivalent to Mount Everest's. The mice employed in the study generally have short life spans.

The group of mice with their oxygen restricted lived, on average, 24 weeks, compared to 16 weeks for those who experienced normal oxygen levels. Harvard Medical School also found the maximum lifespan for mice with oxygen restriction was about 30% longer.

The researchers also noted that oxygen-restricted mice preserved neurologic function longer.

“Epidemiological studies have hinted that populations that live at higher altitudes tend to live longer and stay healthier as they age. We wanted to test whether, in a more controlled setting, restricting oxygen appears to do the same in our mouse model of aging,” said study senior author Vamsi Mootha.

The researchers did not lower the atmospheric pressure of the oxygen-restricted chamber. Instead, they displaced some of the oxygen with nitrogen gas.

Harvard Medical School and study author Robert Rogers said in a press release that future studies should examine whether oxygen restriction can similarly extend life span in wild-type mice, should seek to define what mechanisms might be responsible for the life-extending effects of restricted oxygen, and determine whether these mechanisms affect all organs.

In 2011, the National Institutes of Health released data that found that men who live 1,500 meters above sea level live an average of 1.2 to 3.6 years longer than those who live within 100 meters of sea level. Women who live at high altitudes live an average of 0.5 to 2.5 years longer.

Cities like Albuquerque, New Mexico, and Denver sit over 1,500 meters above sea level.