Proposing Slow Metabolism to Explain Primate Longevity

Researchers here suggest that primates - and humans especially - are comparatively long-lived among mammalian species because of differences in metabolism that lead them to burn fewer calories. There is a strong association between resting metabolic rate and longevity in mammals, although one should view this as an emergent property of other aspects of biology, such as the structure and operation of mitochondria, known to be important in aging. High metabolic rates also correlate with increased mortality within a species. This is interesting, but not really actionable when it comes to doing something about aging:

Most mammals, like the family dog or pet hamster, live a fast-paced life, reaching adulthood in a matter of months, reproducing prodigiously (if we let them), and dying in their teens if not well before. By comparison, humans and our primate relatives (apes, monkeys, tarsiers, lorises, and lemurs) have long childhoods, reproduce infrequently, and live exceptionally long lives. Primates' slow pace of life has long puzzled biologists because the mechanisms underlying it were unknown.

An international team of scientists working with primates in zoos, sanctuaries, and in the wild examined daily energy expenditure in 17 primate species, from gorillas to mouse lemurs, to test whether primates' slow pace of life results from a slow metabolism. Using a safe and non-invasive technique known as "doubly labeled water," which tracks the body's production of carbon dioxide, the researchers measured the number of calories that primates burned over a 10 day period. Combining these measurements with similar data from other studies, the team compared daily energy expenditure among primates to that of other mammals.

"The results were a real surprise. Humans, chimpanzees, baboons, and other primates expend only half the calories we'd expect for a mammal. To put that in perspective, a human - even someone with a very physically active lifestyle - would need to run a marathon each day just to approach the average daily energy expenditure of a mammal their size."



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