My fountain of youth? Why, it’s up in the trees
Living in the trees may be the secret to longevity – in the evolutionary long run, at least. Tree-dwelling mammals live nearly twice as long as their ground-bound cousins.
Evolutionary biologists have long predicted that natural selection should favour extending the lifespan of animals that live relatively safe lifestyles. And in fact, birds and bats, whose ability to fly helps them escape from predators, do have particularly long lives.
Like fliers, tree-dwelling mammals can easily escape many predators. To see if this might also help them live longer, biological anthropologists Milena Shattuck and Scott Williams at the University of Illinois at Urbana-Champaign gathered data on the lifespans of 776 species representing all the major groups of mammals. They discovered that the maximum lifespans of tree-dwellers were almost twice those of terrestrial species of similar sizes.
It is well established that larger mammals tend to live longer than smaller ones. The kinkajou (pictured), however, is clearly not aware of this: it is a tree-living relative of the racoon and it lives longer than the tiger, even though it is just 1/40th the size.
The team is now setting its sights on burrowing mammals, to see if life underground also reduces risk and so ultimately extends the lifespans of those species.
Journal reference: Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.0911439107
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