Live in Trees for a Longer Life?

It's recently been proven that arboreal creatures (species that live in trees) live longer than creatures on the ground. I find this interesting because it is an example about how very young the field of aging is. Researchers are still able to go into nature and make observations about the aging and longevity of different species and these observations inform theories and ideas about aging. It reminds me of reading about botany research in the 1800s, when a simple garden could provide cutting-edge insight.

Aging Observations from Nature

Two of the observations from nature that have been made are that larger animals tend to live longer (some whales, for example, can live hundreds of years) and that animals who have little external danger (e.g. they have little risk of being eaten) tend to live longer.

The theory about larger animals living longer has led to theories of aging involving metabolic rate. Smaller animals tend to have higher metabolic rates (think hyper shrews compared to sleeping lions). So, this theory of age states that aging is basically a by-product of the speed at which an organism processes food and burns energy.

The second theory attempts to explain why creatures that live in trees seem to live longer than creatures on the ground. The idea here is that animals with fewer external dangers live longer, and that over time, evolution will set in to change their basic genetics.

Birds and bats, for example, are relatively small creatures, but their life expectancy is longer than land-dwelling animals of the same size. The theory is that, by flying, these animals are generally safer than their land-dwelling counterparts. Now, researchers are looking into the same type of argument to explain why tree dwelling animals have a longer life expectancy. A study examined the life expectancy and living environments of animals (while controlling for size) and discovered that, indeed, tree-dwelling animals have greater longevity (for their size) than land-dwelling mammals.

Learning from Tree Dwelling Creatures

What can we learn from these tree dwelling creatures? It's not clear yet. Not only is not being eaten young good for the average life expectancy of a species (obviously), but something changed over time as these creatures in trees lived longer and longer. Just not being eaten doesn't explain away metabolic aging. Something evolutionary changed in these small but long-lived creatures to give them extra years. If researchers can figure that out, then perhaps developments can be made in understanding our own aging and longevity.

_Source(s):

_{Milena R. Shattuck and Scott A. Williams Arboreality has allowed for the evolution of increased longevity in mammals PNAS 2010 107 (10) 4635-4639; published ahead of print February 22, 2010, doi:10.1073/pnas.0911439107}