Gene Expression

Be safe and live long

Arboreality has allowed for the evolution of increased longevity in mammals:

The evolutionary theory of aging predicts that species will experience delayed senescence and increased longevity when rates of extrinsic mortality are reduced. It has long been recognized that birds and bats are characterized by lower rates of extrinsic mortality and greater longevities than nonvolant endotherms, presumably because flight reduces exposure to terrestrial predators, disease, and environmental hazards. Like flight, arboreality may act to reduce extrinsic mortality, delay senescence, and increase longevity and has been suggested as an explanation for the long lifespans of primates. However, this hypothesis has yet to be tested in mammals in general. We analyze a large dataset of mammalian longevity records to test whether arboreal mammals are characterized by greater longevities than terrestrial mammals. Here, we show that arboreal mammals are longer lived than terrestrial mammals at common body sizes, independent of phylogeny. Subclade analyses demonstrate that this trend holds true in nearly every mammalian subgroup, with two notable exceptions–metatherians (marsupials) and euarchontans (primates and their close relatives). These subgroups are unique in that each has experienced a long and persistent arboreal evolutionary history, with subsequent transitions to terrestriality occurring multiple times within each group. In all other clades examined, terrestriality appears to be the primitive condition, and species that become arboreal tend to experience increased longevity, often independently in multiple lineages within each clade. Adoption of an arboreal lifestyle may have allowed for increased longevity in these lineages and in primates in general. Overall, these results confirm the fundamental predictions of the evolutionary theory of aging.

The same logic probably explains the long lifespans of tortises. Until humans showed up their shells were pretty good at insulating them from the risks of predation.

Citation: Milena R. Shattuck and Scott A. Williams, Arboreality has allowed for the evolution of increased longevity in mammals, doi:10.1073/pnas.0911439107

Comments

  1. #1 Ray in Seattle
    February 25, 2010

    “The same logic probably explains the long lifespans of tortises. Until humans showed up their shells were pretty good at insulating them from the risks of predation.”

    Perhaps elephants too. In this case large size reduces the number of predators that could make a meal of them. That seems to be an effect on tortoises as well. The Aldabra Tortoise (Giant Toirtoise) has a life span of 152 years. With tortoises I suspect it has to do with the number of predators that could easily get their mouths around them to even have a chance at crushing them.

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