According to a study made by a University of Illinois, the squirrels that litter your lawn with acorns as they leap overhead will survive to infect your yard even longer than the ones that ventilate it with their burrows.
Scientists are already aware from past studies that bats and flying birds live more than animals of similar size that are earth bounded. Scott Williams and Milena Shattuck, both doctoral candidates in the field of anthropology, chose to take a more in depth look at the relationship between the habitat and lifetime, in mammals, in comparison to treetop and terrestrial life. They have published their results in the Proceedings of the National Academy of Sciences.
The two made hypothesis that, just like treetop, flight or arboreal dwelling decreases a species’ external mortality – death from disease, predators and environmental hazards; that it, reasons apart from age.
According to Williams’s explanation, one of the forecasts of the theory of evolutionary theory of aging is that if a person can bring a reduction in the sources of external mortality, that person might finish off exposing a number of the late-acting transformations to natural selection, and as a result develop longer lifespans.
Shattuck and Williams discovered that the theory holds true for arboreality. Mammals which spend their majority of time up a tree tend to enjoy a greater life compared to those who scurry on the ground. The patterns are reliable both on the large scale among all mammals as well as in particular classes that the two studied, like tree squirrels as opposed to ground squirrels.
Nevertheless, the duo also exposed two classes of mammals that go against the longevity trend; marsupials like kangaroos and primates, consisting of ground walkers like gorillas and human in addition to their branch-swinging counterparts. On the ground or not, these groups of mammals demonstrate no important difference, even though in general primates have the tendency to have long lives.
Shattuck states that these mammals are the exceptions that in fact prove the rule. The essential feature that appears to link those two groups is in fact a long history of arboreal ancestors. Primates and marsupials appear to have started out in the trees and afterwards the terrestrial primates and marsupials have descended from the arboreal ancestors.
This arboreal ancestry may explain in part the reason why human beings have such an extended lifespan compared to other mammals. Since primates descended from the trees, they need to work out new strategies to survive on the ground. Terrestrial primates, including man, have the tendency to be larger and more social, offering some sort of security from extrinsic obstacles such as predators and environmental factors.
“It is fascinating to imagine that man, at least to some extent, had live so long and do well as we had this evolutionary history when we live in trees,” states Shattuck. He moreover advances that due to the fact that human beings are now better equipped, with medicine and cultural intervention, they might possibly lengthen their lifespan even more.”
Source: Eurekalert
Fri, Jun 4, 2010
Bioscience, Gerontology, Lifestyle, Longevity