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Steven Austad, of the Barshop Institute for Longevity and Aging Studies, at the University of Texas Health Science Center at San Antonio, has applied the longevity quotient—which he developed—to many species, including those depicted here. The quotient is determined by dividing the greatest recorded longevity for a species by the life span that would be expected based on the species's average weight. Except for humans and Brandt's bat, the scores refer to animals in captivity.
» View a slide show of mammals ranked by their longevity quotients
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9 Comments
Add CommentI see something of a trend; except for the African lions, social mammals (naked mole rats, bats, and humans) appear to have exceptionally larger longevity quotients.
Reply | Report Abuse | Link to thisIs the number for lions taken from data on wild lions, or those in captivity? Is there a significant difference? I recall reading that animals in captivity tend to live longer than in the wild, though that can be attributed to the lack of predators (or the stress of the chase, for captive predators) and veterinary care.
Another thought; lions are predators while the others are mostly considered prey animals (possibly excepting humans). It may be that social prey mammals have longer lifespans than solitaries because of social support.
I notice that the focus was on mammals; what about birds?
Reply | Report Abuse | Link to thisIt would be of interest how these indices relate to the reproduction rate of the according animal.
Reply | Report Abuse | Link to thisIt's odd that the authors provide no lifespan numbers. Here are some I found online:
Reply | Report Abuse | Link to thisWhite-eared opossum 4 years
Asian house shrew 2.5
*House mouse 3
Giraffe 36
African lion 30
Southern flying squirrel 17
Vampire bat 19.5
Human 90
*Naked mole rat 30
*Brandt's bat 20
Most are from S.N.Austad and K.E.Fischer, "Mammalian Aging, Metabolism, and Ecology: Evidence from the Bats and Marsupials", Journal of Gerontology 46 (1991): B47-B53, cited by the Museum of Longevity http://www.netpilot.ca/jardinsbellerive/eng/museum/page10.htm. The three with asterisks are from other online sources. The sources' use of average or longest lifespan may not be consistent.
Birds, yes. I've heard that parrots live very long lives. Ans what about turtles--although I guess they're pretty heavy.
Reply | Report Abuse | Link to thisResponse to Percival: These are very astute observations. The evolutionary theory of aging posits that species with relatively low "extrinsic" mortality risks--the risk of predation, infections, starvation, dying of winter cold, etc.--tend to evolve longer lifespans. Social lifestyles are thought to help lower such extrinsic risks. (More on this can be found in my book, by the way, as well as in Steve Austad's excellent "Why We Age.") This basic idea explains a lot, e.g., prey animals, such as small rodents, tend to have unusually short lifespans for their body sizes (and high rates of development, aging and reproduction) due to their high extrinsic mortality risk. Large animals tend to be at risk from fewer predators, carry more bodily resources to survive lean/cold times, etc., and so also have less extrinsic risk, longer lifespans. And smart animals like us are obviously masters at cutting our extrinsic risks with clever tricks.
Reply | Report Abuse | Link to thisReply to Mythusmage: Birds and other flyers (bats, in particular) tend to have relatively low extrinsic risks of mortality (see my response to Percival), presumably because they are harder for predators to catch than ground animals, and thus many species of them have remarkably long lifespans -- even the lowly pigeon reportedly can live at least 35 years.
Reply | Report Abuse | Link to thisReply to Bob Grumman: The temperature of cold-blooded species' environments can have a major influence on their metabolic rates and lifespans, a phenomenon that puts them in a different world from mammals, so to speak, when it comes to aging (you can freeze nematodes, for example, and revive them years later after having pretty much totally arrested their aging while on ice) -- thus, it doesn't make sense to calculate longevity quotients for them in the way that it does for mammals.
Reply | Report Abuse | Link to thisReply to Disentangled: This is a very interesting question, and there are lots of data suggesting that there's a tradeoff between rate-of-aging and fertility. For instance, the longest-lived bats tend to be the ones that produce the smallest number of offspring during their lives. And small, short-lived prey animals tend to have large litters--think mice and rabbits. This is closely related to r/K selection theory, by the way, as well as to the disposable soma theory of aging.
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