Re : Re : Cornering the causes of aging (was Re: AGING: Accumulation of DNAdamage)

From: Joao Pedro de Magalhaes (
Date: Thu Jul 06 2000 - 09:56:08 MDT


>>I've got another question, why don't reptilians or amphibians show
>>widespread aging?
>They do show widespread aging.

Reference? I've seen a few papers identifying aging changes (not increased
mortality with age) in reptilians and amphibians with average lifespans of
a few of years. However, many turles, salamanders, crocodiles and
alligators, bullfrogs, and snakes do not show signs of aging and yet live
on average as much as ducks, horses, or cows.

>The only sexual species for which I've
>ever seen a "non-aging" claim are extremely long-lived ones like
>lobsters. Even with those species, there's a problem with catch
>records. If they didn't age, we should find some 200-year old
>lobsters; but we don't.

Just a detail: it's very difficul to determine the age of a lobster.
Second, Marion's tortoise shows increased mortality after 60 in the wild;
but not in captivity where it can live well beyond a century. This suggests
extrinsic factors as the cause of aging (continually growing species can
have their mortality increased due to increased predations or change in
diet because they are growing too big -- I have references showing this.)
Also, what you call "extremely long-lived ones" are species that have
average lifespans in the range of whales and elephants. So why whales and
elephants age but not lobsters, or rockfishes, or tortoises? (remember they
have the same mortality rates).

>>Even species such as Desmognathus that live less than 15
>>years do not show signs of increased mortality with age (in fact, they
>>show decreased mortality after adulthood is reached).
>Do you have a cite for this?

Finch's "Longevity, Senescence, and the Genome", pag 219.


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