What evidence for "non-aging" species?
steve at chambers.ak.planet.co.nz
Thu Mar 16 01:50:27 EST 1995
>> I'm just reviewing "How and Why We Age" by Leonard Hayflick. In
>> Chapter 2, with reference to the tortoise, lobster, flounder etc.
>> he states:
>> Unlike us, [these] animals that do not age have the SAME chance of
>> dying every year after sexual maturation.
>> He offers no reference for this statement and I personally find it
>> hard to accept. Can anyone point me to a study of any such species
>> which shows a constant age-independant mortality rate?
A personal correspondent replied:
> Have a look at Finch's 1990 tome. (e.g. p.220--cites Gibbons 1987.
> Bioscience 37:262-269). Seems like a true statement.
Thanks for this. A quick review of Caleb Finch's "Longevity , Senescence
and the Genome", however shows that he's not a believer in non-aging
species. Finch uses the terms "gradual senescence" and "negligable
senescence" to describe aging in such species.
Perhaps I should, at this stage, point out that there ARE species that
evidence suggests don't senesce. But is it because they just don't age
or is it because they die too soon to show it? (for whatever reason.)
Without question, Hayflick is suggesting the former. Finch, on the
other hand, sits on the fence but is clearly falling toward the latter.
On page 220 of LS&G Finch says "No mortality acceleration with age is
shown in three turtles," but "up to the population maximum ages of
15 to 25 years." Few turtles live much longer than this, and given
their low level of metabolic activity it's certainly too short a span
to conclude that they don't age.
(I_lurk,_therefore_I_am!_\ ,,, Steve Chambers
(o o) steve at chambers.ak.planet.co.nz
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