Re: Re: Human Cell Lifespan Extended

CurtAdams (
Fri, 16 Jan 1998 20:15:16 EST

In a message dated 1/16/98 12:37:31 PM, wrote:

>On Fri, 16 Jan 1998, CurtAdams wrote:
>> [...]
>> Yes, but my point, in some post, was that whole-body levels of
>> telomerase are probably already close to optimal. If the gains
>> from increasing telomerase exceeded the risks, evolution would
>> already have cranked it up. In order to get big gains from
>Not necessarily so, for the timescales available for the darwinian
>optimization seem to be be smaller than the demand invoked by the
>(evolutionary) quite recent memetic takeover. No refs whatsoever, of
>course. (Otoh other suspectedly antigeriatric shenanigans as glutathione
>level in serum which is close at the biological tolerance threshold seem
>to prove otherwise, so nyanya).

Well, the memes might benefit from longer-lived humans, but being
able to transmit memes does not in and of itself change the biology.
While memes add to the benefit of long life, most species gene sets
have already evolved to let the individuals live as long as
as possible.

It's true that humans have been through a major lifespan change
recently that extended lifespan by 50%-100% (the old 100% oft cited
seems to exaggerate a bit; chimps live longer than we had thought).
The genes might not yet have reached an optimum. There's an
interesting Danish twin longevity study which tackled whether
genetic variation in human lifespans can evolve (generally species
have a fair amount of genetic variability in lifespan but it's
not evolvable). Frustratingly, they considered only the options
of "it's all evolvable" and "none is evolvable". "None" won
out by a statistical hair. Realistically, probably some of the
variation can evolve and some can't; if we assume that the similar
predictive power of the two approaches means we should split the
difference (completely uncalled for but oh well...) then 10%
of variation in human lifespan comes from evolvable genetic variation.
This is very high - fruit flies are at 3% - and would make broad-spectrum
approaches like whole-body telomerase stimulation somewhat plausible.