[ExI] Are Limited Lifespans An Evolutionary Adaptation? (BillK)
hkeithhenson at gmail.com
Fri Jun 19 14:42:09 UTC 2015
On Fri, Jun 19, 2015 at 5:00 AM, BillK <pharos at gmail.com> wrote:
> The simulation shows "evolution favors shorter lifespans in
> environments where resources are scarce and when pressures to
> procreate are particularly intense".
That's not surprising, but what is known with small stature races
(pigmies) is that the growth process is chopped off by early sexual
maturity. Apparently the environment they are in kills them at a rate
that requires early reproduction.
> That might well not be the
> complete answer. But traits that benefit species survival rather than
> individuals seem likely.
This has been logically dismissed by Dawkins and company back in the
70s. Genes induce individuals to things that result in the survival
and propagation of genes. End of story. Our social nature seems to
lead us to account for the world in terms of "traits that benefit
species survival" but this completely fails to pass a logical
examination. "Hamilton's rule" does not change this.
> Assuming a species had a very long lifespan, then what might the results be?
> Reproduction beyond the capacity of the environment to support them is
> obvious, (boom and bust) so that would be a limiting factor. Long-life
> species would grow to match their environment and become slow
> reproducers, so they would have less evolution. A change in the
> environment would wipe them out.
"Reproduction beyond the capacity" is just a feature of living things,
rabbits, elephants and humans alike. If they did not have excess
reproductive capacity, they would not recover from an environmental
> In the continually changing early world environment, there would be no
> evolutionary benefit to very long lifespan.
That's not the case for humans, and it seems possible that relatively
rare events where the very old knew what could be eaten in a famine
drove humans living into an advance age where their knowledge was
critical to the survival of their close relatives. Another factor is
grandmothers directly contributing to raising children.
> Now that we are finding
> genes that appear to affect ageing, we may soon be able to switch
> these genes off and extend lifespan.
That may be true regardless of the origin.
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