[ExI] Are Limited Lifespans An Evolutionary Adaptation?
William Flynn Wallace
foozler83 at gmail.com
Sat Jun 20 18:11:17 UTC 2015
On Sat, Jun 20, 2015 at 11:25 AM, John Clark <johnkclark at gmail.com> wrote:
> On Tue, Jun 16, 2015 BillK <pharos at gmail.com> wrote:
> > Assuming a species had a very long lifespan, then what might the results
> A mutation would happen to a gene in one individual that caused it to
> devote more of its bodies finite resources to reproduction and away from
> long term maintenance; the result would be a individual that had a shorter
> lifetime but had more children, and so the mutated gene for this would soon
> spread through the population. However if the lifetime was too short the
> individual would die before it could care for its young children and so
> would have no grandchildren. Evolution must find a good compromise between
> maintenance and reproduction that passes the most genes into the next
> John K Clark
> One result may be more deformed babies, resulting from deformed sperm, a
problem after a man's late 30s.
> Are Limited Lifespans An Evolutionary Adaptation?
>> George Dvorsky 6/12/15
>> By running variations of their model hundreds of thousands of times, a
>> research team led by Yaneer Bar-Yam from the New England Complex
>> Systems Institute (NECSI), in collaboration with the Harvard Wyss
>> Institute for Biologically Inspired Engineering, observed that
>> evolution favors shorter lifespans in environments where resources are
>> scarce and when pressures to procreate are particularly intense. The
>> simulations appeared to show that lifespans of animals — humans
>> included — are genetically conditioned, and not the result of gradual
>> wear-and-tear. It’s a surprising result, one that gives added credence
>> to the burgeoning paradigm known as “programmed aging.”
>> Without genetically programmed aging, he argues, animals wouldn’t be
>> able to leave sufficient resources for their offspring. And this holds
>> true for all animals, whether they be rabbits, dolphins, or humans.
>> Fascinatingly, group selection — the idea that natural selection acts
>> at the group level — was never a consideration in the model. Yet the
>> simulations consistently showed that a built-in life expectancy
>> emerged among the simulated organisms to preserve the integrity of
>> their species over time. This is surprising because a pro-group result
>> was produced via an individualized selectional process.
>> “Beyond a certain point of living longer, you over-exploit local
>> resources and leave reduced resources for your offspring that inhabit
>> the same area,” Bar-Yam said. “And because of that, it turns out that
>> it’s better to have a specific lifespan than a lifespan of arbitrary
>> length. So, when it comes to the evolution of lifespans, the longest
>> possible lifespans are not selected for.”
>> This new theory is still controversial and the article continues to
>> discuss the alternatives.
>> Aubrey de Grey also comments.
>> But I like it. Resource driven ageing via evolution just seems 'right'.
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