[ExI] Are Limited Lifespans An Evolutionary Adaptation?

Rafal Smigrodzki rafal.smigrodzki at gmail.com
Thu Jun 18 23:42:23 UTC 2015

On Tue, Jun 16, 2015 at 7:13 AM, BillK <pharos at gmail.com> wrote:

> Are Limited Lifespans An Evolutionary Adaptation?
> George Dvorsky   6/12/15
> <
> http://io9.com/are-limited-lifespans-an-evolutionary-adaptation-1710634703
> >
> Quotes:
> 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'.

### Sounds like complete nonsense. You can produce arbitrary results in
complex models by fiddling with your parameters, so this modeling effort is
not evidence of anything.

There are a few known examples of predetermined lifespans (e.g. mayflies,
bamboo) but these are not related to aging, and are not applicable to
humans. Humans only infrequently age under natural conditions, the vast
majority die long before aging sets in, so any evolved mechanism actively
killing old humans as an adaptation would very quickly be removed by random
genetic drift (just like skin pigment disappears in cave-dwelling animals -
it's not an active adaptation but rather lack of selective pressure needed
to maintain the genes for pigmentation).

In modeling, GIGO reigns supreme.

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