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Comment by lotusleaf1987 | Hacker News Reader

lotusleaf1987

Maybe somehow it speeds up the system of evolution by keeping life expectancies shorter, thereby increasing turnover (death and new births)? I have no clue just throwing that out there.

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To survive natural selection the gene must give the animal some reproductive advantage. I can understand that promoting longevity beyond the reproductive stage of one's life cycle affords no such benefit. But one still has to account for the fact that the lack of the gene appears to increase the survivability in the reproductive pahse as well. Something more must be going on.

Perhaps not having the ability to regenerate leads to more cautious behaviour, avoiding life threatening situations to a much greater extent? Puzzling...

I don't think the ability to regenerate means that losing a limb doesn't hurt...

> To survive natural selection the gene must give the animal some reproductive advantage.

Most probably, but not necessarily.

A gene can be present without being useful because it is linked to another gene that is itself useful; or it can be a leftover from an earlier moment of evolution where it was useful, and then it ceased to be useful but there was never an evolution pressure strong enough to have it disappear.

In summary, just because a gene is present and active does not mean it's useful today.

Strictly speaking, it must give the _gene_ a reproductive advantage, not necessarily the animal. Often, these two advantages are aligned. But they need not be. This is the case in kin altruism. And this is also, why "promoting longevity beyond the reproductive stage of one's life cycle" affords sometimes very much such benefits. Example: grandparents can help raising their children's children (and their children's children's children ;)). Kin altruism becomes even more apparent in ants (or other social animals). Worker ants or bees are pretty much infertile but they help a lot.

It should be noted that the difference is much more extreme for ants than it can be for mammals due to a genetic quirk where a female ant shares 50% of her genes with her children and 75% with her sisters. (Therefore having more sisters is better than having children.)

Still there are mammals that live eusocial. The naked mole rat comes to mind.

Not necessarily. The mutation could have survived for any number of reasons including genetic drift. As long as it didn't kill the organism right away there wouldn't be significant negative pressure to get rid of it.

Individual organisms don't work for "the system of evolution"'s benefit. They work for themselves.

But mammals do! They are social creatures. A social group that has more efficient food use due to turnover of injured members would be selected for.

Group-selection explanations are rarely correct.

Yet empirically the effect exists.

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