For the 4th of July, on the 5th of July. |
For the 4th of July, on the 5th of July. | 5. Jul 2011 @ 14:45 |
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> As for natural selection of long-living adults, there is a nice contradiction in that although you are likely to live longer in a society that looks after your health and social needs, you are less likely to be needed to share the burden of caring for grandchildren in such a society, and there is, therefore, less scope for natural selection to play its part. -- Well, from the perspective of natural selection, the only criteria for long life as evolutionary trait would seem to have your own children late in the life. I mean -- if you only get children when young, then you pass your genes anyway, even if you have some genetic screwup that kicks in at, let's say around 30. If you also have children when older, then you have qualified as somebody who can give genes that have better chance to live for longer (since you did).
OK, I will keep my eyes open for that shark - if it is the case, then I find it a little unsettling - as if a natural law has been proven false.
Regarding the natural selection of genes which result in greater longevity, then I would say that there is another factor at play, as well. If grandparents have this longevity gene, and are active and caring in their old age, then in a situation in which this could give their grandchildren an advantage, this gene will be selected for (as their DNA will have been passed on to their offspring and their offspring's offspring).
Doubtless, there are a lot indirect advantages that can be passed on to next generations by longevity. It does seem also that a lot of people ARE in fact living longer, although it would probably be more due to the living conditions and better knowledge of the body requirements.
Regarding the fish -- it really depends on what you call living. AFAI understand, there are bacteria that also have the possibility to live near endlessly; however, you would be hard pressed to determine the "original" speciman, due to their multiplication by division. I wouldn't be surprised if the further down the chain of complexity you go, the more there would be organisms that can survive eternally, assuming external factors are favourable.
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