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I know death and cancer doesn't hurt humans' reproductive success. It's not helping either.

Why do we die? Why dying humans (all of us) are common? What's the point of dying?

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Not everything has an evolutionary advantage... –  nico Mar 20 '12 at 6:55
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Cancer does hurt human's reproductive success; and evolution does fight with it. –  Piotr Migdal Mar 20 '12 at 8:15
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Most cancers are post-reproductive, so fitness (strictly speaking) is 0 at that point. –  kmm Mar 20 '12 at 16:04
    
This is kind of relevant to a senescence question on SE I was just came across. A book referred to in that question, Geriatric Medicine: An Evidence Based Approach by Cassel, said biologists argue that senescence is an evolutionary byproduct rather than a bestowed advantage and is probably a result of "interaction of many genes with the environment". –  Zoidberg Mar 24 '12 at 9:38
    
@nico is correct, and he's not likely saying so with any religious zeal... for example, genetic drift is a powerful evolutionary force that has no obvious "advantage" per se. I've edited your title to remove that suggestion. but +1 anyway since it's an interesting question. –  hello_there_andy May 8 at 19:32

3 Answers 3

up vote 17 down vote accepted

Death is not only for humans. All 'complicated enough' organisms die (with a notable exception of Hydra, tough you may argue when it comes to the complexity). It is is easier to create a new organism from scratch than to repair both internal factors (free radicals, metabolic by-products, ...) and external (physical damage, exposure to toxins, ...).

Underlying causes of death actually can be evolutionary beneficial. For example, telomere offers protection against cancer (on a cellular level) but also bounds lifespan.

So actually they may be evolutionary competition (within the same species) of young and old. Mutations helping young but harming older may be preferred to the opposite ones.

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perfec. thanks a lot. –  Jim Thio May 3 '12 at 2:13

Who is to say that having living Humans isn't hurting our reproductive success? Older non-reproducing humans cost the human network valuable resources and take up a sizeable portion of our living niche. Metabolically unstreamlined aged organisms are certainly not the most efficient and could potentially get in the way of better suited young'uns.

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It's naive group-selection argument. Like "I'd sacrifice myself when I get old so that others could produce more children". But if one would live longer and help his own grandchildren - he would spread his genes better even if it would hurt the society. –  Marta Cz-C Mar 21 '12 at 6:41
    
@MartaCz-C: how does helping grandchildren spread genes? The only way for an old person to continue spreading his/her own gene is to have kids which would actually be bad. –  nico Apr 6 '12 at 6:12
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@nico if person X have even 15 children but non of them have their own children through their lifespan, then genes of person X did not spread at all. One of measures of fitness is number of grandchildren. –  Marta Cz-C Apr 6 '12 at 9:28
    
@MartaCz-C: sure, but my question is about "helping his own granchildren". The fact of helping them in no way means you are spreading your own genes. The fact of having granchildren means you spread your own genes in the past which... well is the purpose of reproduction. –  nico Apr 6 '12 at 10:29
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@nico Helping your relatives spread their genes is equal to spreading your own genes (if you multiply your effort in helping others by the percentage of consanguinity). That's what I mean but maybe I use wrong terminology. –  Marta Cz-C Apr 6 '12 at 14:29

From a systemic point of view, if we wish to evolutionarily induce our descendants (descendants of the current human race on the whole) to live longer lives, we would need to pro-create later.

If the whole of human race enforced a statute that prohibits pro-creation before the age of 40, then two pronged dynamics would happen

  • only adults fit enough to pro-create after 40 would produce off-springs.
  • only off-springs born to parents older than 40 who are fit enough would survive.

Since, there is a high tendency of abnormality and low survival of off-springs born to parents of older ages, absence of resource contention and genetic dynamics would encourage the initial propagation of the rare few fit off-springs.

Hence, unnatural "natural selection" would encourage the propagation of humans of longer life-spans. Perhaps, a natural disaster or viral outbreak could discourage humans from pro-creating before age 40. Perhaps, high rates of abortion. So long as the human race does not die out due to such restrictions. Perhaps, to the satisfaction of conspiracy lovers, a secretive organisation carries out a plan every 100K years to raise the bar for child-bearing age.

Therefore, it might be less of a question of advantage and more of the effects of motivation. That current status where

  • high motivation for humans to pro-create early in life.
  • low motivation for humans to have more children as they wise-up by being tired of raising kids too early.

Therefore, since no such secret organisation exists, there is infinitesimally little motivation for the existence of a "super-virus" type of humans to exist.

There is no motivation for super-humans to exist, because the distribution of life-spans have crowded out the food and survival resources of any possible primeval super-human.

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