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The evolution of aging is an arms race to the bottom. Very few species can succeed without aging once any competitors evolve aging, and this happened very early

The evolution of aging is an arms race to the bottom. Very few species can succeed without aging once any competitors evolve aging, and this happened very early on. Here is thinking on "we age because the world changes." Of course what is great for evolutionary success has nothing to do with what is great for the individual, and the two should not be confused. http://arxiv.org/abs/1103.4649 http://arxiv.org/abs/1103.4649 "Understanding why we age is a long-lived open problem in evolutionary biology. Aging is prejudicial to the individual and evolutionary forces should prevent it, but many species show signs of senescence as individuals age. Here, I will propose a model for aging based on assumptions that are compatible with evolutionary theory: i) competition is between individuals; ii) there is some degree of locality, so quite often competition will between parents and their progeny; iii) optimal conditions are not stationary, mutation helps each species to keep competitive. When conditions change, a senescent species can drive immortal competitors to extinction. This counter-intuitive result arises from the pruning caused by the death of elder individuals. When there is change and mutation, each generation is slightly better adapted to the new conditions, but some older individuals survive by random chance. Senescence can eliminate those from the genetic pool. Even though individual selection forces always win over group selection ones, it is not exactly the individual that is selected, but its lineage. While senescence damages the individuals and has an evolutionary cost, it has a benefit of its own. It allows each lineage to adapt faster to changing conditions. We age because the world changes."

BurningFrog 10y ago
That was valid in the old world. Now we're on the verge of human assisted gene design vastly outperforming natural evolution.
adrianN 10y ago
Negligible senescence does not mean immortality. You still get eaten or die in other accidents. There are a number species that show this trait. https://en.wikipedia.org/wiki/Negligible_senescence https://en.wikipedia.org/wiki/Negligible_senescence So I don't really buy that argument.
- reasonattlm 10y ago
  Immortality has a specific meaning here, which is that risk of death due to intrinsic causes does not increase over time. This is distinct from negligible senescence, which is more a case of few manifestations of aging until very late life. Immortality seems to be the case for hydra, for example. (http://www.ncbi.nlm.nih.gov/pubmed/22689361 http://www.ncbi.nlm.nih.gov/pubmed/22689361) Immortality is also observed for flies in late life (http://discovermagazine.com/2001/may/breakdialogue http://discovermagazine.com/2001/may/breakdialogue). They have a very high mortality rate at that point, but it doesn't increase further over time. That doesn't seem to be the case for humans, though, based on the very sparse data for people at extreme old age.
  - Ericson2314 10y ago
    Human cancer cells are another interesting example besides hydras.
tomp 10y ago
Why would survival of older individuals be in any way detrimental to the species' success? In the absence of aging, organisms living longer simply means that they are still sufficiently-well adapted to the environment. When the environment changes beyond what they can adapt to, they die off and (hopefully at least parts of) the new(er) generation will carry on.
- fossuser 10y ago
  Speculating - older individuals take resources and even if they were continuing to reproduce advancement comes through successive generations of genetic mixing. It's probably advantageous for the species if an individual has a child (mixing up genetic code) and then that child has children while the parent dies. Otherwise you might have less biodiversity which may make the species less adaptable overtime (and maybe lose to another species with aging).
- dasil003 10y ago
  Because we are social creatures and there are still limited resources. Older generations have outsized influence on the tribe based on their experience which can drag the rest down. For a contemporary example, consider the real estate bubble. When the bubble burst and everyone realized how badly the banks had screwed up, what happened? Well, everyone who owned a home worried about losing its value. The banks took some stock off the market to hide it, and all the leadership up to the president vowed to do everything possible to "maintain real estate values", even though the "value" was predicated on sub-prime mortgages that people couldn't actually afford. In this way, the older generation whose experience is tied to a particular environment exerts its influence in a way that damages the younger population. Being young and inexperienced means being adaptable but naive and inefficient, being old and wise means knowing how things work and a vested interest in keeping them that way.
  - aetherson 10y ago
    Aging is present in non-social species.
    - 10y ago

BurningFrog 10y ago

That was valid in the old world. Now we're on the verge of human assisted gene design vastly outperforming natural evolution.

adrianN 10y ago

Negligible senescence does not mean immortality. You still get eaten or die in other accidents. There are a number species that show this trait. https://en.wikipedia.org/wiki/Negligible_senescence https://en.wikipedia.org/wiki/Negligible_senescence So I don't really buy that argument.

reasonattlm 10y ago
Immortality has a specific meaning here, which is that risk of death due to intrinsic causes does not increase over time. This is distinct from negligible senescence, which is more a case of few manifestations of aging until very late life. Immortality seems to be the case for hydra, for example. (http://www.ncbi.nlm.nih.gov/pubmed/22689361 http://www.ncbi.nlm.nih.gov/pubmed/22689361) Immortality is also observed for flies in late life (http://discovermagazine.com/2001/may/breakdialogue http://discovermagazine.com/2001/may/breakdialogue). They have a very high mortality rate at that point, but it doesn't increase further over time. That doesn't seem to be the case for humans, though, based on the very sparse data for people at extreme old age.
- Ericson2314 10y ago
  Human cancer cells are another interesting example besides hydras.

tomp 10y ago

Why would survival of older individuals be in any way detrimental to the species' success? In the absence of aging, organisms living longer simply means that they are still sufficiently-well adapted to the environment. When the environment changes beyond what they can adapt to, they die off and (hopefully at least parts of) the new(er) generation will carry on.

fossuser 10y ago
Speculating - older individuals take resources and even if they were continuing to reproduce advancement comes through successive generations of genetic mixing. It's probably advantageous for the species if an individual has a child (mixing up genetic code) and then that child has children while the parent dies. Otherwise you might have less biodiversity which may make the species less adaptable overtime (and maybe lose to another species with aging).
dasil003 10y ago
Because we are social creatures and there are still limited resources. Older generations have outsized influence on the tribe based on their experience which can drag the rest down. For a contemporary example, consider the real estate bubble. When the bubble burst and everyone realized how badly the banks had screwed up, what happened? Well, everyone who owned a home worried about losing its value. The banks took some stock off the market to hide it, and all the leadership up to the president vowed to do everything possible to "maintain real estate values", even though the "value" was predicated on sub-prime mortgages that people couldn't actually afford. In this way, the older generation whose experience is tied to a particular environment exerts its influence in a way that damages the younger population. Being young and inexperienced means being adaptable but naive and inefficient, being old and wise means knowing how things work and a vested interest in keeping them that way.
- aetherson 10y ago
  Aging is present in non-social species.
  - 10y ago