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> Evolution optimizes for procreation not for longevity. Incorrect. Evolution optimises for propagation of genes. Procreation is one but not the element of tha
by nkoren 13y ago
> Evolution optimizes for procreation not for longevity.
Incorrect. Evolution optimises for propagation of genes. Procreation is one but not the element of that process.
Think about this way: if you are living by yourself in the forest and have octuplets, then you are very good at procreation; if you die immediately afterwards, then you are evolutionarily unfit despite your procreative abilities, because none of your young will survive to pass on their genes. For creatures like humans -- born with helpless young -- the person who has two children and lives long enough to ensure that they can pass on their own genes is more evolutionarily fit than the person who procreates like mad but lets all their children die.
In our evolutionary environment, post-procreative individuals played vital roles in ensuring the survival of the young: taking care of children while their parents were off hunting and gathering; preparing foodstuffs; passing on lore about which plants were dangerous to eat, etc. In this way, the presence of elders facilitated the propagation of genes -- right up to the point where the care and maintenance of said elders becomes such a drain on resources that it begins to diminish rather than enhance the survival and procreation prospects for the young. That's quite a long time, however, so generally speaking, genetic lines that produce long-lived healthy individuals who enhance the survival prospects of the young will be more successful than genetic lines which don't.
- fauigerzigerk 13y agoIf most people have children in their 20s, there is very little evolutionary advantage to living beyond, say, 60. Until then, they will have passed on all their valuable wisdom.
- dllthomas 13y agoI think the key point is that ability to help ensure survival and reproduction of great-grandchildren matters (evolutionarily) half as much as the same of grandchildren, which matters half as much as the same of children. Though in principle there's nothing preventing continued ability to have children in later years...
- fauigerzigerk 13y agoI understand the argument, I just don't believe that surviving elders were actually helpful for the procreation and survival of their offspring during most of evolution. Not beyond an age where cancer and heart disease start to play a role. Older men can have children in principle, but older women can not. So those men would have to compete with younger men for the remaining fertile women. The birth rate of a woman would probably not change just because there are more old men available to her.
- dllthomas 13y ago"Older men can have children in principle, but older women can not." I didn't mean "ignoring social factors" - I meant "in theoretical human-design-space". Women don't produce new ova, but why does that necessarily have to be the case? Most cells in the body divide regularly.
- dllthomas 13y ago"I understand the argument, I just don't believe that surviving elders were actually helpful for the procreation and survival of their offspring during most of evolution. Not beyond an age where cancer and heart disease start to play a role." I don't think I was disagreeing with you, there. My point was that regardless of how much benefit an ancestor can give to their descendants, if you have declining fertility beyond some age the benefits of doing so attenuate with time.
- fauigerzigerk 13y agoI do agree with you that the benefit attenuates with time, but we seem to disagree a great deal about steepness of that attenuation. You're talking about great-grandchildren. I believe that in a hunter-gatherer society the benefit of having parents goes to zero within 20 years after reaching adulthood and there is never any benefit to having gandparents.
- dllthomas 13y ago