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Why would evolution "tweak the obvious knobs" for something well beyond our breeding age 100-500-5000 years ago? The best argument is that those same tweaks af

by kurthr 2y ago

Why would evolution "tweak the obvious knobs" for something well beyond our breeding age 100-500-5000 years ago? The best argument is that those same tweaks affect child bearing/survival performance in the same direction. Since sickle cell and other diseases were selected for, it seems unlikely all of them go the same way.

marcus_holmes 2y ago
This. If anything, evolution would seem to select for lower longevity so more breeding sooner (assuming that if we live longer we would put off breeding until later, which may not be true, and if it is, is probably only true with contraception). And, of course, the oft-repeated "anything that happens after reproduction is irrelevant to evolution". Which isn't 100% true (it takes a village to raise a child, after all).
brigadier132 2y ago
For humans I can speculate generational knowledge is much more valuable since we can communicate using language.
- sdwr 2y ago
  Yeah, this, paired with a social scorekeeping system that literally kills old people if they are less useful (lonelier -> general health problems)
sjducb 2y ago
Grandparents contribute to the survival of their grandchildren. Evolution has selected for long lived grandparents. The same thing happened in elephants and whales.
- hirenj 2y ago
  This is my favourite bit of research regarding the grandmother effect - linking pathogen evasion to neuroprotective activities in old age, all at the molecular level, in an evolutionary context. https://pubmed.ncbi.nlm.nih.gov/35809046/ https://pubmed.ncbi.nlm.nih.gov/35809046/
- roenxi 2y ago
  True in the sense that evolution does select for populations with grandparents, but not entirely obvious in the sense that it is optimising the long lifetime of those grandparents. You don't need a lot of grandparents lying around in the community evolutionary speaking, they take resources to maintain. And there might be a limit to how long knowledge is useful for that evolution has sniffed out and calibrated lifespans to. Human life seems to go through 3-4 phases (roughly youth, middle age and old age). The role of each of those is distinct and fairly clear, but it isn't easy to pick why evolution settled on specific numbers of years.
- aziaziazi 2y ago
  GP used to live within their family, caring of kids and helping with vegetable garden. Their modern “living” in hospices, hospitals, far away neighborhood or vacation resorts have a minor effect on survival on their grand children. Probably negative effect for some pension systems.
  - Lutger 2y ago
    By the age we currently stop being 'useful' as members of clan human, i.e. retirement, our forefathers in an evolutionary sense could already have been (great) great grandfathers. Our life as a pensionado or geriatric patient is already a form of life extension, an extra age compared to the stages we used to go through. Evolution doesn't mean only what is useful stays, it is only when selected for under evolutionary pressure that things are forced to go a certain way, and only after many generations. The uselessness of old age will only affect evolution if A) there will be a society that is mad enough to really 'do something about it' and B) such a society will eventually outcompete other ways of life and its values start to dominate. I can imagine a politics where money spend on welfare and healthcare for elderly is minimized to such an extent that life expectancy starts dropping significantly. In a way, the US has something like such a 'make money or die' politics and indeed, life expectancy there is quite a bit lower than would you would expect from such as prosperous nation. Can be economically effective. But it competes which economies where people are productive at an older age, being more focused on staying healthy and significantly less stressed.
  - sjducb 2y ago
    Yes our modern world does not make good use of grandparents. Given enough time you might expect that the cost of carrying elderly relatives is enough to select for quick dying grandparents. It might also select for healthy long lived grandparents who are not a burden. Probably both will be selected for in parallel .
    - JumpCrisscross 2y ago
      > our modern world does not make good use of grandparents Senior citizens today probably have more power (and productivity) than they ever have.
- layer8 2y ago
  What are you basing this assessment on?
  - sjducb 2y ago
    https://en.m.wikipedia.org/wiki/Grandmother_hypothesis https://en.m.wikipedia.org/wiki/Grandmother_hypothesis
n4r9 2y ago
What do you mean by "breeding age"? Women of course undergo menopause at some point. Men may have peak vigour around age 40, but can continue reproducing into their sixties or beyond. In modern forager populations in Africa and Australia, it's common for men to take wives at such an advanced age. See eg https://d1wqtxts1xzle7.cloudfront.net/46398103/s12110-000-1001-720160611-15509-1afrpfu-libre.pdf?1465652678=&response-content-disposition=inline%3B+filename%3DThe_patriarch_hypothesis.pdf&Expires=1722847016&Signature=I4seuZfUOOgji40VjRiEGFiKZA6YFn1dyZt-Gwaevz2I9NH5NeYDWKR0Qp4NTzu-Pvq-k~uzRYZXGsRLFc3Ba4nWlfCKbplDN4oWhIRmitriR3FDtqXn36scjakBgsWsOY3tq6KM6wTTrAVG7Za3Qj2c6hfbd4Xz6DY~7OPYiIz8dOSvM-slj2ZxB5Hv6TR3sE53k0DwBosGBm1NNSfZZ-kVJV2BtOKzp0vaq1-tj1X-lb6~IEfScdJhOSQ09v58FHXFgkM9GTJsaoSKZgqZg7RtDMMpQ9o8iF9xPKp8XM4486mNE~zXqkMct3pKBrs0EJ0qtgTgIXQsWTvw1xQCgg__&Key-Pair-Id=APKAJLOHF5GGSLRBV4ZA https://d1wqtxts1xzle7.cloudfront.net/46398103/s12110-000-10... . I don't know about the overall hypothesis, but there's some fascinating data there about how old men can get whole still playing important tribal roles.
- n4r9 2y ago
  Hmm, that link isn't working. Anyone interested should be able to access it by clicking the "PDF" link in the top right of Google scholar: https://scholar.google.com/scholar_lookup?title=The+patriarch+hypothesis&author=Marlowe+F.&publication+year=2000&journal=Human+Nature&volume=11&doi=10.1007%2Fs12110-000-1001-7&pages=27-42 https://scholar.google.com/scholar_lookup?title=The+patriarc...
abecedarius 2y ago
Why is a good question, but if you draw a log-log plot of lifespan against mass for mammals, humans appear above the main curve. "That's unlikely by my model" doesn't change that.

by kurthr 2y ago

marcus_holmes 2y ago

This. If anything, evolution would seem to select for lower longevity so more breeding sooner (assuming that if we live longer we would put off breeding until later, which may not be true, and if it is, is probably only true with contraception). And, of course, the oft-repeated "anything that happens after reproduction is irrelevant to evolution". Which isn't 100% true (it takes a village to raise a child, after all).

brigadier132 2y ago

For humans I can speculate generational knowledge is much more valuable since we can communicate using language.

sdwr 2y ago
Yeah, this, paired with a social scorekeeping system that literally kills old people if they are less useful (lonelier -> general health problems)

sjducb 2y ago

Grandparents contribute to the survival of their grandchildren. Evolution has selected for long lived grandparents. The same thing happened in elephants and whales.

hirenj 2y ago
This is my favourite bit of research regarding the grandmother effect - linking pathogen evasion to neuroprotective activities in old age, all at the molecular level, in an evolutionary context. https://pubmed.ncbi.nlm.nih.gov/35809046/ https://pubmed.ncbi.nlm.nih.gov/35809046/
roenxi 2y ago
True in the sense that evolution does select for populations with grandparents, but not entirely obvious in the sense that it is optimising the long lifetime of those grandparents. You don't need a lot of grandparents lying around in the community evolutionary speaking, they take resources to maintain. And there might be a limit to how long knowledge is useful for that evolution has sniffed out and calibrated lifespans to. Human life seems to go through 3-4 phases (roughly youth, middle age and old age). The role of each of those is distinct and fairly clear, but it isn't easy to pick why evolution settled on specific numbers of years.
aziaziazi 2y ago
GP used to live within their family, caring of kids and helping with vegetable garden. Their modern “living” in hospices, hospitals, far away neighborhood or vacation resorts have a minor effect on survival on their grand children. Probably negative effect for some pension systems.
- Lutger 2y ago
  By the age we currently stop being 'useful' as members of clan human, i.e. retirement, our forefathers in an evolutionary sense could already have been (great) great grandfathers. Our life as a pensionado or geriatric patient is already a form of life extension, an extra age compared to the stages we used to go through. Evolution doesn't mean only what is useful stays, it is only when selected for under evolutionary pressure that things are forced to go a certain way, and only after many generations. The uselessness of old age will only affect evolution if A) there will be a society that is mad enough to really 'do something about it' and B) such a society will eventually outcompete other ways of life and its values start to dominate. I can imagine a politics where money spend on welfare and healthcare for elderly is minimized to such an extent that life expectancy starts dropping significantly. In a way, the US has something like such a 'make money or die' politics and indeed, life expectancy there is quite a bit lower than would you would expect from such as prosperous nation. Can be economically effective. But it competes which economies where people are productive at an older age, being more focused on staying healthy and significantly less stressed.
- sjducb 2y ago
  Yes our modern world does not make good use of grandparents. Given enough time you might expect that the cost of carrying elderly relatives is enough to select for quick dying grandparents. It might also select for healthy long lived grandparents who are not a burden. Probably both will be selected for in parallel .
  - JumpCrisscross 2y ago
    > our modern world does not make good use of grandparents Senior citizens today probably have more power (and productivity) than they ever have.
layer8 2y ago
What are you basing this assessment on?
- sjducb 2y ago
  https://en.m.wikipedia.org/wiki/Grandmother_hypothesis https://en.m.wikipedia.org/wiki/Grandmother_hypothesis

n4r9 2y ago

What do you mean by "breeding age"? Women of course undergo menopause at some point. Men may have peak vigour around age 40, but can continue reproducing into their sixties or beyond. In modern forager populations in Africa and Australia, it's common for men to take wives at such an advanced age. See eg https://d1wqtxts1xzle7.cloudfront.net/46398103/s12110-000-1001-720160611-15509-1afrpfu-libre.pdf?1465652678=&response-content-disposition=inline%3B+filename%3DThe_patriarch_hypothesis.pdf&Expires=1722847016&Signature=I4seuZfUOOgji40VjRiEGFiKZA6YFn1dyZt-Gwaevz2I9NH5NeYDWKR0Qp4NTzu-Pvq-k~uzRYZXGsRLFc3Ba4nWlfCKbplDN4oWhIRmitriR3FDtqXn36scjakBgsWsOY3tq6KM6wTTrAVG7Za3Qj2c6hfbd4Xz6DY~7OPYiIz8dOSvM-slj2ZxB5Hv6TR3sE53k0DwBosGBm1NNSfZZ-kVJV2BtOKzp0vaq1-tj1X-lb6~IEfScdJhOSQ09v58FHXFgkM9GTJsaoSKZgqZg7RtDMMpQ9o8iF9xPKp8XM4486mNE~zXqkMct3pKBrs0EJ0qtgTgIXQsWTvw1xQCgg__&Key-Pair-Id=APKAJLOHF5GGSLRBV4ZA https://d1wqtxts1xzle7.cloudfront.net/46398103/s12110-000-10... . I don't know about the overall hypothesis, but there's some fascinating data there about how old men can get whole still playing important tribal roles.

n4r9 2y ago
Hmm, that link isn't working. Anyone interested should be able to access it by clicking the "PDF" link in the top right of Google scholar: https://scholar.google.com/scholar_lookup?title=The+patriarch+hypothesis&author=Marlowe+F.&publication+year=2000&journal=Human+Nature&volume=11&doi=10.1007%2Fs12110-000-1001-7&pages=27-42 https://scholar.google.com/scholar_lookup?title=The+patriarc...

abecedarius 2y ago

Why is a good question, but if you draw a log-log plot of lifespan against mass for mammals, humans appear above the main curve. "That's unlikely by my model" doesn't change that.