A big issue with the programmed aging theory is that while we already have pretty good evidence from a biological perspective of a programmed aging clock, it is harder to find an evolutionary justification for it.
I don't know how the antagonistic pleiotropy theory is doing. If true it would be a satisfactory explanation from an evolutionary point of view but I recall that it had some problems.
Otherwise I don't find the other evolutionary explanations of programmed aging to be satisfactory, especially when you consider that genes are selfish and act on the individual rather than population level.
Perhaps reproductive aging (egg quality) is the ultimate limiter, and then overall aging is adaptive downstream of that because hunter-gatherer families benefit (in terms of evolutionary fitness) from fewer old people to increase the percentage of people at reproductive age? That would fit the modern evidence of early egg freezing significantly increasing reproductive success in older women, showing that the problem of fertility decline by age is primarily cellular.
Or perhaps the aging mechanism is leftover from pre-human ancestry and there simply wasn't enough time in our evolutionary history for humans to evolve longer lifespans, maybe because it's slightly helpful but not nearly as helpful as other traits like intelligence, and lifespan is hard to improve via genetic adaptation due to bottleneck effects?
Great article on programmed aging as a tradeoff of telomeres versus cancer: <a href="https://dynomight.substack.com/p/liver" rel="nofollow">https://dynomight.substack.com/p/liver
2001zhaozhao · · focus · HN ↗
I don't know how the antagonistic pleiotropy theory is doing. If true it would be a satisfactory explanation from an evolutionary point of view but I recall that it had some problems.
Otherwise I don't find the other evolutionary explanations of programmed aging to be satisfactory, especially when you consider that genes are selfish and act on the individual rather than population level.
Perhaps reproductive aging (egg quality) is the ultimate limiter, and then overall aging is adaptive downstream of that because hunter-gatherer families benefit (in terms of evolutionary fitness) from fewer old people to increase the percentage of people at reproductive age? That would fit the modern evidence of early egg freezing significantly increasing reproductive success in older women, showing that the problem of fertility decline by age is primarily cellular.
Or perhaps the aging mechanism is leftover from pre-human ancestry and there simply wasn't enough time in our evolutionary history for humans to evolve longer lifespans, maybe because it's slightly helpful but not nearly as helpful as other traits like intelligence, and lifespan is hard to improve via genetic adaptation due to bottleneck effects?
robocat · · focus · HN ↗