Comment by avalys
5 years ago
Someone once told me that the finite human lifetime is not a constraint of physics or biology, but evolution. The fact that older organisms decay and die gives an opportunity for new organisms (potentially, with superior genes) to thrive.
If there was no finite lifetime, then the benefit of physical maturity would allow older organisms to perpetually outcompete the younger ones, reducing the rate of genetic adaptation and the fitness of species overall.
Does anyone with specific knowledge know if this is true? If so, it's a little bit depressing to think that aging is simply a programmed biological process, "deliberately" degrading our bodies on a schedule and killing us off to make room for something new, rather than any sort of fundamental limitation of the underlying system.
I've read it's not so much that a particular aging trajectory is selected for, it's that mechanisms that shorten lifespan aren't selected against depending on ecology, social structure, and so forth. I imagine that's not entirely accurate, though, as there are some species that have definite senescence patterns that are closely tied to important developmental events (e.g., octopuses and egg laying).
It's difficult for me to imagine something that selects for individual death per se, but I can imagine certain cellular repair mechanisms and so forth, with death at a certain age being a secondary consequence, being selected for depending on a host of factors. Evolution tends to be somewhat chaotic in that what's adaptive depends on prior evolutionary history to some extent.
I mean during a long period humans were probably mainly dying of other things than old age? Wisdom and skill transfer must have had huge importance, but the chance of reaching 200 years of age must have been miniscule for a long part of our race's time on earth even if they could live that long.
On the other hand it means that there are some benefits which are correlated with age or else this mechanism wouldn’t be necessary.
Our culture mostly looks on old age with disdain. And indeed not just old age but any kind of aging past 25. And to be sure there are many objective downsides to being old compared to young. However one does also have the opportunity to attain knowledge and wisdom as one gets older. And that can continue until one starts to become senile, which might only start in very advanced years for many or most people!
Even though they're more athletic in their early twenties, most basketball players seem to peak around 27-29, I assume because of the intersection of athleticism and skill gained from experience.
See how Wikipedia describes it: https://en.wikipedia.org/wiki/Ageing#Ageing_versus_immortali...
If very process of sexual reproduction that brought humans into existence is entangled with the process of aging, there is probably no reason to think that humans (or any species that reproduces sexually) could somehow change or evolve to become immortal.
Makes sense. We could sure use fewer 80yo congresspeople and more 40yo congresspeople in America.