A couple of remarks to expand on RowanE’s points for anyone who may be skeptical that evolution cares at all about longevity past (something like) typical childrearing age:
Men (but not women) can continue to father children pretty much as long as they live.
Children may receive some support from extended families; the longer (e.g.) grandparents remain alive and healthy, the better for them (hence for their genes, which overlap a lot with the grandparents’).
I bet most things that make you more likely still to be alive at 80 also make you likely to be healthier (hence more useful to your children) at 30.
This is all true. However buyandbuydavis has a point. Evolution optimizes for offspring and longevity is only selected for as a means to that end. When you selectively breed and mutate fruit flies and nematodes for lifespan over hundreds of generations you can double or triple them, universally at the expense of total offspring. Granted mammals are much more k selected, putting lots of effort into a few offspring, than those r selected species that throw hundreds or even thousands of eggs to the wind per generation so lifespan does matter at least some to us and we probably already lie somewhere along that evolutionary axis away from the flies. But you can still see how there might be some tension between the two optimizations and we’re certainly not perfectly optimized for longevity.
That doesnt change my assessment that within any given existing evolved tuned organism a lot of the evidence ive seen suggests that mucking with hormone levels exogenously (as opposed to endogenously through general health activity diet etc) to try to keep energy or cell division or whatever up in the absence of an existing pathology of that hormone system will probably increase cancer rates.
Theres actually a promising line of research on a substance being developed by one of the scientific grandaddies of my current metabolism research that appears to be broadly neuroprotective via messing with regulation of aerobic respiration, something that also goes weird in muscles with age. I greatly look forward to seeing if it increases tumor rates too [there are biochemical mechanistic reasons i think it might] or if that particular dysregulation is something you can attack without nasty side effects (though i gotta say i would take a raised cancer risk to hold off alzheimers or parkinsonism or traumatic brain injury any day).
A couple of remarks to expand on RowanE’s points for anyone who may be skeptical that evolution cares at all about longevity past (something like) typical childrearing age:
Men (but not women) can continue to father children pretty much as long as they live.
Children may receive some support from extended families; the longer (e.g.) grandparents remain alive and healthy, the better for them (hence for their genes, which overlap a lot with the grandparents’).
I bet most things that make you more likely still to be alive at 80 also make you likely to be healthier (hence more useful to your children) at 30.
This is all true. However buyandbuydavis has a point. Evolution optimizes for offspring and longevity is only selected for as a means to that end. When you selectively breed and mutate fruit flies and nematodes for lifespan over hundreds of generations you can double or triple them, universally at the expense of total offspring. Granted mammals are much more k selected, putting lots of effort into a few offspring, than those r selected species that throw hundreds or even thousands of eggs to the wind per generation so lifespan does matter at least some to us and we probably already lie somewhere along that evolutionary axis away from the flies. But you can still see how there might be some tension between the two optimizations and we’re certainly not perfectly optimized for longevity.
That doesnt change my assessment that within any given existing evolved tuned organism a lot of the evidence ive seen suggests that mucking with hormone levels exogenously (as opposed to endogenously through general health activity diet etc) to try to keep energy or cell division or whatever up in the absence of an existing pathology of that hormone system will probably increase cancer rates.
Theres actually a promising line of research on a substance being developed by one of the scientific grandaddies of my current metabolism research that appears to be broadly neuroprotective via messing with regulation of aerobic respiration, something that also goes weird in muscles with age. I greatly look forward to seeing if it increases tumor rates too [there are biochemical mechanistic reasons i think it might] or if that particular dysregulation is something you can attack without nasty side effects (though i gotta say i would take a raised cancer risk to hold off alzheimers or parkinsonism or traumatic brain injury any day).