Source for this? Middle-aged runners look like they're in great shape. Evidence suggests long-distance running, if done correctly, has no adverse effects on the body. We've literally evolved for it
That’s not a valid argument. It could be survivor bias, with those still running (and not dead, bound to a wheelchair at 30, etc) looking great.
Even if, taking that into account, runners look better than non-runners, there, a priori, is no guarantee they wouldn’t have looked even better without it.
https://www.active.com/health/articles/why-too-much-running-...
Not to mention shin splints, torn Achilles, etc.
Of course there are diminishing returns if you are running for the purpose of living a longer, healthier life.
As far what we “evolved for”. There is no evolutionary benefit of living past the age where you can pass on your genes and endure the next generation can do the same. There is no evolutionary pressure for a people to live pass that age.
Evolution would never favor a trait that would allow a population to live be 100 instead of 60.
Kin selection is the term you need to read up on for our current explanation on why we live so far beyond reproductive age.
It would. Grandparents care for grand children. In fact, they seem to have an uncanny ability to inculcate them with the desire for having more children, of their own. Hmmmm ;)
Naturally, knowledge transfer won’t be complete or perfect, so it seems plausible that there’s an evolutionary benefit to much younger generations to having some really, really old people around.
I mean, I’m not trying to argue for exactly what happens, mostly just contesting the idea that there’s no evolutionary reason for people to live way past child-rearing.