Dunking on medawar selection shadow

Peter Mernyei asks:

Would there really be any evolutionary pressure to keep the body alive longer in old age at the cost of increased frailty? I’d have thought in an ancestral environment you’re likely to die anyway if you’re making either choice, and in any case you’re very likely not reproducing anymore. So my naive expectation would be that evolution just programs whatever works for younger bodies that it actually “sees clearly” and it “doesn’t think about” what happens to older bodies very much.

What you’re describing is known in biogerontology as Medawar’s “selection shadow”. It’s a very intuitive