"there never was selection pressure favouring people who thrive well into old age and age in supreme health on any chow or fodder without suffering severe degen

"there never was selection pressure favouring people who thrive well into old age and age in supreme health on any chow or fodder without suffering severe degeneration and disease" Can you back that up? Actually having living healthy grand-parents can be a boon to reproductive success: they can take care of kids, while parents are out hunting or gathering. So yes, if you have genetic mutations favoring living old enough to be grand-parents, it is subject to selection pressure. Plus, it's been a while since we started caring for old people. In that context, because evolution is all about context, having healthy elderly is also a boon to reproductive success since it doesn't divert resources from child care to elderly care. Any genetic mutation that is expressed and results into higer reproductive success in a specific context is subject to selection.