It still seems to me that this is all a red herring, and you're ignoring the overall thrust of my comments to argue with a point I did not even really make. As I said, whether grandparents offer zero evolutionary benefit or simply less evolutionary benefit than immediate parents is immaterial.

My point is that nobody has yet presented enough evidence to argue that simply "listening to our bodies" rather than taking any proactive measures is the best path to longevity. The view that evolution has given us natural lifespans that are as long as can be doesn't seem to be supported by the evidence.