It doesn’t mean it can’t be done, just that it is not likely to be as easy as pushing a few chemical buttons or turning something on or off.
The best argument is that those same tweaks affect child bearing/survival performance in the same direction. Since sickle cell and other diseases were selected for, it seems unlikely all of them go the same way.
And, of course, the oft-repeated "anything that happens after reproduction is irrelevant to evolution". Which isn't 100% true (it takes a village to raise a child, after all).
Human life seems to go through 3-4 phases (roughly youth, middle age and old age). The role of each of those is distinct and fairly clear, but it isn't easy to pick why evolution settled on specific numbers of years.
Their modern “living” in hospices, hospitals, far away neighborhood or vacation resorts have a minor effect on survival on their grand children. Probably negative effect for some pension systems.
Evolution doesn't mean only what is useful stays, it is only when selected for under evolutionary pressure that things are forced to go a certain way, and only after many generations.
The uselessness of old age will only affect evolution if A) there will be a society that is mad enough to really 'do something about it' and B) such a society will eventually outcompete other ways of life and its values start to dominate.
I can imagine a politics where money spend on welfare and healthcare for elderly is minimized to such an extent that life expectancy starts dropping significantly. In a way, the US has something like such a 'make money or die' politics and indeed, life expectancy there is quite a bit lower than would you would expect from such as prosperous nation. Can be economically effective. But it competes which economies where people are productive at an older age, being more focused on staying healthy and significantly less stressed.
Senior citizens today probably have more power (and productivity) than they ever have.
Grandparents used to be younger, too. Women used to have kids before 20, often at 15. You could be a grandparent at 30.
But even old and infirm, still stories could be told, and caring for grandma was distracting for kids too.
There were a lot more kids too. Most women gave birth yearly, and yes more died, but there were still more.
Keeping those kids busy was a plus. Training them vital.
Last 100 years? Forget it.
See eg https://d1wqtxts1xzle7.cloudfront.net/46398103/s12110-000-10... . I don't know about the overall hypothesis, but there's some fascinating data there about how old men can get whole still playing important tribal roles.
>long enough for grandparents to help with kids and pass on valuable knowledge
>short enough that new generations are able to adapt as needed to changing environments and throw out out of date information or cultural "technology" that is no longer relevant
increasing human lifespan significantly seems like a nightmare, especially if only the richest have access. The saying "science advances one death at a time" and just the thought of political leaders being able to entrench themselves over longer times spans is awful. Seems like it would most likely lead to complete stagnation
But 16 year olds think they will live forever, so I’m not sure how that would work.