Having kids takes a long time, especially when many of them die of infection or malnutrition. So yes, you're absolutely right that evolution "cares" about human beings up until they hit ~40. At that point, human beings enter the selection shadow, when improvements to survivability have a negligible impact on selection. I was eliding this point for clarity but I don't think it really alters my broader argument.
This is all pretty obvious when you look at one of the main diseases of aging, cardiovascular disease. There are natural genetic variations that result in very low free LDL blood levels, which basically prevents artherosclerosis from every developing and which inspired the development of the PCSK-9 inhibitors. However, there's no evolutionary benefit to not dying of cardiac arrest when you're 60, but there are marginal benefits to the liver binding to fewer LDL particles when people are in a starvation environment, so these variations never became widespread.
The grandparent hypothesis is certainly compelling and might explain some marginal improvements in human lifespan relative to e.g. chimps (who live about 10-20 years less than us even in captivity). But if anything, that reinforces my broader point, which is that aging did not develop as some kind of culling agent by evolution and that we should be looking for ways to extend human longevity now that we have the resources to.
This is all pretty obvious when you look at one of the main diseases of aging, cardiovascular disease. There are natural genetic variations that result in very low free LDL blood levels, which basically prevents artherosclerosis from every developing and which inspired the development of the PCSK-9 inhibitors. However, there's no evolutionary benefit to not dying of cardiac arrest when you're 60, but there are marginal benefits to the liver binding to fewer LDL particles when people are in a starvation environment, so these variations never became widespread.
The grandparent hypothesis is certainly compelling and might explain some marginal improvements in human lifespan relative to e.g. chimps (who live about 10-20 years less than us even in captivity). But if anything, that reinforces my broader point, which is that aging did not develop as some kind of culling agent by evolution and that we should be looking for ways to extend human longevity now that we have the resources to.