Assume half of babies die in childbirth or by age 3. Assume another half die before they reach 25. Even assume that another half die before age 60. That means there are still tribal elders that can pass on information and educate the small children they take care of while parents are out getting food. It's a huge deal for a species based on cultural learning.

> That means there are still tribal elders that can pass on information [...] It's a huge deal for a species based on cultural learning.

True, it might be easy to claim that there is no way to select for longevity because longevity happens after the birth of the offspring. Having elder generations around to improve the odds of survival for the descendants should make longevity a possible factor in selection.

FWIW, the human birth process is not viable without cultural accumulation. Baby heads are too damn big and kill women if they don't have a midwife to help them through. But it's a cycle and the midwife is only helpful herself because she has an oversized brain to pass along cultural knowledge.