Genes for living longer reproduce in a population only if they enhance fertility rates, but I suspect throughout history humans have been food constrained, and

Genes for living longer reproduce in a population only if they enhance fertility rates, but I suspect throughout history humans have been food constrained, and so there was never an opportunity for an older couple to have another baby when the younger couples were “maxed out” with babies already. Given food scarcity, living longer only means the clan needs more food, which hurts the clan’s overall fertility.