Brilliantly illustrated here:
Evolutionary biologists have long been struck by two unique features of humans. The first is that we enjoy some of the longest life spans in the animal kingdom. In just the past 200 years, there has been an unprecedented increase in how long we live, not just in the richest countries but also in the poorest. We have moved so far away from our hunter-gatherer ancestors that their life spans are more similar to those of apes and chimpanzees than to modern human beings.
This feature is coupled with another. To a biologist, an organism that cannot reproduce is of little value in evolutionary terms, an unmitigated oddity. So scientists have been puzzled by the long postmenopausal life of human females. From a purely evolutionary perspective, grandmothers can be considered a failure of reproductive fitness: What good is an organism that cannot reproduce and cannot help perpetuate the species?Haider
Warreich , “‘Grandmother effect’ helps explain human longevity” at Stat News
First, what’s increased is not our lifespans but our likelihood of achieving a “normal” human lifespan, seventy to eighty years (as articulated at least three or four thousand years ago but surely known from much earlier). Some individuals live much longer simply because nothing kills them.
Second, only a “purely evolutionary perspective” would fail to see that the primary reasons for the survival of old women are intelligence and culture.
Some old women are useful; some are not. But intelligence causes most of them not to avoid stupid situations where they just get killed (the way an animal might). And cultural values, carefully nurtured by the old women themselves, cause their survival to be valued.
Treat this sort of evolutionary biology the way you would treat grievance studies. Be polite.
See also: Darwinian grandmother hypothesis takes another hit Sadly, it probably doesn’t matter whether the grandmother hypothesis explains anything about human history because it doesn’t need to. It needs only to be a Darwinian talking point, trotted out at the correct time.
Shock! Darwinism does not explain why old women exist
Evolutionary medicine: Insomnia in the elderly is due to evolution?
The Grandmother Hypothesis, yet again
Menopause caused by guys staying home
“Grandmother” Thesis In Human Evolution Takes A Hit: The “grandmother” thesis is that the reason our ancestors didn’t kill granny was that she helped out. (And then somehow religion got involved, and …) An actual study showed that “The hazard of death for Dogon children was twofold higher if the resident paternal grandmother was alive rather than dead. This finding may reflect the frailty of elderly grandmothers who become net consumers rather than net producers in this resource-poor society.”
and
Evolutionary psychology: The grandmother hypothesis yet again