Well, it would seem to me that the mighty hunter appeals to the eligible women, and men of course were attracted to a female with more reproductive ages ahead of her - but the limiting factor would probably be the drive for monogamy, in a small tribe and a group where the sex balance is pretty equal - monogamy would also be socially enforced to limit the tendency to for men to fight over women.
The idea that some old goat too old to chase down antelope would appeal to a 22-year-old woman would be something that probably came with the invention of money. But until nowadays, usually young women were traded or sold to those old geezers so “atttraction” was not really a factor for her.
“The grandmother hypothesis” is the standard response, but human longevity has evolved in males as well, and a father has less confidence of parenthood: why then do males live long also?
I think @Sage_Rat is on the right track - that the driver is not just the help to the adult children and thus increasing the ability of them to have more progeny who have better odds of surviving, but of the extended kinship in an intelligent social animal that lives in groups and has cultural transmission of accumulated knowledge. The elders of the extended kinship are the repositories of that culture, of that knowledge, and teachers of it to the subsequent generations, increasing the fitness of their direct descendents directly and to them as well indirectly by way of the extended kinship/tribe being more competitive with neighboring groups.
Very true. Evolutionary advantage rarely has one driver. All of them are factors - the grandma hypothesis, the strain of pregnancy on an older body, the need for children to be nurtured a great deal for a year or two and still need nuturing for a decade or more… Which requires the mother to be present more than the father in a tribal group.
But the “elder” factor is very important too. So many of the more traditional societies put a heavy emphasis on the value of the elders as repositories of knowledge. Also, not being as heavily invested in the hunt or other strenuous tasks, at an advanced age, have more time to sit and talk about the past so as to pass on wisdom. .
Not sure if it’s been mentioned, but grandparents raising a child frees up the mother to be more productive. She can go foraging or work on making important tools while her folks keep an eye on junior.
I think this is a good selection mechanism for old age - our emotional response. Those getting older tend to get additional attention and care, thereby extending their lives. We don’t like seeing members of our tribe die suddenly, so the tribe itself is a survival mechanism that extends lives. While no longer biologically necessary, we have other reasons, as mentioned, to keep people alive and adding value to the group long after they are done reproducing. Other species may not have this sort of emotional attachment to their elders.
I think there is a simpler explanation that @TriPolar already gave in post #7. No “death” gene exists.
Animals are known to live to extraordinary ages when kept in zoos. That implies that in their natural habitats they die only from outside causes: predators, starvation, diseases. If left alone they just keep on living.
The nonsense that humans used to live only 40 years derived from a misunderstanding of statistics. High death rates among children under five negated the much longer life span of adults who survived. (And survived also high mortality during birth for women and high mortality in wars for men.) The Founders, a group who avoided early death, typically had long lives (and longer than their wives).
No advantages have to be posited for humans’ long lives after reproductive age. That is natural in a zoo where all the animals are kept healthy. The modern western world is in effect a zoo with those conditions. Elsewhere, starvation, disease, and predators in the shape of other humans create lower lifespans.
Grandmothers may be helpful when they live and can help their children. But that’s a post hoc explanation that is unnecessary. Human lifespans would be the same without them.
The core OP question is why women stop being able to reproduce well before they die - i.e. why menopause.
o me the obvious ansswer was the strain pregnancy puts on especially an older body, and the need for the woman to stay alive to help the survival of other earlier offspring.
So I guess the collateral question is what happens to the reproductive cycles of those zoo animals of advanced age? It was mentioned earlier that some apes also experience a form of menopause at an elder age, and I vaguely recall a study that said that Orcas(?) also do.
Or do zookeepers deliberately avoid encouraging offspring in elder females? Or is the “winding down” of female pregnancy capabilities a common trait of old age in more advanced mammals?
This is usually the case - it is not quite universally the case. In ancient Egypt a combination of endemic mild malnutrition and continuous hard labor meant that peasants actually did live very, very short adult lives (very much as opposed to the Egyptian aristocracy, who are often recorded with suspiciously long lifespans past the century mark which may reflect cultural ideals). In Roman Egypt average male life expectancy was purportedly in the 20’s - that was a result of both high childhood mortality AND the fact that those who did live didn’t make it much past 40, if that.
In general though, yeah - there probably is an upper hard limit (perhaps the much-debated Mitochondrial Free Radical Theory, perhaps something else). But just generally there is no “deliberately” programmed death because someone has outlived their biological usefulness. It’s hard to see how and why that would be selected for.
This number is much debated. I don’t want to hijack this thread too much, but I found a set of interesting tables, which provide data on ordinary households, including servants and slaves, that is illustrative of the difficulties of making any claims.
They show high mortality in children under 10. It was still high through the 20s, but about half the population who survived childhood lived longer, some until their 70s. Yet those percentages are starkly different for women who lived in villages instead of towns, but not men. The total population is fairly small so you can’t do too much in the way of analysis. I couldn’t use these findings to support that most men that survived childhood died by age 30 but I also wouldn’t say that lifespans were very long either.
The point remains that given good health and luck there was and is no natural age of death for humans and so no natural genetic driver preventing humans from living regardless of reproductive ability.
Ramses II was about 90 when he died. Being someone important obviousy helped with his health. Avoiding being killed in war helped too.
Living into your 90’s (and some, over 100) is not an unknown situation throughout history. Some historical accounts are obviously exaggerated, but there seems to be significant documentation for Ramses. (and the ability to examine his body)
The problem with mortality too, was that while many early people escaped many of today’s lifestyle issues like too much red meat or sugar, there was limited control of diseaes. Epidemics were common and there was no easy treatment. A further problem likely came with agriculture leading to urbanization, as control of sewage and garbage, and crowded conditions, proximity to livestock and their diseases, would exacerbate the conditions where diseases spread easily.
Although worth noting that it was the opposite for medieval European nobility in terms of red meat, though still no masses of refined sugar. Plus lots and lots of booze. There a number of examples of big, fat kings and nobles (some like William the Conqueror were very notably obese). Not entirely shockingly, even those medieval European nobility who died in their sleep did not tend to make it past their 60’s.
Plus omnipresent parasites like fleas and lice, not to mention grit from stone-ground meal wearing down teeth. Pre-modern living sucked .
I should have phrased it correctly: If a child has living grandparents, the child is more likely to live to adulthood. If their grandparents lived long enough to help with grandchildren, the grandchildren have the genes to become grandparents themselves.
Yes, in the past rich people who didnt have to work all their life doing backbreaking labor 14+ hours a day 6 1/2 days a week- once they successfully got out of childhood- could sometimes, rarely live to 70 or 80.
But now so many people are living past 70 it is putting stress on retirement plans and services.
Having grandparents that lived is nice, and yeah as a child I had even a great grandmother. But Prostate cancer would have done me in before 60, even if I hadnt died from some mysterious disease when I was 13. (they wont take my blood for donations as I have a weird antibody). I mean not to mention all the diseases I was given vaccinations for that would have killed half my generation before we got into High School.
Medical Science mean you can live out what your genes might allow you to.
Do we have any useful statistics for hunter gatherer societies?
The effects of more organised and larger societies may skew things in ways that don’t reflect evolutionary pressures - partly because there probably hasn’t been enough time for evolution to catch up. Certainly not exactly time to cope with gold-diggers, but likely not a huge amount of time to catch up with stratification of a society, or organised conflict.
One would ideally like a measure of life expectancy at age of menopause for women. That might be hard.
I just looked this up; Segovia’s last child was born when he was 77. Tony Randall also had two children while in his 70s, having remarried a much younger woman after his first wife, with whom he had no children, died. I also understand that Mick Jagger has a child younger than his oldest great-grandchild (ewww).
You forgoot Larry King who had his last two children when he was 66 and 67,
The problem is the elite are not a good representation of the typical person. Henry VII was so big he supposedly had to turn sideways to get through doors, had an ulcerated leg and died early at 56. Queen Victoria had 9 children between ages 21 and 38… according to sources, she couldn’t get enough. Albert was the prissy one that gave rise to the concept of Victorian prudery.
The average person was not overfed although alcoholism seems to be a common problem since the advent of agriculture. There are studies that suggest that in fact, agriculture was a step backward to a less varied, more monotonous and less nutrious diet.
It occurs to me that a good example is the Atkins or Keto diet, which demonstrates that although humans adapted to hunting and a diet with much more meat (protien) and fat many millennia ago, evolution has not found it necessary to adjust the factors that tell the metabolism using carbohydrate intake that a person is starving and needs to consume body fat.
And while children may be adopted if the mother and father die, traditional literature is full of stories that suggest those adoptees were more likely to be starved and abused, and the direct offspring more favoured. So having grandparents around invested in the continuation of their genetic material is a survival factor.
An interesting book to read is The World Until Yesterday by Jared Diamond, who looks at some surviving groups still living the traditional ways (as much as they can in the modern world) to give an idea what earlier societies were like.
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