On the one hand, the existence of food that would keep humans healthy significantly past reproductive age has only been selected for in the past 10,000 years.
This is a flat-out misunderstanding of human history. The existence of female menopause, plus substantial evidence from existing hunter-gatherer tribes, suggest that longevity is adaptive. In tribes studied, post-menopausal women gather far, far more than their daily calorie intake, helping their descendants by providing extra resources. The reason prehistoric man had a low life expectancy is more due to high infant mortality than dying early. If long lives were not evolutionarily relevant, the existence of human menopause makes even less sense than it currently does.
Menopause makes sense the way I’ve heard it explained. Being pregnant, or having a young dependent child, reduces the ability to care for preexisting children. This is so obvious in resource-poor cultures that infanticide (preferentially of weak or closely spaced children) has been commonplace through much of history. The drain on resources that a new child represents increases with age: it is easier and less costly to have a child while young. After a certain point, the expected extra descendants gained by the ability to bear more babies is less than the expected extra descendants gained by investing the pregnancy & subsequent resources instead in the last one(s) born.
That’s the exact point. Menopause is very rare in the animal kingdom. The fact that it exists in humans shows that some portion of our ancestors lived long enough for it to be selected for to the point of total dominance in the population.
The “don’t bother with children when you are old” incentive is also helped along by the decreasing genetic value of children born to old mothers. The likelyhood of Down Syndrome is increased by an order of magnitude or two, for example.
I would like this whole comment thread a lot more if anyone linked to any studies or at least blog posts or books on amazon or something detailing where they got their ideas from (I don’t mean to be picking on anyone I just have very little knowledge of the subject and I’m curious where people got their first notions of things like “there exists a good diet which will make people feel healthier and live longer by a significant margin”)
My source is a book, and thus not terribly accessible. As Alicorn points out, menopause makes sense, but its existence strongly suggests enough women lived long enough for it to actually be selected for. It is not common in other animals.
This is a flat-out misunderstanding of human history. The existence of female menopause, plus substantial evidence from existing hunter-gatherer tribes, suggest that longevity is adaptive. In tribes studied, post-menopausal women gather far, far more than their daily calorie intake, helping their descendants by providing extra resources. The reason prehistoric man had a low life expectancy is more due to high infant mortality than dying early. If long lives were not evolutionarily relevant, the existence of human menopause makes even less sense than it currently does.
Menopause makes sense the way I’ve heard it explained. Being pregnant, or having a young dependent child, reduces the ability to care for preexisting children. This is so obvious in resource-poor cultures that infanticide (preferentially of weak or closely spaced children) has been commonplace through much of history. The drain on resources that a new child represents increases with age: it is easier and less costly to have a child while young. After a certain point, the expected extra descendants gained by the ability to bear more babies is less than the expected extra descendants gained by investing the pregnancy & subsequent resources instead in the last one(s) born.
That’s the story I’ve heard too. I wonder just how many women in the relevant resource poor cultures aged long enough for it to matter.
That’s the exact point. Menopause is very rare in the animal kingdom. The fact that it exists in humans shows that some portion of our ancestors lived long enough for it to be selected for to the point of total dominance in the population.
That’s true.
The “don’t bother with children when you are old” incentive is also helped along by the decreasing genetic value of children born to old mothers. The likelyhood of Down Syndrome is increased by an order of magnitude or two, for example.
I would like this whole comment thread a lot more if anyone linked to any studies or at least blog posts or books on amazon or something detailing where they got their ideas from (I don’t mean to be picking on anyone I just have very little knowledge of the subject and I’m curious where people got their first notions of things like “there exists a good diet which will make people feel healthier and live longer by a significant margin”)
My source is a book, and thus not terribly accessible. As Alicorn points out, menopause makes sense, but its existence strongly suggests enough women lived long enough for it to actually be selected for. It is not common in other animals.