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.
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.