Certainly in an idealized world the reproductive capacity of a tribe of humans is only limited by the number of women. C.f. Randy the guinea pig, father of 400.
But on the other hand, neither modern humans nor ancestral humans lived in that kind of idealized world. In the modern world we have limited monogamy and reduced pressure to have kids. Somewhere around 18% of women in the U.S. don’t end up having kids—I’d expect that a woman surviving would lead to more kids, but not actually 2 more, and similarly a missing man wouldn’t just be replaced by the nearest available sperm-producer. I dunno how to put a number to it.
In an ancestral environment close to equilibrium (what you imply by saying that each person has 1 kid on average), the situation is even more egalitarian. That equilibrium is maintained by something other than birth rate. If the issue is limited resources, and if an additional person can gather additional resources, then a man and a woman will both be able to increase the long-term number of children about the same. If the population is growing exponentially but is occasionally devastated by war, a man will lead to a larger population the war is in five years but a woman will lead to a larger population if the war is thirty years. If by disease or famine, there might be very little dependence on gender.
I’d expect that a woman surviving would lead to more kids, but not actually 2 more, and similarly a missing man wouldn’t just be replaced by the nearest available sperm-producer. I dunno how to put a number to it.
One way to start estimating it would be to correlate local sex ratios with local birth rates and try to control for as many things as possible. Unfortunately, this is probably very hard to do...
In an ancestral environment close to equilibrium (what you imply by saying that each person has 1 kid on average), the situation is even more egalitarian.
I’m actually most interested in the answer for modern poor countries, which are neither stable in population nor Malthusian. Basically, I’m wondering how interventions that save lives of one gender (but not the other) today will affect the population size 20 to 30 years in the future. Non-replacement fertility doesn’t qualitatively change things: the question just becomes whether a life saved increases the population by more or less than “next generation’s size / current generation’s size”. Replacement fertility is just the special case where the ratio is 1; I used that number in my question only for simplicity.
Certainly in an idealized world the reproductive capacity of a tribe of humans is only limited by the number of women. C.f. Randy the guinea pig, father of 400.
But on the other hand, neither modern humans nor ancestral humans lived in that kind of idealized world. In the modern world we have limited monogamy and reduced pressure to have kids. Somewhere around 18% of women in the U.S. don’t end up having kids—I’d expect that a woman surviving would lead to more kids, but not actually 2 more, and similarly a missing man wouldn’t just be replaced by the nearest available sperm-producer. I dunno how to put a number to it.
In an ancestral environment close to equilibrium (what you imply by saying that each person has 1 kid on average), the situation is even more egalitarian. That equilibrium is maintained by something other than birth rate. If the issue is limited resources, and if an additional person can gather additional resources, then a man and a woman will both be able to increase the long-term number of children about the same. If the population is growing exponentially but is occasionally devastated by war, a man will lead to a larger population the war is in five years but a woman will lead to a larger population if the war is thirty years. If by disease or famine, there might be very little dependence on gender.
One way to start estimating it would be to correlate local sex ratios with local birth rates and try to control for as many things as possible. Unfortunately, this is probably very hard to do...
I’m actually most interested in the answer for modern poor countries, which are neither stable in population nor Malthusian. Basically, I’m wondering how interventions that save lives of one gender (but not the other) today will affect the population size 20 to 30 years in the future. Non-replacement fertility doesn’t qualitatively change things: the question just becomes whether a life saved increases the population by more or less than “next generation’s size / current generation’s size”. Replacement fertility is just the special case where the ratio is 1; I used that number in my question only for simplicity.