Being a man greatly reduces reproductive fitness, compared to the reproductive success of women. E.g., at age 12, for example, the death rate for boys is 46 percent higher than the rate for girls. And there are probably other factors that add to less reproductive success among males besides death. Being both gay and male doesn’t seem like that much of a difference.
If this were true, then the human species would acquire an unequal ratio of men to women (with more women), until the fitness of both was the same (because men would be in greater demand). There are species which work that way, like sea lions. This is known as Fisher’s Principle.
Gender can affect reproductive fitness, in a population that isn’t at a stable sex ratio. For instance, if people kill most girl babies at birth because they prefer sons to daughters, then the few women who do grow up will necessarily have higher fitness than the average man—because most men won’t reproduce at all.
The 50% who get killed lowers the reproductive fitness of having a girl by the exact amount that the reproductive fitness of having girls is raised by the lower percentage of them relative to men.
Or to take it from another route, the average number of children had by men and women must remain equal.
The 50% who get killed lowers the reproductive fitness of having a girl by the exact amount that the reproductive fitness of having girls is raised by the lower percentage of them relative to men.
That’s why I said the women who grow up have higher fitness, not all women born.
The detail of my example, that girl babies are born and then killed, is easy to modify. Imagine a drug that, when taken by a woman before sex, selectively kills XY sperm. Or a sex-selective early abortifact.
The average number of children by men and women must remain equal, but the average number of men children and woman children doesn’t have to.
Being a man greatly reduces reproductive fitness, compared to the reproductive success of women. E.g., at age 12, for example, the death rate for boys is 46 percent higher than the rate for girls. And there are probably other factors that add to less reproductive success among males besides death. Being both gay and male doesn’t seem like that much of a difference.
If this were true, then the human species would acquire an unequal ratio of men to women (with more women), until the fitness of both was the same (because men would be in greater demand). There are species which work that way, like sea lions. This is known as Fisher’s Principle.
Men and women have, on average, the same number of children. Gender doesn’t affect reproductive fitness in and of itself.
Gender can affect reproductive fitness, in a population that isn’t at a stable sex ratio. For instance, if people kill most girl babies at birth because they prefer sons to daughters, then the few women who do grow up will necessarily have higher fitness than the average man—because most men won’t reproduce at all.
You’re correct about stable sex ratios. (It’s unimportant, but your example doesn’t apply to stable sex ratios as far as evolution goes.)
What do you mean?
The 50% who get killed lowers the reproductive fitness of having a girl by the exact amount that the reproductive fitness of having girls is raised by the lower percentage of them relative to men.
Or to take it from another route, the average number of children had by men and women must remain equal.
That’s why I said the women who grow up have higher fitness, not all women born.
The detail of my example, that girl babies are born and then killed, is easy to modify. Imagine a drug that, when taken by a woman before sex, selectively kills XY sperm. Or a sex-selective early abortifact.
The average number of children by men and women must remain equal, but the average number of men children and woman children doesn’t have to.