Given the stunted nature of the Y chromosome [...] and the fact that all other genetic material is shared, this still means the burden of proof is stacked against the idea of non-obviously essential sexual dimorphism
I don’t think simply counting genes tells us much of anything about the amount of sexual dimorphism in a species, one way or the other. The vast majority of genetic material is shared between sexes in any species, and some species don’t even use genes to determine sex. If the fact that most genetic material is shared between sexes really did stack the deck against large sex differences, then we would never see large sex differences anywhere.
Futhermore, I’m not sure what you mean by “non-obviously essential.” Obvious to whom? It’s not at all obvious to me why (say) it would be adaptive for human males to have so much facial hair compared to human females, and yet human males really do have a lot of facial hair.
The discussion here was about behavior, not physical differences. My apologies if I was unclear about that. Furthermore, you seem to be reading “stack the deck against” as referring to likelihood of differences arising, I meant it more in the sense of “here is an observed behavioral difference between human sexes, is it due to 1) statistical noise 2) learned social behaviors 3) intrinsic genetic differences, &c.” It seems reasonable to have a fairly low prior for #3 vs. #2.
Also, “obviously essential” in the the sense of “the whole point of sexual dimorphism”. Suckling an infant is pretty clearly essential behavior. “Women are more practical”, not so much.
I agree that in the case of behavioral differences, we have a prominent “learned social behavior” hypothesis that we do not have in the case of physiological differences, but it’s not because of the number of genes shared between sexes; it’s because of the common-sense intuition that culture influences behavior in a dramatic way that it doesn’t influence physiology.
Suckling an infant is pretty clearly essential behavior. “Women are more practical”, not so much.
I agree here. (In particular, “Women are more practical” is vague to the point of not-even-wrong-ness.) However, it does seem worth noting that if there are non-obviously-essential physiological differences (such as male facial hair), then it’s at least not implausible that there might also be non-obviously-essential brain development differences that manifest as behavioral differences.
Well, in a counterfactual world where somehow genetic differences between the sexes were much larger, comparable to the genetic differences between humans and other primates, genetic reasons for behavior differences would be a lot more plausible, just as genetic differences explain behavioral differences between us and other primates now. That this is not the case in reality is why “learned behavior” is a stronger, common-sense hypothesis.
it’s at least not implausible that there might also be non-obviously-essential brain development differences that manifest as behavioral differences.
Of course. In fact, there are probably quite a few. But for any given observed behavioral difference, it’s sensible to assume it’s a learned behavior lacking strong evidence otherwise (such as consistent observation of the same difference in multiple unrelated cultures).
I think we’re arguing 95% terminology and 5% substance here.
I suspect there is a substantive disagreement lurking here. Specifically, as much as it hurts my liberal feminist heart to say it (or it did hurt, before I got jaded), I’m going to have to deny this:
But for any given observed behavioral difference, it’s sensible to assume it’s a learned behavior lacking strong evidence otherwise
Maybe we’re tripping over this word genetic? When I say that the number of shared genes doesn’t matter, what I’m getting at is that while SRY may “just” be “one gene,” it triggers this entire masculinizing developmental process, and while I haven’t studied the details (yet), it doesn’t look trivial. Obviously culture exists, but the capacity to generate and transmit culture is a specific ability of human brains that happens in a specific manner, and if there are innate sex differences in human brains, then we are not justified in assuming that a given behavioral sex difference is a strictly cultural artifact that could have just as easily gone the other way. Culture is—I don’t have the word for it—informed, constrained?---by human nature. We have to reason these things out on a case-by-case basis. Suppose—suppose American males score better than females on a test of mental rotation by eight-tenths of a standard deviation, and suppose we don’t have any cross-cultural data, however dearly we might wish for it. I can’t bring myself to presume a social explanation.
I don’t think simply counting genes tells us much of anything about the amount of sexual dimorphism in a species, one way or the other. The vast majority of genetic material is shared between sexes in any species, and some species don’t even use genes to determine sex. If the fact that most genetic material is shared between sexes really did stack the deck against large sex differences, then we would never see large sex differences anywhere.
Futhermore, I’m not sure what you mean by “non-obviously essential.” Obvious to whom? It’s not at all obvious to me why (say) it would be adaptive for human males to have so much facial hair compared to human females, and yet human males really do have a lot of facial hair.
The discussion here was about behavior, not physical differences. My apologies if I was unclear about that. Furthermore, you seem to be reading “stack the deck against” as referring to likelihood of differences arising, I meant it more in the sense of “here is an observed behavioral difference between human sexes, is it due to 1) statistical noise 2) learned social behaviors 3) intrinsic genetic differences, &c.” It seems reasonable to have a fairly low prior for #3 vs. #2.
Also, “obviously essential” in the the sense of “the whole point of sexual dimorphism”. Suckling an infant is pretty clearly essential behavior. “Women are more practical”, not so much.
I agree that in the case of behavioral differences, we have a prominent “learned social behavior” hypothesis that we do not have in the case of physiological differences, but it’s not because of the number of genes shared between sexes; it’s because of the common-sense intuition that culture influences behavior in a dramatic way that it doesn’t influence physiology.
I agree here. (In particular, “Women are more practical” is vague to the point of not-even-wrong-ness.) However, it does seem worth noting that if there are non-obviously-essential physiological differences (such as male facial hair), then it’s at least not implausible that there might also be non-obviously-essential brain development differences that manifest as behavioral differences.
Well, in a counterfactual world where somehow genetic differences between the sexes were much larger, comparable to the genetic differences between humans and other primates, genetic reasons for behavior differences would be a lot more plausible, just as genetic differences explain behavioral differences between us and other primates now. That this is not the case in reality is why “learned behavior” is a stronger, common-sense hypothesis.
Of course. In fact, there are probably quite a few. But for any given observed behavioral difference, it’s sensible to assume it’s a learned behavior lacking strong evidence otherwise (such as consistent observation of the same difference in multiple unrelated cultures).
I think we’re arguing 95% terminology and 5% substance here.
I suspect there is a substantive disagreement lurking here. Specifically, as much as it hurts my liberal feminist heart to say it (or it did hurt, before I got jaded), I’m going to have to deny this:
Maybe we’re tripping over this word genetic? When I say that the number of shared genes doesn’t matter, what I’m getting at is that while SRY may “just” be “one gene,” it triggers this entire masculinizing developmental process, and while I haven’t studied the details (yet), it doesn’t look trivial. Obviously culture exists, but the capacity to generate and transmit culture is a specific ability of human brains that happens in a specific manner, and if there are innate sex differences in human brains, then we are not justified in assuming that a given behavioral sex difference is a strictly cultural artifact that could have just as easily gone the other way. Culture is—I don’t have the word for it—informed, constrained?---by human nature. We have to reason these things out on a case-by-case basis. Suppose—suppose American males score better than females on a test of mental rotation by eight-tenths of a standard deviation, and suppose we don’t have any cross-cultural data, however dearly we might wish for it. I can’t bring myself to presume a social explanation.