When I asked ChatGPT, as far as it can tell we don’t have straight evidence that the EDAR gene affects breast size.
Even if it does have an effect, one interesting question would be whether there are multiple genes that result in the difference or one gene. If it’s multiple genes that would suggest that there’s a difference in evolutionary pressure on breast size, maybe because of cultural reasons or something else.
Within studied populations Eriksson et al. 2012 suggests that no single mutations carries the majority of the effect and breast size differences spread over many different genes.
Yes, the Eriksson study was one of ones supporting an early draft of this analysis. I didn’t end up using it because it didn’t make much sense to do so. Size isn’t the issue here; permanence is.
Erikkson only looks at Europeans, so I don’t know about the cross-population comparison here.
EDAR polymorphism does work through plausible pathways to produce the size difference and has other drastic phenotypic effects, but yeah nothing’s proven.
I don’t think this post is clear enough about knowing what’s going on that saying size isn’t the issue makes sense. When a phenomenon is unclear it’s hard to see what the central issue is.
One interesting aspect is that breastfeeding human mothers are infertile while they breastfeed. Yet continuing to have sex with the father is good for pairbonding and the father investing in supporting the mother in childcare.
Humans are fairly unique in that regard among primates and only Bonobos also have frequent sex during that period of fertility.
Moving from big breasts being a sign of infertility and thus not having sex in most primates to big breasts being seen as sexually desirable is an interesting change.
I think a lot of the European/(East?) Asian difference you’re referring to is because of polymorphism in the EDAR gene.
When I asked ChatGPT, as far as it can tell we don’t have straight evidence that the EDAR gene affects breast size.
Even if it does have an effect, one interesting question would be whether there are multiple genes that result in the difference or one gene. If it’s multiple genes that would suggest that there’s a difference in evolutionary pressure on breast size, maybe because of cultural reasons or something else.
Within studied populations Eriksson et al. 2012 suggests that no single mutations carries the majority of the effect and breast size differences spread over many different genes.
Yes, the Eriksson study was one of ones supporting an early draft of this analysis. I didn’t end up using it because it didn’t make much sense to do so. Size isn’t the issue here; permanence is.
Erikkson only looks at Europeans, so I don’t know about the cross-population comparison here.
EDAR polymorphism does work through plausible pathways to produce the size difference and has other drastic phenotypic effects, but yeah nothing’s proven.
I don’t think this post is clear enough about knowing what’s going on that saying size isn’t the issue makes sense. When a phenomenon is unclear it’s hard to see what the central issue is.
One interesting aspect is that breastfeeding human mothers are infertile while they breastfeed. Yet continuing to have sex with the father is good for pairbonding and the father investing in supporting the mother in childcare.
Humans are fairly unique in that regard among primates and only Bonobos also have frequent sex during that period of fertility.
Moving from big breasts being a sign of infertility and thus not having sex in most primates to big breasts being seen as sexually desirable is an interesting change.