A hypothesis imho important but you leave out entirely: permanent breasts as part of a broader signaling complex co-evolved with the other unusual human female trait: cycle-independent sexual receptivity. Humans aren’t unique in extended sexuality (bonobos and some Old World primates have it too), but we’re at the extreme end, and we’re also the species with permanent breasts. The natural a priori thus, imho: selection for cycle-independent male sexual interest favors traits signaling “potentially receptive” outside the fertile window, and permanent breast tissue feels like a strong candidate.
While AnthonyC’s comment would seem to object it indirectly, as pre-permanence breasts would have signaled ‘currently lactating, not fertile’ and thus been a turn-off, this seems to miss: In ancestral high-fertility conditions, most adult women would have been pregnant or lactating most of the time, and you got pregnant while lactating, not only later! Even today, e.g. my mum had 4 children in 4 years. If an ancestral female is lactating for 6 months to 2 years, having big breasts can be mostly a good signal for fertility not the other way round.
I don’t think your timing result is incompatible with this story; it just locates the co-evolution in deep hominin time. ((Actually, if your approach could be extended to genes regulating the cycle and sexual receptivity that could be interesting))
Women who have reproduced recently are less likely to have passed the menopause.
I guess that was exactly part of what I meant.
Other mammals don’t live for decades after the menopause like we do.
Interesting point!! Apparently women really live exceptionally long, while their menopause (and its timing) itself is not unusual at all, and the most prevalent hypothesis is “grandmothering”, which posits what its name suggests, and essentially is, for our purposes, yet another symptom of them (say, our genes, or figuratively thus ‘our children’) desperately wanting us to stick around to care for these slow-up-growing and nerve-and-everything-wrecking offspring. In that sense, indirect extra, tiny support of the idea ‘they want to lure into having sex anytime as a loyalty encouraging devise and preventing us from straying too far’ or something like that. I’m vary if it sounds too simple but it does all seem to make sense (?).
Maybe our longevity after the menopause also led to human men evolving to be strongly attracted to women with a more youthful appearance. Attraction to boobs was then a counter-adaptation to prevent men from putting all their effort into pursuing pre-pubescent children.
I’d argue the more interesting and potentially related human trait isn’t cycle-independent sexual receptivity, but hidden estrous, which is even more uniquely human.
For either trait, I don’t know how you would assemble a gene panel for study. You can’t use GWAS results because all of these traits are fixed in modern humans. The only reason the involution panel supports this type of analysis is because of extensive and unrelated experimentation in mice.
A hypothesis imho important but you leave out entirely: permanent breasts as part of a broader signaling complex co-evolved with the other unusual human female trait: cycle-independent sexual receptivity. Humans aren’t unique in extended sexuality (bonobos and some Old World primates have it too), but we’re at the extreme end, and we’re also the species with permanent breasts. The natural a priori thus, imho: selection for cycle-independent male sexual interest favors traits signaling “potentially receptive” outside the fertile window, and permanent breast tissue feels like a strong candidate.
While AnthonyC’s comment would seem to object it indirectly, as pre-permanence breasts would have signaled ‘currently lactating, not fertile’ and thus been a turn-off, this seems to miss: In ancestral high-fertility conditions, most adult women would have been pregnant or lactating most of the time, and you got pregnant while lactating, not only later! Even today, e.g. my mum had 4 children in 4 years. If an ancestral female is lactating for 6 months to 2 years, having big breasts can be mostly a good signal for fertility not the other way round.
I don’t think your timing result is incompatible with this story; it just locates the co-evolution in deep hominin time. ((Actually, if your approach could be extended to genes regulating the cycle and sexual receptivity that could be interesting))
Women who have reproduced recently are less likely to have passed the menopause.
Other mammals don’t live for decades after the menopause like we do.
I guess that was exactly part of what I meant.
Interesting point!! Apparently women really live exceptionally long, while their menopause (and its timing) itself is not unusual at all, and the most prevalent hypothesis is “grandmothering”, which posits what its name suggests, and essentially is, for our purposes, yet another symptom of them (say, our genes, or figuratively thus ‘our children’) desperately wanting us to stick around to care for these slow-up-growing and nerve-and-everything-wrecking offspring. In that sense, indirect extra, tiny support of the idea ‘they want to lure into having sex anytime as a loyalty encouraging devise and preventing us from straying too far’ or something like that. I’m vary if it sounds too simple but it does all seem to make sense (?).
Maybe our longevity after the menopause also led to human men evolving to be strongly attracted to women with a more youthful appearance. Attraction to boobs was then a counter-adaptation to prevent men from putting all their effort into pursuing pre-pubescent children.
I’d argue the more interesting and potentially related human trait isn’t cycle-independent sexual receptivity, but hidden estrous, which is even more uniquely human.
For either trait, I don’t know how you would assemble a gene panel for study. You can’t use GWAS results because all of these traits are fixed in modern humans. The only reason the involution panel supports this type of analysis is because of extensive and unrelated experimentation in mice.