Why are they attracted to other women?
I use scare quotes because they’re really bisexual, not that there’s anything wrong with that. Most women who “become” lesbians later in life for various reasons (like having a lot of bad experiences with men) were always bisexual, because it makes evolutionary sense for them to be. It also explains “LUG”s (lesbian until graduation).
I would go beyond the thesis here and note that women compete with other women on their looks, so they’re actually pretty finely attuned to the attractiveness of other women.
So male proto-humans developed sexual dimorphism (with males being bigger and stronger) in order to build bigger harems? Could be, I suppose. The article didn’t conjecture that female proto-humans developed bigger boobs to trick the alpha males into thinking they were pregnant and so shouldn’t be abandoned for a younger female. It would have provided some support for their conjecture if they had mentioned if girl-on-girl chimp sex was a thing.
I was reading an article several years ago about a modern man spending quite some time with a stone-age hunter-gatherer tribe. That tribe, at least, didn’t seem to have much in the way of a harem culture–instead, they paired off every night and swapped partners when they felt like it. I have no idea how common that was–I don’t think there are many stone-age tribes around anymore to investigate. I wouldn’t be too surprised if large harems were corelated to agriculture.
I think that girl-on-girl sex chimps is a thing, at least with bonabos. Pretty sure that the sexual dimorphism in humans is because the males hunted and fought (probably for females, but in general, and war).
I agree that war and hunting seem much more likely to be the primary reason for men getting big and strong and tough and fast.
I have no idea if women trading sex with other women in exchange for sharing childcare was ever enough of a thing for there to be evolutionary pressure to favor it. It seems like something the Greeks would have written about if it were common, but I’ve read almost no classical literature.
For what it’s worth, Google says that polygyny in hunter-gatherer societies isn’t universal and seems to be more dependent on social status than strength and such. Take that with a dump truck of salt–anthropology was going woke when I was in college and has only gotten worse. It also says that male:female ratios tend to oscillate back and forth–apparently, it wasn’t a stone age Surf City, with two girls for every boy.
Well, consider that, with harems, largely the only regular sexual outlet for many women was other women…
Whether that constituted evolutionary pressure is an interesting conundrum.