I remember reading this some years ago:
The author writes: “Women all over the world, from every culture, race and tribe, [do] exactly the same thing when having sexual intercourse: They spread their legs apart and eventually raise them high in the air. Why is that?
Even virgins and girls unfamiliar with sex seem to do this automatically. Why is that?
This is one of those timeless questions. I have discussed this issue with others, but I have never seen it mentioned in any book or article.”
The author then writes that he thinks “Cindy” gave the right answer: “I read the guys’ theories and you’re all wrong. It feels better to spread our legs during sex and masturbation. If any of you guys actually have girlfriends, ask them if they spread their legs when they jack off [sic] as well. I think you will find that it is almost impossible not to. So, I conclude that the cause of this spreading of the legs and raising of the hips can’t be based on deeper penetration because masturbation does not have to involve any penetration at all. For me, the wider I spread my legs, during sex or masturbation, the better it feels. Ask a woman.”
I have always had a problem with Cindy’s reply. The reason is simply this: masturbation is a kind of simulation of normal sex. So what a woman feels like doing during masturbation, including spreading her legs, is probably due to the fact that what she is doing is causing herself sexual excitement that is like that she will experience in actual intercourse.
I don’t know if women all round the world really do always “spread their legs apart and eventually raise them high in the air” but it seems possible that there is some instinctive sexual posturing in women. The fact that it also happens when a woman masturbates is not an argument against it being a sexual instinct related to sexual intercourse with a man.
Another possible answer is that a woman spreads her legs and raises them for simple biomechanical reasons: because it is physically convenient. However, in some respects, Cindy’s argument about masturbation militates against this idea and in fact suggests that this behaviour is instinctive female sexual behaviour.