I find it hard to believe that a tendency to rape (or more specifically, the psychological traits that make one more likely to be a rapist today) wouldn't have been a fitness advantage in at least some of our forager ancestors. There are too many examples in societies close to our own where various forms of rape or were forgivable/forgiven (by society, not necessarily by the victim): rape of foreigners in war, marital rape, rape as punishment, protection of the rapist by an influent member of his family, marrying the rapist ... sure, some of those situations may not happen in a forager society, but there may be different ones that do happen.
Having a reputation as a rapist makes it harder for him to survive
This supposes that the society in question has a concept of "rapist" analogous to our own; I suspect many societies would have different concepts, and only harshly punish some of the behaviors (rape of enemies and marital rape seem to usually get off the hook, except in very recent history).
As an illustration of the way different societies approach the problem, I've already been in a conversation with African men who were saying how under certain conditions rape was an acceptable way of getting sex from a girl.
That being said, I don't know much about how foragers approach the question of rape, I'm merely skeptical of the idea that they have very few children of rape.
There are too many examples in societies close to our own where various forms of rape or were forgivable/forgiven (by society, not necessarily by the victim): rape of foreigners in war, marital rape, rape as punishment, protection of the rapist by an influent member of his family, marrying the rapist ...
Also, date rape of course, duh.
One of the lessons highlighted in the thread "Less Wrong NYC: Case Study of a Successful Rationalist Chapter" is Gender ratio matters.
There have recently been a number of articles addressing one social skills issue that might be affecting this, from the perspective of a geeky/sciencefiction community with similar attributes to LessWrong, and I want to link to these, not just so the people potentially causing problems get to read them, but also so everyone else knows the resource is there and has a name for the problem, which may facilitate wider discussion and make it easier for others to know when to point towards the resources those who would benefit by them.
However before I do, in the light of RedRobot's comment in the "Of Gender and Rationality" thread, I'd like to echo a sentiment from one of the articles, that people exhibiting this behaviour may be of any gender and may victimise upon any gender. And so, while it may be correlated with a particular gender, it is the behaviour that should be focused upon, and turning this thread into bashing of one gender (or defensiveness against perceived bashing) would be unhelpful.
Ok, disclaimers out of the way, here are the links:
Some of those raise deeper issues about rape culture and audience as enabler, but the TLDR summary is:
EDITED TO ADD:
Despite the way some of the links are framed as being addressed to creepers, this post is aimed at least as much at the community as a whole, intended to trigger a discussion on how the community should best go about handling such a problem once identified, with the TLDR being "set of restraints to place on someone who is burning the commons", rather that a complete description that guarantees that anyone who doesn't meet it isn't creepy. (Thank you to jsteinhardt for clearly verbalising the misinterpretation - for discussion see his reply to this post)