I don’t think this phenomenon has all that much to do with rape. Rape is a social construct; its definition has changed drastically in the last 100 years, let alone over the course of human evolution. In order to have evolved an ‘instinct’ for it, ‘it’ would need to be constant force over human history.
What you’re really saying is that men have evolved to ignore the negative social aspects of ogling women who don’t want to be ogled, because the positive evolutionary impact has been generally greater. You explain this because, you allege, in evolutionary history men could always just rape the woman. But a much easier explanation is the one that Churo offers: most women don’t mind being ogled. An additional supposition would have to be that the consequences of ogling a woman who does not want to be ogled are less negative than the consequences of not ogling a woman who does want to be ogled (or who would be receptive to sexual advances like being ogled).
Both of these seem better suppositions than that there is a strong rape instinct, both because of the flimsy ontological status of rape, and because the two seem to mesh with our experience: women wear most revealing clothing, they wear make-up, they are generally the sex that is advertising*; and ogling without being wanted even today has almost no negative social consequences, and through our evolution had even less. (It’s worth noting that rape has long had highly negative social consequences; even if the definition had been constant, it would most likely be selected against).
Churo, I’m not sure what you meant to show by pointing out that many women fantasize about rape, but if there is an evolutionary argument being made, it should be taken with a grain of salt. Almost all women are sexually abused at some point in their life, and there are few avenues for dealing with the trauma. Taking your statistic at face value, we still can’t say whether there is an instinct for fantasizing about rape, or whether rape fantasy is an internalization of traumatic sexual experience.
*This is changing, and for good reason. In many other animal species, males are the ones who display. The reason for the difference across species is that the sex that advertises is determined by the relative abundance of access to the opposite sex. In many other species, because females bear a limited number of offspring at a time, there is an abundance of males and a scarcity of females, so males advertise to differentiate themselves. In humans, reproduction is a less valuable resource than social power, so women advertise to men to try to secure influence for their offspring. As women become socially enfranchised, men have begun advertising more.