Genital response to sexual stimuli may be an evolved self-protection mechanism. Female genital response is an automatic reflex that is elicited by sexual stimuli and produces vaginal lubrication, even if the woman does not subjectively feel sexually aroused...Female genital response entails increased genital vasocongestion, necessary for the production of vaginal lubrication, and can, in turn, reduce discomfort and the possibility of injury during vaginal penetration. Ancestral women who did not show an automatic vaginal response to sexual cues may have been more likely to experience injuries that resulted in illness, infertility, or even death subsequent to unexpected or unwanted vaginal penetration, and thus would be less likely to have passed on this trait to their offspring....Reports of women's genital response and orgasm during sexual assaults suggests that genital responses do occur in women under conditions of sexual threat.
The theory in regards to the threat of rape is bad enough. But let me start with an even more ridiculous theory - a good number of sex researchers have actually suggested that this same rape facilitation mechanism is the reason that women are found to have physical arousal from various sexually themed images and stories which they subjectively report as not being sexy, including not only depictions of rape, but also lesbian sex and, in at least one case, monkey sex.
Here's a couple examples of this theory being presented:
"women’s genital responses are usually non-specific: self-identified hetereosexual women have been shown to have similar genital responses to stimuli that depict hetereosexual, gay, or lesbian sex (Chivers et al., 2004). Women even show some genital responses to nonhuman primates having sex, while men do not (Chivers & Bailey, 2005). Importantly, this genital arousal in women seems to be automatic: it occurs before women even report feeling aroused (Laan, 1994) and even when they are not aware of its presence (Ponseti & Bosinski, 2010).
Men and women, then, seem to have strong differences in the type of stimuli that causes genital arousal. What might have caused this? It has been suggested that there is a functional account of the nonspecificity and automaticity of female genital arousal: The Preparation Hypothesis. It has been shown that increased blood flow is a precursor to vaginal lubrication (Levin, 2003) and suggested that this may serve as a protective function for women engaged in intercourse – consensual or otherwise (Chivers, 2005)." http://www.jimaceverett.com/genital_lubrication.html
"Men’s genital arousal occurs in response to a limited number of sexual stimuli, whereas women’s genital arousal occurs in response to a wide range of sexual stimuli, including those depicting nonpreferred cues. Researchers have hypothesized that women’s nonspecific pattern of genital arousal prepares the body for sexual activity, thus functioning to protect the genital organs against injury. If this hypothesis is correct, women should show genital responses to any cues suggesting sexual activity..." http://www.centenary.edu/attachments/psychology/journal/archive/mar2011journalclub.pdf
"Women, she says, are physically aroused by non-specific stimuli, everything from copulating primates to two men having sex. Even rape scenes can trigger a physical response...Dr. Chivers looks at the question from an evolutionary standpoint. As modern humans evolved, women who became lubricated at the slightest sexual signal would have been less likely to get injured or to contract diseases during sex, especially if it was forced on them. It could be a protective mechanism." http://www.theglobeandmail.com/incoming/her-parts-desire/article1154587/
First of all, the theory doesn't even fit with available information. One study after another, with different researchers and different methods of determining arousal (vaginal lubrication, blood flow, heart rate, pupil dilation, brain scans) have all consistently found that the majority of women - regardless of stated sexual orientation, fetishes and preferences, exhibit physiological arousal from straight, gay male, and lesbian sexual imagry. Some have even found arousal in response to images of non-humans engaged in sex.
However, one thing that consistently fails to elicit a response is images of an erect human penis without a larger sexual context.
These theories for why women are so easily aroused by so many things (compared to men), echos the theory presented above in regards to assault - women's physical arousal is on a hair trigger for the purpose of facilitating being raped without injury.
It shouldn't take much to realize how absolutely stupid that theory is - which would women in the early stages of human evolution facing a threat of rape be more likely to see: two women having sex, two monkeys having sex, or an erect human penis?
How often in human evolutionary theory were women presented with the threat of injury due to attempted rape by lesbians, gay men, or monkeys? Probably close to never percent of the time.
In contrast, heterosexual non-consensual intercourse forced by a male attacker would include an erect penis exactly always percent of the time.
This theory is so unbelievably nonsensical that I am literally at a loss for how to express just how stupid it is.
And yet it is being suggested by quite a few otherwise respectable intelligent psychologists and sociologists and other sex researchers who work on investigating this sort of thing scientifically for a living!
I won't go any further in debunking the "women lubricate to lesbian porn so they won't be injured by male rapists" line of reasoning, because it is just plain stupid.
Instead, for the rest of this I'll focus on what appears on the surface to at least be logically consistent (although still wrong): that women are physically turned on by the threat of rape as a method of self-protection.
and an array of natural products as well as common commercial p
roducts such as alum, boric acid, and bactericides. According to Halperin, many women use these produc ts for ‘dry sex.’ Their partners have been found to suffer penile injuries, lacerations to the foreskin, and bleeding (Halperin 1999).
Unfortunately, none of them have any mention of the relative prevalence of pain or injury to male vs female partners.
In a cross-sectional survey of general population residents of Cape Town, South Africa, 21% of men and 16% of women reported coital bleeding in the past 3 months,
My only purpose here is questioning the validity of the "facilitating rape is self-protective" claim, the very idea of which I suspect is only possible in a society with a deeply internalized misogyny.