Everyone loves evolution so much right now, so let's talk about the utility of sexual assault. More and more people claim to be pro-evolution, pro-eugenic, et cetera, but they're shying away from the logical conclusions of those policies. Let's illuminate.
Man Raping Woman
Raping grown-up females is generally understood as an evolutionary advantage, even if an "unfair" one, assuming one adheres to a theory of evolution where the behavior developed before the easy availability of birth control, abortion, and/or social acceptance/encouragement of the latter two technologies. The simplest example is a man raping a woman without being caught: if he can do it, and if they're both fertile, then he might get a genetic gain at her expense: 50% (in theory) of his genes are passed on, while she and/or society at large has to bear 100% of the burden of raising the offspring. The woman gets a 50% gain, too, but not pursuant to her own selection preference (in theory), and while sacrificing 50% of the effort (because by choosing a partner who stayed with her, she would receive 50% of the necessary labor in turn, and could therefore double her genetic output by raising two of her own children for the same theoretical effort, instead of covering 100% of the bill for only the rapist's child).
Man Raping Man
The female one is the simplest. The "man rapes man" angle is less well understood, but still comparatively simple. Besides being indicia of dominance, which has its own evolutionary utility, man-rapes-man is likely to privately humiliate and potentially engayen (made-up word: en-gay-en) the victim, or in some other way make him less likely to reproduce, therefore producing a marginal benefit--but still a benefit--to the assailant, and/or the assailant's genetic group.
...but wouldn't simply killing the man, rather than raping him, produce the same benefit? No. Absent a victim-friendly culture (and, biologically speaking, even inside a victim-friendly culture), the rape victim is less likely (or not-at-all likely) to report the assault than the murder victim's body is to be discovered, but instead to start avoiding sexual contact, kill himself, become a pariah, and/or in some other way become a net genetic loss or drain to his own people. With the assault not reported, and not discoverable (because the embarrassed victim in an "honor" or "face" culture never wants anyone to find out), the attack by the rapist's genetic group is unknown, and the secret man-on-man rape can occur without interfering with the two groups' public relationship. Ergo the rapists' group gains at the expense of the majority-unknowing victims' group, whereas the murderer's group might be resisted by the majority-knowing victims' group (a string of dead men being far more difficult to conceal versus a string of privately shattered men). Indeed, it would be a historically successful evolutionary strategy for any ethnic group to develop a sub-population of bisexuals or homosexuals, cultivate disease among them, then employ them in raping outside men, thereby reducing the genetic diversity available to the enemy population's breeding stock, as well as spreading disease in relative secret.
Many modern institutions, perhaps in particular prisons, could be viewed as an expression of this model: a designated group is fostered and cultivated as a "rapist population," diseased and sexually aggressive, then used to instill shame and/or disease among designated victim groups. Biologically (if you like evolution more) and socially (if you like gender studies more), the rape of women is more likely to be noticed by a victim culture, due to pregnancy, attentiveness to female virginity, implacable male chauvinist self-vulnerability-denial, or what-have-you. Raping women, like killing men, is more likely to be perceived as an attack by the victim group, whereas raping men--while not as directly effective at spreading the aggressor group's genes--is a more effective group evolutionary strategy overall, because it reduces the blowback costs of overt assaults.
(Even more effective would be a primary aggressor group encouraging the killing/rape of a competing group by a different competing group--the "subordinate" or "contingent aggressors"--and then eventually allowing the assault to be discovered, causing the victim group to retaliate against the contingent aggressor group, and therefore destroy the murder weapon employed by the primary aggressor group. To make the cycle sustainable, victim/aggressor groups should be regularly switched; e.g., it should become globally permissible, every few generations or so, to stop punishing one group and begin punishing another. The former victim group will be groomed to become the new subordinate aggressor group, and the former subordinate aggressor group will become, again, the victim group--primed to later resume its role as subordinate aggressor, with seeming justification, against what it perceives as the cause of its harms. When the time for the switch draws near, scientists would be able to observe members of the primary aggressor group begin to speak vitriolically about the crimes of the subordinate aggressor group, and to encourage the victim group to recognize and defend itself from the depredations of those subordinate aggressors.)
Modern cultures' openness toward rape makes the secret-shame aspect of this strategy less viable, but the right cultural engineering can produce a situation where embracing shame itself produces the same effect, e.g., lowered rates of reproductive confidence, higher rates of reproductive refusal, and/or inability to reproduce--all without anything other than "random lust" being formally responsible for the damage to the victim. Individualized, situational, and otherwise non-genetically-motivated "medical issues," including lasting injuries and "psychological issues," can be deemed responsible for the resulting reduced reproduction rates, leaving less-intelligent population groups and/or group-members unable to see the move and countermove of the true genetic conflict that is occurring. In particular, because of a lack of both widespread creative intelligence and time machines, it is impossible for most people to conceive of the opportunity costs of a successful rape.
In American prisons (including "school" and "military" installations), damage to a rape victim's orifice(s) is generally left unspoken but presumed; left unspoken and largely unknown is how many male victims suffer permanent damage to the penis and/or testicles, rendering them impotent and/or infertile as a result of the assault. If male-on-male rape is more realistically understood as "forced sterilization," the notion that homosexuality is maladaptive is discredited. Homosexuality possesses vast evolutionary utility; in fact, because of the seeming incongruity between non-reproductive sex and the birth of infants, Terran scientists have been embarrassingly lax in exploring, or even conceiving of, this avenue of inquiry.
Still fairly easy. Let's take it down a notch.
Man Raping Girl
After discussing Man Raping Woman, this one should be easy. Raping girls within a genetic group may have an individual evolutionary benefit, either in the case of telegony, first-shot at pubescence, et cetera, and in the case of fertile victims, it would have all the genetic benefits of raping a woman. In the case of infertile victims, though--pedophilia--rape's evolutionary advantage in regards victim groups is, besides all of the obvious psychological and sociological factors (which have been massively discussed recently in regards the Islamization of Europe, so I won't re-cover it), a step toward destroying not only the victim group's girls' ability to successfully become impregnated or carry future pregnancies to term, but to scar them psychologically against healthy emotional relationships, sociocultural bonding, and/or motherhood.
Ironically, feminism in the West has helped an appreciation of the awful evolutionary benefits of this kind of rape to be generally understood, even if not always expressed in the context of evolutionary utility. Let's move on to lesser-known territory.
Man Raping Boy
Now that we've discussed the evolutionary utility of men raping other men, the comparatively increased genetic utility of a man raping a boy should be obvious. A younger victim is easier to shame, easier to damage both physically and mentally, and therefore, easier to exploit to achieve a genetic advantage. A genetic group which cultivates and protects a sub-population of homosexuals has the advantage of releasing those homosexuals on a potential competitors' young males, which can then be raped to prevent their becoming successful reproducers and/or providers for the enemy group. Regardless of culture, children are more easy to shame, and more easy to intimidate, making the development of child rape a highly successful tactic: while the adults of two competing groups can come to formal co-habitation arrangements, the rapists of one group can destroy the children of the second, and terrify the children into silence, without the adults in the victim group suspecting what is being done to their children. Boy victims can be traumatized against reproduction, have their reproductive capability destroyed physically or mentally, or can have their vulnerability exploited to duplicate their trauma within the victim society. If a rapist-cultivating group attacks a victim-group's children, and the victims become homosexual and grow up to prey on their own children, the rapist-cultivating group has achieved a twofold success: not only was one generation of reproductive ability directly affected, but additional generations as well. And those victims who become attackers, by being native to the victim group, fully funded their own (in truth, the competing group's) task, calorically and defensively.
Those who understand and control homosexuality, rather than those merely averse to it, have the advantage. The Torah/Talmud and the Qur'an/Hadith are extremely effective in this regard, as they doth protest too much about in-group and adult homosexual relationships, while encouraging child rape and adult rape as a reward for the chosen; the Gospels, by contrast, are naively averse to the topic, thus designed for victim groups who can be preyed upon by rabbis, vicars, and other Jenomic jihadists.
This theory accommodates both germ, genetic, and learned-behavior theories of homosexuality. If germ, then identifying and cultivating the homosexual sub-population provides an ethnic group with a useful weapon to employ against competitors (or their children), with the bonus of knowing that, once the germ has been spread, the infection would take root. The risk of that strategy is that the victim group, once it has cultivated its own homosexual sub-population, might employ it against the men or children of the original aggressor group. Easy to solve: integration for the victim group, segregation for the original aggressor group.
Learned-behavior theories of homosexuality work the same. If a genetic group can encourage a sub-population to learn homosexuality, then have that sub-population forcibly teach homosexuality to members of a targeted outsider-group, the victims will learn it and potentially spread it further among their own group.
Genetically speaking, if homosexuality were wholly genetic (or partly, or potentially-pre-dispositionally), then we now understand the value of having deciding- or trigger-genes for homosexuality: to provide a genetically similar group with a weapon to use against competitor populations. If not by rape, then by seduction, homosexuality genes could activate/trigger, increasing homosexual prevalence among the target group.
(If you prefer to see homosexuality as a personal spiritual choice and nothing else, you can still appreciate the most basic elements of those who might be so wicked as to use their sexuality as a weapon against the unconsenting: e.g., causing anal, penile, and testicular damage to victims, in order to prevent them from discovering their own selves. It's a spiritual assault as well as a genetic one.)
We're seeing here how homosexuality is an incredibly effective adapted trait. All existing analyses of homosexuality are naively Rousseauian, postulating homosexuality only on the level of individuals and hypothetically-pastorally isolated groups, and decreeing it, therefore, maladaptive, when in fact homosexuality is an essential adaptive behavior for surviving between-group competition on a planet that has more than one human population competing for resources. Considering history in this way gives us a view as to how homosexuality could have been used to quietly destroy large groups of genetic competitors, and how mimicry, crypsis, and/or comparative femininity could have been a major factor in evolutionary history. Consider, e.g., the interbreeding dissolution of the neanderthal.
Neanderthal v. Femboi
Posit year 2100. Sexbots and VR have been perfected, and for $200 (or $10? provided free by the United Earth Authority?), every man can purchase a completely interactive, AI sexbot (or fully immersive VR, your choice) with perfect looks, endless optional features, sweet and obedient (or feisty or dominatrix--I said "optional features," right?), et cetera. Effects on reproduction rates? Sure, there are vat-grown babies, but what if the sexbots are so cheap that going to work at the vat factory only takes unnecessary time away from your perfect lifetime companion-bot?
Assume, then, that a couple generations later, the predictable effects on the world's population have occurred. Aliens land, meet minimal resistance, and take over. They laugh at the remaining humans: "Haha, you fools! You were evolutionarily designed to prefer the sexbots' soft features and sweet-sixteen bodies, but didn't you realize, they weren't actual women? Hahahahahaha we win!"
(So that's why they were so cheap!)
But anyway, now posit a similar example, but thousands and thousands of years ago. Thick, strong, intelligent neanderthals are in control of Europe. The males have been genetically designed to mate with bipedal humanoids who are feminine, which they judge based upon smaller size, weaker, softer/rounder features, et cetera. Do you see the evolutionary mandate for the much-weaker humans? Human females have an obvious mandate, and one that, for Europeoid and Mongoloid populations, we know they followed. Human males, though, even the biggest and brawniest, are fiddling twinks compared to neanderthals; neanderthal bone and brain structures show that they had muscles strong enough that, if humans had them, flexing them fully would risk breaking the human skeleton, which is far too weak by comparison. Whatever steroid-laden person you think is strong and manly is a little pussy compared to a neanderthal or a gorilla.
What, in such a situation, can passed-over human males do to contribute to the great homo sapiens sapiens evolutionary project? Here we see homosexuality coming into play: neanderthal males would be mating with both neanderthal females and human females. To prevent the extinction of humans--their absorption into neanderthal lines, rather than vice versa--the neanderthal-only line needs to be destroyed, since it would always be the stronger, and would eventually out-survive the human-only line, as well as the human-neanderthal hybrid (which was to become later Europeoiods and Mongoloids). This can be accomplished by preventing neanderthal-only matches. Human-only and human-neanderthal females would be working on this as hard as they could, while human-only males would face a dwindling number of human-only females to choose as potential mates, and would see their own time ending.
In such a situation, homosexuality produces a positive genetic contribution to the human-line, permitting the disenfranchised human males' lines to continue. By using mimicry of neanderthal female features--e.g., by being smaller, rounder, softer, smoother, et cetera.--human males could break up neanderthal-neanderthal relationships, destroying the pure neanderthal lines, and permitting humans to absorb neanderthal genes, rather than the other way around. Like the sexbot-users in the earlier example, the neanderthal men would be being "tricked," in the sense that they wouldn't be reproducing. Yet, like the sexbot-users, all of the features of "genetic success lottery!" that they'd been programmed to seek out and impregnate would be present. Symmetrical humanoid, soft and pliant, vocalizing and signaling in familiar ways.
Male chimpanzees, far more removed from homo sapiens sapiens, have raped (human) female researchers, and the lengthy, terminal cross breeding of homo neanderthalensis is beyond current scientific dispute. The human crossdressing and transsexuality that endures today today, and the manic and showy way in which they are often pursued, can be best explained in light of these brutal evolutionary conflicts of the past, where every facet of sexuality had to be explored in order to achieve survival.