Want a provocative thesis? Try this one for size: rape is not a crime of violence and power, as social scientists tell us, it鈥檚 motivated simply by sexual desire. In fact, rape is not even abnormal-it鈥檚 a mechanism for spreading genes that is as much a part of the natural landscape of sexual behaviour as courtship and flirting. Randy Thornhill, the biologist from the University of New Mexico at Albuquerque who advocates this view, is no stranger to controversy. Yet even he has been astonished at the outrage provoked by A Natural History of Rape, a book he wrote with an anthropologist colleague, Craig Palmer, to air these views. Brave assault on political correctness or Darwinian thinking gone mad? David Concar spoke to Thornhill to find out.
Part of your argument that rape is natural is based on the notion that forced copulation occurs in many other species. Just how widespread is rape?
That has yet to be determined, although there鈥檚 been a big burst of research activity recently, in birds, insects, primates and so forth. Until the last seven years, research into rape was pretty stagnant. I think biologists found it too politically incorrect to study, even in dung flies.
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Years ago, you spent a lot of time studying rape in insects, especially scorpion flies. Why these creatures?
I had watched and collected scorpion flies as a kid growing up in northern Alabama, and got interested in their mating behaviour as a graduate student at the University of Michigan. The females are interesting because they鈥檙e conspicuously choosy about who they mate with, and the males are interesting because they have to compete with each other to copulate with these discriminating females. The males have two options: attract the females by offering them nuptial gifts of food, then mate with them while they鈥檙e eating the food-or rape.
What sort of food gifts are we talking about?
Some scorpion fly species, the so-called hanging flies, offer live prey. Others, of the genus Panorpa, will scavenge a dead arthropod to offer as a nuptial gift, or failing that, secrete a salivary ball of food. Males that lose out in the competition for dead arthropods or food to fuel their salivary glands have no choice but to rape because the females all run away from them. For these flies, there鈥檚 no question about it: rape is a natural, evolved reproductive strategy.
Couldn鈥檛 it just as easily be regarded as an abnormal insect behaviour expressed by a deviant minority?
I did some experiments showing that all male scorpion flies will switch to raping when they lack a nuptial gift to offer a female-they鈥檙e designed to make the best of a bad job. The females, meanwhile, are designed to resist rape. They have some mechanism that reduces the chance of insemination by a male lacking a nuptial gift. That indicates an evolutionary arms race between males and females, the males to fertilise eggs, the females to retain control of fertilisation.
Your insect work is highly regarded, but many biologists are scathing about applying similar evolutionary logic to the complexities of human rape.
Well, the scorpion fly work may be accepted now, but that鈥檚 not the way it was viewed initially. When I first discovered active female choice in hanging flies, I got up at an entomological conference and they laughed me off the stage. They said insects can鈥檛 do these things. They鈥檙e just too simple to discriminate between males with and without nuptial gifts, and so on. It was a very bad experience. I even thought about quitting the insect work.
But the heat generated by your evolutionary analysis of rape in humans has been on a different scale, hasn鈥檛 it?
My first terrible experience was in the early 80s. I was asked to give a lecture on the evolutionary biology of rape. The local women鈥檚 group picketed it with placards saying biology rapes women, that kind of stuff, and because of the yelling and screaming, it took about three hours to get through a 45-minute lecture. Afterwards a woman came and spat in my face.
You say rape in humans-like rape in scorpion flies-is better viewed as a strategy for passing on genes than as an expression of male violence. What鈥檚 your evidence?
One of the things we look at in the book is the fertilisation rate currently associated with rape. In war, it鈥檚 very high. Studies based on interviews with rape victims in recent war zones like Bosnia estimate that up to 35 per cent get pregnant from rape.
But the pregnancy rate you estimate for peacetime is only 2.5 per cent. Given the threat of punishment, can it be in a man鈥檚 reproductive interests to rape?
The book presents two hypotheses for how rape and human evolutionary history are connected. One sees rape as a strategy that was directly favoured by natural selection because it increased reproductive success. In the other case, rape is a by-product of men鈥檚 sexual adaptation, not for rape, but for obtaining multiple mates without commitment. Crucially, neither hypothesis implies that rape should currently promote reproductive success, only that it once did so for our ancestors.
You say that the age profile of rape victims supports your view. How?
The prediction from biology is that men will primarily rape young, attractive women of high fertility. And that鈥檚 what studies show. Some of the book鈥檚 critics claim that we鈥檙e wrong on this point because old ladies and children are raped a lot too. But the numbers tell a different story. Studies of girls up to the age of 12 find the older a girl is, the higher the risk of rape. A 12-year-old girl is about 20 times as likely to be raped as a 6-year-old.
But couldn鈥檛 young women be at greater risk simply because they spend more time going out at night and mixing socially with young aggressive men?
That wouldn鈥檛 explain all the observations. For example, the figures show when a man breaks into a woman鈥檚 apartment to commit a robbery, he is more likely to rape as well as rob her if she is of reproductive age. Here the man has a choice, and he rapes when the female is young. If rapists were primarily motivated to socially dominate women, you would expect them to be raping older, more powerful women-but they don鈥檛.
You suggest rape is a crime of passion, not violence. How do you square that with the fact that many rapes involve extreme violence?
I鈥檓 not saying violence is not involved. A male rapes because he鈥檚 horny and wants the sexual experience, but he has to use violence to achieve that goal. What the evolutionary model says is that men are going to use no more violence than is needed. That鈥檚 because males in evolutionary history who killed their victims would have also killed off any reproductive benefits. And this prediction is backed by all the big studies that have looked at how much violence rape perpetrators use.
You also claim that young women suffer more psychological pain . . .
This finding comes from a big database of interviews with rape victims. We showed that young women reported more psychological pain than older women or girls, and married victims more pain than unmarried victims. Which is what you鈥檇 predict biologically: women of reproductive age suffer more because they have the most to lose-they could get pregnant, or lose their mates. Married women may lose their husband鈥檚 investment because rape lowers his paternity confidence.
So rape is more serious when it involves a 20-year-old rather than a 60-year-old? Can you understand why that notion might upset a lot of people?
Yes, I can understand it. Feminists want more opportunity for women and less oppression from men. We are 100 per cent behind that. What we take issue with is the theoretical framework in which they think their goals can be achieved.
One of your most inflammatory claims is that rape victims suffer less psychological pain when more violence is involved. How can evolutionary biology explain that?
If a rape includes a lot of violence, then through the cuts and bruises, a victim can show to onlookers, especially her mate, that she was forced to have sex.
Isn鈥檛 a rapist going to hear this and think, hey, what I did was OK, even the violence? Won鈥檛 defence lawyers claim their clients were acting on natural urges?
If anyone asks me to be an expert witness and defend a guy accused of rape, I would simply reiterate what is in the book-yes, rape may be natural, but what is natural is not necessarily what ought to be. Evolutionary science cannot say what is right or wrong. Many social scientists seem to find that hard to accept. They seem to think, wrongly, that calling a behaviour evolved in the Darwinian sense means it鈥檚 either moral or inevitable, or both.
What good is evolutionary biology when it comes to preventing rape and counselling victims?
Women will find real knowledge about rape more useful than all the ideologically driven stuff that they get in rape crisis centres. For example, we can imagine education courses, based on evolutionary biology, where people are taught why a victim鈥檚 relationship may go bad in the aftermath of a rape-the victim鈥檚 partner may be reacting to the rape as a case of infidelity.
What鈥檚 wrong with the information currently available to victims and people who deal with rape?
Misinformation. Some rape counsellors over here, for example, are still using Freudian explanations. You know, 鈥淵ou got raped, the guy used you as substitute of his mother, who he wanted to have sex with.鈥� And rape prevention handbooks used by the police often contain all the standard myths: that rape is not about sex, that all women are equally likely to be raped, regardless of age or how you dress. This isn鈥檛 just wrong, it鈥檚 dangerous. If you tell men rape is not about sex, they might think anything they do with an erect penis cannot be rape.
So a woman who wears skimpy clothing is, according to evolutionary theory, making herself more vulnerable. Isn鈥檛 that shifting the blame for rape onto women?
The educational programme we have in mind would look at the risks of going out alone, at night, with strange men on dates. How women dress is not irrelevant to this. Men have to know that just because a woman wears a low-cut blouse, that does not imply that she wishes to mate with every guy she encounters. Women have to understand that men are designed to see 鈥渃ome-ons鈥� where none are intended.
One of the hallmarks of a scientific theory is that it should be falsifiable. What would refute your theory that rape is motivated by sex rather than violence?
Falsifiability in science includes how the world would be if a hypothesis were wrong. If rape isn鈥檛 sexual, one would find that rape is not accompanied by penile erection. In fact, however, this is the common denominator across all rapes even those with relatively little violence.