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Wednesday, July 1, 2015

Are we hard-wired for rape?

Has rape been an evolutionarily viable strategy for most of human history? It's not a question you hear asked, but it's worth thinking about. A clear-eyed view of evolution -- how we have been selected for traits which best help us spread our genes into the next generation -- is necessary for a full understanding of human nature.

Let me emphasize at the outset that this post is not in any way a justification of rape; it is merely raising the question of whether, in the past, rape has been an evolutionarily adaptive behavior.

Human evolution has been going on for roughly four million years, and for the vast majority of that time we were hunter gatherers, or, as the cartoons sometimes depict us, "cavemen." Agriculture only started around 12,000 years ago, and didn't become widespread for long thereafter. The industrial revolution really only started 300 years ago.

So what we think of as "civilization" has been around for only a very tiny fraction of our existence, and has had only a negligible effect on our evolution, and on our instincts.

What we have been conditioned to be for most of our four million years of evolution is cavemen. In fact, many of our instincts evolved even before we were human, back when we were still our common ancestor with chimpanzees. (We do share 99% of our genes with chimps.)

So we are essentially cavemen -- in a technological age.

Basic evolutionary strategies are fairly simple. For females, maximizing their reproductive output meant having a man who would stick around after mating with her and help provide resources (read: meat) and protection for her and her offspring. It also meant choosing a man who was most able -- and most likely -- to do those things.

For males, this meant spreading their seed as widely as possible, by mating with as many women as they could. Men could do this in two ways: by seducing women, whatever that entailed back in the caveman days, or by raping them.

The evolutionary upside of raping a woman was, obviously, more offspring. The downside was that you might be killed by vengeful fathers or brothers or mates. Or, by your victim, after you had dozed off. So, we would have been selected to rape only when there was little chance of being killed in revenge.

Thus, we were also selected to be discerning enough to know whether the risk of retaliation in any given situation was high or low.

Back in the caveman days, vengeful relatives, or other men who desired the same woman were basically the only risks you had to face if you were inclined to rape. There were no police forces, no court systems, no jail sentences, no DNA kits, and no feminists waving placards.

Of course, there were no such restraints on vengeful relatives or romantic rivals, either. It was simply….the jungle. And the "law of the jungle" prevailed.

So, was rape a viable evolutionary strategy? At times -- when the risk of revenge was low -- the answer has to be, yes. 

This is probably why the incidence of rape among conquering armies is so high. When your army has prevailed, the risk of retaliation by a member of the defeated enemy is low. Sacking, killing, and looting are usually followed by raping.

Rape is a low investment evolutionary strategy, meaning, you probably wouldn't stick around to help raise the offspring that resulted from such an act. But, you did get to possibly impregnate an otherwise unwilling female, who might manage to raise that offspring to maturity on her own. 

It's a pretty sure bet that a lot of your ancestors were products of rape, which means that a lot of your ancestors were rapists. Go back far enough and it's inevitable. Ergo, you are carrying the genes -- and instincts -- of a lot of rapists.

Rape is certainly a common enough fantasy among both men and women -- as Bernie Sanders once pointed out -- to think it's somehow wired into our brains.

Let me emphasize, once again, I'm not condoning rape. It is, unquestionably, morally repugnant.

But that is an entirely different matter from the question of whether evolutionary selection has favored rapists -- under the right circumstances.


LBD said...

I have to disagree. First of all, rapists frequently murder their victims, so it's a darwinian dead end. This is especially so in invading army scenarios. Also, if a child is produced iits chances of survival to adulthood are pretty dismal, another dead end. Mothers tend to give little nurturing to children who look just like the guy who humiliated and hurt them, and their communities tend to reject members who look like the conqureors. Half American Vietnamese are a case in point even though most of them were not products of rape but unions that were disapproved of. The winning army's men aren't usually around ro care for them, and the offspring are rejected from both sides.

John Craig said...

LBD --
Certainly Ted Bundy-style behavior is an evolutionary dead end. (I actually originally had a paragraph about that in the post, but took it out.) But actually, only a small fraction of rapists kill their victims.

Yes, if a child is produced it is less likely to be well looked after, but the alternative -- not raping -- would result in no offspring. So there is a lower chance of viable offspring reaching maturity, but there is some chance -- which is more of a chance than if the rapist had not raped at all.

LBD said...

Children of war rape identify with their mothers, not their fathers. Fathering a son under those circumstances is fashioning a knife that will cut your throat a generation later. Those are exactly the kind of young men who foment revolution to overthrow the new regime .

John Craig said...

LBD --
What you say is interesting, and I'm sure true,

It's also still a somewhat separate issue from the question of whether rape is an evolutionarily viable strategy.

Steven said...

Interesting analysis.

Rape can have really damaging long term psychological effects on the victim but I'm not sure men would intuitively know that or at least the extent of it without being educated about it. They might just think I'll have sex with her and then that's that. Knowing about that could be a restraining factor. That's just something that has occurred to me before.

I would take issue with this part:

'So what we think of as "civilization" has been around for only a very tiny fraction of our existence, and has had only a negligible effect on our evolution, and on our instincts.'

Most of our genetic makeup comes from before 8,00 years ago and has evolved over millions of years but I don't think evolution in the past 8,000 years has been *negligible*, which is why there are racial differences. Wade's thesis in his recent book was that evolution has been "recent, copious and regional".

An example is the high altitude adaptations of Tibetans. This is from memory but I think a large majority of them have an allele that allows them to metabolize oxygen better at high altitude while only 5% of the lowland Chinese have that allele. These populations split 5,000 years ago. Obviously that allelle has been under strong selective pressure.

John Craig said...

Steven --
I re-posted your comment to this post (you originally put it after the Greece" post).

Yes, rape is unquestionably psychologically damaging to the female who gets raped, but again, that's a separate point.

I think the past 8000 or so years have been negligible in term of our basic instincts: lust, jealousy, the desire for revenge, and so on. The Tibetan adaptation you speak of is a relatively narrow one that affects one aspect of the anatomy. Unquestionably, if circumstances change drastically, as they did for the Tibetans, it will have an effect on their physiology. But I doubt that their instincts changed in any way, and that's more what I"m talking about here.

Also keep in mind, agriculture was "invented' roughly 12,000 years ago, but it hasn't been widespread for all that long, and in fact up until very recently there were large parts of the world where it was unknown. All of the Amerindians were basically hunter-gatherers up until the white man came to the New World 500 years ago. And sub-Saharan Africa was the province of hunter-gatherers until recent times as well.

As far as the races separating, I think the timetable for that was much longer than 8000 years. There's one school of thought that it happened roughly 50,000 years ago, another that it was closer to 200,000. I don't know. But I don't think anyone thinks it was 8000 years ago.

Steven said...

Thanks. I wondered why some woman posted an irrelevant comment about Greece lol.

I didn't mean to imply the races split 8000 years ago. The figure I had in mind for divergence were 50,000 for some, 20,000 for others. I just meant to make the point that some non negligible evolution has happened over a few thousand years and its because evolution can happen at that speed that quite big racial differences could appear over tens of thousands of years. I hope that's clearer. Obviously the Tibetan example is just one among many. It seems plausible to me that some character traits could have been selected or deselected, and so altered in frequency, since the invention of agriculture, in Eurasia at least.

I do take your point about instincts and I do accept the basic premise of evolutionary psychology, which you outlined.

I won't pursue the point about rape now but it wasn't just that it harms women. I think I was getting at something sort of relevant or at least trying to!

Mark Caplan said...

Anthropologists have studied many isolated hunter-gatherer societies. Have they reported a consistent mating behavior among hunter-gatherers? In some hunter-gatherer societies, warriors would raid neighboring groups expressly to steal their young women. Women captives became the spoils of war and also the principal incentive for war. But I don't know how typical this courting ritual was among our distant forebears.

John Craig said...

Mark --
I'd have to imagine that that behavior -- which qualifies as rape -- was fairly widespread. Those tribes which succeeded in those raids benefited evolutionarily, so the instinct to kidnap women would have been selected for. It makes sense that wherever there is a male sex drive, there is a rape drive. Most people today are socialized (and smart enough) to keep that drive under control; but that doesn't mean it's not there.

Anonymous said...

In fact, females do not look for a male to stick around to take care of the baby and herself; rather, she nurtures the baby herself as she definitely knows the baby carries her genetic material. For males, however, whether the baby carries his genetic material is not certain, particularly for polygamous populations. Therefore, male chooses to reproduce with as many females as he can, and choose not to invest on the baby by nurturing it but to spread his genes as much as possible hoping that some baby somewhere will carry his genes and pass them to the next generation.
With that, the evolution of sex in primates is quite complicated and is not fully understood yet, as far as i know. There's an interesting book, a part of which covers this subject: The Third Chimpanzee by Jared Diamond.
As for the rape, males capable of subduing a female would be physically strong (in a primitive world) and would have been chosen by the females for reproduction anyway. So, I don't agree.

John Craig said...

Anon --
A woman will almost always care for her baby for that reason, but in the old "caveman" days, it definitely helped to have a man to do the hunting (of protein) while she did the gathering (of carbs). That was almost always the division of labor back then: the men, often in groups, tried to bring down the big game, and women did more of the gathering.

Yes, men can be tricked that way, and can never ben 100% certain that a child is theirs. But they can have indications, some sense of the faithfulness of their mate. And yes, human sexuality is complicated, but I'm just addressing one aspect of it here: was rape positively selected for through most of human (pre)history?

A woman wouldn't have necessarily chosen a man just because he was strong (though that would certainly be one factor in her decision). And to be strong enough to rape a woman, a man doesn't have to be the strongest man around; merely strong enough to commit rape.

Anonymous said...

As a female, I would hope that makes are not hard-wired for rape. In any group, you'll have good guys and bad guys. Possibly, it's the bad guys (non-thinkers) who would resort to raping.

- Susan

John Craig said...

Susan --
The difference between good and bad guys is not that the good guys don't have bad urges; it's that they don't act on them. Nobody with a conscience, or even half a brain, goes around raping women these days. But that's not to say that we don't all have those instincts.

Anonymous said...

I don't think that rape was ever an evolutionary strategy, believing that humans were never created to be that way.


John Craig said...

Birdie --
I'm afraid your religion and my view of evolution are not going to have much common ground here. But you're well versed in sociopathy, so think of it this way: were human beings "created" to be sociopaths? No, but they exist.

Anonymous said...

Yeah, no.

You DO hear this asked a lot -- by a certain crowd who-shall-not-be-named.

I agree with LBD -- abortion was probably invented by the first woman who was raped. I know personally several women who aborted their rapist's babies -- one a devout Catholic who kept this secret for decades. Other women will simply just kill themselves, baby and all, instead of carrying and birthing a rapist's baby.

But no, women don't always kill those babies. Sometimes they simply abandon them. (Google Bosnia and abandon and rape for some interesting reading).

The mother might raise the child herself -- with neglect if not outright abuse. These kids tend to have accidents and die before puberty.

So yes, from the male standpoint I could see why you would ask this question. It's like a bad shot emptying a clip -- one of these bullets has to hit, right?

From a female standpoint, unless she is FORCED to carry the baby to term, it's a no-brainer. Abortion has been around forever and women knew how to kill what was growing inside. No one ever has to know.

But the child of the man the woman admires/loves/respects -- whatever -- is fed, nurtured, protected etc. and lives to reproductive age.

Evolutionary advantage goes to provider/protector male. Also, men don't like it when you rape their daughters/mothers/sisters and tend to kill men when they do. Death is a definite evolutionary disadvantage.


Anonymous said...

Just wanted to add that I was referring to the kind of rape you see in war zones like the Sudan, and not the institutionalized and codified rape of the arranged marriage you see with say, Boko Haram or Isis, which I think does have its roots in at least cultural evolution.

What I mean is using a girl's sexuality (most often against her will) as a way to cement loyalty, neutralize opposition and expand the tribe and the tribe/family's power. This is a systematic and cultural use of rape that helps that group.


John Craig said...

Gardner --
Actually, I'd never heard the question before. I'll assume you're referring to the comments section on Heartiste (which I never read).

Keep in mind that when we're talking about evolution, we're talking about roughly four million years, so things like abortion -- and birth control --both of which are modern inventions, have had an extremely small effect on human evolution. We're still cavemen, for better or worse. (You say abortion has been around "forever," but it hasn't; in the caveman days, there were undoubtedly people who didn't even necessarily understand the relationship between sex and pregnancy.)

I also think that you and LBD are confusing the question of whether rape is evolutionarily viable with whether a child born to a single mother who was raped has as good a chance of surviving to adulthood as a child with both parents present. The answer to the latter question is of course no. But the second question is not the same as the first.

The first question is better analyzed by your metaphor of a bad shot emptying his clip -- yes, even if each of his individual offspring has less of a chance of survival to reproductive age themselves, he's still going to have spread his seed more widely than a man who doesn't rape. Also, what is to prevent a rapist from also having his own family whom he helps nurture on the side? There must have been men who helped raise their own families, but, when out marauding with their tribesmen, would occasionally rape the slave girls they would capture.

No question, revenge was a big discouraging factor, as I said in the post, so men would have been selected for knowing when that risk was high.

Anonymous said...

"so things like abortion -- and birth control --both of which are modern inventions, have had an extremely small effect on human evolution."

I'm not convinced this is true, at all.

You write "there were undoubtedly people who didn't even necessarily understand the relationship between sex and pregnancy" -- do horses understand the relationship? Do monkeys? Because they abort their fetuses.

Primates have been known to engage in "family planning" -- such as abortion and infanticide, so why wouldn't homo sapiens?

Did you know horses can labor their fetuses? This article on mares has echoes of a rape victim aborting her fetus:

Other aborting animals, from the NYT (

"Among several mammals, including lions, mice and monkeys, females will either spontaneously abort their fetuses or abandon their newborns when times prove rocky or a new male swaggers into town."

- Gardner

John Craig said...

Gardner --
Just finished reading all three articles, thank you for that, they were interesting. I had known about male lions coming into a pride and killing all of the young cubs, but hadn't know about spontaneous abortions among horses and geladas. (To be honest, I hadn't even known there was a subspecies of baboon known as a "gelada.") All of that makes evolutionary sense among animals where males will kill the offspring of other males. (I wonder if it happens with lionesses too.) The females of these species all maximize their own reproductive success that way, since it makes no sense to carry a fetus to term if it's only going to be killed after it's born.

i've never heard of humans aborting, though I suppose it's possible. (Certainly plenty of women miscarry, which is effectively the same thing, though I've never seen any statistics on miscarriages of rape-caused pregnancies vs. others.) And killing the offspring of other men is also something I've never heard of, though it makes evolutionary sense. (I've read that women are less fertile while still nursing an infant.)

But, I've also heard of children of rape, and their existence is proof that for some men, rape was a good evolutionary strategy (assuming they weren't then killed by vengeful relatives, which is unlikely to be the case if, say, they were members of a conquering army). And while there are some women who will always resent a baby who was conceived through rape, they do exist. In fact, as per the following article, some studies even indicate that a rape is MORE likely to end up in pregnancy than regular intercourse:

Anyway, we agree on most things, but I don't think we're going to come to an agreement here. From my point of view, you're looking at things partly from a moral point of view, and while I certainly agree with you that rape is reprehensible, I'm just looking at it from an evolutionary point of view, and evolution has no morality.

Anonymous said...

I am not looking at it from a moral point of view, I don't think I am at least. I am not vaguely religious. But I think that sometimes men see culture and history from such a distinctly male point of view that it blinds them.

I will make one more point and then move on.

You are arguing that rape makes sense in the evolution of mankind, but I think it only makes sense in the evolution of MAN.

(Like murder, which also made sense in an evolutionary standpoint -- for some, right? But does it mean we are "hard-wired" to murder?)

Women also evolved, alongside men, and I believed they evolved to avoid men who rape and rapists -- these are not the guys who will provide and protect them and their children. So they gravitated towards these other males, killing the offspring of the rapists who were taking up valuable space/time/resources to make themselves available and appealing to these "better" men.

Certainly some men benefited from rape (passed along their genetic material) but clearly it did not become the winning reproductive strategy and was soon taboo/illegal -- just like murder.


John Craig said...

Gardner --
I may be looking at things from a male point of view, but the evolution of men and women is not separate, it's intertwined, and women instinctively want to breed children who will reach maturity and be successful at propagating their own genes. And that means sons who will be successful using whatever mating strategies work, and daughters who will do whatever is best for them to propagate their genes too.

I actually think we ARE hard-wired to murder -- under the right circumstances, i.e., when we can get away with it. If we didn't have a desire for revenge, and if other weren't aware of this, they would do us all sorts of harm. I was surprised the other day when someone over the age of 50 told me that for the first time in his life he knew someone he wanted to see dead. I've had all sorts of people in my life I've wanted to see dead, and whom I felt like killing. I never would have done it, of course, but that is partly because I knew I might not get away with it. But the fact that that desire is within me shows that I am "hard-wired" to murder, even if I would never do it. But who knows what I would have done, back in the caveman days…..

I agree that women evolved to avoid rapists, and look for males who would form a strong pair bond and help them raise their offspring. But that doesn't mean that women were always successful in avoiding rapists.

Maybe I'm just more cynical than you. I think that humans evolved to become nasty, deceitful creatures. We're capable of love above and beyond the sexual kind, but we're also programmed to be capable of hatred, and to take advantage of situations when we can. I even think sociopathy can be an evolutionarily adaptive strategy, as i wrote here:

(And I think it's pretty clear from this blog that I'm not particularly fond of sociopaths.)

Anyway, it's always good to hear from you, even when we disagree. Hearing from a high IQ like you -- and a few of the others who write in -- actually makes me feel better about this blog.

John Craig said...

Gardner --
PS - I think the maternal instinct is strong enough that the vast majority of women would not kill their own offspring, even if those offspring were the products of rape.

LBD said...

I think what is being confused is that a degree of aggression is hardwired in men and it's connected to male sexuality. Competition, courtship, confidence, getting to "yes" by breaking through "no" is all part of normal male makeup and is not equivalent to rape. In evolutionary terms a confident man gets plenty of opportunity to "spread his seed". Men in committed relationships are often sought out by single women, so "sticking around to support his offspring" is no barrier to evolutionary success. Women in all eras have had consensual relations with successful men of higher status. Their status doesn't even have to be very high, just higher than hers. Throughout the eons players have had more offspring reach reproductive age than have criminals.

John Craig said...

LBD --
I agree with everything you just said. But the point of the post -- and I guess I could have made it clearer -- is that players can also be opportunistic criminals. Bill Clinton would actually be a good example of this. He was unquestionably a high status player, and he spread his seed far and wide -- although in this age of readily available birth control all the old rules of reproductive fitness have been repealed, to a certain extent. But Clinton was also a rapist, according to many accounts, when that opportunity presented itself.

MarieCurie said...

No, you (and imho most people) are not "hard-wired for rape."

Unless you have NO (that absolute ZERO) conscience, and your statement: "Let me emphasize, once again, I'm not condoning rape. It is, unquestionably, morally repugnant," indicates otherwise (thankfully!!!)

MarieCurie said...

"I think the maternal instinct is strong enough that the vast majority of women would not kill their own offspring, even if those offspring were the products of rape."

If you had spent any time in a vivarium, you might know otherwise.

I recall (as a lowly research assistant) having to rush to the vivarium to separate mother rats from their babies so they would not eat their babies heads off (literally).

Presumably the cage environment was in itself quite toxic (even before the senior scientists began their experiments).

Horrible :-(

Archaic research laws need reforming.

Mahatma Gandhi — 'The greatness of a nation and its moral progress can be judged by the way its animals are treated.'

John Craig said...

Marie Curie --
Being "hard-wired" for rape doesn't mean we would necessarily act on it. There was a book out a while back whose title expressed this idea perfectly: Bad Men Do What Good Men Dream.

In other words, all men have the desire to do bad things from time to time, but their consciences, or inhibitions, prevent them from acting on them, whereas sociopaths have no such compunctions. For instance, I could ask the question, are we hard-wired for murder? It doesn't mean we're al a bunch of murderers, merely that we feel that desire (for revenge) and under the right extenuating circumstances might be capable of it.

Full disclosure: I've had both desires, though to date I haven't raped or killed anybody.

Not sure I'd quite equate humans with rats on this issue. Yes, there are mothers who kill their children, but even in cases of rape, they are the very small minority.