Sex at Dawn

Exploring the evolutionary origins of modern sexuality

Is Evolutionary Psychology a Used Car?

Is Satoshi Kanazawa the Rush Limbaugh of evolutionary psychology?
Satoshi Kanazawa
This post is a response to The power of female choice: Fat chicks get laid more by Satoshi Kanazawa

Anyone who takes evolutionary psychology seriously has to overcome the fact that many of the most prominent voices in the field don't.

One gets the sense, reading their sweeping, provocative proclamations that they are more salesmen than scientists. The more shock and schlock they can pack in to whatever they're selling, the better. As soon-to-be authors of a book on sexuality (with plenty to shock attentive readers), we're certainly not claiming to be blind to the sales appeal of taking a new approach to inherently interesting material. But there's a point beyond which the science crumbles under the weight of the salesmanship.

Take Kanazawa's latest blog entry, entitled: The power of female choice: Why fat chicks get laid more. As an attention-grabber, it's pretty darned good stuff. You've got offensive language sure to insult many readers (thus generating irate responses and activity in the comments section). The same insulting language will attract other readers, who love to see their own ignorance confirmed by supposed "scientific experts" like Dr. Kanazawa.

Because sexuality is so entangled with power in American culture, it's hard to talk about sex without getting political. The two are nearly inseparable to Republicans especially, as has been demonstrated repeatedly in their opposition to "non-traditional marriage" (only a near-complete ignorance of the history of marriage could lead one to think what we have now is "traditional"), Senator Craig's "wide stance" in the bathroom stall, and their glee in bringing down Bill Clinton over his "unnatural acts."

Find a Therapist

Search for a mental health professional near you.

If Rush Limbaugh, Bill O'Reilly, or Ann Coulter had studied science, they'd be penning articles like some of Kanazawa's: provocative attention-grabbers empty at the core.

Let's go back to the article. First paragraph:

"In all species in which the female makes greater parental investment into the offspring than the male does (including humans and all mammals), mating is a female choice; it happens when the female wants it to happen and with whom she wants it to happen, not when the male wants it to happen or with whom he wants it to happen. The male has virtually no choice in the matter. A recent study neatly illustrates the principle of female choice."

What does Kanazawa mean by "mating?" In the context of parental investment, "mating" refers to forming a durable pair bond that will last until the offspring are more or less independent, and has little to do with sex. As Kanazawa is well aware, a sizeable percentage of the offspring of various purportedly monogamous species turn out to be genetically unrelated to the male "father."

But Kanazawa appears to be using the term to simply mean "getting laid," in that he writes "it happens when the female wants it to happen and with whom she wants it to happen ..." So, it appears we're talking only about sex. But if so, then Kanazawa is already misleading readers by ignoring the fact that along with female choice, male choice figures in the sexual interactions of many, many species of mammal -- including our own.

High status males have a wide range of options when it comes to mating. Ask any professional athlete, musician, or high-flying businessman what he thinks of Kanazawa's claim that "the male has virtually no choice in the matter." Ask a gorilla, chimp, or bonobo while you're at it.

Female gorillas have precisely no say in the matter, being the reward awaiting the winner of battles for dominance among males. Does Kanazawa believe female lions choose with whom to mate? Elk? Bighorn sheep? In species in which an alpha male dominates mating opportunities, females have little opportunity to refuse.

Kanazawa's understanding of female choice (or at least his statement of it here) is highly simplistic and factually wrong.

And it's not just high-status males who enjoy plentiful female attention. Speaking specifically of female libido among various primates, for example, primatologist Meredith Small writes that, “Interest in novelty has been clearly documented for twelve species of primates. But more striking is the regularity with which females choose these males…. In fact, the search for the unfamiliar is documented as a female preference more often than is any other characteristic our human eyes can perceive."

Here's the end of Kanazawa's piece:

Most men would simply not choose overweight and obese women as their preferred sexual partners. Overweight and obese women can have more sex than normal-weight women only if women decide when and with whom to have sex, and men have little say in the matter.

When a man propositions a woman, she can respond in one of two ways; she can say “yes” or she can say “no.” When a woman propositions a man, he can also respond in one of two ways; he can say “yes” or he can say “yes, please.” He has no realistic choice to say no. Men may not be saying “yes, please” to overweight and obese women, but Kaneshiro et al.’s study clearly suggests that they are definitely saying “yes.”

Look at the structure of Kanazawa's argument here:

1. "Most men would simply not choose overweight ... women as preferred sexual partners."

2. Yet the study cited suggests that on some measures overweight women are statistically more likely to have had sex than randomly chosen women of normal weight. Therefore,

3. "Men have little say in the matter … He can say 'yes' or he can say 'yes, please' … He has no realistic chance to say no."

Say what?

One could fly a blimp through the gaping holes in that argument. Only a man who has never had occasion to pass up an offer of sex could follow that line of reasoning.

Assuming the study cited by Kanazawa actually says what he claims it does, the only statistically significant finding was that overweight women were more likely to ever have had sex. Even if it was just once. Even if it occured a long, long time ago. Even if the woman in question was a sixteen year-old of normal weight when it occurred. And given the fact that this is a self-reported study, even if she's lying.

In other words, the study cited by Kanazawa lends no support whatsoever to his claims re: female choice!

So, while I'd wager that Kanazawa's posts here at Psychology Today probably get more hits than most of the other bloggers, one wonders just how much is substantive information vs. misleading attention-seeking balderdash.

Thank you!

Thank you, thank you, thank you, for taking the time to thoroughly refute that article of his.

Yes, this article was

Yes, this article was amazing. Thank you for de-venting me from walking away from my computer extremely pissed off.

crossing a line of respect?

I agree with a lot (maybe all?) of your criticism of Kanazawa's article, but I think comparing ANYONE to Rush Limbaugh is needlessly cruel...

To be fair, while Kanazawa's article may have been provacative/attention grabbing, there are TONS of distinctions to be made between what Kanazawa was doing and what unethical used car salespeople do or what Rush Limbaugh does--for example, Rush Limbaugh goes on hateful rants and stuff.

What do you have personally against Kanazawa? If you wrote an article with some flawed arguments and a misinterpretation of a study, would you want one of your peers to compare you to Hitler or to a prostitute or something?

You claim that Kanazawa is like Rush Limbaugh by trying to get attention and be provactive, but your post is a blatantly disrespectful and personal attack, and I feel it is patently hypocritical since personal attacks are very provocative. This isn't science, this is like the Jerry Springer show, watching scientists bash each other (which is kind of lame, because your insults are not that creative or entertaining).

misspelling provocation

I am usually an excellent speller, I do not know what got into me (although to be fair, I wrote that thing a lot faster than I usually right comments). Please forgive me, please don't compare me to Paris Hilton or something since I made spelling mistakes.

See where a lack of civility gets us? Now I don't even feel safe to make spelling mistakes lest I be attacked as brutally as poor Kanazawa.


my spelling problem

faster than I *write* comments... Not right..

You probably think I am a liar for saying my spelling is good, but I swear, when I was in grade school 100% on all the spelling pre-tests!! I did not even need to study. And if you ever need someone to explain the difference between their, there and they're, it's me, not to mention the difference between its and it's. Maybe it is because I am in caffeine withdrawal.


You are the psychologist, you should be able to come up with a psychological explanation for a sudden inability to type properly.

Limbaugh = Hitler?

Hey. Thanks for your comments (misspelled or not). Briefly, I'd respond by saying that: 1) I'd never compare Limbaugh to Hitler, so I'm certainly not comparing Kanazawa to Hitler! 2) I'd never compare Hitler to a prostitute, having nothing against prostitutes whatsoever. 3) What I wrote was not "blatantly disrespectful and personal" in that I addressed Kanazawa's argument and not his person -- about which I know practically nothing except that he likes Bill Maher a lot, which is a positive in my book (I'd never compare Bill Maher to Hitler, in case you're wondering). 4) As an evolutionary psychologist, I have a responsibility to say something when prominent members of the union publish sloppy thinking that makes us all look bad (I'm kidding -- there's no union). 5) "Poor Kanazawa" is quite capable of taking care of himself. Now go have a decaf coffee and take a few deep breaths! CPR

I have to agree, thank you

I have to agree, thank you for a well thought out reply to that article.

And I have read this post twice now and I can't seem to find any personal attacks of any kind. All the attacks are on the (lack of) integrity of his articles.

Oh well again thanks for the reply to the origonal article

Thank you for a dose of real science

Thanks for setting the record straight on this "bully" pushing around false ideas. Your points are simple and convincing. I too read about this study in the news and was immediately skeptical when I found that more of the heavier girls reported having sex themselves. It's hard to imagine there wasn't plenty of stretching of the truth in their reports. This is dubious science and of course further studies are needed before such "sure" conclusions can be reached about it.

Kanazawa does hold a Ph.D.

Come on...All you had to do was Google the guy to find out whether he holds a Ph.D. or not (he does, from the University of Arizona--see link below). You should have at least done a LITTLE research before publicly casting doubt upon Kanazawa's academic credentials. Sheesh...

Sheesh yourself

I did do "a little research." I looked at his bio on the Psychology Today web site, as I pointed out.

Whether or not someone holds a Ph.D. (or any other degree) is immaterial to the integrity of their arguments. No casting of doubt was intended. It was more a matter of not wanting to seem disrespectful by repeatedly calling the writer "Kanazawa" with no "Doctor" or "Mister" before.

Funny how the negative responses to the post all try to personalize the matter, rather than responding to the analysis of the argument. Wonder why that is?

Kanazawa writes: "Men have

Kanazawa writes:

"Men have little say in the matter … He can say 'yes' or he can say 'yes, please'

Kanazawa is a man. Does that mean he has sex every time it's offered to him? I hope not :)

Okay maybe that was a tasteless joke, but sometimes men actually do say no to sex. Sometimes women go for the nerdy guy with the Phd who teaches at a university and makes crappy wages, over the more higher status and beefer banker or lawyer. As a former nerdy female professor, I know that some women prefer the company of a fellow nerd rather than heading towards the nearest martini bar and trying to pick up a higher status medical doctor.

And sometimes a woman with the proper waist-to-hip ratio will be dumped by a guy so he can pursue a woman just as pretty, symmetrical, and just as old even though she might slim hips. I guess that guy knows although sometimes slim hipped women have a harder time birthing babies, c-sections are generally safe.

Thank you for showing the PT blog readers some of the many debates surrounding evolutionary science. People who spend a lot of time at R1 universities know that evolutionary psychology get critiqued on many different sides (neuroscience, religion, sociology, cultural anthropology, demography ect).

But you pointed out that on the pop culture front evolutionary psychologists do alright because their arguments are headline grabbing and sexy.

I do have one major problem with your post. Why are you so critical of used cars? Everyone knows new cars depreciate once you drive them off the lot. In fact, I might actually go for the sensible guy who recognizes this fact over the guy who wants to be a show off by buying an expensive new car every year. Maybe I am just bad at "mating"? Kidding.

In Defense of Used Cars

Right you are. Fact is, I'd never buy a new car. But I'd also be very careful with the used car salesman. Thanks for your comments.

"Funny how the negative

"Funny how the negative responses to the post all try to personalize the matter, rather than responding to the analysis of the argument. Wonder why that is?"

Because your post is mostly an inappropriate, content-free, embarrassingly low and ignorant personal attack. This post is actually much closer to the pugnacious style of the conservative attack pundits you list than anything on Kanazawa's blog.

"High status males have a wide range of options when it comes to mating. Ask any professional athlete, musician, or high-flying businessman what he thinks of Kanazawa's claim..."

Yes, and these very high status males, who are a very small fraction of all men, have about as much mating opportunity as an *average* female. Recall the famous Clark and Hatfield study: *75%* of the desirable men that were approached by average women agreed to casual sex. The figure for men was 0%.

If Johnny Depp walked around a shopping mall asking women to come back to his hotel for sex, it is plausible that even he wouldn't have a 75% success rate.

I don't get the impression you are thinking too deeply about the extent and significance of female choice. The same can not be said of Kanazawa.

"One could fly a blimp through the gaping holes in that argument. Only a man who has never had occasion to pass up an offer of sex could follow that line of reasoning."

Seriously? This is about as immature as personal attacks get. If you are trying to take the high road against sensationalism, you shouldn't engage in low class, machismo sexual insults like this. I'm embarrassed for you.

Anyway, using the General Social Survey, I too have found that overweight women have more sex partners than normal weight women. However, men in developed nations do not find overweight women more desirable and there is much research that converges in this direction. Parental investment theory squares this circle. Men are more likely to *invest* in ecologically attractive women, and simply have no-strings sex with unattractive women if the opportunity presents itself. Unattractive women are more likely to use sex to seek investment than attractive women, who can more successfully withhold sex to obtain investment.

e.g. See this paper:

"Attractive men and women were more successful in implementing their preferred mating strategies according to parental investment theory. Men with attractive faces and bodies enjoyed significantly more short-term mating success than their peers, with no cost in their long-term mating success, whereas women with attractive faces had more long-term mating success than their peers."

Clark & Hatfield (in reply to angry Jason)

I responded to your comment in a new blog posting, called "Response to Readers," here:

Rejecting EP as 'deterministic thus immoral' simplistic

Regarding determinism in Psychology/Social Sciences, my article “Determinism and the Antiquated Deontology of the Social Sciences” might be of interest:

It basically argues that the common gut-level reaction in the psychology/social sciences to anything deemed “deterministic” is overly simplistic and out of touch with the last half century of important developments concerning free will and ethics in philosophy.

Thanks. Very good response.

Thanks. Very good response.

EP Salesmen

You make some very good points, and if you read the comments to Kanazawa's piece you'd see that the readers themselves pointed out many flaws. I, myself, pointed out many flaws and over-simplifications in the argument presented and suggested alternative hypotheses that are supported by the apparent study results.

Now that you've clarified the actual conditions of the test, the potential list of supported hypotheses grows even greater, mean it leaves more questions than answers.

That being said, you make a valid point about some areas of EP being presented as if by used car salesmen. This is true to some degree, and I always highly recommend that everyone play devils advocate to try to come up with an argument that disproves the presented hypothesis while being consistent with the data.

However, I don't believe this is limited to EP. You see this sort of confirmation bias in many fields of science. The more complex the system being studied the easier it is, and greater pressure exists, to oversimplify. Even in something as simple as toxicity studies (e.g., BPA) and cancer statistics (cell phones) there are great efforts to "sell" a certain point of view.

Granted, much of that occurs once the activists take over and the sales brochures look less and less like the science they pretend to represent, but scientists do tend to come with their own pre-conceived notions. I recall a huge argument locally over a study suggesting that biking on the street is safer than on dedicated bike paths, something the study author incorrectly concluded when the exact opposite conclusion could be supported by the same data with a slightly modified hypothesis.

Perhaps it is unique in EP that the scientists also tend to be a little bit activist. Perhaps it is a field just too young to have developed thorough and robust methods to maintain objectivity. My hope is that this side of EP firms up before it becomes more mainstream. I see it as a revolutionary leap in understanding, but it hasn't caught on in the mainstream press, public, or activist circles yet which still seems to think in terms of the long discredited tabula rasa model.

I just hope that EP can get its act together before it obtains escape velocity into the wilds of public space. There are some pretty radical and important EP ideas so I can see many longterm public rifts forming into EP religions if EP doesn't get it's act together in that respect.

That being said, EP offers the potential to develop such a mitigating gravitational pull to keep the ideas from flying off publicly. If EP put as much effort into studying how and why people develop such "dig your heals in" activist biases, regardless of the real data, perhaps it could offer the best way to present its own findings without causing such sociopolitical chaos.


Many thanks to everyone who has read and commented on this post. Just wanted to say a few words in response to DL, who has obviously given these issues much thought. We couldn't agree more that this sort of confirmation bias is a huge issue in many fields that consider themselves scientific. Medicine is, as you note, riddled with it. Another form it takes is the myth of mechanism: if the mechanism of action can't be explained (think: hypnosis), then medical students don't want to hear about it. When we explain that the action of aspirin wasn't understood until recently, they soften, but rarely give in. We are all slaves to our paradigms, to some degree. We also share your sense that EP represents a "revolutionary leap in understanding," but we're very troubled by the overtly political uses to which EP is often bent. We see treatment of data that goes beyond sloppy, well into fraudulent in some of the most prominent authorities in the field (we get specific in the book). It seems that, as long as this shameless misrepresentation of the data continues, the public will be wise to ignore a lot of what they hear coming out of this field. As we said in the post, there are a lot of serious people, doing serious work, but their voices are drowned out by hucksters who are more interested in attracting attention than in careful analysis. Take a look at Steven Pinker's TED presentation on the history of violence for a prime example of what we're talking about. In any case, thanks for lending us your eyes and taking the time to engage, DL and everyone else.

Just rubbish

I amazes me that in all this evaluation of theory, it is taken as fact that overweight women are not sexually desirable and therefore any number of sex partners she may have would all be men that she propositioned, who are unable to turn down free casual sex. A male's first choice would be to have sex with someone attractive. This is just plain rubbish.
I am an overweight, attractive woman. I don't think that I have more sexual opportunities than my thinner sisters, but I would say that I have a much easier time finding single, heterosexual men that are willing to commit to a relationship.I have an equally attractive sister that is very thin who has a hard time with men. She runs into men that say they will call and don't or just aren't interested in a relationship. During one six month period, she couldn't find someone to date at all. During that same six months, I had to explain to several very eligible men that I was just not looking for a serious relationship. I have, at different points in my life, looked for casual sex without much luck, because typically if I sleep with someone, they tend to start pressuring me for a commitment. I realize that this goes against the whole premise, but it is true.
It has nothing to do with the idea that women get to chose, and that men have no say in the matter. The truth is women don't always get to chose. Take a quick look at the statistics for arranged marriages, the selling of virgin daughters, stranger rape, date rape, societal pressures, forced female genital mutilation and coerced sex and you will see that women don't get to chose most of the time. It is all well and good for men to hold a pity party about how women can have sex with any man they want while "Joe the plumber" has to try hard just to get the fat chicks, but we still live in a world where there are men that SELL women to other men.
Back to the point, if I assume that "overweight women have more sex", and I don't think that is true across the board, it has more to do with living in an image based society. The men who are looking for a trophy lay don't bother approaching an overweight woman. Other men are looking for a woman that is comfortable in her own skin. A woman that they can be themselves with and not worry that they aren't good enough. I think that in our image based society there are many men who are tired of trying to have everything in their life look like an advertisement, only to end up broke and alone when they get left for a bigger, better deal. Believe it or not, there are a vast number of men that find a smart, funny, beautiful, good-hearted woman irresistible, regardless of size.
I blogged about a similar thing here

Wow. If I heard that at a

Wow. If I heard that at a mall somewhere, I wouldn't be surprised, but here..? Just wow.

Did Christopher Ryan PhD get his degree out of a crackerjack box

Did anyone note the irony that Christopher Ryan, a PhD and thus a "high status male," believes he can, through speculation and an uncanny ability to ignore common sense, propose to set the record straight about female sexual choice?

"only a male who has never had an occasion to turn down sex would agree with such an assumption."

I would wager that's the vast majority of American men. In my 30 years as a low status male, I have never been hit on by a woman or offered sex by a woman acting on her own initiative. Maybe I should have gotten a PhD so I could play make believe too. What the study clearly shows is what everyone knew anyway: women choose when and with whom to have sex, while men mercilessly compete for the opportunity with women obese or otherwise. Any woman who doesn't believe this can test the theory: go to a bar and sit there alone, see how long it takes for a male to attempt to pick you up.

*Only* high status males choose. Durrr. To be a high status male implies that you are not the average status male, you are therefore a minority among males. Is this rocket science? Meanwhile, average to low status females, including the obese, as the study shows, enjoy the freedom to choose only afforded to the high status male. Of course women are confined to the status as the *object* of male sexual competition, but then again, they're free to court males any time they please, which they seldom do (something we all know is true, although the obligatory female will come out of the woodwork and claim otherwise, of course). Therefore, the ball is in the females' court. For us average to low status males, which is the majority of us, the female, obese or otherwise, remains the employer who sits behind the desk and screens applicants. They choose, we do not. It must be nice to live in the fantasy land that your PhD affords you.

Thanks, Christopher. Well

Thanks, Christopher. Well done. Did Mr. Kanazawa author anything good at all? What a quack.

I would assume the study to

I would assume the study to be true because it's commonly known fat girls will have sex with anything, in any way because of a notoriously low self-esteem. Attractive women are pickier and tend to wait for someone they find especially desireable. That's all the study really says. I'm sure normal weight women have considerably less sex than their overweight counterparts and that would be by having higher standards than a one night stand with a desperate chubby chaser that happened to look at them twice in the bar when they were drunk.


You argued,

"In the context of parental investment, "mating" refers to forming a durable pair bond that will last until the offspring are more or less independent, and has little to do with sex."

This is simply wrong. The pattern of parental investment in a species affects mating pattern of that species but these two concepts are different things. Even in the context of parental investment, a "mating" does not requires a durable pair bond. For example, in many animal species, males simply "mate" and leave the female and future offspring but we still can talk about the parental investment by the male and female, which is asymmetric in this case. The term, "short-term mating" strategy, will be a nonsense under your definition of "mating". But it is legitimate to talk about short-term mating strategy of the male and female in a species which is shaped by the pattern of maternal and paternal parental investment in that species.


Mr. Kanazawa has a series called "Men do everything they do to get laid." I suggest you read it. I think this offers clues as to Mr. Ryan's heavy handed, political (he knows that a bunch of libs read these blogs), and ultimately personal attack on Mr. Kanazawa. Mr. Ryan is just trying to appease his liberal peer group and thus increase his chances of getting some booty.

Female choice

"Female gorillas have precisely no say in the matter, being the reward awaiting the winner of battles for dominance among males."

This is not stricly true.
Females choose to move to a new male a number of times over their lifespan. Male gorillas try to entice females away from other males, admittedly by demonstrating their physical powers and sometimes even killing the infants of those females, but female gorillas are not stuck with any particuar male necessarily. If there is a second male in the group they will also secretly mate with him if they choose. They also sometimes pressure the silverback to mate, sometimes when not actually fertile, as a way of competing with other females in the group.

Also chimpanzee and bonobo females make their mate choice when they choose which group of males to join. The chimpanzee females will likely have to mate with the alpha males and other males due to male coercion but sometimes will be able to choose too.
Female bonobos have much more choice as female alliances quash male coercion. Females are particularly choosy when actually fertile - at these times they have less sex with fewer different males than chimpanzee females.

female primates and novelty

"primatologist Meredith Small writes that, “Interest in novelty has been clearly documented for twelve species of primates. But more striking is the regularity with which females choose these males…. In fact, the search for the unfamiliar is documented as a female preference more often than is any other characteristic our human eyes can perceive."

This is because stranger males are potentially killers of the offspring of those females. By mating with novel males the females are creating paternity uncertainty and are protecting their reproductive interests. They are even mating outside of estrus by faking estrous behavior to better trick the males. The females are not doing it for their sexual pleasure - whatever that might be when they are in estrus.

Post new comment

The content of this field is kept private and will not be shown publicly.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Allowed HTML tags: <a> <em> <strong> <cite> <code> <ul> <ol> <li> <dl> <dt> <dd>
  • Lines and paragraphs break automatically.
  • You may quote other posts using [quote] tags.

More information about formatting options

Christopher Ryan, Ph.D., is co-author of Sex at Dawn: The Prehistoric Origins of Modern Sexuality (HarperCollins 2010).


Subscribe to Sex at Dawn

Current Issue

Let It Go!

It can take a radical reboot to get past old hurts and injustices.