In The Case of the Female Orgasm: Bias in the Science of Evolution, Elisabeth Lloyd (Arnold and Maxine Tanis Chair of History and Philosophy of Science and Professor of Biology at Indiana University, Bloomington) examined the data supporting the 21 evolutionary explanations for the origin of female orgasm. She concluded that the evidence as it currently stands best supports the hypothesis that female orgasm is not an adaptation, but a byproduct of embryological development and the adaptiveness of orgasm in the male, and that there is inadequate evidence to support any of the hypotheses indicating that female orgasm is an adaptation. The book has generated a great deal of response from feminists as well as scientists. Prof. Lloyd spoke with Thinking Meat in April 2006.
TM: Did you expect the book to get the reaction it did?
EL: Oh, no. Several people had warned me; a couple of my friends had a much better idea than I did that I would run into some of the problems that I did run into. I was expecting the objections from evolutionary adaptationists (for example, the reaction from David Barash, although I didn’t anticipate that it would be quite so ad hominem. I would like to note, however, that David Barash very generously arranged the unique opportunity for my rebuttal—which is posted on my web site—to be linked to directly within the journal Evolutionary Psychology immediately following his highly critical review), because the book did show that at least on this occasion, pursuing an adaptationist program single-mindedly led to pretty deficient science.
What I didn’t anticipate at all was the feminist backlash, because I’ve been a feminist since I was 20 years old, and the book offers a feminist analysis. My friends warned me that it would be misread and misinterpreted, and that some feminists would take the point of view that I was promoting a male model of female orgasm, that is, that the byproduct account is somehow male in essence because it says female orgasm is derived from the selected male orgasm. But that’s “derived from” in only the most trivial sense. It says only that male orgasm is adaptive; it doesn’t mean “derived from” in any metaphysical, meaningful, cultural sense. I mean, we don’t care what’s adapted or a byproduct in real life and in culture; most of the important traits that we care about in society are byproducts. Most of the functions of the brain, the things we do in everyday life, like reading and writing and using a computer and going to the opera, these are all byproducts, and we don’t care about whether they’re byproducts or not. So I guess I didn’t really believe that anyone would misunderstand the theory so profoundly to take me to task for it, especially feminists, since I was a feminist. But a couple of friends of mine who anticipated that that would happen were absolutely right, and it was a very vicious set of reactions. It caught me completely off guard; I was absolutely stunned.
TM: What surprised me was that it came from two different directions which logically couldn’t both be right.
EL: I couldn’t win for losing; one side said I was overly influenced by my ideological beliefs to make a scientific conclusion, and the other one said that I was overly influenced by my science to make an ideologically incorrect conclusion. But both of those perspectives are actually wrong. You can understand why the adaptationists would get paranoid, because they look at what I did, which is to take the 20 adaptive explanations of female orgasm and find every one at fault, and they say, “She was out to get adaptationist explanations, she had an agenda. She went out and said: I’m going to show that every one of these evolutionary explanations for female orgasm is wrong.” That’s one way to think about why it is that I ended up saying that every explanation turned out to be deficient in its evidence. But the other obvious explanation for why I came to the conclusion I did was that I approached every explanation individually and examined it and used the ordinary standards of evidence for evolutionary explanations and found independently that each one was deficient, which is in fact what happened.
When I first started looking at female orgasm, I was trying to answer this question for a friend, who had asked me, “What’s the function of female orgasm?” I assumed it was an adaptation, so I wasn’t on the warpath at all. But I was struck by how the explanations that I found conflicted with what I knew about the sex literature. They seemed evidentially deficient on their faces, so I thought, oh, these aren’t very good adaptive explanations, and so the ball started rolling…I went in assuming it was an adaptation and ended up thinking it wasn’t; it’s not that I set out to show that it wasn’t an adaptation. They just made that up; it’s pure fantasy!
TM: Do you think they might be defensive, because some of these hypotheses seem surprisingly poorly supported, and they’re wondering why they didn’t ask these questions themselves?
EL: In the last few years that I was researching the book I kept getting told again and again that it had been proved that female orgasm was an adaptation, and I’d better damn well go back and look at that uterine upsuck evidence. [The uterine upsuck hypothesis is that orgasm aids in conception by causing contractions that suck sperm into the uterus.] And I went over that stuff with a fine-tooth comb; you can see my analysis in chapter 7. I found what I found, which was a sort of smoke and mirrors with very shoddy statistical evidence, which does not pass muster for even the most primitive statistical standards of any scientific journal that I have run across. And so far even my worst critics agree with me about that.
So, yeah, I imagine there would be a certain degree of embarrassment about this, because this stuff has been taught all over the world as fact, for the last twelve years. I cite more than half a dozen publications in my book which deliver it as the uncontested fact of the matter about the evolution of female orgasm. Now the fact that it turns out, on closer inspection, to be little more than speculation at this point in time, would I think naturally be an embarrassment to the evolutionary community, because it’s evidence of a failure of self-policing. When they were writing that female orgasm was an adaptation and that it was in fact this type of adaptation, there was a competitive explanation that it was a byproduct that was well supported by evidence and that they had dismissed out of hand. They claimed that in contrast this other explanation was well supported. That turned out to be not true. As a result, they ended up delivering a story—a fable—about the state of the evidence, and in fact, a fable about the evolutionary standing of female orgasm to all their students over twelve years all around the world. That’s a lot to be responsible for. So it isn’t just that they said the one thing was a fact, it’s that they also said that the other thing, the byproduct view, was wrong. And what that means is that they’ve said it exactly backwards: The byproduct view has the evidence; the upsuck view does not have the evidence. That’s a serious thing in my book. So yeah, I think that they have something to answer to, and I think that if they are embarrassed they should be, and if they’re not, they should be starting to be embarrassed.
TM: So why do some people believe so strongly that most traits are adaptations—why are they adaptationists?
EL: I think the best thing to do would be to ask them why they’re adaptationists. I don’t know why they’re adaptationists. I would like to know, for example, why John Alcock thinks what he thinks, very much, in fact. He has a well-documented, savage, and implacable hatred of Stephen Jay Gould that was sort of manifested in this discussion of female orgasm. It made it very nice for me in my discussions and exploration of the literature, because he wrote so much about it. But that might have contributed to his making some claims that might be considered ill judged on the evidence.
There’s something really, really exciting when you realize how natural selection works to shape and create mechanisms that contribute to the reproductive success of organisms. The power of the combination of random mutations and selection to produce such creativity, the power of creativity is so mind-boggling that many a researcher, I think, is captivated for life by that, and pursues the mission of looking at the natural world in those terms, which is an understandable and admirable way to approach things. A problem with that is that we know that evolutionary processes involve more than mutation and selection, and in particular more than selection processes. Evolutionary change involves historical and developmental processes as well, and of course all of these are also shaped by selection over time, so there is a very complex interaction. But the interaction of, for example, selection and development, and selection and history, is something that may not be as exciting. To get inside the adaptationists, though, I think you’d need to ask a self-styled ardent adaptationist like John Alcock or David Barash.
TM: After all, it’s not like evolution created human beings out of nothing; it had to work with what was there.
EL: One of the most common confusions I’ve run across with the book, and I was discussing this recently with Frans de Waal, is that people have gotten confused about the evolution of the clitoris in terms of its role in sexual excitement. Donald Symons since 1979 and Gould and I have always been very clear that it’s adaptive in its role as producer of sexual excitement and trigger for the variety of responses that are involved in preparing for sexual intercourse (for example, keying up the changes in vaginal length and increased lubrication and so forth, and sexual interest in intercourse), all of which are clearly adaptive. What we claim is that it’s not adaptive in the very specific function of producing the spinal reflex of orgasm itself, which is only one of the many possible reactions that the clitoral physiology can be involved in. It’s perfectly clear that the role of the clitoris in all these other things, sexual excitement, lubrication, etc., is adaptive and there would be plenty of selection for the clitoris in all of those functions, and therefore selection for it and maintenance in that role. It’s just that there’s no evidence for its selection for the reflex. It’s never been correlated with fitness; there’s no evidence for design; there’s no evidence for function; it’s not correlated with anything that we know of.
TM: I like the list at the very beginning of the book of characteristics that a trait must have to be an adaptation. To my mind that would be a good thing for the average reader to keep in mind when reading evolutionary explanations for human behavior in the media. Particularly for anything related to sex, it seems like a very hard area to be well-informed in.
EL: There’s some really interesting possibilities with the uterine upsuck. I mean the Baker and Bellis research, because of the statistical problems, and because of the logic of their own account, which is self-defeating, is kind of in a ditch. But there are a couple of new studies that came out this year that you might have seen about the heritability of female orgasm. One of them was by Dunn et al.; the other one was by Khytam Dawood, a researcher out of the University of Chicago. There was a big twin study cohort and she and her group found that female orgasm was moderately heritable. There’s all kinds of things to say about that; I’ve discussed it in my blog contributions. Female orgasm and female orgasmic capacity is so very highly variable among women; you have some women who are very highly orgasmic in a number of different situations, with intercourse, outside of intercourse, with masturbation. And then you have quite a few women at the middle of the pack where sometimes they have orgasm and sometimes they don’t; it depends on the situation and it’s much tougher for them. And then you have a large set of women who really don’t have orgasm that often in their lives; maybe they have, I don’t know, 500 orgasms in their lives, and then you have another set that have maybe 20 orgasms in their lives, and then you have 5 to 10% of women, maybe more, who never have orgasms in their lives, ever. That’s a very big chunk of women who never have orgasms in their lives, if you’re going to consider orgasm an adaptation. This is kind of a problem.
At any rate, if you look at all the different samples of women that people have studied over the years (I summarize 32 studies in my book), if you look at, for example, Dawood’s new study or Dunn’s new study, this just confirms the kind of flat distribution of this variety. You get this picture of women that they just come in all these different varieties of orgasmic capacity, whether it’s with intercourse or whether it’s just in terms of orgasmic capacity altogether, and this is everything that we’ve learned from the sexology over the years. This poses a very difficult problem for anyone who wants to give an evolutionary account, because what it basically means is that you can’t just give one. A favorite one these days says that women have orgasm during sex “when it’s with a high-quality male”. But women who only have orgasm with a high-quality male, well, they have to be women who sometimes do and sometimes don’t have orgasm with intercourse. Maximally, that includes about 35% of women, so that’s a minority of women. And that’s a problem, because all the women who always have orgasm with intercourse, they’re not included, and all the women who rarely or never have orgasm with orgasm, they’re not included. So that’s 20% plus 34%, so 54%, of women who aren’t included in the hypothesis. If you’re going to have a hypothesis that includes only a minority of women in it, you need to have a separate hypothesis for each little subgroup of women.
And that is the model for the only sustainable type of evolutionary hypothesis that could be floated today that would be consistent with the evidence we have, because of that flat distribution of female orgasmic capacity. It means that what’s called a multistrategy set of adaptive hypotheses is necessary. We’ve got to have one situation that’s going to produce the high-orgasmic always-have-an-orgasm strategy, and another one where it’s the only-have-an-orgasm-once-in-awhile strategy that’s going to be adaptive.
And then the tricky bit comes in that there’s going to have to be fairly high resemblance between the offspring and the parent, or fairly high heritability, or else you’re not going to be able to tell an adaptive story about it. And then you’re going to have to slice up the distribution into these different components in order to tell an adaptive story about each one. But you see, because of the distribution being the way it is, that’s the only type of adaptive story that could possibly work. Because other adaptive stories have peaks, sharp peaks where you have an adaptive account and it says, “Look, the best way to be is to have a long snout, and everybody has a long snout.” Now clearly that’s not the case for orgasm, so that kind of account isn’t going to work. And the only account that’s going to be even floatable now is this multistrategy account, and so they’ve got to come up with something like that.
Going back to Dawood, I think that she’s got some of the best samples right now, and her group is pursuing this sort of multistrategy story along the lines of Baker and Bellis, but hopefully with more care, and she might be able to pursue the more interesting and more promising adaptive accounts, and that’s what I’m hoping her group is going to be doing. The oxytocin research, as I indicated in my book, is by far the most promising avenue for something having to do with the sperm upsuck; that might well have to do with sperm competition. This is the most promising avenue and that needs to be pursued, and her group is looking at that. So I’m really hoping that they develop a well-qualified set of classes so that they can then develop individual hypotheses about these subgroups and substrategies, and then float a multistrategy hypothesis that might be testable, rather than just what has happened before. Because one of the bad things about this state of affairs for the past twelve years is that because people had been saying “It’s a fact,” there was a certain laziness about testing.
TM: We’ve already answered that question, so…
EL: Yes, yes, and in fact that question hadn’t been answered, the tests were not adequate, and so I’m really hoping that the future work, especially by Dawood’s group, which I’m quite optimistic about, will fill out the most carefully articulated and theoretically plausible adaptive hypotheses that could then be tested, because I think that’s the way to go.
TM: In the book you talked about how we can’t rely on folk wisdom about orgasm the way we can on other things, because individually we know so little. Some assumptions that are “common knowledge” are wrong—e.g., increased fertility is obviously better—so I start to wonder what else we think we know that’s wrong.
EL: It didn’t strike me when I first started working on orgasm as an adaptation that the assumption that more orgasms leading to more babies was problematic until a number of years later. I don’t recall the exact circumstances but it’s quite clear that you can’t assume that more pregnancies is better. Sarah Hrdy made the case most eloquently in her book Motherhood that I cite in my book, but it’s a general principle in biology that the higher the investment in the offspring, the fewer pregnancies are going to be invested in by the mother. And the investigation of optimal birth spacing that had been done in the ’70s for human hunter-gatherer groups was done because of precisely this issue, the recognition that more babies is not better and does not mean higher reproductive success for the human species. So that’s been recognized for forever. And yet you had, for some reason, in the literature just this old assumption, apparently, that more orgasms and more fertilizations were better, whereas obviously that’s not true. I go through a series of different questions that need to be answered about connecting up uterine upsuck and fertility, and fertility with high quality males, and high-quality males with birth spacing, and birth timing, and so on and so forth.
TM: Why do people (some feminists, for example) think it’s not important if it’s not an adaptation?
EL: I really don’t know why people think that something has to be an adaptation in order for it to be important. The depth of naiveté of that is sort of hard to fathom.
TM: People sometimes take evolutionary explanations of behavior as normative, and they don’t want to hear, for example, about possible adaptive features of sexual infidelity, because they think that means that’s how we have to be. But answering the question of why females have orgasms seems to me to involve description more than prescription.
EL: I don’t know. Just in the last six weeks, I’ve done two interviews with women’s magazines, one from Glamour and one from Self, and both of them were cashing out consequences for women’s sexual behavior from the byproduct view. Both of them were following the dotted line from what I described in the book to what they were recommending to their readers in terms of sexual practices. In particular, one of them was recommending the practice of self-stimulation during intercourse in order to achieve orgasm, because of the well-documented lack of orgasm during unassisted intercourse, as I document in the book. And the second was following the dotted line from the byproduct view to the
recommendation that women not follow the sexual script of first-base, second-base, home-run, sex, that they urge their boyfriends to pursue a “more roundabout method” in the bedroom, so that the woman too can achieve orgasm. And so in this case, you have Glamour and Self, following on the heels of a recent Cosmo article that was based on the book, also all about self-stimulation during intercourse. And a piece in Redbook…they’re all drawing conclusions based on what as you know is simply the delivery of a summation of 75 years of sex research. So yes, they are finding applications.
TM: I wonder if it’s possible to talk about anything involving human nature, sexuality, behavior that people wouldn’t take a prescription from.
EL: What I found in discussing these issues with the young women writers of these women’s magazines is that there’s a dearth of discussion of some of the basics of physiology out there. And I guess more importantly from a normative point of view, what appeals to them about the byproduct view is that this, to them, does seem to give them some kind of normative basis. Because they do seek some account that goes like this: Evolution made you like this; it’s a developmental thing, and you came out like this because biology made you like this. Therefore when your boyfriend head-trips you because you don’t have orgasms during intercourse, you just tell him, “I didn’t evolve in order to have orgasms from intercourse, you schmuck.” And this was never so clear to me as during a recent discussion with one of these writers, that this was a line that they were interested in taking. But yes, this is something that’s important to them to convey to their readers. And this is how it’s carrying out into the broader culture.
(Originally posted April 13, 2006)