ELAH FEDER: Hey everyone.
ANNIE MINOFF: Hey.
ELAH FEDER: So it's been a little while, and you might not have expected to hear from us again. Some of you declared us dead prematurely, but after two seasons Undiscovered is unfortunately saying goodbye.
ANNIE MINOFF: It has been an honor to play in your ears, to get your emails and reviews and tweets and see you sticking your Undiscovered stickers on things. That was really cool.
ELAH FEDER: That has meant so much to us, and we're going to really miss sharing these stories with you. But the good news is before we go, we do have a few final episodes for you. So Undiscovered, it's always been about how science happens, and it's not a steady march toward truth and wisdom and it wouldn't be nearly as interesting if it was.
ANNIE MINOFF: And some of our very favorite stories that we have discovered in the process of making this show are about things that us humans, scientists included, got wrong and how we changed our minds.
ELAH FEDER: And how we'll probably change it again.
ANNIE MINOFF: Inevitably. So this is Undiscovered, we were wrong edition. First up, we have a story about sex.
ELAH FEDER: I want you to imagine it's 1978, Florida State University. There's a young woman. She's standing in one of the quads on campus. It's a weekday. I know that it was not raining. That is all I know about that day.
ANNIE MINOFF: Cool. Cool.
ELAH FEDER: And this woman she's scanning the area for men that she finds attractive.
ANNIE MINOFF: This is what we female college students do.
ELAH FEDER: So he has to be not only attractive but attractive enough that she would consider sleeping with him.
ANNIE MINOFF: According to whose rule?
ELAH FEDER: I'm going to get to that. You'll find out who's pulling the strings here.
ANNIE MINOFF: OK, it feels-- it already feels like kind of perverted.
ELAH FEDER: Stay with me. So she's scanning for attractive men, and when she finds one she consults a notebook that she's carrying. The notebook tells her what she's supposed to do next. So the notebook always contains one of three instructions. It tells her to ask this man on a date or to ask him to come back to her place tonight.
ANNIE MINOFF: What?
ELAH FEDER: Or to ask him to have sex. So this time, let's say it's option three, just like sex.
ANNIE MINOFF: Hey you.
ELAH FEDER: Well, here's how it goes. She walks up to the man. She tells him she's noticed him on campus. She finds him very attractive. And then she asks him-- the actual wording is would you go to bed with me tonight. And when he gives her his answer, she thanks him for his participation in a psychology study.
ANNIE MINOFF: Yep. Yep. That's the worst.
ELAH FEDER: Yeah, awkward, awkward study. But there was a reason for it. It all started when a professor was having an argument with some students about who wants more casual sex, men or women? It was the late 70s. By now the sexual revolution had come, women's liberation.
Our views about women were changing. Women were now judges and astronauts. And Billie Jean King had beaten a man at tennis. And some people thought, hey, without all our old cultural baggage, men and women are more similar than different.
And this professor was saying, not so fast. When it comes to sex, we are still different. Men he thinks are always down for sex. A man, he says, will sleep with any woman who asks, but women whole other story. His message is not well received.
One woman threw a pencil at him. But this professor figures, OK, we can actually settle this. We don't have to debate it. We can do an experiment, and that's how this study happens.
He sends out young college students, some men, some women to ask strangers of the opposite sex one of three questions, do you want to go on a date, do you want to go to my apartment, do you want to go to bed.
ANNIE MINOFF: I really want to know what happened. I mean, I think I know what happened.
ELAH FEDER: Do you though?
ANNIE MINOFF: I'm Annie.
ELAH FEDER: And I'm Elah. And in the next few episodes of undiscovered, we're talking about the science we used to believe and how we changed our minds. Today's episode, we're talking about the idea that men want sex with as many people as possible, while women are monogamous. They're looking for love and commitment from just one person, that this is in our biology. And it's an idea that might not sound so unfamiliar even today.
ANNIE MINOFF: I feel like we've heard all probably a version of this idea.
ELAH FEDER: Today we're going to find out what could possibly be wrong with it.
ANGELA SAINI: Do you know I think for a long time I always bought into this idea too.
ELAH FEDER: That's Angela Saini, science journalist.
ANGELA SAINI: This was how it was, that biologically this is really how men and women are.
ELAH FEDER: So sure it sounds like a tired old stereotype, but on the other hand, it is an old idea. And there's some science that seems to support it.
ANGELA SAINI: Even Darwin wrote about this. He took it for granted. He took it as a given that women are naturally more chaste and modest. In a Victorian society, certainly, they must have seemed that way to him.
ELAH FEDER: Darwin wrote that the males of almost all animals have, quote, stronger passions than the females, but Darwin didn't really have a good explanation for why. And then in 1948 a geneticist named Angus John Bateman comes up with a simple experiment. He puts male and female fruit flies in bottles, leaves them out for a few days to have sex and make baby flies, and he finds that for a male fruit fly the more sexual partners he has the more babies he makes. For a female, one partner often plenty. More partners didn't necessarily mean more babies.
And if evolution is about reproducing and spreading your genes, this would explain what Darwin noticed. You'll see biologists talking about eager males and choosy females. Eager males that have a lot of mates make more babies, get more of their genes into the next generation. Choosy females, on the other hand, they'll mate with only the very best male available to them, because why bother with extra males if you get diminishing returns on the baby front.
So I actually studied evolutionary biology, and I incredibly never question this idea, setting aside that me and a lot of people I know are actually gay and don't see ourselves in these rules of sexuality. From a theoretical perspective, it just made so much sense. And there was evidence backing it up, lots of species that fit this pattern, Bateman's cool fruit fly experiment. And by the 70s, there's human evidence too.
ANNIE MINOFF: Oh, no, coming back to the study. Yeah.
ELAH FEDER: OK, so here's what that study found. Remember we're going back to Florida in the late 70s. When it came to dates, men and women were about equally likely to agree to go on a date with a stranger. Actually, higher than I thought. About half agreed to go on a date with a stranger.
ANNIE MINOFF: I mean, it's very nice to hear that someone has been noticing you.
ELAH FEDER: Well, it depends on what they're proposing. When it came to going back to a stranger's apartment, men agreed 69% of the time.
ANNIE MINOFF: Wow.
ELAH FEDER: And when it came to being invited back for sex, even higher. 75% of men said yes.
ANNIE MINOFF: Wait if it was just like because you're getting rid of the ambiguity of the apartment.
ELAH FEDER: Yeah, this is clearly a sex invitation. Women, on the other hand, none of them said yes to sex with a stranger, and they made it known just how offended they were to even be asked.
ANGELA SAINI: So the people who wrote this study assumed that this confirmed this stereotype that men are promiscuous. They must be in order to be so willing to have casual sex with a stranger, whereas women were clearly not interested in sex because otherwise at least a few of them would have taken up this offer.
ANNIE MINOFF: OK, but here-- the man number being that high is surprising to me. Wow. But I feel like actually the low number for women it's like a safety issue.
ELAH FEDER: That is one of the criticisms of this study, and someone does eventually put that to the test. But we're going to get there. For now, this professor seems to have won the argument. He actually does the study a second time in 1982, nearly identical results.
And the newspapers eat this up. He tells them that men want recreational sex. Women are looking for love and commitment. He actually adds that the results are offensive to most of his female grad students.
ANNIE MINOFF: And he's just like, well, sorry dudes. Like, my data has spoken.
ELAH FEDER: I mean, basically. It seemed like science was backing up our stereotypes. Feminists might not like it, but look at the theory, look at other animals, look at these college students at Florida State. Evolution made us this way or so it seemed. After the break, a young biologist notices some animals are not playing by the rules.
SPEAKER 1: Keep your best leg forward sweetie. Oh.
ELAH FEDER: This one March day in 1970, a group of women headed out to Wall Street to sexually harass men.
SPEAKER 1: Oh, there so beautiful, all of them. Ah, those men are sex objects.
ELAH FEDER: This is some of the least credible sexual harassment I've ever heard.
SPEAKER 2: Hey, how do you like that hat over there?
SPEAKER 1: Oh, what a chapeau.
SPEAKER 2: How about the glasses? I like them with glasses.
ELAH FEDER: ABC trailed them around for this documentary. Some men look amused. Others are just ignoring them. A few actually crowd around to sneer and heckle, but these women have the microphone.
SPEAKER 1: We'd like people to understand what it feels like to have someone go [KISSING SOUND] and calling at us. And they feel like we're supposed to take that as a compliment. [CALLS]
ELAH FEDER: In the early 70s, women's liberation took center stage. All of the major networks ran reports about it, and feminists were challenging ideas about how women should be treated, who we were, what we were capable of. And a young biologist named Patricia Adair Gowaty, she was here for it.
PATRICIA ADAIR GOWATY: I simultaneously became a biologist and a feminist. These happened at the same time.
ELAH FEDER: I called up Patty a few months ago, and obviously for her feminism and science, they are not inherently in conflict. She says a lot of feminism's ideas you can actually turn them into testable hypotheses, and science can be used to test if they're true.
In the 1970s, Patty's studying eastern bluebirds for PhD. They're like little songbirds, like the kind that dance around Disney princesses. Male and female bluebirds raise their babies together in pairs.
PATRICIA ADAIR GOWATY: And the reason that was given in the old literature was that females needed all the help they could get to raise all those kids. And I thought, hmm, and so I did an experiment.
ELAH FEDER: She took their males away, and she found--
PATRICIA ADAIR GOWATY: Females do quite well fine thank you. They can do a whole lot of work without the additional help from males.
ELAH FEDER: Next Patty decides to test another bit of conventional wisdom about songbirds, technically passerines, which is that they were almost all monogamous and that females never or rarely had sex outside the nest, shall we say. And Patty again thinks, hmm, let's find out if that's really true. Why don't we run bird maternity and paternity tests?
ANNIE MINOFF: This is like Jerry Springer for bluebirds.
ELAH FEDER: Yes, somebody is going to be throwing chairs by the end of this, because it does not end well. She takes blood samples from dozens of bluebird nests, including 16 complete bird families. These weren't fancy DNA tests back then. She's looking at just two proteins. And what she finds is that in at least four of the nests something is up.
There's a baby whose proteins don't match either the mother's or they don't match the father's, and some of that could be basically bird adoption. Eastern bluebirds sometimes lay eggs in other bluebirds nests. But Patty thinks another part of it, females are having sex with males other than their main partner. Patty will not call it cheating, because they're birds and to be fair we do not know the terms of their couple hood. But whatever you call it, in the mid 80s, she's talking about this at a conference.
PATRICIA ADAIR GOWATY: And a very famous ornithologists said, oh, Patty, those females are being raped. And those were his words, and I just rolled my eyes.
ANNIE MINOFF: Oh, the took a dark turn. I mean, there is a lot of rape in-- well, this seems like an inappropriate word to use, but--
ELAH FEDER: Forced population.
ANGELA SAINI: Yes, that's the word I'm looking for. There is a lot of that in the bird world.
ELAH FEDER: Yeah, in the duck and goose world especially. But in bluebirds, Patty says no way, not if you know anything about bluebirds and their physiology. She says females are mating with other males. But this guy dismisses it out of hand, and actually at this point it's not super clear what's going on. There is no smoking gun of infidelity, just a surprising number of baby birds that don't match their parents.
But Patty wasn't the only one noticing that female animals seemed to be breaking the rules. A bunch of studies were coming out in the 70s that found female animals are not all as choosy and monogamous as people had previously thought. Like red-winged blackbirds, so they live in herons, groups where multiple females apparently mate with just one male-- emphasis on apparently. Because in this one study, they gave that male of a vasectomy, and yet the females eggs were still getting fertilized.
Other researchers cut female lion sneaking off to places where their current male partners couldn't see them or waiting till their partners fell asleep to go have sex with other males. And in songbirds, remember how when Patty started conventional wisdom said that songbirds were almost all monogamous. Yeah, well, after a bunch more paternity and maternity tests, it turns out that even though they do generally pair off, males and females still sometimes have sex with other birds. In the songbird species, we've studied strict monogamy is the exception. The list of a not so coy females goes on and on, pipe fish, baboons, our closest relatives, the chimps.
But you know these examples they don't necessarily prove that the idea of eager males, choosy females is wrong.
ANNIE MINOFF: Like, this could just be kind of exceptions to a very well-established rule.
ELAH FEDER: Exactly, there are always exceptions. We still have lots of examples that do work with this rule, and we had that really cool study in fruit flies. So do you remember the main takeaway from that study?
ANNIE MINOFF: Yes.
ELAH FEDER: I'll remind you. Yes, please do. For a male fruit fly, more sexual partners meant more babies, not so much for females. But remember, this was 1948.
So if Bateman throws a bunch of fruit flies in a bottle, how does he know who had how much sex with who aside from watching them day in day out.
PATRICIA ADAIR GOWATY: So it's actually very, very clever for its time.
ELAH FEDER: Bateman gives every fly its own visible mutation, things like having a tiny head or hairy wings. So when you look at the babies, if you see one with say, Bob's, tiny head-- Bob's a fly.
ANNIE MINOFF: Yeah, I got it.
ELAH FEDER: OK. If you see one with Bob's tiny head and Cheryl's hairy wings, you can see a-ha that means that Bob and Cheryl did it.
ANNIE MINOFF: Got it.
ELAH FEDER: And so that's how he calculated who had sex with who. So it's a great idea, except just over a decade ago Patty decides to take a more careful look at that paper, and she notices a few things that don't add up. For one, babies are missing, because Bateman hadn't fully taken into account just how powerful and harmful these mutations were.
PATRICIA ADAIR GOWATY: They died like flies.
ELAH FEDER: So Bateman wasn't totally clueless. He knew that if a baby fly got two copies of, say, the curly wings mutation, it was dead. But what patty figures out is that if you get two different mutations, that kills flies to which threw his calculations way off. And there were a few more problems with this study, but the upshot.
PATRICIA ADAIR GOWATY: His estimates were biased, and they were biased in such a way that, oh my goodness, made his point.
ELAH FEDER: And yet somehow for decades people missed this. And despite Patty's work, they still miss it. I looked at Patty's paper on Google Scholar, 69 citations since it was published in 2012, which is respectable. Bateman's paper though in the same time, over 1,400.
PATRICIA ADAIR GOWATY: Bateman's paper, there's only one way to really understand the fact that people continue to cite Bateman's paper. They believe it. They believe it without data, but I think most people don't understand it. Because if they understood it, they would see the empirical difficulties.
ELAH FEDER: So to recap, our famous foundational study has massive cracks in it, and we've got a lot of species where females do you go after sex with more than one sexual partner, sometimes very enthusiastically. And if that's true, you have to ask why. Based on what we said earlier, females should not be doing this. They shouldn't get anything out of it.
Well, Patty thinks it's time to scrap that whole theory. She's come up with something called the switch point theorem, which doesn't have any a priori assumptions about males versus females. But a lot of other people will tell you it's not that the theory is wrong, it's just not the whole picture. Because it turns out there are a lot of reasons for females to have sex besides making more babies.
ANNIE MINOFF: It's fun.
ELAH FEDER: On top of fun.
ANNIE MINOFF: OK.
ELAH FEDER: Like hedging your bets. More fathers means more genetic diversity in your kids, which ups the odds at least one of your kids is really successful in the evolutionary sense. Another one, in crickets-- and I'm going to put a gross warning on this.
ANNIE MINOFF: OK.
ELAH FEDER: So the male will present a female with what's called the spermatafore. Are you familiar with these?
ANNIE MINOFF: No, not at all.
ELAH FEDER: It's like-- it's a bundle of sperm and food. Basically, she's getting sperm, but she's also not getting it.
ANNIE MINOFF: Is she eating it?
ELAH FEDER: Yeah, so it's a meal--
ANNIE MINOFF: Oh.
ELAH FEDER: --and also somehow a sperm delivery vehicle. And so for these female crickets, more sex, more snacks. And on the flip side, for males we were saying more sex, more babies. Well, that's not the only thing they need to consider either. For example, STIs is not just a thing that affects humans if you're a male and you have sex and you contract a virus that kills you or weakens you and makes you vulnerable to predation, maybe that's not going to result in more babies long-term.
And so I think we're at is a lot of people still believe that the general trend across species is that males are more eager, and females are more choosy. Because all else equal, males should get more babies out of meeting a lot. But as one of my old profs told me, not all else is equal. They're actually a lot of factors at play, which is why you see so much variation across species. Angela Saini, the science journalist we met earlier, she credits people like Patty for the progress we've made, know people who see female bluebirds cheating when other people don't.
ANGELA SAINI: When we all bring our particular assumptions and biases to the table, and we all do have them men, women, everybody, then we get a kind of check on the mistakes. Then it's more difficult for people to propagate bad ideas, because there are people there to ask, actually, well, have you taken this perspective. Have you thought again.
ELAH FEDER: And the other big lesson for Angela is actually if we're going to go back to our original question are human men and women fundamentally biologically different, we got to watch how much we're reading into animal studies. Angela says, look, scientists will run these great experiments in mice or in flies.
ANGELA SAINI: And then the natural tendency of the scientists is to say not just published a paper saying we see this in mice or we see this in fruit flies. Isn't that interesting for mice and fruit flies? But to say, well, what implications does this have for us, and this is where you get a hell of a lot of speculation. We are not fruit flies. We are not mice.
ELAH FEDER: What about us humans if we're going to ask that question?
ANNIE MINOFF: I really, really hope are going back to Florida.
ELAH FEDER: We are going back to Florida.
ANNIE MINOFF: Because that study upset me so much, and I would like you to tell me now why it is wrong.
ELAH FEDER: OK, so a few years ago some researchers in Germany were wondering. They instinctively did not buy this study or at least they looked around at the men and women that they knew, and they knew plenty of women who were interested in casual sex. So they decided to do the study again. This time it was in 2013. And basically, what they found-- you're not going to like this-- it held up the original finding.
ANNIE MINOFF: But.
ELAH FEDER: But.
ANGELA SAINI: As a woman in the 70s on a college campus, some strange man comes up to you, the things going through your head are not just do I feel like sex right now, but also will this guy kill me, you know? What is going on here? There were so many other social factors, not least-- let's be honest-- the idea of judgment. is not OK even now for a woman to go around saying to people yeah I'm up for casual sex in the same way that it's OK for men. There is still a social taboo around that.
ANNIE MINOFF: Yeah, social taboo and safety. Like, this dude is already kind of acting outside of norms by being like I just saw you for the first time and have been watching you from a distance, and then you're like come to my place where it's just going to be us and we're going to have sex out. So this is actually what the German scientists were thinking. Why don't we do another experiment that's a little safer?
ANGELA SAINI: So they presented men and women with pictures of people who were interested in having sex with them they were told, and they said would you have sex with any of these people.
ELAH FEDER: It actually wasn't just a hypothetical as far as the subjects knew. They were like we will-- if you choose some people for sex, we will set that up.
ANGELA SAINI: In a controlled environment. And what they found instead was that very many women were interested then in having casual sex with one of these people.
ELAH FEDER: In fact, 97% of women chose at least one man for possible sex.
ANGELA SAINI: So that run completely countered the original study.
ELAH FEDER: And if you're wondering, 100% of men chose at least one woman for sex but statistically no difference. So this experiment, it's not perfect either. I mean, yes, they take out the danger component, but it's totally artificial. So think about it you're looking at pictures in a lab telling researchers, yes, please kindly arrange this sex meeting.
And actually not only do they do they say we'll set up sex in a controlled environment, they say we're going to film the first 30 minutes of the encounter before we leave you alone to do as you please. Like, who is signing up for that? Did they really buy that this was going to happen?
The researchers actually did ask people afterwards, hey, did you buy the experimental setup? And people said, yes, they did for the most part. So I don't know. Maybe I don't understand people, or maybe they were being very polite to the researchers. Either way, I doubt this is the final word on human sexual appetites.
But I hope this is the last of this particularly awkward kind of study, because these people have feelings damn it.
ANNIE MINOFF: Right.
ELAH FEDER: Like, don't tell them that somebody is into them, and then you yank the rug out when they say they're interested back. Undiscovered is reported and produced by me, Ellah Feder.
ANNIE MINOFF: And me, Annie Minoff. Our senior editor is Christopher and Talley Ata, and our composer is Daniel Peter Schmidt.
ELAH FEDER: You can read more about Patty and this story in Angeles Saini's book, Inferior, How Science got Women Wrong. And as always, get links, get footnotes, get all that good stuff an undiscoveredpodcast.org.