Sex

why do you have sex all the time? Now, those of you who are seated alone maybe thinking, lady, you are mistaken because I am definitely not having sex all the time. And those of you sitting with the date might be thinking that's obvious. We have sex because it feels good. But I assure you that is only half the story. You are in for an evening of evolution, wonder and Victorian perversions. We're about to find find out why humans have sex at times that our fellow mammals don't.

Let the show begin. My name is Steve Gangstead. I am a professor of psychology at the University in New Mexico, and I study sex. I study sexual interests. I study hormone influences on sex. Perfect, I'm interested in sex. Okay. To understand the quirks of human sex, we first need to know how it works for most mammals. Here's Steve giving us the lay of the land. Okay, let's just call it like it is. Yes, a show about sex is going to have a lot of unintentional dad puns.

There will be double and triple entendres. But I'm just gonna ask that we call on our better angels and take the high road. Okay, Steve, please tell us about mammal sex. So, for most female ammalst it's two or three days out of a cycle that they have sex, and otherwise they're not willing to have sex with males that initiated, and they're really not that attractive to males either. Males seem to know. And why would most mammals schedule their whole sex life into just a couple of days

of the cycle. Well, sex takes time and energy and even risks injury. Most female mammals are only into it during the fertile phase. But how do the males know when those days are? Well? In? In some species, like particularly some of our close relatives in the primate order, females have sexual swellings. They have these swellings on their rumps that to mess, that is, they grow, they swell when females are sexually active. That said smell typically trumps

that as a cue. The females of most mammal species are out there clearly signaling when they're conceptive, when they're in the fertile phase. They're giving big, obvious cues and their scent or appearance. The natural question then becomes can

human dudes tell when lady humans are fertile? There are these sort of coquil called a stinky T shirt studies where women have worn T shirts for a couple of nights and they're either conceptive or not conceptive, And men on average do prefer the scent of conceptive females, but they're not that good. They're telling you mean or they're getting a very close up with you know, they're smelling a T shirt that's been worn for a couple of days. So in normal just interaction now, they're not very good.

Even women can't sense exactly when we're conceptive, though some women can feel the moment of ovulation. The biological details of our menstral cycles are hidden even from us. That's why women trying to get pregnant make color code their calendars or download apps like Fertility friend. The typical term that's used with regard to humans as that we have so called concealed ovulation. So there's not really any real cues of when women are ovulating, which is weird when

you think about it. We're ignorant to one of the most basic bodily functions. There might be some very little cues, but for the most part, where a black box. This concealed ovulation might help explain why humans are game to have sex at any time in a woman's cycle. What you have is what has been termed extended sexuality. Sounds funky, but it's the extension part is really just referring to the fact that it's extended beyond that conceptive period, so

there's non conceptive sex. There are some mammals who have extended sexuality, and in fact most primates actually have some period of extended sexuality. Interestingly, but as opposed to humans, usually in primates it's a few days. Possibly to the best of our knowledge. Are we the most extended extended sexuality? You can't get anymore. There might be a species or two that ties us, but we are as extended as you can get. So you really are having sex all

the time. Maybe not relative to your friends or your ex guy, and is maddeningly likable new girlfriend. But compared to wild mammals who have never heard of Netflix and might not get to chill, you are Humans have a lot more sex during phases of the cycle where pregnancy isn't a possibility. It's worth noting that most mammals have different reproductive cycles than we do. Most don't get periods, and sometimes ovulation is even induced by the mail, so

the systems are different. But still we're the ones doing it all over the calendar. We're the ones with concealed ovulation and extended sexuality. But of course none of that goes through your mind as making eyes at a special someone. Evolution doesn't have to shape your thoughts to shape your behavior. Most of us are driven to have sex just because it feels good. And with that, let's welcome Dr David Puts to stage from the Department of Anthropology at Penn State.

Both David and his wife are sex researchers. In fact, we've published on orgasm together. So funny enough, I met her at a sex conference and she had just presented a paper on the genetics of the female orgasm. So after her talk we started talking about the topic and the science and YadA YadA, we have three kids. One of David's specialties is the female orgasm, which actually poses

something of a mystery for academics. Nobody really knows what women's orgasm is for, and there's a lot of debate about whether it's for anything at all, whether it might just be a nonfunctional byproduct, and one suggestion is that it's a by aroductive orgasm in men, and that really

in men, that's where the adaptation lies. Um, I think, just for a second, because I think too listeners who who aren't looking at this through an evolutionary lens, the idea that like, we don't know what a female orgasm is for, I think a lot of hands in the air, like, yeah, so you have to ask what it's for. Then you're not doing it right. Have you ever seen a female orgasm? When scientists say they don't know what it's for, they mean they're not sure how it might help us to

survive and pass on our genes. Like, how could orgasms increase a person's likelihood of having kids and grandkids? Well, the dude's orgasm helps deliver sperm to where it has to go, so okay, we can see how that helps in procreation. Some scientists think female orgasms don't have any

similar purpose. They just developed as a happy accident. The common analogy that's used as male nipples that you can have an adaptation in one sex, So you've got a functional trait in one sex that just some vestiges of it occur in the other sex. I think some dudes might be thinking, no, dude, my nipples are awesome, Like, yeah, they are not functionless brov. So yeah, they hold up

my nipple ring. Yeah. So by function and evolutionary biologist means that there was some way in which it contributed to reproductive success ancestral e. Either by increasing survival or by increasing you know, mating success or you know survival of offspring or something like that. You could use your nipples for whatever you want, um, but that doesn't mean that they evolved for that purpose. But there's another camp that think female orgasms do serve a purpose of their own.

Ladies and gentlemen, I present to you the up suck theory. The idea here is that the contractions of the female orgasm actually draw semen into the female reproductive tract, where it has a better chance of for realizing an egg.

To test this idea, researchers of dosed women with oxytocin, a hormone that triggers the muscle contractions during orgasm two different labs found that women who went into the lab those that were treated with oxytocin that that caused the transport of a fluid the same viscosity of seemen up into the overducts, and the closer the women were to ovulation, the more of that transport was just into the oviduct

where the egg was coming down. So is there essentially an argument to be made that if a woman orgasms with a partner, she's more likely to be impregnated by him then when she has sex where she does not organs. Yes, yes, but we don't really know that it's clearly not necessary, right, I mean, plenty of women have kids that have never had an orgasm. The up stuck theory is still hotly debated. Other experiments have yielded results that don't support the idea.

And so far no one's run a big study to find out if women's orgasms during actual sex are more likely to lead to a pregnancy in the real world. But up suck isn't the only possible purpose for the female orgasm. The intense feeling of pleasure, the idea that that has no function at all. It's hard to swallow because, uh, jeez, I shouldn't say, come David, better angels, let's keep it classy.

It's hard. It's hard to believe because you would think that that kind of intense feeling would have some effect on behavior. Right. It seems likely, and there's some evidence that this is the case, that if women have more orgasms with a partner, then they feel more emotionally close, and that that would then tend to sort of strengthen a long term pair bond. So the contractions of a

female orgasm might improve the likelihood of fertilization. Or maybe the pleasure is the purpose and that it strengthens the emotional bonds between sexual partners. They're different hypotheses, but they're not mutually exclusive. Steve Gang said, the dude who told us about mammal sex at the very start of this program. Says that our concealed ovulation may also encourage pair bonds

between mates. And here's why. Mammal species males don't care for they're young at all, But humans take a lot of work to raise and concealed ovulation maybe a strategy to help get dad's involved. This takes a little bit of explaining, so bear with me. Picture a world where it's somehow very obvious when human women are in the fertile phase of their psycho they act a certain way, or they look a certain way, or they only whistle show tunes, whatever, all the guys would be interested in

mating at this time. The proverbial milkshake bringing all the boys to the yard. But with an abundance of boys and only so much milkshake, not every dude would get the chance to copulate. Males are not of equal ability to be able to take advantage of that. There are some that are going to be more dominant and they can monopolize the fertile phase matings. M h. The alpha males could just chase the other suitors out of the yard.

Most offspring are sired by just a few dominant males. Then, when the lady next door enters her fertile phase, the dominant males would head over to her yard, leaving the pregnant female to raise the young alone. But this situation doesn't serve the genetic interests of the female all that well. For her, it'd be better if both parents cared for the baby, improving the kid's chances of growing up and one day mating two. The problem with those dominant males

is they're doing just fine. Caring for babies would take away from the dominant males mating time, which is their best bet for genetic success, and so to mate with males who would provide care for her young. Female bodies evolved to hide their fertile phases by concealing ovulation. Then the male, the dominant males can't just guard, so that's an argument for the evolution of concealed opulation that arose

early antien Needy late nineteen seventies. The alpha males can't fend off other suitors from all the females all the time, so other males get the chance to mate, and these non dominant males, they're not the high octane studs who can fight off rivals and mate with all the females. They're best chance at getting their genes out there is to lock it down, to form pair bonds and invest in the kids to give them a better shot at growing up and continuing the line. The top theory I

think is that extended sexuality is about biparental care. It co evolved with biparental care and humans, and that extended sexuality is partly about strengthening that pair bond, ensuring investment from a primary partner. In conversations like these, it can be tempting to try to retrofit the whole world with an evolutionary explanation. But not every feature of our body

or our behavior is perfectly adapted to our environments. Evolution works on transmutations, and we're just the best models that have emerged so far. And also, responsible scientists need more evidence than yeah, that it totally makes sense. What do we know for sure about extended sexuality in humans? If anything? Well, being a scientist, very very cautious about what we say that we know for sure because it's tough to prove stuff, And that, my friends, is the full and complete story

of human sexuality. We ovulate in secret, we get it on all the time, and female orgasms are Hello, mysterious. Okay, let's bring up the house lights drive to say if everybody to be bartenders and good night. Nope, wrong, stop. Obviously we cannot end the show that way. We can't talk about all this sex we're having only in terms of genetics and reproduction and up sick. Our horizontal lives are shaped by culture, too, so let's pan out for

some much needed context. So far, we've been using the terms male and female as absolute and discreet, which isn't how we consider them in the real and complicated world. We've also been pretty heteronormative. Let's bring in sex historian Kate Lister for a quick vocab check on that last term.

Can you tell me what the term heteronormative means. It's when all of our assumptions and our biases are coming from a place where we are making pains and vagina sexual sex the default, and everything else around that is not the default. Homosexual behavior has been abundantly documented all over the animal kingdom, from swans to lions to lizards, and sex isn't only procreative either if it's about making babies, And how do we account for masturbation and oral sex

anal sex same sex sex. Keith is a researcher. It leads Trinity University in England. In her book A Curious History of Sex, she documents all sorts of sexual fantasies and fears and prohibitions throughout the ages. The actual act of sex itself is pretty standard, but what changes and what's different is people's attitudes to it, the rituals that go around it, the things that are shamed, things are acceptable,

things that are condemned. The Puritans who left our jolly shows and turned up on yours, bringing with them sexual repression and shame and mad hats with buckles on. That was they were really caught up about sexuality. And the Puritans, they were a movement that started largely out of this denying pleasure, but a very excessive and strict version of Puritanism that rejected where they thought of as Catholic decadence, and sex was something very much that they wanted to repress.

But a whole society can't just go called turkey. You have to have some sex otherwise we're all just going to die out. So then it becomes about controlling the act very very carefully, and the Puritans are sort of very much in that vein. You could have sex, but you couldn't enjoy it. It was for making babies only. Victorian England has become sort of like the poster child for sexual hang ups. There is a real emphasis on trying to stop people, women and men, but particularly men

from masturbating. And what you've got anti masturbation devices that came around in sort of the mid nineteenth century, and the idea was to stop quote unquote nocturnal emissions. So that's a wet dream. So what you get is these rings, sper matter zoa rings, which are basically were tied on the penis but had really sharp, jagged teeth on the inside, so you'd put the penis into it, and then the idea would be that if he got an erection the middle of the night, the teeth would bite out and

wake him up before he could lose his special seed. Okay, So so I am currently looking at your hardcover book and there is like a pen and ink drawing that's labeled the four pointed urethril ring. Yep, yep. And it's quite horrendous thing, isn't it. Yeah, it's one of those things. It's like even as even as a lady. The legs cross a little bit, isn't it's it's that awful. But yeah, it looks like a napkin ring yep, that has spikes

on the inside of the circumference. Yeah, that's pretty much it. Yeah, it's a bummer kate, it's a realm. But Victorians also produced a bunch of kinky porn, like they're really into stuff like whips and lashes. So there's this sort of choreograph hypocrisy about what's publicly forbidden but still happens in private. Look at our own society, you know, Paul, you know I don't watch Part up Master Bag. Of course you do.

We just don't talk about it, impolite society. With the passage of time and a better understanding of our own bodies, our attitudes about sex and sexuality have changed in big, like head spinning ways. The pill sparked a revolution. It just radicalized everything because suddenly you could control your own reproduction and it placed in the hands of women as well.

That's amazing. I do get asked a lot. Was there ever a period in history when we had it all figured out, when when everyone was just coverting in a

shame free sexual paradise. And the answer to the question is is the closest we've ever come is probably now, and which feels really uncomfortable because like we look around and to go, you're freaking kidding me, Like there's still places around the world where people will be killed for their sexuality, but the fact that there is a movement to not shame people, to not execute people because of their sexuality or chemically castrate them or do so, we

are the closest now that we've been to getting it all figured out. And that's quite scary. Humans have culture and birth control, religious mandates and weaponized napkin rings. So does that put us above the freight of evolutionary forces? I'm betting that when researchers Steve goes to a restaurant with friends, everybody at the table is fascinated by his work, but few are really convinced it applies to their own lives.

Did you ever talked to people who kind of dismiss your work as reductive, like, Oh, that's the way it works in animals, but that's not the way it works for us. Well, certainly some people what they say is, oh, the magic is gone, but I don't see it that way. The thing is the magic is what you feel. But what's under the magic, what's giving rise to all this? The loves there? The question is why is the love there?

It's at a different level of analysis. The way that we experience lust and love of and jealousy and intimacy. They feel so real, so fundamental to our humanity, that I don't think we want them undermined by chemical accounts. We don't want to hear our most poignant experiences boiled down to only genes and reproduction. But I agree with Steve, there are motors to the magic, and learning how the

gears fit doesn't have to break the spell. If concealed ovulation encourages pair bonds, Hey lucky us, a proclivity to love one another is written in the code of our design. If our species has evolved to have sex all around the cycle, Hey lucky, Yes, put a date night on the calendar. Any day will do. And that concludes our show. Be safe, be kind to one another, maybe make a milkshake,

see who comes around, and for the final bows. Be Human is a BBC World Service, an American public media co production with I Heart Media and hosted by MESA. Next Time a deeply human Our topic is standing in line and why it turns us into low rage monsters. There is a meme that's been going around. It has a picture of Beyonce and it says, why aren't you Beyonce? She has the same twenty four hours you do, um,

and I don't think that's accurate at all. We all do have objectively twenty four hours, but we are often forced to use those hours in very distinct ways. I think about people who have very long commutes to their second job, and time is very different for them. The people in a grocery store line who have to, you know, use food stamps or cash and count coupons. They're using their time at that check out stand very differently than I have to. Oh,