Modern WisdomWhat Psychology Says About Women Who Cheat - Macken Murphy
EVERY SPOKEN WORD
150 min read · 30,008 words- 0:00 – 10:09
Groundbreaking New Research on Infidelity
- CWChris Williamson
You have caused some drama in the world of evolutionary psychology.
- MMMacken Murphy
A little bit of drama. I- I try not to get in trouble, but certainly this, uh, last publication, uh, might be a little controversial within the field, sure.
- CWChris Williamson
What have you done? What's the current state of the leading infidelity hypothesis?
- MMMacken Murphy
Well, I- I- I mean, (sighs) I guess we've got time to get into it, but it is a bit of a long story. So I would say that- that the background to know for someone who's just completely entry level here and has not heard about the evo infidelity debate is that there's been a long running debate as to the evolutionary drivers of women's infidelity, female infidelity in humans. And, you know, during the late '90s and the early 2000s and to an extent, uh, the- the 2010s as well, I would say that most evolutionary psychologists would have said that the primary driver of women's infidelity, from an evolutionary perspective, is the powerful benefit of being able to obtain better genes, right, better in a fitness sense, not... (laughs) obviously, not in a moral sense. And we might end up saying, you know, the phrase "good genes" quite a bit, uh, on this show, and- and every time it's always in, it's always good in a fitness sense. But in any case, the mainstream idea was that infidelity is a conditional strategy that women sometimes employ in order to obtain better genes for their offspring, right, so to pair the genetic benefits of one male with the parental investment benefits of another male. So everyone, when we're looking for mates, there are two things that they can give our offspring. They can give our offspring genes, obviously, uh, or they can give our offspring investment. And normally women get genes and investment from the same person, but the idea was is that women's infidelity allows them to get genes from one person and parenting from another. Let's say if they're with a mate who is very high investment, right? They're- they- they love them, they've got lots of resources, but they don't necessarily have, you know, the heretable traits that a woman might want to pass on. So that was the mainstream idea for a very, for a very long time, uh, a- almost 20 years. And then in the late 2010s there was a bit of a reckoning, right, which stemmed from the fact that during the- the 2010s, the original suite of experiments that were used to evidence this idea, which from here on we'll call the dual mating hypothesis... In this case, um, I mean, there's a few ways to use that term. I'm using it to describe that specific strategy. There was a bit of a reckoning because the original support for the dual mating hypothesis was based on these ovulatory shift experiments. So the idea was, and it was a very clever hypothesis, uh, originally put forward by Steve Gangestad and- and Randy Thornell, which is that if it's true that women's infidelity functions to pair, quote-unquote, "good genes with good parenting," well, women can only get pregnant during a brief window in their monthly cycle. And so it would only really make sense for them to have affairs during that time, right? Because the risks of infidelity are evenly distributed, right? Infidelity is a very risky behavior. You could lose your relationship, you could be subject to retaliatory violence or- or social penalties, and- a- and so- it would make sense for women to engage in the, you know, genetic strategy during their peri-ovulatory phase and the parental investment strategy during the rest of their cycle. And so that was their hypothesis. And the first tests which were with, and this isn't their fault, but small samples and relatively primitive methods, those looked quite positive. Then as methods got better, th- th- these effects either shrank or disappeared depending on who you ask, right? It seemed to be-
- CWChris Williamson
Re-analyzing the original data?
- MMMacken Murphy
No, not re-analyzing the original data. Collecting new data with better methods, right? Although th- uh, there has been some questions about the original data as well. So- so one example of this is that some of the early studies would use, would determine when a woman was in her cycle based on self-report counting, so count since your last, uh, period essentially. And that's just not, uh, that- that- that's not a completely inaccurate method but it's not exactly high reliability. And then later methods that use more, you know, uh, direct tests, um, uh, a- and just better, bigger samples and also, you know, pre-registered in some cases, uh, ju- just better methods overall, they- they ma- they made this ovulatory shifts sub-hypothesis of the dual mating hypothesis, right? They made this look less good. And so some scientists, uh, led by David Buss, but it- it was, it was quite a large number, said, "Well, hang on. Maybe it's not just that ovulatory shifts aren't happening, maybe dual mating isn't happening," right? So dual mating is something that we see in some other animals to an extent, like we see for example that red-winged blackbirds, uh, the- the females will engage in infidelity with males who have more robust bodies, right? Uh, flycatchers, another one where they- they've got nicer plumage, uh, the- the- the affair partners compared to the primary partner. So it's not something that's without precedent in the animal kingdom. But other animals like cockatiels, for example, when they have affairs, their affairs are geared towards something called mate switching.So the affair is a way of cultivating and obtaining a new, and from a reproductive standpoint, probably overall better mate. So they put forward this idea that, you know, hey, maybe humans are more like cockatiels than flycatchers. Maybe the underlying theory, so we've got dual mating, this, you know, uh, quote-unquote, "Good genes, good parenting combo deal." Maybe it's not a combo deal, maybe it's a best whole package type situation, maybe that's what female infidelity is geared towards obtaining. So that was the history of the debate, and they put this alternative idea forward, and it wasn't based on, you know, this new idea. It, it was a hypothesis that was put forward, it is a hypothesis that is put forward, based largely on w- what we would call circumstantial evidence, right? So it's drawing together a variety of facts from past studies and forming inferences about them, right? About- about these, about what's happening from that. So it's not that there was some experiment that showed mate switching was very common in humans, it wasn't that we collected some, you know, awesome dataset and it showed mate switching. Uh, that's not what happened. It was just an alternative hypothesis. And then after that, uh, Brooke Schelze tried to test the mate switching hypothesis in her population, at least the trading up function of it. She tried to test it in her study population, the Himba, of, uh, that's a group of agro-pastoralists in Namibia. And she didn't find evidence for the mate switching hypothesis. She found slight evidence for dual mating, and then she found evidence that a lot of women's infidelity in this area was geared towards obtaining additional resources from additional mates. So it has an additional function, and this is a theme that we'll probably talk about more. So there was a little bit of evidence for dual mating. Women seemed to have a h- put a higher premium on physical attractiveness in affair partners, uh, but the mate switching hypothesis camp, at least in what I read, they seemed to kind of, I won't say brush it away, but they seemed to interpret that as saying, as just applying to that population, right? So it's like, okay, the mate switching hypothesis didn't work, but it's in this pretty unique population. And I think that's fair enough, because, uh, the Himba are, do have a unique relationship to infidelity. And so what we wanted to do is we wanted to actually, you know, set up an empirical design that directly pitted the predictions of the dual mating hypothesis against the mate switching hypothesis. And what did that design look like? Well, the mate switching hypothesis has quite obvious and intuitive predictions. If you're looking at the trading up function, some scholars, they would classify backup mating and breakup mating as part of mate switching, but we're loo- we're looking at trading up. If women are cheating to obtain a better mate, then they should perceive their affair partners as better. Very simple prediction. Uh, probably better looking, better as, specifically as a potential co-parent, since that's who they want to switch to. Overall mate value should be higher. Maybe a more attractive personality, right? That, I guess that could go both ways. And so what we did was we set up an experiment where we had them, where, where we collected women who, uh, and men, so we collected a large sample of women and men who had actually had affairs. Because this was a problem with the previous literature, even the li- uh, especially the literature, you know, in the mate switching, dual mating debate, not Brooke Schelze's work, was that most of it was done on people who hadn't had affairs, right?
- 10:09 – 20:31
Studying People Who Have Cheated
- MMMacken Murphy
- CWChris Williamson
Where do you find people that have had affairs?
- MMMacken Murphy
Uh, I wish I could say something fun, like, like Ashley Madison or something, but, uh, that we're recruiting on Ashley Madison, but that's not what we did. What we actually did was we put up a large survey that in essence-
- CWChris Williamson
Have you cheated on your partner? Come and do our survey.
- MMMacken Murphy
Yes. Yeah, well, yeah. It was basically three questions. It was like, um, well it was demographic questions, and then it was have you ever been in a relationship that was, you know, sexually exclusive? In any of those relationships, have you slept with somebody else at any point? And would you like to do our study, right? (laughs) And we sent that out to, I think it was 1,500 people. And quite a lot of people said, "Yeah, I actually have had an affair at some point." But, uh, it was a relatively, uh, uh, small subgroup, let's say, that actually wanted to go through all the way and do further research with us. So, and, and that final sample was 254 people, for those who are interested. So, let- let's circle back to the predictions here. So if the mate switching hypothesis is true, and we're looking at people who have actually had affairs, well, then women should rate their affair partners as more attractive in some way, but certainly more attractive overall, and more attractive as a potential co-parent. Those would be the things that you'd really expect to see if the mate switching hypothesis were true. The dual mating hypothesis has different predictions. So the dual mating hypothesis would predict that there'd be kind of this crossover effect, where the affair partner is rated as better physically, right? Like, physically more attractive, but parentally, they should be less attractive, right? So if- if- if women's affairs function evolutionarily to pair good genes with good parenting, well, then the primary partner should have better parenting, right? It wouldn't, uh, uh, the alternative wouldn't really make much sense.
- CWChris Williamson
I'm not sure, I- I don't quite understand that. Why would it be the case... Why would dual mating not predict, uh, better parenting as well?
- MMMacken Murphy
... because dual mating is pairing the good genes of the affair partner with the parenting of the primary partner, so it's essentially a process where women will have an affair, right? Or female animals, uh, other species, will have an affair-
- NANarrator
Right.
- MMMacken Murphy
... and try to pair the genes of one male. And this, and this is again, none of this is meant to be conscious.
- NANarrator
Mm-hmm.
- MMMacken Murphy
We're, we're looking at the subconscious evolutionary drivers of our behavior, the structured psychology underlying it. So it's... So, I guess to summarize, mate switching would predict that affairs function to obtain a better mate overall, whereas dual mating would propose that female infidelity functions to capture, quote-unquote, "Better genes," and pair it with better parenting, uh, better investment. And so these, these are, these are distinct, uh, distinct hypotheses and, you know, uh, uh, I'll- I'll flag post here that, or sign post here, that none of this is meant to be conscious per se. Right? It doesn't, it d- this isn't implying that anyone's deliberately trying to, you know... I- in the same way that w- when we enjoy sex, right? We're not thinking consciously, "Oh, this is great because I'm gonna get to have kids." In fact, we might be thinking the opposite, right? It's more what psychological biases undergird our infidelity. And, you know, we have very good reasons to suspect that infidelity did evolve. Uh, it appears cross-culturally. That's the first sign. It appears, you know, this is something that your, your friend, uh, Stephen Stuart Williams likes to share which is that if a behavior appears even where it is socially discouraged, it's probably not socially constructed, right? And we see that infidelity is very harshly punished and people still do it. And then, also, humans are socially, are mostly socially monogamous mammals. And if you look at other socially monogamous mammals, and other socially monogamous primates, extra-pair paternity has some degree of presence, extra-pair copulation is documented with quite a high frequency. So we have very good reasons to suspect that this evolved. And so given the dueling predictions, right? That the dual mating hypothesis proposes that it's better physical attract- oh, and here I, I actually, not to just over caveat but, why would physical attractiveness be a sign of good genet- good genetics, quote-unquote. I would say listen to (laughs) our last episode (laughs) . Uh, me and Chris's last episode covers that in very high detail. Um, but the short TL;DR version would be that one, a lot of the things that we find conventionally attractive are just cues to health, so, you know, the things that we think are good-looking, the reason that they're conventional is 'cause they signal heritable benefits, such as good health. And then another idea is just that physical attractiveness itself offers benefits and is itself heritable. Good-looking people tend to have good-looking children, and so it would make sense that, given the tremendous benefits that come with being good-looking, you would want a partner with quote-unquote "Good-looking genes." Anyway, so different predictions. Mate switching predicts that the affair partner will be better overall, and better as a co-parent. Dual mating predicts that the affair partner will be better looking, but worse parenting, right? Or, uh, yeah, worse parenting, really it's the primary partner should have better parenting is the, is the correct way to think about it. And so what we did was we took, uh, everyone in our sample and we had them rate their affair partner and their primary partner separately on valid and reliable scales. And our study was preregistered, it's a very diverse sample, and compared for differences. So we had them rate their affair partner and their primary partner's physical attractiveness, parental attractiveness, mate value, their overall desirability, and also their personal attractiveness, although th- to be fair that could've gone, that could've gone both ways, it might, it would, it would've been interesting, but not necessarily consistent or inconsistent with either hypothesis. And what did we find? Well, we found that affair partners were about two points more physically attractive on our scale, on average. And primary partners were about three points more parentally attractive. So we had this, you know, crossover interaction between rating type and attractiveness, which was really the best case scenario for the dual mating hypothesis. It's also very unlikely, just for, for those at home, it's very unlikely that you would find this sort of structure by accident, because usually better looking people, because the halo effect ends just positive perceptions in general, they're going to get better ratings on everything, and so it's very strange for one group to be-
- NANarrator
Hmm.
- MMMacken Murphy
... better looking, but worse parenting. This, this is a very unlikely thing to see if there's no structured psychological adaptation involved. So the dual mating hypothesis was, I would say, strongly supported, best case scenario, a preregistered study on actual women who have had affairs signaling this. And the mate switching hypothesis th- there was no difference in mate value. Overall mate value, overall desirability, even between a- affair partners and primary partners, no statistically significant difference, and no statistically significant difference in personality either. So our study ended up being the best case scenario for dual mating, and the worst case scenario for mate switching. So I guess we started this conversation with, you know, w- why has this... Why would this cause controversy? Well, it- it ki- it kind of seems like everyone has been a little too hasty in dismissing dual mating based on the fact that the ovulatory shift studies don't replicate.But the truth is, is that ovulatory shifts are just a sub-hypothesis of dual mating, and human sexuality is actually unusually stable across the cycle. And so maybe it was a... I mean, I still think it's a cool hypothesis and maybe more complex methods will prove that there are, there is something to, you know, human estrus, but the truth is that dual mating doesn't need this hypothesis. Uh, uh, it's just a sub-hypothesis, and the more important thing i- is that, um, is that we do seem to have different priorities in our affair partners versus our primary partners. And one thing that I'll flag, maybe we can talk about this later, 'cause it's more confusing and maybe the most (laughs) interesting result from our study, is that men showed the same pattern. So men also, contrary to conventional wisdom, men also tended to cheat up in terms of physical attractiveness, and cheat down in terms of parental attractiveness. A lot of people responded to our study basically saying, "Huh, I would have thought that men cheat down across the board. Uh, basically because it's easier, right?" Kind of the, the, the a man is only as faithful as his options, and most men have more options that are less attractive than themselves. That, that didn't really seem to be supported. And then in our qualitative data, we d- we also didn't find any differences in novelty-based, uh... So I, I would say that the overall picture, the dual mating hypothesis traditionally has focused on women, but I would say that it's really a human strategy in the sense that humans in general, i- it's, it's different what benefits are sought, but humans in general see- seem to prioritize conceptive benefits in affair partners and parental benefits in primary partners. This is just one study, of course, and, you know, I, I, I did design the study to be persuasive to myself, so, uh, I, I am persuaded by the result, right? (laughs) Uh, but there are other results that converge with, uh, that converge with us in terms of at least the physical attraction side of thing, that affair partners tend to be more attractive and primary partners less so. I've spoken for quite some time so I'll, I'll...
- CWChris Williamson
Not at
- 20:31 – 25:36
Are There Evolutionary Benefits to Men Cheating?
- CWChris Williamson
all. What-
- MMMacken Murphy
Yeah.
- CWChris Williamson
What is the evolutionary function of men following that same pattern when it comes to infidelity?
- MMMacken Murphy
It's a little confusing, right? So I know that you've obviously had a pretty intense crash course in ev psych talking to (laughs) all the, uh, the world leaders in the field, let's say. And so you would be aware of the fact that if you ask an evolutionary psychologist, "Why do men cheat?" They're gonna say, "Oh, easy. More mates means more offspring for male mammals." They're gonna talk about, you know, Genghis Khan, and they're gonna talk about, you know, uh, how the ceiling is basically unlimited for a man reproductively if he just has enough mates. Uh, whereas for women, the ceiling... You know, uh, in theory, and, you know, if you believe the accounts of Valentina Vassilyev, uh, this is, this is kind of a, uh, a funny anecdote to illustrate the conventional ev psych view. Valentina Ves- Vassilyev was a Russian peasant, and I believe she had 60-something children all with her husband, right? And then her own husband... So she's the, uh, she would be, if it's true, she would be the world record setting, uh, mother as a woman, right? The, the most prolific, uh, the most prolific women, woman in childbirth. And then her own husband, if you believe the gossip, her own husband outpaced her by having affairs, and he had like 80-something. So the idea being that a woman can, in theory, and potentially in practice, maximize her reproductive output with just one male, whereas a male can only maximize the reproductive output by seeking additional mates. So that's the conventional wisdom in ev psych. Our study, i- i- it's not inconsistent with that, right? Like we didn't design our study to test that hypothesis, but then we didn't find support for this hypothesis where we expected to find it. So one prediction that I think would be pretty natural from that idea, that men's infidelity is purely quantity driven, right? So the women's infidelity hypothesis, mate switching, dual mating, both of those are, both of those are quality hypotheses, and then the main male hypothesis is a qual- is a quantity hypothesis, right? And so you'd expect, I think, that you'd expect to find that men cheat down, right? To maximize their numbers, so to say, uh, and then you'd also expect when you ask men why they cheated, you'd expect them to report variety driven motives at a higher rate than women. It could have been because of our study design. We also asked participants just straight up, "Why did you cheat?" Uh, I believe we've got, certainly in the evo literature, the maybe, I, I won't say this, but certainly one of the largest datasets on just people saying why they cheated from our qualitative data. And men and women both reported, you know, sexual boredom, a desire for novelty. There were no statistically significant differences in that area. Maybe a better design would sh- uh, find that, but our study didn't-
- CWChris Williamson
There was no...
- MMMacken Murphy
Yeah.
- CWChris Williamson
There was no, uh, sex differences in proximate reasons for why people cheat-
- MMMacken Murphy
There, well, well-
- CWChris Williamson
... in your study?
- MMMacken Murphy
There were sex differences in proximate reasons, but not the, not in the novelty area.
- CWChris Williamson
Right. Okay, okay.
- MMMacken Murphy
And not in the boredom area, and not in the combined measures of both of those. Not in the variety area-
- CWChris Williamson
Right.
- MMMacken Murphy
... generally. But I think that that's just because, I mean, maybe I'm being too generous, but I think that we have to be really skeptical. I think our quantitative data is r- is really good, really reliable. Our qualitative data has unavoidable shortcomings that come from just, you know, interviewing people, right? If you just ask someone why they cheated, people don't have perfect insight into their own motivations.And then they also aren't perfectly honest, right? Humans are storytellers. We like telling stories where we're the hero, and so we're gonna, you know, downplay motivations that are unseemly or subconscious, and we're gonna play up motivations that are flattering. Like, I'll- I'll give you an example of this that's- that's pretty stark. So we asked women, "What motivated you to have an affair?" And about 5% of them said, "Oh, it was because my affair partner was really hot." Right? Just, "He was super attractive. That's part of the reason why I had an affair." So 95% of women didn't even mention it. But then, in our quantitative data, women were 77% more likely to prefer their affair partner's physical attractiveness than to prefer their primary partner's physical attractiveness. What a coincidence if that's not a motivating factor, right? So we have to be... I am happy with our qualitative data, but we have to be careful with it. I think the only thing that it really shows is strategic diversity.
- 25:36 – 28:30
The Novelty of Infidelity
- MMMacken Murphy
- CWChris Williamson
How do you know that that's not just novelty seeking? It doesn't need to be better, it just needs to be different?
- MMMacken Murphy
Hmm. Yeah. So there- there- there was, there was a bit of that. I would say that about one in ten people in our- our... Again, our- our quantitative data doesn't really get at novelty, but it does suggest that it's not just novelty, because from a physical attractiveness perspective, on average, it was better, right?
- CWChris Williamson
But that's the- the, my point being that physical attractiveness is inherently a subjective. You're asking-
- MMMacken Murphy
Yeah.
- CWChris Williamson
... you, participant, "What do you think about the rating-"
- MMMacken Murphy
Yeah.
- CWChris Williamson
"... of A and B," which I'm sure you can-
- MMMacken Murphy
Yeah.
- CWChris Williamson
... see as being open to just straight novelty itself. As you've said, we are not a clear pool of water that we can see down into the depths of. Uh, if you were to get people to say, "Okay, show me a photo of both your affair partner and your main partner, then let's get other people to rate whether they think which one is more attractive-"
- MMMacken Murphy
Yeah. Yeah.
- CWChris Williamson
"... and compare that to their answers," that would be fascinating.
- MMMacken Murphy
That would be a very good test, yeah.
- CWChris Williamson
How much of a role... "Can you send me a photo of the person that you're in a relationship with and the person that you cheated on them with, please? Ehh, th- that would be great. Thank you."
- MMMacken Murphy
Yeah. The, uh, the ethical nightmares that you've just designed-
- CWChris Williamson
Oh, yeah. And by the way, I'm gonna show these. I'm gonna-
- MMMacken Murphy
Yeah.
- CWChris Williamson
... show these to loads of people.
- MMMacken Murphy
Yeah, yeah, yeah (laughs) .
- CWChris Williamson
Yeah.
- MMMacken Murphy
So that would be a bit ethically fraught, but a good, genuinely good study design. That would, that would be a test of our hypothesis. I guess, one... And I think that that's a legitimate limitation. It could be that novelty itself is causing more physical attraction. That seems plausible to me. But if it were just positive illusions associated with novelty, I think you'd expect higher ratings overall. It's weird that this is only happening with physical attractiveness. So we all know that, you know, in the early stages of a relationship, we tend to have these, you know, very biased views, very positively-
- CWChris Williamson
They're great at everything.
- MMMacken Murphy
... biased views of someone. Yes, they're wonderful. They're perfect. And so if that's what's causing the physical attractiveness gap, very peculiar that didn't happen for mate value, very peculiar that it didn't happen for personality, and extremely peculiar that it actually reversed for parental attractiveness. So it's a legitimate critique, and I- I would be interested in the r- I would be very interested (laughs) in the results of that study, if anyone can get ethics approval for it.
- CWChris Williamson
Oh, dude, I-
- MMMacken Murphy
But-
- CWChris Williamson
... I'm the king, I'm the absolute king of coming up with studies that you can't do. You know, like, I'm like a... I'm like one of those rock stars that never actually learned to play classically and is able to... Like, I'll do it left-handed and upside down.
- MMMacken Murphy
(laughs) .
- CWChris Williamson
It'll look awesome, but sound terrible.
- MMMacken Murphy
Yes. Yeah.
- CWChris Williamson
That's my, that's my sort of contribution to the world of- of ev psych and human behavior ecology.
- 28:30 – 35:23
Most Surprising Research Takeaways
- CWChris Williamson
what else you learned from a qualitative perspective. What was, what was interesting? What did men say? What did women say?
- MMMacken Murphy
Mm.
- CWChris Williamson
And sort of, how does that tie in with your new reinforced perspective of infidelity?
- MMMacken Murphy
Well, sure. I mean... So the top moto- the first thing to notice would be that the top motivation for men and for women was relationship dissatisfaction in their stated motivations. So the way we did this was we read... It was, it took a very long time. We read all of the responses. And our data is public, by the way. Other people can also look at, you know... If you wanna read hundreds of reasons why people had affairs and get a gist, uh, you can just access our data. It's fine. And we read through all of these. We coded them for themes. So that's when you basically write down, like, "Oh, this one mentions that the affair partner was hot," that kind of thing. So we coded them for themes, and then we went through and we found the themes that were repeating themselves. And then myself and a lab assistant went through, and we separately recoded these items to see, you know, where th- which themes were occurring at what rate, and then we ran statistical analyses to test for sex differences. So that's our methodology. Relationship dissatisfaction was the number one stated motivation for infidelity in both men and women. However, it was a big sex difference as well. So only 30% ish of men, uh, mentioned relationship dissatisfaction in their answers. So most men, even though this was the most common response, most men didn't bring it up, whereas 65%, about, uh, about 65% of women mentioned relationship dissatisfaction. So women were twice as likely to bring this up, essentially, over twice as likely.
- CWChris Williamson
Even though it was number one for men?
- MMMacken Murphy
Even though it was number one for men, correct.
- CWChris Williamson
Wait. Does that mean that men had, uh, a, sort of flatter distribution of reasons in that case?
- MMMacken Murphy
Uh, not necessarily. Uh, that, that inference would be correct if we coded them one-to-one, but the way that we coded it was that one m- one affair could have multiple motivations. So for example, a participant might say, "Ugh, I was in a long distance relationship and things weren't going well. You know, she really wasn't treating me right. And my affair partner was just gorgeous," right? That would be a pretty, that would be a pretty reasonable answer, that would be the sort of thing that we'd see. And then that would get coded as attractive affair partner, long distance relationship, and relationship dissatisfaction.
- CWChris Williamson
Yep.
- MMMacken Murphy
So it doesn't necessarily flatter distribution of reasons, because we can recode variables in this way. But great question. So historically, right, the whole women are more likely to have relationship dissatisfaction when they commit infidelity, that, that's a, that's an expected sex difference, it's something that pops up in the literature quite a bit since the '80s.
- CWChris Williamson
Why? Why is it expected?
- MMMacken Murphy
Well, it's funny because the original logic was that s- was that it was evidence for the mate switching hypothesis.
- CWChris Williamson
Mm-hmm.
- MMMacken Murphy
Because it's like, oh, if women are usually dissatisfied when they have affairs, that means that they want their relationship to end, right? Two reasons I'm skeptical of this. One, women are, women often have higher relationship dissatisfaction anyway, right? I- given, given certain circumstances. They might be more, more sensitive to queues that the relationship is not going well. There also might just be a difference where they're more likely to express dissatisfaction even if dissatisfaction levels are in actuality even between the sexes. That's number one. Number two, and this is more important and more deeply theoretical, which is that infidelity, as we discussed earlier, is a very risky activity. And it is especially risky for women. So based on Martin Daly's research, who I believe you might have spoken to... No, haven't?
- CWChris Williamson
Uh, he is, uh, I'm, I'm lining up. I would have called him Daly, so I'm glad that you fact-checked me on that first one.
- MMMacken Murphy
It might be Daly, it might be Daly. I've only read his name.
- CWChris Williamson
I mean, it's only, it's only your industry, mate, so, um-
- MMMacken Murphy
(laughs) Yeah, I, I can't get away with it.
- CWChris Williamson
But no, I, I, I'm speaking, I'm speaking to Martin through a combination of Rob Kurzban and Steve.
- MMMacken Murphy
Okay.
- CWChris Williamson
Um, I think, I think he'll be great.
- MMMacken Murphy
Yeah, no, uh, uh, y- he surely will be. He's written just some of, some of my favorite stuff has been written by him. But some of his early research basically found that women's infidelity is more likely to result in relationship dissolution than men's infidelity. And so this is a funny way of thinking about this, but in ev psych, it's pretty common to think of relationship satisfaction as an internal regulatory variable that partially tracks the value of your relationship. And so if your relationship satisfaction, if you risk your relationship every time you have an affair, and your relationship satisfaction is low, well, then you're literally risking less than someone who's relationship-
- CWChris Williamson
What are you giving up?
- MMMacken Murphy
Exactly, exactly. And so if infidelity is more likely to result in relationship dissolution for women than men, then the risk is at a baseline higher, and so you should expect that women should be more likely, right, to be attuned to whether they have the infidelity discount that comes with relationship dissatisfaction. And so i- this has been interpreted as evidence for the mate switching hypothesis, and I think it's reasonable to say that someone who's relationally dissatisfied is more likely to be mate switching with their affair. And some, some people do mate switch, you know, several women in our sample, but only several said that they were mate switching. But I think it's reasonable to assume that they're more likely to be mate switching than someone who's really relationally happy. But I don't think it's reasonable to do the reverse inference, which is that because they're relationally unhappy, they want to mate switch. There are plenty of people who are relationally dissatisfied, having an affair, but also want their relationship to keep going. And that's also quite intuitive, to me, this idea that, you know, sometimes relationships are unhappy, but you, you wanna stick things out.
- 35:23 – 46:20
Can Women Separate Emotions From Sex?
- MMMacken Murphy
- CWChris Williamson
What do you make of the, uh, difficulty that women supposedly have in separating their emotions from, uh, having sex with a guy, that women will fall, uh, more when they are physically intimate with a man-
- MMMacken Murphy
Mm-hmm.
- CWChris Williamson
... because there is a higher hurdle for this man to get over, that it is her being more risky. Um, would it not be the case for mate switching that women would be more likely to fall for that partner still, even if it's not... Uh, sorry, for dual mating, uh, even if it's not for the purpose of mate switching, while they're dual mating, would it not-
- MMMacken Murphy
Mm-hmm.
- CWChris Williamson
... be more likely that they were going to fall for that partner in any case as a sort of, a natural byproduct of the, the feminine desire to, uh, be emotionally intimate with someone?
- MMMacken Murphy
That's very clever. I haven't considered that. And I have to think about it more, because, uh, I mean, you're familiar with the mate switching hypothesis, but w- what, what Chris is referring to here, I believe, is that there's a... One of the flagship pieces of evidence for the mate switching hypothesis is that women are more likely to fall in love with their affair partners than men are.And what you're saying is that women are more likely to feel emotionally entangled with sexual partners in general, and so that also isn't necessarily particularly good evidence. One thing that I will note is that we didn't find that love for affair partners was coming up much at all. Right? We're talking like 1, 2%. Like, like no just, it was v- uh, I can't remember. It was sub 5%. Uh, n- very few people in our sample, men or women, said that they were motivated by love for their affair partner.
- CWChris Williamson
Mm.
- MMMacken Murphy
It just didn't come up very much, and so I, I'm a bit skeptical. I mean, maybe it is the case that women are more likely to be in love with their affair partner, right? But at least in their stated motivations, it doesn't seem to be a big factor in why they had the affair to begin with. And so, it mi- th- uh, uh, that might be... Even though that's my favorite evidence for the mate switching hypothesis, as you say, it might not have as much theoretical oomph to it as it seems to at first, first glance. And then also, uh, the- there's an inference involved there where it's like, if they love them, that must be their motivation, and it's possible to be in love with your affair partner and have that be pretty low on the list of why you had an affair.
- CWChris Williamson
(laughs)
- MMMacken Murphy
Yeah.
- CWChris Williamson
Yeah. I remember, um, Andrew Thomas talking about what women say that they want in terms of traits when choosing for sperm donors. So-
- MMMacken Murphy
Hm.
- CWChris Williamson
Um, everybody's a eugenicist, right? Everyone is. Everyone is, whether you like it or not. Uh, and some people are more, uh, quantitatively and obviously eugenicists if they choose sperm donors, or if they choose a, a, a, like t-
- MMMacken Murphy
Hm.
- CWChris Williamson
If they go through, uh, IVF with a donor for either side, I suppose. And, um, one of the things that I thought was really interesting that Andrew brought up is, um, women who choose sperm donors, it is the only time where the traits that you want in your future child are divorced from the traits of the man that is able to get you into bed to be able to create that future child. So you have this sort of weird territorial cutoff-
- MMMacken Murphy
Hm.
- CWChris Williamson
Which is, "What do I, what, what do I want my future kid to be like?" Without having to jump through the hoop of, "What is the sort of thing that I find attractive that gets me into bed?" So it's kind of a, a much more sterile, controlled environment when it comes to doing that. Uh, and given that, with regards to dual mating, it surprises me that things like, uh, personality didn't include in that, given the, although you want sexy son hypothesis, presumably you want likable son hypothesis.
- MMMacken Murphy
It's interesting. In our pre-registration, we didn't make specific... I guess, I guess one thing that I'll note on the, uh, on the eugenics point is that I've, I've heard a lot of people say the, say the same thing of kinda like, "It's, it's sexual selection is eugenics." I personally do see a difference between individual level what do, what traits do I want my child to have, right? Uh, uh, in the case of, you know, embryo selection, in the case of, uh, IVF and, and sperm donation, and then what traits do I want to be high frequency in society at large?
- CWChris Williamson
Oh, that's a good-
- MMMacken Murphy
Right? Yeah.
- CWChris Williamson
That's a... I'm, I'm, I'm, yeah. That's, you're perfectly acceptable to do that. There's a difference between, you know-
- MMMacken Murphy
Yeah.
- CWChris Williamson
Um, uh, Tooby's concern about that gene erosion thing, um, that, that's sort of scaling up, even though I think it's r- still largely ethical. Um, uh, that's a, that's more of a scaling up. Uh, that being said, the one conversation that I've ever had about, uh, embryo selection, I got called an actual Nazi, uh, for having.
- MMMacken Murphy
Oh.
- CWChris Williamson
Uh, so, but it's, it's, it's, it's-
- MMMacken Murphy
Yeah.
- CWChris Williamson
Uh, it's okay. I'm over it.
- MMMacken Murphy
I, I mean, I'm not, uh, I'm not someone who's super into science philosophy. I'm sure that someone's listening and just thinking that I sound like a bit of an idiot. But I will say that I don't see a huge difference between... I, I mean, maybe I'm just thinking about this wrong, but I don't see a huge difference between selecting an embryo and selecting a mate at the individual level. Where I would find it, where I would start defining it as eugenics and start defining it as, you know, ethically abhorrent to myself would be when people are telling other people what they should do or when the government is getting involved and-
- CWChris Williamson
Stepping in.
- 46:20 – 53:14
Top 3 Motivations for Women Cheating
- MMMacken Murphy
stuff. So, uh, so that was a, that was a diversion but a, but a happy one. And, and one that's actually relevant because we, in a way, we found the same result. Again, 5% of women mentioned that their affair partner was physically attractive, and then they were 77% (laughs) more likely to prefer their affair partner physically. What a coincidence. But top motivations for women. Relationship dissatisfaction, number one. And a high number one. Again, most women mentioned that. Second place, and, and second place by quite a bit, only, only 20%, that's still a high, 22%, um, mentioned that their primary partner was uninvested. And this also illustrates an important point, which is that not all women's affairs are explained by dual mating. It seems that there might be a psychological bias towards the dual mating strategy. But many women had affairs with affair partners who they perceived as less attractive, right? 77% more likely is not, you know, (laughs) that's not an infinite gap. And then, um, a fair, ver- uh, one of the reasons that many women cheated, one in five women cheated precisely because they thought that their primary partner wasn't invested enough. So if it's pairing good genes and good investment, that doesn't make, that doesn't make a lot of sense, um, with, for those women. And then the third most popular motivation for women was revenge. So 15.5% of women said that they were cheating to get revenge. And then-
- CWChris Williamson
Did they say, did they say what on?
- MMMacken Murphy
Um, well, in this case the 15.5% figure is revenge for their partner's affair specifically. So I remember I spoke to, uh, a guy who's kind of a unofficial marriage counselor in his neighborhood, and I asked him, you know, "Why, why do women cheat, in your experience? Like what, what do you see?" And he very flatly said, he said, "Women cheat when men cheat." Now, that doesn't seem to be 100% true, but there's certainly some truth to it in our data in the sense that women were much more likely to cheat for revenge. And you could interpret that as a genuine strategic difference, but since men cheat more than women, women have more opportunity to cheat for revenge. Or at the very least-
- CWChris Williamson
Hmm.
- MMMacken Murphy
... they have more opportunity, at the very least they have more opportunity to cite revenge as one of the reasons why they cheated.
- CWChris Williamson
Whether it was gonna happen or not.
- MMMacken Murphy
Yes.
- CWChris Williamson
What are, what- what is the state of who cheats more, men or women?
- MMMacken Murphy
Oh, that- that- that's a pretty open and shut case. Men cheat more. Men say they cheat more when you ask them. Uh, men say they get cheated on less when you ask them, so women report getting cheated on more. And then women who are the third person, right, so some people might say, "Oh, well, maybe women are just understating things." When you ask, you know, who's more successful as a mate poacher, uh, women who mate poach tend to have a higher hit rate. So there are three people involved in any given affair. There's the primary partner, there's the person who's cheating, and then there's the affair partner. And you can do studies on any one of those three groups and you generally find the same result, which is that the man is generally more likely to have an affair. In some studies, it's not a big gap. In some cultural contexts, it's a huge gap. But that would- that would be the overall state of the science there. And so the revenge difference, it may just be downstream of, uh, the sex difference in committing infidelity. They have more opportunity to have an affair.
- CWChris Williamson
What do you- what do you learn from a woman's concern about investment from their partner?
- MMMacken Murphy
That's a good question. So this is pretty consistent with... It's not consistent with the dual mating strategy, but it's consis- And it- it's actually a really good thing to illustrate that women cheat for many reasons. They cheat maybe for traditional variety-based motivations, such as genetic heterogeneity, or, you know, uh, fertility backup. So, uh, some percent of couples are infertile, and so if you're mating with multiple males, you're really lowering the probability that that's going to result in the end of your lineage. Um, there- there- there are many motivations for affairs. Revenge, um, so uni- so uni- having, be- being an uninvested partner, low investment, I would say that it signals... I would say that it signals kind of the traditional ev psych difference, which is that women's investment in offspring is largely obligate, physically obligate, in the sense that women have to go through pregnancy and lactation. This is part of why women seem to be more careful about who they mate with, more choosy. Uh, a lot of men complain about, you know, women having high standards for their mates. But really, what do you expect, right? Like if you could get pregnant, surely you'd be pretty careful as well about who you mate with. And so women's investment is partially obligate, whereas men's investment is not morally, but pragmatically, entirely optional. Men have the option to seduce and abandon mates. And so you'd expect, given that, that women would be very sensitive-
- CWChris Williamson
Mm-hmm.
- MMMacken Murphy
... to cues that a man might seduce and abandon her-
- CWChris Williamson
Mm-hmm.
- MMMacken Murphy
... and really try to avoid that as much as possible. And so if they're in a relationship and they think, "Oh, my- my partner's not investing in me, he's not invested," well, that's a huge signal that he's a low mate value mate, essentially. It's like, "Oh, I, this isn't gonna work." And maybe that, maybe that's evidence for mate switching, but maybe it's also evidence for breakup or backup or just lowering the cost of infidelity, again, the discount infidelity idea.
- CWChris Williamson
I was gonna say, you know, this doesn't mean that no woman ever leaves her partner to get into a relationship-
- MMMacken Murphy
No.
- CWChris Williamson
... with the cheating partner. Yeah. Reliably, that does happen. And also, I'm going to guess that if you looked at the cohorts of women and you were to find the one that said, "I was worried about investment from my relationship partner," that would probably result in more likely of a pivot to the new, uh, infidelity partner as a new relationship. I'm gonna guess-
- MMMacken Murphy
Mm-hmm.
- CWChris Williamson
... that that would probably be predictive of that. Because like, what am I sticking about for? If I'm going to have genes and investment and I don't have-
- MMMacken Murphy
Yep.
- CWChris Williamson
... investment, then I might as well try and get genes and investment together.
- MMMacken Murphy
Yes. Yes. Exactly. So the, so the dual mating, it doesn't explain all of women's infidelity, certainly. And we did see some mate switching in our samples. Several women in our sample were mate switching.
- 53:14 – 1:02:53
How Society Views Cuckolding
- MMMacken Murphy
- CWChris Williamson
I'm wondering whether the, uh, era that we were in, in sort of 2017, when we look at the mate switching hypothesis, the dual mating hypothesis feels a bit icky to me.
- MMMacken Murphy
Mm-hmm.
- CWChris Williamson
Like when you think about it, when you think about, uh, and maybe this is just me as a man, but thinking about some guy, male parental uncertainty, raising another man's children, uh, whether this is or is not during a period of ovulatory shift where you're fertile as a woman, um, it makes me go like, "Ugh." You know, it's a little bit more Machiavellian, it feels like, in that way. Whereas mate switching seems to just be, okay, you're monkey branching from one relationship to the other. People have backup mates. People have, you know, their- their friends, uh, females friends that are men often tend to have the attributes of the sorts of men that they would get into a relationship with, which kind of has these sort of weird quasi-orbiter backup mate things floating around a little bit. Uh, I wonder whether in a post-Me Too world, that was just a bit more, uh, it was a little bit easier to digest, uh, to have something that was a bit less like, "Oh."
- MMMacken Murphy
I know. I mean, I don't really, in terms of assessing theories, I don't really care about how icky they are or how... Yeah, it just doesn't affect my assessment of the facts. I just wanna know what's true, whether or not it's kind of gross.
- CWChris Williamson
Mm-hmm.
- MMMacken Murphy
And I would say that the evidence points to this idea that this is a part of human evolution. I mean, in modern populations, quote unquote "cuckoldry" is quite uncommon. Uh-You know, 1%, 2%, 3%. That would be good. Tho- those would be the sorts of estimates that you'd get from people-
- CWChris Williamson
That-
- MMMacken Murphy
... who really understand the subject.
- CWChris Williamson
That would be-
- MMMacken Murphy
But-
- CWChris Williamson
... of a one to two, one to 3% are men raising a child that they are unaware is not their genetic offspring.
- MMMacken Murphy
Yeah. Well, yeah, yeah, yeah, exactly. Uh, one, one, two, 3% kids, of kids are in a "you are not the father" type situation. But-
- CWChris Williamson
The, the male sensitivity to, uh, parental uncertainty though has to exist for a reason. If it was-
- MMMacken Murphy
Yeah, exact- exactly. If it never happened, exactly. We wouldn't, how could we have, how could we have such concern with paternity certainty if there was no paternity uncertainty to be concerned about? That's number one. Number two, the modern percentages are based on, they're based in a cultural context where infidelity has been highly suppressed socially, and they're based in a technological context where we can choose through contraceptives and whatnot who, uh, consciously who you have kids with, to some extent. There's much more control over it. If you look at populations with less contraceptives, well then you start to see rates of 5%, 10%. Uh, among the Himba, 48%. Really high rates of extra-pair paternity. So i- it's, some evolutionary psychologists have said, "Oh, dual mating isn't true because it happens at such low rates." And it's like, well first reconsider that, you know, 2% number in terms of the 15% of women who have affairs. Uh, reconsider it as a hit rate as opposed to an attempt rate, and then also reconsider it in the sense that that's not nothing over millions of years, right? From an evolutionary timescale. But also it's not necessarily relevant, uh, to our understanding of our ancestry given that we have contraceptives now and we really didn't then.
- CWChris Williamson
What about men's motivations? What did you learn from them?
- MMMacken Murphy
Yeah, men's motivations. Um... I guess I, I actually do wanna say one more thing on the, on the icky point, because I think that there is a... And then I'll talk about men's motivations right after. I'll just go straight into it. I guess one issue from outside evopsych is this idea that the dual mating hypothesis is somehow, or the mate switching hypothesis, or any of these, that it's somehow sexist to talk about the evolved psychological influences on human sexual behavior. The first thing that I would say to that is just that the evolved psychological influences on men's sexual behavior are also very unfavorable, right? The portrait that you can paint of men's behavior using evopsych is downright dastardly, right? It's, uh, it, it's full of deception, uh, men's affairs, just, you know, as much variety as possible, uh, you know, completely emotionally detached. We've talked about the seduce and abandon strategy. All of this is very ugly, and it's important that we have, if we want to reduce ugly behaviors, it's vitally important that we have a good understanding of what's actually happening instead of deluding ourselves that other influences are at play. More, you know, comforting ones. Another thing is that the primary advocates for the dual mating hypothesis, I mean, the senior author on our paper, uh, Candice, who you've spoken to, uh, she has a gender studies degree. Uh, everyone on our paper is a feminist, right? Like we all, we, we all believe in, you know, gender egalitarianism. And, you know, some of the chief advocates for dual mating, Elizabeth A. Pillsworth back in the day, Marti Hazleton even today, these, th- these are women and feminists who are interested in this topic. So the kind of outside evopsych view that it's like, "Oh, this is like some kind of like anti-woman agenda." No. We're just interested in what's true, what's false, and we're trying to take the politics out of it as much as possible so we can just buckle down and do good science.
- CWChris Williamson
Yeah, I think it's-
- MMMacken Murphy
Uh, we can talk about top motivations.
- CWChris Williamson
... it's certainly, um, it doesn't paint women in a particularly flattering light, but we're talking about infidelity. Like-
- MMMacken Murphy
Yes.
- CWChris Williamson
... y- you know, you've been talking about infidelity-
- MMMacken Murphy
Yeah, and most women don't cheat.
- CWChris Williamson
But what this, what this does show, I think, uh, if you do get pushback, more pushback saying, "This is unfair. This is you trying to control women's sexuality. This is you painting them as Machiavellian," and all the rest of it, I think that what that betrays is the typical social expectation and interpretation of women's behavior, which is that sexually women are not the protagonists. That they are almost always responding. Uh, it's actually low key quite a sexist perspective-
- MMMacken Murphy
Mm.
- CWChris Williamson
... on women that they don't have agency to go and chase down a new partner. You know, it's the same people that will tweet, uh, "You're too good for him, bae." You know, like, "Remember, remember your value, queen." Whilst also saying, "No, no, no, no, no, women are never the ones that initiate."
- MMMacken Murphy
Yeah.
- CWChris Williamson
"Women should never be the ones that..." so on and so forth. It's such a, it's such a low, like it's such a midwit take from people that pretend to be egalitarian between the sexes. Uh, i- i- it's not. It's not. It's like the soft bigotry of, of-
- MMMacken Murphy
Yes. Yeah.
- CWChris Williamson
... male expectations.
- 1:02:53 – 1:12:03
Men’s Motivations for Cheating
- CWChris Williamson
motivations. What did you learn?
- MMMacken Murphy
Yeah. That was, that was a, that was a rich segue. This n- this now feels relatively, uh-
- CWChris Williamson
Hm. Mm-hmm.
- MMMacken Murphy
This now feels relatively lightweight by comparison. But again, top male motivation is relationship dissati- dissatisfaction again, but it's at relatively, uh, comparatively more frequency. The, the, the, the, the comparatively lower frequency. That's the sense that I'm using relatively here. So about a third of men, about 30%, said that they were dissatisfied. Uh, about 16%, so significantly more than women, said that it was because they had an attractive affair partner. And about 14% of men said that it was motivated by sexual desire. And here, again, (laughs) I just wanna note that the qualitative data is qualitative, and so it's subject to these reporting biases. It's subject to these interpretation biases. Are we really meant to believe that only 14% of men's sexual affairs are motivated by sexual desire? I mean, that... (laughs) Uh, uh, surely it was part of it for much more men.
- CWChris Williamson
Hm.
- MMMacken Murphy
It's just that it's not particularly flattering or self-flattering to talk about those things. And so m- men are gonna be want to report that at a lower rate because it seems a little inappropriate. That would be my interpretation of that. But it is interesting that there's a sex difference there, and that actually was something that's consistent with the mainstream evo takes on infidelity, that men's infidelity is somewhat more sexually driven, directly sexually driven than women's infidelity because for men's infidelity, the only benefit really is, is sexual. That's, that's the mainstream take. It's not my take. I think that men cheat for a lot... Men and women both cheat for lots of reasons. Some men in our sample were mate switching. Some men in our sample had an affair 'cause they wanted a new girlfriend.
- CWChris Williamson
Hm.
- MMMacken Murphy
That happened, um, at a similar rate to women as well.
- CWChris Williamson
What was the rate of men saying that their partner wasn't invested?
- MMMacken Murphy
Uh, I think it was 5%. Um-
- CWChris Williamson
Right. That's interesting. We're gonna get onto talking about jealousy, uh, shortly, but, b- just to kind of round this out, what are the, what are the exo-planets, the unspoken, uh, ghosts and sort of potential orbiters of, uh, infidelity hypotheses? Is there anything else that's still lurking out there in the ether that isn't dual mating, mate switching?
- MMMacken Murphy
Oh, yeah. Yeah. Uh, multiple investors is the, is the elephant... is the, has to be the elephant in the room. I mean, there's a few elephants in the room. Uh, one that, uh, I think you've talked to Jeff Miller. Have you? Yes.
- CWChris Williamson
Multiple times, yep.
- MMMacken Murphy
Yeah, yeah, yeah. I actually... I, I've seen clips. So Jeff Miller had a hypothesis that didn't really get hardly any attention, which is that part of the affairs that we have are to gain information, right, to calibrate our own mate value, to gain skills in seduction. And that theory has largely been brushed off, but it did pop up quite a bit that, uh, l- l- I can actually check the percentage here. Um, it wasn't nothing. You know, about one in 20 people said that they were cheating for some variety of information acquisition, right? So-
- CWChris Williamson
What, like... What do you mean information acquisition? Are they fucking spies? What's going on?
- MMMacken Murphy
(laughs) Uh, so, so for example, one woman said that she wanted to, uh... basically wanted to obtain skills in seduction. (laughs) Like, she didn't phrase it that way-
- CWChris Williamson
Hm.
- MMMacken Murphy
... but it was like, "I wanted to be able to do this. I wanted to have this ability." And so that's kind of a... that's a reason for infidelity that's strategically legitimate, where it's like, "Look, I don't really know my own mate value," or, "I don't really know how to get guys," or, "I don't really know how to get girls, and that's a very important life skill. It's gonna be important throughout my life. Let me go work on it, right, on the side."... that I, I wouldn't expect it to be the main motivation for infidelity-
- CWChris Williamson
Hmm.
- MMMacken Murphy
... but it's a motivation. You can imagine someone who is, you know, let's say a college student, they're in their first big relationship, they're halfway through college and they realize, "Huh, I actually don't really know what I'm doing still dating and I'm gonna have to date my whole life, right, until I get married at least, so let me go get some skills here."
- CWChris Williamson
I said this about, uh, people who get into, uh, marriage with the first person that they ever have sex with.
- MMMacken Murphy
Mm-hmm.
- CWChris Williamson
Uh, and it's kind of like being with your first-ever therapist. I- I'm- I'm-
- MMMacken Murphy
Yeah.
- CWChris Williamson
... d- doing therapy at the moment and a lot of people, it's the first time I've ever worked with someone for this long in-person, et cetera. People go, "What's your therapist like?" I go, "Oh, I- I think she's great, but I don't really know-"
- MMMacken Murphy
(laughs)
- CWChris Williamson
... because I (laughs) got nothing else-
- MMMacken Murphy
Yeah.
- CWChris Williamson
... to compare her to.
- MMMacken Murphy
Yeah, yeah, yeah.
- 1:12:03 – 1:20:28
The Science Behind Jealous
- CWChris Williamson
... How does this fold into your new sort of perspective on this? How does this fold into the discussion around jealousy, about sex differences in jealousy, about why men and women get jealous, its evolutionary-
- MMMacken Murphy
Mm-hmm.
- CWChris Williamson
... function, et cetera?
- MMMacken Murphy
Well, I mean, this is what's funny is that the dual mating hypothesis is more consistent with the evolutionary psychology literature on jealousy. Uh, I mean, it's quite conspicuous to me, but, m- uh, it doesn't seem to have been, uh, uh, acknowledged generally. It's something that we've touched on earlier, which is just that if... So, okay, well, for everybody... to give everyone the download if they don't have this information yet. On average, it varies the degree of the sex difference, the size of the sex difference varies-And then it also varies what people care about, right? So there are plenty of cultures where everybody cares more about sexual infidelity, or everyone cares more about emotional infidelity. But the general difference is that within a culture, on average, men will be relatively more concerned with sexual infidelity and women will be relatively more concerned with emotional infidelity. And that makes sense if dual mating is the concern, because men aren't protecting against a woman leaving them for another partner, they're protecting against the potential that they will be, quote-unquote, "cuckolded," right? They- they don't want... They're- they're more upset by sexual infidelity 'cause men can be cuckolded where women really, at least not in the same way, right? In a- in a euphemistic way maybe, but not in, not in the literal sense. On women's, on the women's end, we've talked quite a bit about investment. They're gonna be chiefly concerned, or not chiefly necessarily, but they're going to be, um, more concerned than men with losing investment, because women's investment is more obligate, men's investment is more, not morally but pragmatically, optional. And so that's really the landscape in terms of sex differences and jealousy. It pops up everywhere it's looked for. And I will note though that some people have taken it... (laughs) Some people have- have exported this ePSYC finding and said that like, "Oh, women- women don't care at all about sexual infidelity. Their main concern is emotional infidelity. As long as it's just sexual, it's fine." That's not what... That- that doesn't pop up. Uh, women are very upset by sexual infidelity. And then also on the other end, men are very upset by emotional infidelity. It's just that relative to one another within a culture, you'll generally find the difference in that direction, and this makes sense under a dual mating view because men are paranoid about (laughs) getting cuckolded, and then it also makes sense from a traditional kind of what- what women stand to gain from relationships in the view that it's like, "Well, if he is invested in her emotionally, then he might go off and raise her kids instead of mine, and maybe he's not invested in me."
- CWChris Williamson
Uh...
- MMMacken Murphy
Men have paternity uncertainty, women have investment uncertainty. That's how I'd summarize it.
- CWChris Williamson
A consequence of this being accurate, dual mating being the leading infidelity theory, would be more men being cuckolded ancestrally. Is that right?
- MMMacken Murphy
Yeah, and I think it's very reasonable to think that that happened quite a bit. I mean, if you look at even- even like rural American populations, uh, I've seen higher numbers, like close to 10% in terms of estimated... Uh, like- like if contraception is low and infidelity is high, you're gonna get a lot of men raising kids that aren't theirs. Um, that doesn't happen a lot in the mod- in modern America, in modern Britain, in modern Australia where there's contraception and strong social norms against infidelity. Uh, uh, we don't really see, we don't really see a lot of that- eh, uh, i- so it's not really something to worry about in a modern context. But in an ancestral context, I would say that this would be a real worry. I will also note that, uh, there's a great new paper, relatively new paper from, uh, again Burk Schelzer called The Cuckoldry Conundrum, which is just pointing out that sometimes, you know, our conception of cuckoldry does- isn't necessarily exportable in the sense that, and this might sound strange, but sometimes you know that a child isn't yours, but it still makes evolutionary sense to invest in them. So for example, among the Himba, there's tremendous status to be gained and social clout from being a good father to your wife's affair partner's children. So, you would be-
- CWChris Williamson
Fuck me. That's- that's pro-social in some ways. Jesus.
- MMMacken Murphy
Yeah, so it's like you would be... Because y- and- and you gotta keep in mind that, you know, uh, they've probably played both sides of the field here, so they've probably got, they've probably got eggs in other nests themselves, to use a metaphor-
- CWChris Williamson
Oh, this is like a-
- MMMacken Murphy
... and so it's kind of, it's kind of in everyone's best interest to be like, "You know, let's just invest in the kids that are in our nest."
- CWChris Williamson
It's a free-for-all. It's a pull.
- MMMacken Murphy
Yeah.
- CWChris Williamson
But this is kind of like the human equivalent of the, um, why female chimps mate with multiple males, because the risk of infanticide gets reduced because each male is uncertain about whether or not that child might be his.
- MMMacken Murphy
Yeah.
- CWChris Williamson
I'm not sure if that's even true, but it seems to me this seems to be a more kind of, uh, yeah, socially enforced equivalent of that, uh, in, in humans.
- MMMacken Murphy
Yeah, I would call that a t- yeah, I would call that a tangentially related hypothesis, for sure. I- I- I don't know how high, and this is something that you should talk to Martin Dally about actually is 'cause he's- his Cinderella Effect book is, uh, uh, just um, the truth about Cinderella. So yeah, that such a fun one about infanticide in humans. I say fun. Oh my gosh, don't clip that.
- CWChris Williamson
Ruthless.
- MMMacken Murphy
But inter- yeah, interesting how it... I- I really did mean it when I said I don't care how gross the theory is, (laughs) I just wanna know if it's true.
- CWChris Williamson
(laughs)
- MMMacken Murphy
Uh, but I don't know how much infanticide has actually played a role in humans, but it's kinda funny, and this actually relates back to the political conversation we were having earlier, is that some of the initial theories from Sarah Hrdy on women's infidelity in humans were related to paternity uncertainty. And hilariously, given that, you know, this is something that Louis Bachode, uh, pointed out to me, which is that, you know, in the '70s, '80s, and '90s, these findings on women as sexual strat- strategists, dual mating, uh, paternity uncertainty, creation, these sorts of things, they were championed at that time as feminist ideas and pushed back upon (laughs) by right wing people who wanted women to... You know, they had this archaic view of women as passive and, you know, not engaging in the sexual marketplace as active agents.And now, today, we have the complete political reverse where it's the same set of scientific findings, but it's the super feminist groups that are saying, "Oh, that's just not true, da-da-da-da-da." They're kind of acting like the old right-wingers. And it's the really misogynistic groups, uh, such as, you know, the, the tail end of incels and, and, and such who are holding up these same findings and saying they're great. So tha- (laughs) I think that that's better evidence than, than I've heard for anything that, uh... Uh, these, uh, facts, facts are, facts are neutral, and if you have an agenda, you can collect a set of facts and spin them in a way that si- fits whatever agenda you like. The same findings that today we call are sex- we call sexist were originally, you know, championed by, by feminist scholars and, uh, that's- that's just the way the cookie crumbles, so.
- CWChris Williamson
Well, the, the, the horseshoe is very horseshoe-y, and, uh, it ends up being a, a total fucking circle eventually.
- MMMacken Murphy
Yeah.
- CWChris Williamson
I think.
- MMMacken Murphy
It's more like a merry-go-round, uh, in the history of this debate. The same, the same sexual findings that were considered liberal are now considered conservative, and if you give it another 20 years, it'll probably flip back.
- CWChris Williamson
Come back around again.
- MMMacken Murphy
Meanwhile, we're just gonna keep our heads down and try to figure out what's actually going on.
- 1:20:28 – 1:28:57
What Are the Predictors of Infidelity?
- MMMacken Murphy
- CWChris Williamson
What are the predictors of infidelity? How can you tell if someone's going to cheat?
- MMMacken Murphy
Okay. There, th- there's actually a, there's actually a long list here. The most obvious one would be have they cheated on a past partner. Once a cheater, always a cheater. This lines up with our folk psychology. It's not exactly true in the sense that many people cheat on one person and then never cheat again, but i- i- i- it's, it's true enough, let's say. So there was one s- longitudinal study from Kayla Knopp that found that if someone had cheated in their last relationship, they were three times more likely to cheat in their next relationship.
- CWChris Williamson
Have you got any idea what the base rate is?
- MMMacken Murphy
Oh, the base rate of infidelity?
- CWChris Williamson
Yeah.
- MMMacken Murphy
It's difficult to find in dating couples. I'll say two things that I'm quite confident in. I would say that about a fourth of marriages will encounter infidelity at some point in their lifespan, and I would say that about half of people, maybe a little more than half in men, a little less than half in women, but, uh, somewhere floating around that kind of mid-range, not like, um, a super majority or a super minority, will cheat on somebody at some point, but that doesn't mean that they'll cheat on you specifically in one relationship. So for example, there are plenty of people who, you know, cheated on their college boyfriend or college girlfriend and then they never cheat again for the rest of their lives. Uh, but given that most people have several relationships, and also given the data showing that most people report getting cheated on by somebody at some point, I would say that the inverse is also, though n- though it doesn't logically necessarily follow, I would say that it is likely that about half of people will cheat on somebody at some point. But I would love to see better data on that. Unfortunately, the really good data has been collected on marriage and married couples, and, uh, again, I would say that, I would say that a conservative and reasonable estimate would be about a fourth of marriages will experience infidelity, and it's usually gonna be the man who does it.
- CWChris Williamson
Okay. What else? Someone was a cheater in the past, that's a pretty good predictor that they-
- MMMacken Murphy
Yeah.
- CWChris Williamson
... might be in future. What else?
- MMMacken Murphy
Yeah. Uh, e- extra pair interest. Uh, we are naturally quite sensitive to extra pair interest. We notice it. So people tend to notice if their boyfriend is constantly checking other girls out. That seems to predict infidelity empirically, and I, I believe there was even (laughs) a study where they tested, you know, how long, uh, a man's eyes lingered on other women and that was predictive of infidelity, which is kind of funny. And, you know, extra pair flirtation, that sort of thing. Uh, uh, I, I would, I would be attuned to that. Uh, there are people who are, let's call it laser focused on their partner, and then there are people who, you know, you go to the social event and they just wanna, they just wanna talk to, talk to all the hot guys or all the hot girls and they, they, uh, that kind of thing. That probably doesn't, doesn't bode well. Narcissism is another thing to look out for. That's another thing that I think people find quite intuitive. And a general history of... And I don't, I don't say this in, like, a loaded way, but a general history of promiscuity, I would say would be something to look out for. Like, if you're, if you're a woman and you are choosing between two guys, and one guy, he's slept with over 100 women, he loves going to the club, he loves having one night stands, he rarely has long term relationships, and the other guy has had, like, two long term girlfriends and has never had casual sex. If you're choosing between those two guys, which is more likely to cheat on you? I think it should be obvious, but it is statistically backed as well, that the guy who has the more of a history of monogamy is going to, uh, is gonna be more faithful in practice. So that... Uh, I, I mean, I've given you, like, five things there, so I think... Uh, maybe four? I'm not sure. Uh, that, that, that's quite a bit.
- CWChris Williamson
I seem to remember a line from one of David's books, maybe The Evolution of... I, I can't remember. Um, where he said that the single biggest predictor of extramarital sex is premarital sex.
- MMMacken Murphy
(laughs) That's probably true. That's probably true. I love that line. I'm stealing it. But it's, uh... I'll, I'll have to check it. Yeah.
- CWChris Williamson
I just wonder, I wonder how true that is. I wonder whether it's, whether it's the case, you know, is it, is it just socio-sexuality all the way down?
- MMMacken Murphy
Oh, yes.
- CWChris Williamson
And that's such a driving force-
- MMMacken Murphy
Yeah.
- CWChris Williamson
... that the person who wanted to have a novelty in their teens and in their 20s, um-You know, how much of that is setting a particular type of habit? You know, damaged goods. How much-
- MMMacken Murphy
Yeah.
- CWChris Williamson
... how much are you damaged goods? How much have you set some sort of lifestyle routine versus how much of, uh, how much is this like a natural outgrowth of you and your nature as a person? You know what I mean?
- MMMacken Murphy
Yes, I completely agree. I think that it is, it's possible. I mean, it's, I, I don't find it completely implausible, this idea that it's like if you practice having one night stands over and over again throughout your 20s, maybe in your 30s, it'll be hard for you to not do that when the opportunity arises. Uh, but I also think it's plausible that as you say, and this would be my, this would be what I would think, is that it's sociosexuality all the way down. So it's like if you want novelty and you're just holding yourself back from it, I'm not sure that that actually will... Maybe the ritual of doing that will help you in a marriage, but maybe it won't. Also, maybe you want those things, you want to be sexually unrestricted, but women just don't like you. And so when you're married, the first time that you get the opportunity, may- maybe that's the first time that you take it as well. Uh, so I would say that if someone is... I think that, yeah, it's kind of, you know, humans seem to exist partially on this spectrum, and it's, it's a construct, but it's a useful construct of sociosexuality. Some people are quite, let's say, unrestricted. They like to have sex without love. They like to have some casual sex. And some people are quite restricted. And the people who are more restricted, the people who are, you know, who don't have sex with people who don't love them, the people who would feel, you know, uncomfortable getting naked in front of a stranger, those people are probably gonna be more faithful to you. And I think, I think that's pretty reasonable. And I think, you know, though for all the internet discourse, uh, uh, I know that every podcast I want to put like a moratorium or like a ban on body count because I've talked about it before so many times. But yeah, I would say that body count is a kind of a dull proxy, but it probably is a proxy for likelihood of committing infidelity, at least in the studies that I've seen.
- CWChris Williamson
Yeah, I suppose, eh, the reason that body count's, uh, an interesting discussion, the reason that it comes up so much, is it's such a, uh, low resolution rough-hewn signal in the same way as saying your bank account shows how hard you work.
Episode duration: 1:57:45
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