#1041 - Dr Debra Lieberman - Why Don’t You Have Sex With Your Sister?

Summary

Modern Wisdom with Chris Williamson

Episode #1041 - Dr. Debra Lieberman
Title: Why Don’t You Have Sex With Your Sister?
Date: January 3, 2026
Guest: Dr. Debra Lieberman, evolutionary psychologist and kinship expert

Overview

In this engaging episode, Chris Williamson sits down with Dr. Debra Lieberman to explore the evolutionary roots of incest avoidance, discuss the mechanisms humans (and other animals) use to identify kin, and dive into the psychology behind other emotions such as disgust, gratitude, and crying. The discussion weaves between taboo topics and evolutionary insights, shedding light on why certain aversions exist, how they’re formed, and what they mean for modern behavior and morality.

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Key Topics & Insights

1. The Evolution of Incest Avoidance

[00:00–07:14]

• Why Don't We Feel Sexual Attraction Toward Our Siblings?
  Dr. Lieberman explains that humans have evolved sophisticated systems to avoid inbreeding because of its negative consequences on offspring health.

  • “Evolution engineered into our psychology a very sophisticated system to allow us to detect relatives, close genetic relatives, and develop a sexual aversion towards them.” — Dr. Lieberman [00:48]

• Kin Detection in Animals and Humans
  Animals use non-verbal cues (littermates, smell, imprinting on location or markings) to detect kin in the absence of language.

  • “Humans have language, so language and culture map very nicely onto these systems, but they’re imperfect.” — Dr. Lieberman [01:43]

• The Dual Function of Kin Detection
  Kinship estimation is used both to promote altruism (cooperation) and to avoid sexual relationships with close genetic relatives.

  • “The same kin detection system is operating for evaluating someone as a sexual partner and as someone to be altruistic to.” — Dr. Lieberman [06:54]

Memorable Quote:

• “How close my heart should be and how far my genitals should be from this person.” — Chris Williamson [07:50]

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2. Psychological Cues to Kinship

[07:51–13:01]

• Key Cues:

  • Maternal Care/Breastfeeding: Seeing your mother care for or breastfeed another baby indicates a sibling, regardless of genetic relatedness.
    • “That's an unmistakable cue that their kid… being cared for by my mom is my sibling. And that operates regardless of actual genetic relatedness.” — Dr. Lieberman [08:19]
  • Co-residence Duration (Westermarck Effect): The longer two children live together during early life, the stronger the incest aversion.
    • “The longer the duration of co-residence during early childhood, the more certain you are that an individual is a genetic relative.” — Dr. Lieberman [12:35]

• Natural Experiments:
  Examples such as Taiwan's “minor marriage” system demonstrated that cultural constructs can override—but not erase—evolved sexual aversion; such couples had higher divorce and infidelity rates.

  • “When they were raised together from birth… those marriages tended to end more often in divorce and there were more extramarital affairs.” — Dr. Lieberman [11:14]

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3. Sex Differences and Disgust

[23:09–28:13]

• Greater Female Disgust:
  Studies show women consistently rate incest scenarios at the highest levels of disgust compared to men, reflecting the higher evolutionary cost of poor mate choice for women.

  • “Females… were all at ceiling. The amount of variation that I found in female responses… was like basically touching… all very squeezed right up at ceiling. Males… the variance structure was quite wide, which I found humorous.” — Dr. Lieberman [23:30]
  • “Any bad decision in terms of investing… into an offspring with a reduced chance of survival would have been heavily selected against.” — Dr. Lieberman [24:24]

• Disgust Thresholds:
  Women tend to have a lower disgust threshold for most things, though with exceptions (e.g., changing diapers, sex during menstruation).

  • “There are a couple things that flipped… females were like ‘that’s fine’.” — Dr. Lieberman [25:32]

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4. Modern Manifestations & Outliers

[28:13–36:17]

• Only Children & Incest Aversion:
  Those without siblings (e.g., only children) show a muted disgust response to hypothetical incest scenarios—they simply lack the cues that would’ve triggered this aversion system.

  • “Without that natural aversion, you don’t have such a strong reaction.” — Dr. Lieberman [30:11]

• Incest Porn & Taboo-Fetishization
  The popularity of incest-themed pornography is discussed, with both acknowledging it’s unlikely consumed by people with strong sibling bonds. The draw may partly be the thrill of violating social norms when no genuine disgust response exists.

  • “The hypothesis would be that a guy with six sisters is not the person who's watching this.” — Dr. Lieberman [32:50]

• Cousin Marriage Prevalence:
  Aversion drops off rapidly beyond the nuclear family; cousin marriages are (and have been) common in various cultures.

  • “Cousin marriage is still… one of the more prevalent forms of marriage worldwide.” — Dr. Lieberman [34:48]

Notable Exchange:

• Chris: “That would be such a good study… Does the likelihood of watching incest porn go down based on the number of opposite sex siblings?” [32:59]
• Debra: “I’m really hoping someone in your audience will now undertake that.” [33:18]

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5. Evolutionary Story Behind Crying

[38:57–66:28]

• Crying as Social Signaling:
  Tears evolved as a signal primarily in situations where someone lacks leverage or power in a social interaction, prompting others to stop imposing costs or to offer help.

  • “Tears is one way that we use to communicate costs or, better yet, the intensity of a particular state… a tool used by the lower leveraged to get other people to stop imposing costs or to restart the delivery of benefits.” — Dr. Lieberman [41:04]

• Crocodile Tears vs. Genuine Crying:
  “Crocodile tears” (manipulative crying) tend to be performed openly as a strategic display, unlike genuine tears which we often try to conceal.

  • “People who use crocodile tears need them to be on display.” — Dr. Lieberman [44:26]

• Sex Differences in Crying:
  Women and children cry more than men and adults, reflecting their relative lack of power or leverage, on average, in social situations.

  • “Women cry more than men, kids cry more than adults.” — Dr. Lieberman [43:54]

• Crying Alone or at Media:
  Dr. Lieberman suggests even solitary crying functions as a simulation:

  • “I think there’s simulations all the time… When we think about things, we can absolutely simulate what would be my reaction in this particular situation.” — Dr. Lieberman [53:23]

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6. Group Dynamics & Formidability

[47:34–51:37]

• Nonverbal Status Games:
  Chris reflects on male group dynamics—nonverbal cues, head of the table, who commands silence—interpreted as real-time calculations of hierarchy and formidability.
  • “If you've got some big dude in the room and he starts speaking… what is the likelihood that some or all people shut up?” — Chris Williamson [49:05]

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7. Crying—Function and Future Research

[61:15–66:28]

• Ruminations on Tears as Costly Signals:
  The act of crying (with actual tears) has a cost—it impairs vision and exposes vulnerability, making it hard to fake and therefore a reliable signal of genuine distress or need.

  • “It's front and center… Something that is readily available… This is a negative stimulus.” — Dr. Lieberman [59:20]

• Speculation on Biochemical Functions:
  Dr. Lieberman ponders whether crying serves a physiological “data-dump” role during emotional recalibration, particularly following social loss.

  • “Is it kind of being dumped out through the tears to… reestablish [emotional equilibrium]?” — Dr. Lieberman [64:54]

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Notable Quotes & Timestamps

• On kin detection:

  • “We seek, and we're always looking for people who might value us. So looking for overlap in any dimension is something we do naturally to form friendships.” — Dr. Lieberman [06:12]

• On incest aversion:

  • “You telling me that a person is my sibling… that's not really going to do very much to me, that explicit information…” — Dr. Lieberman [16:22]

• On cousin attraction:

  • “As soon as you start to drop off of nuclear family members, the biological deleterious and harmful effects of mating with close relatives drops off pretty fast.” — Dr. Lieberman [35:13]

• On crying as costly signal:

  • “You really need your eyes… and if you choose to have water pour out of them, you have temporarily incapacitated yourself. And if you… a costly signal add on.” — Chris Williamson [60:24]

• On “crocodile tears”:

  • “People who are trying to use their tears for more manipulative purposes will cry and be like, ‘Don't you see my tears? These are tears because I care.’” — Dr. Lieberman [44:26]

• On the dual function of crying:

  • “How much of crying is about changing other people's behavior and how much is about recalibrating our own emotional state?” — Chris Williamson [65:20]

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References & Further Resources

• Dr. Debra Lieberman
  • Research, articles, and resources are available at the Center for Evolutionary Psychology.
    • “The Center for Evolutionary Psychology is where I would direct everyone.” — Dr. Lieberman [66:59]
  • Upcoming textbook and a business (Mediabyte) to facilitate access to academic journal articles.

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Episode Highlights & Memorable Moments

• Chris’s blunt summary of kin detection as:
  “How close my heart should be and how far my genitals should be from this person.” [07:50]

• Dr. Lieberman’s candid reflections on researching incest aversion and the discomfort of discussing such topics even with fellow scientists.

  • “It was very disturbing talking about these things with your advisors.” [28:13]

• Discussing the popularity of incest porn and the hypothesis that only-children or those lacking strong kin cues might be more likely to consume it.

  • “I don’t know. The hypothesis would be that a guy with six sisters is not the person who's watching this.” — Dr. Lieberman [32:50]

• Explorations into moral dumbfounding around incest:

  • “I actually think that the reason why people say that it's wrong is… not because of Julie and Mark, I don't think people care about Julie and Mark. I think people care about being in that room with Jonathan Haidt and the other experimenters…” — Dr. Lieberman [21:40]

• Dr. Lieberman’s inventive speculation on whether we “tear out” emotional attachments after breakups, suggesting a novel direction for future research.

  • “If you could possibly capture people's tears as they are going through a breakup to see whether… whatever it is that kind of governs social value and attachment… is it kind of being dumped out through the tears...” [64:54]

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Final Thoughts

Chris and Debra’s conversation deftly navigates the boundaries between biology, emotion, and taboo. Listeners walk away understanding that disgust and aversion toward incest—far from arbitrary—are the result of deeply embedded systems shaped by evolution to preserve the health of offspring and promote social cohesion. Emotional signals like crying turn out to be tools for both social communication and personal psychological recalibration. The episode balances humor, depth, and openness, making for a memorable exploration of some of human nature’s most profound operating systems.

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To learn more about Dr. Debra Lieberman's work

• Visit the Center for Evolutionary Psychology
• Watch for her upcoming textbook (2026/2027)
• Stay tuned for Mediabyte: single-article access to academic journals

For the full conversation, listen to Modern Wisdom, Episode #1041.

Transcript

[A]

Why don't people want to have sex.

[B]

With their sister or their brother or other family members? Yep. It ends up that humans have a natural inbreeding avoidance system that develops pretty reliably in most folks exposed to the cues, which I term kinship cues that are available during childhood.

[A]

Right. Well, what about animals? Because I understand there is this label, that's your brother, that's your sister. How do animals actually detect who their relatives are? We just take it for granted. In humans, you can point and say, but animals don't have language, so how do they know?

[B]

This is a really good question. It's always fun to open up a interview with incest. Incest, avoidance.

[A]

Incest of you.

[B]

Yes. And so it's a really good question. How do we know who our close genetic relatives are? And why is that important? Well, first, it's important to know who your close genetic relatives are, not only for the purpose of not mating with them, because mating with close genetic relatives can cause a host of problems. So it leads to less, less healthy offspring, for instance, and offspring who might suffer from greater genetic mutations. So evolution engineered into our psychology a very sophisticated system to allow us to detect relatives, close genetic relatives, and develop a sexual aversion towards them. We don't even typically of them as possible mating partners. It's not foolproof, but this is what tends to happen. And the other reason why we should have a system for naturally detecting and automatically detecting genetic relatedness is for altruism. So being nice to your close genetic relatives follows from Hamilton's theory of inclusive fitness. We're nice to other people as a function. One way altruism can evolve is by being nice to people who tend to share genes by common descent. But you asked the question of, so how do we do this? Because humans aren't the only species that encountered this problem of avoiding mating with close genetic relatives for biological purposes. And so other animals without language or culture, they use cues, cues that correlated with another individual being a close genetic relative in that species. You know, evolutionary history. So. So whether it's being part of the same litter or a smell, or imprinting on a particular place or a marking, these are the kinds of things that evolution can engineer to help guide kin detection. Humans have language, and so language and culture map very nicely onto these systems, but they're imperfect. And so even though we could join a sorority or fraternity and call people brother, sister, or in certain religions, father, mother, you know who your actual father and mother are, you know, well, with good certainty, you know who your mom is, who your Daddy is, is always an interesting question. But certainly siblings are also individuals who you tend to correctly identify or would have, at least in ancestral environments. So we don't use language likely, we just use the cues that correlated. And so if you want to go around the horn of the nuclear family to figure out how do we detect who our close genetic relatives are? Well, how do you know who your mother is? This is the female who tended to primarily breastfeed you. So this type of imprinting or mapping onto the female who nursed you, how does a mom know who her child is? Well, that's kind of. Yes, it falls out of you. Unmistakable. How does a child know who her father is? This is not pinned down. I mean, it is a question. I mean, mommy's baby, daddy's maybe. So the question about how it is that people, how does people identify their father really probably goes through understanding, have I correctly identified my mother and what males are investing in her? Because males are going to rely on their paternity certainty in order to direct investment towards their offspring. So relying on what kind of who's investing in me heavily out there could be one cue that females use. But also the male that was around very early on in development has a better chance of being one's dad than the male that one's mom kind of is hanging out with later on in life. So, but it's a really, it's a really good question. So might phenotype matching occur? It could be. I don't, I'm not a fan.

[A]

What does that mean?

[B]

So, sorry, that is, do people use facial resemblance as a cue to, to understand who's likely a relative? That, that hypothesis does have some interesting data backing it. I, I'm not, I'm not a fan of it only because I think ancestrally people looked really similar. Not only that, just by the assortment of genesis, siblings can look and fathers can look a lot like their offspring or not as much like their offspring, but still be related, you know, with good certainty. And so I'm not quite sure pinning how we determine kinship onto a few genes that happen to govern facial features is the right way to do it. But maybe it contributes to be sure. Certainly when we see people who look similar, similar to us, that can spark a type of kinship. But I think that has more to do with a friendship and in group out, group tribalism maybe, or also we're always looking for people who might value us and identifying people who share features, any feature. Like, you know, if you were to say, oh my gosh, I have A sister. Her name is Deborah Lynn. I'd be like, oh, my God, I like you even more.

[A]

Oh, yeah? What's the naming effect? There's more people called Butcher that end up being butchers and more people called Travis that live in Travis. And my mum and dad's names both start with a K. All right, well, whatever. Like, okay.

[B]

Oh, but they both start with a K. Well, that is very interesting. I mean, the idea that we can. We seek, and we're always looking for people who might value us. So looking for overlap in any dimension is something we do naturally to form friendships.

[A]

So are you saying that the same mechanism that we use to identify who our kin is in order to do reciprocal altruism, I need to look after them more than I would look after a cousin or a third cousin or a friend or a stranger is the same one that does incest avoidance?

[B]

So the system that is being used to identify kin for the purpose of being nice to them, like the inclusive fitness, is the same kin detection system that's operating for evaluating someone as a sexual partner. So one.

[A]

Wow, that's so cool. You don't think that's cool?

[B]

I think it's super cool. I think there's. I mean, it's economical. The idea that the brain computes one kinship estimate. Like, I have an. For every person I meet, I have an estimate of what do I think the probability is. Not explicitly, not consciously, but by exposure to these cues, my brain has kind of ratcheted up or not ratcheted up this estimate that tells me, and I use to determine how related or likely that person is to be a relative. And that is an input into systems about how nice I should be to that person and how avoidant I should be of them sexually.

[A]

Yeah. How close my heart should be and how far my genitals should be from this person. Okay, so has this been. This has to have been tested in adopted siblings. So if you see pregnancy or breastfeeding, but you don't share the, like, early co residence window, like, does that still trigger incest avoidance? Like, you know, how can you play around with some of the triggers here to see. To see what really works?

[B]

So my research focused on siblings. I did a little bit of the. The parent offspring as well. But the bulk of my research was on how do siblings figure out who they are, you know, who's related to them. And it looks as if there's two separate cues. So one unmistakable cue that someone is a close genetic is a sibling, is you see your mom and to the Extent you've mapped the right woman as mom, your mom, you know, pregnant, give birth to caring for, breastfeeding a newborn, that is an unmistakable cue that, that their kid, you know, breastfeeding, breastfeeding from my mom, being cared for by my mom is my sibling. And that actually operates regardless of actual genetic relatedness.

[A]

So you can fake it kind of. You wouldn't need to give birth to it. You would just have to breastfeed it.

[B]

Right. And there's actually natural experiments that have shown this to be true. So in Taiwan, there was. That's no longer being practiced, but a form of marriage called minor marriage, where parents would adopt in a newborn girl into their family, either because they had a son, or they were hoping to have a son in the next year or so. And they brought up this adopted girl alongside their son until teenage years when someone said, and now you will marry.

[A]

Oh God. But they didn't realize that they'd triggered this incest avoidance mechanism.

[B]

Correct. And so, but one of the interesting findings is that the mom, the adopted mom, would oftentimes breastfeed the newborn. And so what had. What happened is, is that the son would have observed his mother breastfeeding a child that is in fact not an actual genetic sibling.

[A]

I imagine that doesn't lay a particularly good foundation for a future successful marriage.

[B]

No, but here's. So we're going. We're going to go a bit far field here, but the idea is here's one of the striking things about that particular natural experiment that occurred. This was documented by anthropologist Arthur Wolff. He found and reported that even among children who were raised together from very early age, many of them did marry and did produce offspring. So when cultural norms are that strong, it can actually cause you to, you know, do things that you otherwise might not choose to do. Now, in those marriages, those unions tended to end more often in divorce and there were more extramarital affairs. So the record keeping was incredible by the colonial government. But it was. So those marriages, when they were raised together from birth, they tend to have fewer kids, but they did produce kids greater. More marriage, more divorce, and more extramarital affairs compared to marriages where it was the traditional arranged marriage where kids were just raised in their natal household and then met as adults.

[A]

Okay, so the first one was breastfeeding.

[B]

So. Yeah, so sorry. So back, back. So the first really potent cue to who is a sibling is who did I see my mom caring for kind of this maternal investment, the second cue. So this is a great cue. But what happens if you're the younger sibling in a pair, you weren't around to see your mom care for your older sibling as a newbor, what are you to do? And so this starts to get into the Westermark effects. So Edward Westermark was a Finnish social scientist and he, you know, recognized that children who were raised together throughout childhood tend to develop a sexual aversion toward one another later in adulthood. This has been termed the Westermark effect. And what he was identifying is this second cue of co residence duration. So I, I like. So it's been operationalized as co residence, meaning that if you're the younger sibling in a pair, you've got an older sibling. How do you know that you're they're actually a genetic relative? How does your brain figure that out? You track how long that they lived with you under the same roof, receiving care from the same two individuals. So it's really still about parental investment, shared parental investment, the amount of time that you see them being cared for by the same two individuals, predominantly, probably mother, over the course of dependency. And so this is why the longer the duration of co residence during early childhood, the more certain you are that an individual, again, implicitly is a genetic relative. And this leads to not only greater altruism towards that person, but also greater disgust about the thought of sex with that person.

[A]

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[B]

So it was thought that perhaps there was a clear kind of imprinting period. My research shows that it basically each year of co residence seems to add a little bit of certainty or I should say reduces the uncertainty that someone is a genetic relative. So it looks like throughout the period of dependency, starting from birth. Starting from birth is key. And so individuals who kind of meet later on, the effect still holds, but it's not as strong as people who are exposed to a sibling right from the get go.

[A]

I imagine the potential for an absentee father to come back into a daughter's life later in her life. This is one of the leapfrog avoided the Westermark window challenges that can cause some pretty uncomfortable outcomes.

[B]

Well, it's. So I would say that fathers don't recognize their daughters by the Westermark effect. So Westernmark effect is going to be all about, yes, it's co residence duration and that might make it seem like it operates for all family members, but it's really about observing who is investing in whom. Right. So the idea of I'm, if I have an older sibling, I see that the same female who's feeding me, yelling at me, you know, caring for me when I'm sick and so forth is also doing the same thing to another older child. I have a good idea that that's my, that's my sibling. So that's. And the longer they require that type of investment, that's the kind of period of co residence that we're talking about for fa. But you raise really important things. So people who are not exposed to these cues. So what does this mean? So this gets us into fun territory. So people who are not exposed to these cues, they really don't map other people on as siblings. And so fast forward to modern environments where you now have these sperm banks, right? So you can have guys who are depositing their sperm and women are collecting it and they're having all these kids and now there's all these half siblings running around and now you can meet them. In fact there I remember, I don't know, 10, 10 years ago, but it was probably more like 20 at this point that there was a show like that kind of brought together all of these paternal half siblings and they all, they were really enjoying each other's company. And I think there was one remark about even being attracted to one another. And so you wonder how does this happen? Well, A couple things. There's a couple things going on. First, there's no natural sexual aversion that's developed. There's no system that's activated to say, this is my sibling. You telling me that you're my sibling, that a person is my sibling, that's not really going to do very much to me, that explicit information, it's like someone. Imagine someone knocking on your door and saying, your mate that you've been living with for 15 years, that's really your genetic relative. And so it really wouldn't really change the way you feel. You might say, well, maybe we shouldn't have more kids. But in general, it's not going to kind of cause a disgust, I would guess. But here's the other thing that's interesting. By virtue of sharing, why is it you find, like, what's called genetic sexual attraction? So it's been thought to be a thing. Have you heard of this genetic sexual attraction? That's good. Maybe it's not out there. Maybe I shouldn't talk about it.

[A]

Get it out there. Information hazard. We need to share it.

[B]

Get it out there, and I'll just kind of wipe it away. So genetic sexual attraction. It's been thought that, oh, we actually really are attracted to our family members. So Freud was right. And we kind of harbor these sexual desires. No, not so much. And so I would say probably what happens is that by virtue of the fact that we share genes in common with our close genetic relatives, we develop very similar preferences. Right? So imagine designing your perfect mate, Right? So what is. What does your mate look like? What do they like to do? What do they like to eat? When do they like to get up? When they like to exercise. What kind of, you know, all these kinds of things. You know, it's like you. And then you finally meet someone. It's like, you like kung fu movies. I like kung fu movies. You like spicy foods. I like spicy foods. You like getting up really early in the morning. Yeah. You like reading and you like evolutionary psychology. Like, I mean, literally, it is. You imagine all these different traits that line up in your really good friends and the mate that you would design if you could suddenly meet a sibling who actually shares a lot of these preferences and these dispositions. And it's like, well, this kind of hits a bullseye. And so the fact that, you know, people might find genetic relatives without a sexual aversion present, people that they enjoy spending time with doesn't surprise me.

[A]

I guess it depends how annoying your brother or sister is. But a lot of People, a lot of people like to spend time with their brothers and sisters, not just because of the history that they've got together. And if you remove the incest aversion, if you remove the disgust response and you're of the sex that that person is attracted to, it's like, well, why wouldn't you. Why wouldn't you do this? And what you're saying is basically, if you weren't brother and sister, but you are. But if you weren't, what would that be like? It'd be pretty sweet because, you know, 50% of everything we are psychologically is at least in some part shaped by our behavioral genetics. Okay, Well, I mean, 50% is a lot more than a lot of relationships that have lasted for quite a while.

[B]

I'm not quite sure what to say in response to that, but what you did. So I'll just say, okay. And this other thing is that what you bring up, though, is Jonathan Haidt's great experiment. Are you familiar with the Mark and Julie experiment, maybe, and moral dumbfounding? Okay, so Jonathan Haidt did a really great study on moral dumbfounding that had to do with inbreeding avoidance. And he brought students into the lab and. Or participants into the lab, and he gave them the following scenario. Imagine there's Julie and Mark, and they're brothers and sisters. They're brother and sister. And they decide they want to have sex. And they decide, you know, they really want to. They're adults, they're consenting. They're going to use like, five condoms. They can't get pregnant. No one's going to know. They're never going to do it again. You wipe their memory and they'll never even remember it. And no one's going to experience any emotional or physical harm. It's something you really want. So it's all positive, all, you know, win, win. And so, you know. And so Jonathan Haidt would pose these questions to participants and say, is it wrong for them to have sex? And, you know, all the participants were like, yes. And then he's like, well, why? Well, the condom could break. No, no, no. Condom doesn't break. They're wearing five of them and she's on birth control, like everything's fine. Someone could find out. No, no, no. And so, you know, they try to kind of find a way and a rationalization as to why it's wrong. And finally they just give up. I don't know. It's just wrong. And so he called this moral dumbfounding. And it's Really a good question as to what's going on. And are people saying that it's wrong because they're concerned about the harm that could befall Julie and Mark? And most people are saying yes, because most people still think that there could be a harm. I actually think that the reason why people say that it's wrong is not because of Julie and Mark. I don't think people care about Julie and Mark. I think that people care about being in that room with Jonathan Haidt and the other extreme experimenters to be like, I think incest is okay. I think it's okay.

[A]

Oh, so you think it's all just like observer effect stuff?

[B]

I think it's the idea that I could be going against a societal norm, that the majority is on the other side and I could be seen as a minority. I think we're very. I think we are very sensitive to sticking our necks out on issues where a majority holds one and we are going to oppose it publicly.

[A]

Well, I mean, surely you could just. To authority, you could just control this by changing the way that people submit their answers. Right. You could submit them in complete anonymity. You could do it through a form. You could do it anonymously on the Internet. Has this been. This has to. If this is such an obvious potential explanation, this has to have been tested.

[B]

I don't think it's obvious because I think people have been so focused as morality, as cooperation, and I think that morality. I mean, you wanted to talk about this. I'm getting back into the disgust and morality stuff. But it's very possible that people are very sensitive about moral condemnation. And anyway, I think you only get to this hypothesis if you think that people don't care about harm to them, but harm to themselves.

[A]

Okay. What was that study where you asked men to imagine tongue kissing their sister?

[B]

That was. Well, there's been a few. I've done other stuff, like on positive things like gratitude.

[A]

No, no, no, no. Sorry, I'm keeping my foot on the neck of incest at the moment.

[B]

Incest avoidance, please. Okay. So, yes, I've done a few studies. So one of the ways that we have to collect data on what people find objectionable and disgusting is to ask them to imagine. Is to ask them to imagine engaging in a variety of sexual behaviors. And so how do you do this and ethic. Ethically? Right. So asking subjects to imagine tongue kissing their sibling or having sex or, you know, taking a shower with them. What's interesting about that is at least a while back, when I collected those data, females were all at ceiling, you couldn't like 1 to 7, they'd be like 10. Like you wouldn't, they wouldn't be happy. The amount of variation that I found in female responses, seriously that the bars on my graph were like oh basically touching. There were very, very little variation. All very squeezed right up at ceiling. Males on the other hand, the variance structure was quite wide which I found humorous. But it all gets back to. I mean it's not humorous. This is a very serious subject. It actually, it is. And so it gets back to some of the cost of reproduction. Females, when selecting a mate have to consider all of, I mean they are on the hook for you know, nine months of, 10 months of gestation, three years of lactation and so getting a baby up and running is easily 3, 4 years ancestrally. So any bad decision in terms of investing time and energy into an offspring with a reduced chance of survival would have been heavily selected against males. The opportunity costs are far less and so males, while they should not be pro sibling incest would find it slightly less horrifically objectionable as compared to females.

[A]

Women also usually have a lower disgust threshold than men, right?

[B]

For most things. Yes, for most things. You know I tested this, I asked women a whole bunch of different things about how disgusting you find a variety of things and you're absolutely right that women are far more disgusted by a great many things. Ends up. There are a couple things that flipped which were, you know, changing diapers. Females were like that's yeah. And then having sex during your period. So that also that. Sorry, it's gross. It's all gross. But. So there you go.

[A]

But that's disgusting. Just specifically in specific situations.

[B]

I think, I think just the word period or tampon grosses guys out a little bit more than women. I think that's probably great.

[A]

We're way less familiar with it. A quick aside. If your sleep's been off, you're taking ages to fall asleep. Waking up at random times, feeling groggy in the morning. Momentous sleep packs are here to help. They're not your typical knock you out supplement, just overloaded with melatonin. It only has the most evidence based ingredients, perfect doses to help you fall asleep more quickly, stay asleep throughout the night and wake up feeling more rested and revitalized in the morning. These things are an absolute game changer. I take them every single night and when I'm on the road they're unbelievable because they're pre dosed. You just take this and your sleep will improve what you read on the label is what's in the product and absolutely nothing else. And if you're still insured, they've got a 30 day money back guarantee. So you can just buy it completely risk free, use it. If you don't like it, if your sleep doesn't improve, they'll just give you your money back. That's how confident they are that you'll love it. Plus, they ship internationally. Right now you can get a 35% discount on your first subscription and that 30 day money back guarantee by going to the link in the description below or or heading to livemomentous.com modernwisdom using modern wisdom at checkout that's L I V E M O M E N T O U s dot com Modern Wisdom Modern Wisdom at checkout so look, I'm an only child and I've realized that I don't have the same visceral disgust response that others have about sibling incest. Like I understand logically why it's a terrible idea, but I don't get the same gut level recoil. Do you know what it's like? It's like hearing smokers say I need a cigarette. Like I get the concept, but I don't have the craving or whatever or the opposite of the craving. Like I don't have that aversion. Why? I mean, is that normal? Have you looked at people who it is literally like I don't have a language. I guess someone could say, well imagine having sex with your mom. And I'm like, yeah, but like you've got the age thing that's already in there on top of like the fact that she's my mum. And so I think for most people that have siblings, it's almost like they have a language of disgust that I don't have the understanding of. Does that make sense?

[B]

Oh, 100%. So I'll tell you about another study that I did that didn't get published, but it's enjoyable nonetheless. And so I don't have a brother and my co authors don't have opposite sex siblings. So Leta Cosmides is an only child and John 2B only had brothers. And so the three of us sitting around talking about how to gross each other out with these acts, it was actually, it was very disturbing talking about these things with your advisors. I, I have a, I remember that conversation and being like, I'm, I'm done, I'm out. So, but it was, we did another study which was videotaping facial expressions. At the time I started kin detection, no one had really started to look into the psychological aspects of it. But one of the things that we had to do was validate disgust as a possible measure. And in science, even though it's obvious if you just ask what emotion comes to mind, if you think about tongue kissing a sibling, most people, it's really gross. And there you have your dependent measure. You have to establish that. So I set up. I set up a lab where I recorded people's facial expressions and did a variety of things to understand what facial. What muscles were actually activated in response to a variety of different acts. Things that we know elicited disgust, but then also the sibling incest stuff. And so there people are looking at the screen, seeing acts come up on the screen and. And just responding to them or just reacting to them. And most of them would have these, you know, so in addition to, like, eating your favorite dessert, it would be like, you know, putting your hand in a toilet and all these other things that you would see the. The muscles. The nose scruncher muscle for disgust activate. When I was matching what was on the screen to participants, because those are two different video feeds, I remember seeing one of the matching up, the. Seeing a guy kind of smile, like, hmm. And I was like, wait a minute. Do I have the time smpte time code right? Like, am I matching it right? Cause it says, like, tongue kiss a sibling. Like, like, what's going on here? I was like, oh, no. And so I was like. And I remember furiously going through all the survey pages to be like, please don't have a sibling. Please don't have a sibling. And it ends up, the guy didn't have any sisters at all. And so I found that really interesting. It kind of gets to what you're talking about, the idea that it doesn't map onto anything. And so it was like, imagine. It was basically like, imagine having sex with a girl. And he's like. And so without that natural aversion, it's. You don't have such a strong. A strong reaction.

[A]

Right. Okay, next topic. Yeah. If incest disgust is so strong, why is incest porn such a huge category online? You'd expect it to barely exist, and yet it's massive.

[B]

Well, I mean, are they really siblings? I mean, people do anything for money. Well, I mean, first off, it's money. And so the idea is, if people are going to pay and you need money, I mean, that's. Sure, people do stuff for money, and people do gross stuff all the time.

[A]

No, no, no, no, no, no, no. Why is there. Why is there an audience for it.

[B]

Oh, why is there an audience for it?

[A]

Because why are people doing it? I don't think that that many brothers and sisters are being employed. That would be. That would be a very special kind of relationship. It would be a really special kind of business. Yeah, I imagine that the margins would be really bad. The amount of money you'd need to pay most people to have sex with their sibling would probably be pretty high.

[B]

Yes.

[A]

Why is there a big audience for it?

[B]

Why is there a big audience for it? Well, I watched Game of Thrones and the idea that, you know, these two people, what is it? Jon Snow and, you know, Daenerys, they were. Ended up being related. I don't think that prevented people from watching that. I think people aren't there. It's just two people who are naked having sex. Like, and not only that. So there's that, there's that. And then the idea of kin detection is imperfect. Right. So if you don't have a sibling and you're like, oh, well, this sounds kind of neat and risque.

[A]

Oh, right. You're saying. Are you saying that incest porn is exclusively watched by only children?

[B]

I don't, I don't. I don't know. The hypothesis would be that a guy with six sisters is not the person who's watching this.

[A]

Unless that would be. So that would be such a fucking good study. You should do this. This is your next study. Your next study is to work out. Is to work out whether the likelihood of watching incest porn goes down based on the number of opposite sex siblings that you've got. Yes. The world needs to know.

[B]

Okay, well, I'm really hoping someone in your audience will now undertake that.

[A]

This is you. You are in. This is you. You're in my audience. What else are you doing?

[B]

I mean, I'm writing a textbook. I'm starting a business. Come on, man, I'm busy.

[A]

Well, this can be another. You know, there's more stuff to do anyway. I, I think, I think you're right. I think people don't. It's not like. In order to watch this incest porn, you need to observe the. These two people grow up in the same household as you for the first 10 years of your life and then watch it and then see, because the fantasy, I guess, is a. I wonder whether it's a little bit of like, contravening, you know, in the kind of the same way that dominatrix stuff or, or being insulted or whatever. It's like, oh, this is a social norm. And by breaking it, this is cheeky, but it's done in a safe way because you don't actually have the disgust response.

[B]

I mean, they're not your siblings.

[A]

That's true. Yeah. This is whatever the thingy and Julie.

[B]

The Mark and Julie.

[A]

Yeah, Mark and Julie. It's Mark and Julie all being watched. All right. Ayla, who I think you'll probably be aware of, she ran a poll and said, if your very attractive cousin wanted to sleep with you, would you? And there was 12,000 votes and it was almost exactly 50. 50. Now I will say her audience is perhaps non typical, like rationalist, sex positive, slightly autistic coded, but that number still surprises me a little.

[B]

It doesn't surprise me. Well, first off, cousins, hot cousin.

[A]

50.

[B]

50 cousins are. Cousin marriage is still, I think, one of the more prevalent forms of marriage worldwide. Okay. You know, as soon as you start to drop off of nuclear family members, the biological deleterious and harmful effects of mating with close relatives drops off pretty fast.

[A]

What's the comparison to parent to sibling to cousin?

[B]

I mean, it really, it drops off really fast. So within the nuclear family are the, the greatest risks. Right. So you have parent offspring, certainly mother child, there's greater certainty. But, you know, degree of relatedness is, you know, 0.5. Siblings tend to be on average, 0.5. But as soon as you go to cousins, you get to an eighth, you go from, you know, a half to an eighth. And so that's on average. So I would say, especially when there are norms kind of pushing all of that and you didn't live with them. And so your structure, your kinship structure is more, it's, your aversions aren't as strong as they would be to nuclear family members.

[A]

And for good reason would you have, is there such a thing as you observing the baby of your mother's sister growing up in the same household as you being close to them, knowing that it's not been raised by your mother, but knowing that your mother and that woman are close and that woman raised that. Is there such a thing as being able to tune up the cousin aversion?

[B]

Yeah, I bet you there is. I mean, just like there's an ability to tune up the sibling aversion by having someone come into the house and be raised by, you know, an adopted child and so forth. And so it's, I suspect that there's, there's a lot more research that needs to be done on this. And now that we have these amazing ways to collect massive amounts of data, it'd be very interesting you asked about a kind of imprinting period or developmental period, a sensitive period. And the quest. The answer is, you know, we don't, we don't exactly know. I mean, there could be my data, I collected data from like a couple hundred people. And so the bins that I have, like I have most people 3 to 18, they lived with their siblings some 4 to 18, 5 to 18. But imagine having the ability for every bin between 0 and 18, filling that with 10,000 people to kind of understand patterns. And so that would be a really great study to answer the question definitively.

[A]

I agree. Okay. You had this fantastic article on crying which I read a few months ago. It is one of the best things that I've read in a long time. I think it's really, really great. So I want to. We've talked about incest, now we can talk about crying before we continue. I've been drinking AG1 every day for years now because it's the simplest way that I found to cover my bases and not overthink nutrition. And that is why I've partnered with them. One scoop gives you 75 vitamins, minerals, probiotics and whole food ingredients in a single drink. And now they've taken it Even further with AG1. Next gen, the same one scoop once a day ritual, but this time backed by four clinical trials. In those trials, it was shown to fill common nutrient gaps, improve key nutrient levels in just three months, and increase healthy gut bacteria by 10 times. Even in people who already eat well. They've upgraded the formula with better probiotics, more bioavailable nutrients and clinical validation. And it's still NSF certified for sport, meaning that even Olympic athletes can use it. Plus, if I ever actually found something better, I would switch. But I haven't, which is why I still use it every day. And if you're on the fence, they've got a 90 day money back guarantee. Buy it and try it and if you don't love it, they will give you your money back. Right now you can get a free bottle of vitamin D3K two free AG1 travel packs, a welcome kit, and that 90 day money back guarantee by going to the link in the description below or heading to drinkag1.com that's drinkag1.com modernwisdom what's the evolutionary story behind crying? Why? Why would leaking water from your face ever be adaptive?

[B]

It is. Well, okay, so before we get into this, I just have to say for the record, because it's an important record, we've talked about Disgust. But I've also done a lot of work on gratitude and other emotions. And so, but it's my work on gratitude that got me into tears. Because gratitude. And so see how I'm kind of changing. But gratitude, it's an important emotion that's responsible for jump starting friendships. It is an emotion that identifies when other people value you, right? So someone does something that you perceive to be a benefit, you say thank you. You are basically saying, you know, I value you for having done that act and it would be great if you continue to do that act with the promise that potentially we can form a cooperative relationship downstream. But it all hinges on what we call kind of social value in the article. It's called welfare trade off ratio. But let's not talk about that. It's really just about how I value you, how I perceive you to value me. Because when we're strangers, I don't think you will value me or I don't value you and then use something nice. It's like, oh, how do I recognize, how do I positively reinforce, enforce that benefit, beneficial behavior, that positive behavior. And gratitude seems to be the way that I say, hey, that was really great, keep doing that. Like, thanks so much. And so. But it all hinges on these internal assessments of value. So how do we get people to value us? If you are, I promise this is going right straight to tears. And so if I am big and strong and formidable, I can just get you to be nice to me, right? Under threat of penalty. Like I can impose costs, I can beat you up, I can have other people beat you up, I have money, I can pay, I can do all sorts of things. And so if I, I can use anger as one device and strategy in order to get you to, to value me. I can also use gratitude. We've talked about this in the literature as prestige and dominance. But I think it tracks a little deeper than that in terms of the strategies of how to get other people to value, you know, but here's the thing. If I'm on the other side, if I am low leveraged, if I'm in a situation in a relationship where someone's imposing costs on me or threatening me, right? How do I, what do I bring to the table? How do I negotiate, you know, what's in my arsenal? And so I could either just kind of give in and be exploited and manipulated all the way to the end, or I can try and kind of express that you are imposing too much of a cost, you are asking me to deliver too high a benefit to you that's going to start digging into my own interests. And tears is one way that we use to communicate costs or better yet, the intensity of a particular state. So tears, I'm mapping it more onto sadness. It's not necessarily just associated with sadness, but using sadness as an example. The idea that my tears communicate to you, you are starting to impose a cost on me that is threatening your value in this relationship as well. It might be worth your while to stop. And so it's a way, it's a tool used by the lower leveraged to get other people to stop imposing costs or to start restart the delivery of benefits. So kids cry, throw tantrums saying, you, you're not feeding me enough or you're not feeding me the right things, you know, because they're not big and burly and they can't be like, you're going to make me that hot dog, right? They're just going to cry, I don't want Mac and cheese. So. But they're. So tears can communicate quite a bit more Generally they communicate value. And so we associate them a lot with the negative value things that cost us, but they can very much be associated with the positive side too. It's indicating the kinds of things that I benefit, you know, that I find quite beneficial. So, you know, someone delivers an, a hugely unexpected gift to you. It's, you know, you could be moved to tears, right? Someone does something and donates a kidney or does something, you know, life saving. The idea that you could be moved to tears by such, by such behaviors, it's showing and illustrating, it's illustrating high value. So it's very much like the screaming, but it's used by the lower leveraged in a, an interaction.

[A]

What does lower leveraged mean?

[B]

Means the person who is less likely to get their way in an interaction. So the could be the less physically formidable, the lower, lower socioeconomic status, the less attractive the, you know, smaller.

[A]

Oh, okay, okay, I get it.

[B]

And so women cry more than men, kids cry more than adults.

[A]

Have you looked at trying to control this stuff? So for instance, let's say that you had a woman in a relationship, but she was socioeconomically more successful than her partner. She was the primary breadwinner. Or you had a mate value discrepancy where the woman was higher mate value, more famous, more statusful, you know, trying to rebalance these scales. Do we tend to see that change?

[B]

I would, I would say you probably absolutely do.

[A]

Wow.

[B]

And then, and. But there's always the fun crocodile tears. Right. So those are the fun ones where it is people who use tears because they know what they do. And so, you know, psychopaths, dark triad people will pull out crocodile tears in order to get you to think that they care. And so that's always an interesting feature. But there's a. You can tell. I came up with one way to tell. This has not been studied, or at least I don't think that this has been studied. And I'd love to study this. So if you've ever cried, like, if you're like me, even in a movie, a dark movie theater, if I like start crying, I like, I like to start to stare. So it's like, dry up, dry up. Don't let anyone see you crying. You know, it's like you kind of like, you hide and you don't want anyone to see you. You don't want anyone to see you. It's kind of like I don't want to be perceived as weak or low leveraged or someone who you can now take advantage of and explo or anything like that. Right. So I don't want to have lost any ground in any type of leverage, you know, in any relationship. Again, it's not explicit, but it's just like, we tend to hide these things. But people who are trying to use their tears for more manipulative purposes will cry and be like, don't you. You see my tears? These are tears because I care. And so I think people who use crocodile tears need them to be on display.

[A]

Oh, that's so great. Yeah. Allow me to put a billboard up so that my tears can run down the front of. But isn't it strange the people who are crying and they've got, you know, if this theory holds true and at least a good bit of the time, I think it does, people are, I'm trying to tell you I value you or the thing that you just did, or you were imposing costs on me and I would really like you to stop. Yeah, I need you to see this. But also I'm ashamed of the fact that my body and my face and my eyes and the water has betrayed me. So I'm going to hide, but I'm going to show. But I'm going to hide, but I'm going to show you, but I'm going to hide. Like there's a tension going on here.

[B]

There is. It's a. I don't want you to. I'm not giving up too much ground in this relationship, but just for this one instance, you should know that you've gone Too far. So an interesting thing is that in what has been studied are tears and anger at the same time. Because women tend to, when they get angry, also tend to tear up. So if you are in a. If you're in a situation where you are. You're out leveraged, so you're in a group situation and you're not being valued and people are pissing you off, right? And so. And you say something, right? You're angry, you're. You. Like, if you had, you know, if you had muscle behind you, you'd be in good shape. But if you find that you're the only one making a case for something, what. So women in these situations, they tend to get angry but also tear. It's like. But again, it's that tension. It's like, if I could, I would, but I can't, so I won't. But if I could.

[A]

Yeah, that's so great. And I don't think I haven't seen guys get. Do the angry cry thing in quite the same way. Their rage is able to sort of burst through it a little bit more.

[B]

I think in most situ. Yeah, no, I don't think that's a tactic for male. Who don't. So listen, I mean, there is a big difference in. There are huge sex differences when it comes to formidability. Walking around the world where, you know, around in modern times. I mean, I love modern times. Like, I can walk around without really under threat of being like, you know, hurt. And so. But that's relatively recent in human evolutionary history. Like there were, you know, you go somewhere foreign and suddenly you realize, like, maybe I shouldn't be walking around alone. Like, this is. This is. I'm gonna hire someone, you know, tomorrow. And so the idea that females are less formidable and they are at risk of being, you know, I mean, you walk around and it's. Here's what I was told. I don't know if this is true. Tell me if this is true that when guys go into a room, a new room, new people at a party, wherever it is, a bar, the. The first thing they do or one of the things they do naturally is they kind of sweep the room. Like, who. Who else is there? What other guys are there and kind of take a. Take a kind of. Of back of the nap, make a back of the napping calculation about who's bigger, who's more formidable, like, who can I take, who's dangerous, who should I be wary of and who don't I have to worry about. Kind of thing is that is that something men do when they walk in a room.

[A]

I, I don't know whether it's that conscious, but I don't think it's conscious. There's certainly stuff that happens that's kind of interesting. Like if you're in a room, this is a cool way to look at it. If it's a mostly guys room, ideally in all guys rooms, as soon as you throw women in the mix it becomes messy. But if you've got a table, you'll see what is the angle of the chair, what are the angles of the chairs mostly pointed toward. And you will see that there is a head of the table even if there isn't a head of the table. Another way that this happens is interesting. When somebody starts speaking. When a guy starts speaking in a room, what is the likelihood that some or all people shut up? I've been in rooms, I've been in rooms with some guys real, real status, full guys that if they fart, everyone will, everyone will decide to be quiet. And you can really tell an awful lot about where the hierarchy falls by who's nearby, proximity to that person, whether they will keep talking, whether they're happy, whether they look regulated or whether they sort of seem a bit more sycophantic appeasing. So it's all that, I mean that's me getting. That's actually me getting a little bit feminine I suppose with it as opposed to the more like brusque shoulders back type way. That's more like status game playing, like relational stuff. But there's still even the formidability I think will play a big part of that too. I think if you've got some big dude in the room and he starts speaking, I think your, let's say formidability, status, status and resource cues, something like that. Like how big are you, who are you and what do you have? Something like that. If you had these buckets and there is this invisible score that is above everybody's head which is some sort of aggregate of all of those things put together. So like the really formidable guy, who nobody really knows that much and the really statusful guy who might not be quite so formidable that that would be an interesting. Like who do we. Oh well actually I'm physically a little bit weaker so maybe I'll be more scared of the formidable guy. But status fully, I'm a little bit stronger. So I don't mind the. You know what I mean? Like where am I in the pecking order? All of that is done in not very long. When you sit down in a room I imagine at the back of my mind.

[B]

Yeah, no, I think, I think that stuff, I think the non verbal behavior is really interesting. Someone that I've read and listened to in terms of the podcast is Joe Navarro who's done a lot of this work on non verbals and so it's fascinating stuff. If you haven't had him on.

[A]

Yeah, he's great. In other news, you've probably heard me talk about Element before and that's because I am frankly dependent on it and it's how I've started my day every single morning. This is the best tasting hydration drink on the market. You might think, why do I need to be more hydrated? Because proper hydration is not just about drinking enough water. It's having sufficient electrolytes to allow your body to use those fluids. Each grab and go stick pack is a science backed electrolyte ratio of sodium, potassium and magnesium. It's got no sugar, coloring, artificial ingredients or any other junk. This plays a critical role in reducing muscle cramps and fatigue while optimizing brain health, regulating your appetite and curbing cravings. This orange flavor in a cold glass of water is a sweet, salty, orangey nectar and you will genuinely feel a difference when you take it versus when you don't. Which is why I keep going on about it. Best of all, there's a no questions asked refund policy with an unlimited duration. Buy it, use it all and if you don't like it for any reason, they give you your money back and you don't even have to return the box. That's how confident they are that you'll love it. Plus they offer free shipping in the US Right now you can get a free sample pack of elements most popular flavors with your first purchase by going to the link in the description below. Heading to drinklmnt.com modernwisdom that's drinklmnt.com ModernWisdom so if, if tiers are telling another person I value this thing or you're imposing costs on me and I would like it to stop. Why do we cry when we're on our own?

[B]

Oh, because I think that we have dramas played out in our head all the time. You know, like we very easy to imagine a whole bunch of stuff. Typically it's not just, you know, nothing sparks us. Usually there's a thought or some type.

[A]

Of sequence, but who are we crying to?

[B]

Oh, I think it's simulating. I think there's simulations all the time. It's just like, you know, haven't you ever, you know, you know, laughed, like, I. I work, you know, in my place, on my own. And if anyone were ever to watch, like, they'd be like, she's crazy because she's laughing all the time. Just by thinking about some of these things, you know, it's hard not to chuckle. And so. But what's that all about? It's like me thinking about stuff, you know, and so I think that when we think about things, we can absolutely simulate what would be my. What would be my reaction in this particular situation. So that kind of playing with possible events that could play out to be prepared for them and so forth.

[A]

Okay. I think most people, and me too, I think that sounds a bit surprising because. Not that it's not true, but I'm like, I'm not gaming this out. I don't want to be fucking in a ball of tears on the floor at the moment having just watched this dog come home to. Oh, this soldier come home to his dog after, you know, three years away. And now the dog faints and now the daughter's there and, you know, but I'm not. I'm.

[B]

I.

[A]

Is it. Am I confusing the fact that I've seen that those people are here with me? Is it the fact that my whatever system, crying system is unable to detect the fact that that's virtual or not? Is it the fact that it's unable to detect the mental imaging that we've given versus a real situation? Is it the fact that our mental situations are just so powerful that it doesn't matter if there's other. That we experience them as if it was happening in front of us?

[B]

I think. I think you have empathy with. Score one for not being a psychopath. Okay, well, good. And so there you go.

[A]

I wish I cried less. I wish I was less of a pussy. My crying threshold is, you know, the discourse threshold thing we said before. My crying threshold is embarrassingly low. It fucking blows.

[B]

That's our. Listen. Empathy is not overrated. And so I would say, you know, I think that that first off TV and story, we evolved with storytelling. We evolved with people in front of us telling stories about people and about, you know, our ancestors and so forth. But I think that when we see them on tv, it's a little confusing to our ancestral brains, that's for sure. And so. But hearing about these things and putting yourself in a situation and simulating, I think is. Or being, you know, showing empathy and putting yourself in the shoes of other people and what you would experience, because there are people who don't have that ability. Right. So you have people who, you know, people who, psychopaths, for instance, who do not have a capacity for empathy and would not cry.

[A]

What about when grief, because some, let's say somebody's passed away. Who are you crying to? They're gone. What are the tears for?

[B]

Well, I think you're showing other people your need state, that's one thing. But I think a lot of things are going on at that point in time. So being upset and depressed and grieving, the idea that it's a loss and typically we would have been around. I mean there's no such thing as privacy to a hunter gatherer. So something happens and you would have been around other people and kind of this automatic response of I am in a need state would have potentially been quite beneficial. I, you know, I haven't done so I, I, I, A lot of this is speculation. So the, the, the, so just to stay on, you know, terra firma here, I, the paper really was about, I was very curious researchers who had been studying tears showing that you, you show subjects emotion, faces displaying various emotions. And if you add tears to some of those emotions there easier to recognize. And when I was so I'm the editor of the fields journal Evolution and Human Behavior and so I had one of these papers in front of me and it struck me like there's a lot of research on tears that it hasn't been hooked up with the cognitive side of things, what's going on internally and what this signal value is. And it had struck me that no one really thought about is, is tearing and adaptation. Like what's going on here. And so thinking about when we tear and what might be going on, it seemed to be very much tied to social value. Right. So being around people who value us and we are going to try to get them to stop imposing costs or try to elicit more benefits from them. Obviously in that I talk science speak, but you know, we don't talk. That's not consciously available to us. We just cry and it has the effects that it does on the people around us.

[A]

Okay, so positive events, the reason that we create positive events is like, this is good. Do more of it. Like an encouraging thing. This is a value to me and I wouldn't do this ridiculous thing if it wasn't reliable signal of receptiveness.

[B]

Yeah, you're marking this is of high value to be. I perceive the events and what's going on now to be registering in my brain as high value.

[A]

Okay, why not, why not make our Whole body shake. Why not raise our hand in the air and wave it? Why? Because crying presumably wasn't. Crying is here to lubricate our eyes. That's why crying. That's why the tear duct exists, primarily. Why has our emotional system repurposed that? Why don't we shit ourselves? Like, why don't we just yell?

[B]

Like, well, maybe you do. I don't know.

[A]

Why tears. What is it about the water coming out of the face that is particularly useful for this?

[B]

It's front and center. And so it is something that is readily available. It's a really good question. And so this was obviously one of the main questions that our reviewers had is like, this, why this? Why now? And so one possibility is that it was built off of. So if you have an onion and you hold it close to your eyes and the acids kind of interact and you start to tear. And so the idea is that this is a negative stimulus. So it's already kind of being associated with. There's something negative in the environment that is affecting me. And so that very much could have been the bootstrapping way that another more negative stuff could then have been registered by other people. So to the extent that. I mean, to the extent that that was possible, that would have been one possible lineage for how this came online.

[A]

Okay, I.

[B]

You're buying that to a degree.

[A]

To a degree, I do.

[B]

I don't. The answer is I don't know. But the.

[A]

Another part of it is, okay, yeah, front and center, right here it is. It's very hard to ignore. It is for most people, I think it would take a bit of. Even me, with my wimpy cry threshold, takes a bit of work for me to get it going. So usually for most people, apart from the psychopaths, a pretty reliable signal of authenticity. So it's not cheap. It's not that cheap. Another thing has to be. You really need your eyes. Like, you really, really need your eyes to see. And if you choose to have water pour out of them, you have temporarily incapacitated yourself. And if you. Again, another sort of reliability, a costly signal add on. Yeah, yeah, yeah, yeah, yeah, yeah, yeah, yeah, yeah.

[B]

That all makes good sense, I think. I mean, look, this paper was just written. It kind of throws out a whole bunch of ideas. And now it's time to, say, put it through its paces, test it and, you know, see where it goes. I think that, you know, on the positive emotion and negative emotion, so things like gratitude, but also depression and sadness and pain, I think that there's a lot There's a lot of work to be done.

[A]

That's a good point. Why, why do people cry during. I remember the last time I cried due to pain, physical pain. And I was I think 13 and it was one of my first adult cricket matches. I don't cry due to pain anymore. Physical pain. I don't think that there is an amount of physical pain that I would be put in. It would have to get toward the emotional pain. It would have to be an emotional element of this. Is it just that as you grow up from child to adult, you are able to better understand your capacity to deal with pain and the fact that it doesn't necessarily have an emotional component to it. Like why is it that kids cry when they bruise their knee?

[B]

But I don't, I mean I, I still cry when I hurt myself. Like, I mean I, I think yes. And I don't tell anyone. And so. It's a really good question. Listen, as a kid, I think the idea that I, I need help, you know, like help me, I'm in pain and this and or you know, stop this, stop this. Unattach this bristle, do something like there I think there that it definitely is a signal. I'm trying to actually think about it now. Like, cause you know, I cut myself with a knife and have I cried? I think I've cursed more than I've cried.

[A]

Isn't that strange? And it's strange because it's not, you know, but I guess look, the same or similar stimulus can cause different responses. Some breakups may cause somebody to shout and scream in someone's face because the specifics, the flavor of that one was cantankerous, it was aggressive, it was adversarial. And then another may be loving and painful and like melancholy. And those two would have very different responses. In one somebody may not cry and in another they may.

[B]

So I want to throw, I want to give you a hair brain idea that I had and I don't think it's going to pay out. But here's what I was thinking. So after a break up and you just, you cry and like you cry uncontrollably. And I was thinking, so while I was crying I was like, why am I crying? This is like I gotta stop crying. This is like I want to stop crying. Like this is done, let's be done with this. And so, but then I was wondering the function of it, is it like a data dump in the sense of someone that you held such high value for and then you realize and you simulate and you realize they don't value you anymore. And that cost and that kind of ratcheting down of someone valuing you. Right. Because you have to literally have that time to have that realization that they do not care about you at all. Right. So and so. But the idea that potentially crying might be a way that, you know, it just, it's a, it's a. So yes our social value is ratcheting down, but might that it's all chemically mediated. So the question is, is it. Are you also ridding yourself of that? So I was. If I had like a well funded lab, you know, I would think like if you could possibly capture people's tears as they are going through a breakup to see whether or not, you know, the pre, the pre. Kind of level of, I don't know, oxytocin, whatever it is that kind of governs social value and attachment and closeness. But is it kind of being dumped out through the tears to kind of help kind of re. Establish?

[A]

So good. I think that's great. I don't agree. I think that's really cool. I think that's really cool. And I think that someone needs to give you a million dollars so you can go and do it. What it makes me think about is how much of crying is about changing other people's behavior and how much is about recalibrating our own emotional state. State.

[B]

I think there could be multiple things going on. I think there's probably because I think that just like shouting can be done in most emotional states, like different types of shouting could be used to help express anger as in joy or gratitude or shame. Like you know, you find that the volume and amplitude of our voice can definitely do that. So why. And those are different types of emotions. Some are internal calibrating, some of them are other calibrating. So my anger and gratitude is to calibrate. Right. So but my shame and my pride is calibrating me potentially. So the. In any case, I think that you just put your finger on a really interesting thing that there's probably multiple things going on.

[A]

So cool. So cool. Deb Lieberman, ladies and gentlemen. You're fantastic. You're part of this weird like council. Masonic, Masonic like group of Cool.

[B]

Keep going.

[A]

Evolutionary psychology. And everybody needs to follow you. And I think it works. I think it works wonderful. And I enjoyed speaking with you at hbess and I think that you need to keep doing more stuff. So where should people go if they want to check out all of your fun cool work about incest?

[B]

Well, actually on the center for Evolutionary Psychology is a whole list of a great set of papers not only on kinship, inbreeding, avoidance, altruism, but also morality and anger and cooperation and coalitional psychology. So center for Evolutionary Psychology is where I would direct everyone. And also you can read about it in the textbook that is hopefully forthcoming at, you know, at the end of 26, beginning of 27. And if you will permit me, just to say one thing as an academic and the frustration that I often hear a lot of people who want to get access to these things is that they're hit with these paywalls. And so my business venture with a partner, the problem we're solving is allowing people to get access to articles, not only news, but journal articles that are currently held behind paywalls for subscription, but allowing people to get just the one article they want, when they want it. So that's what I'm up to.

[A]

When's that available? Can I get that now?

[B]

Check an app store soon. Mediabyte. We are on it.

[A]

Okay. When do you think it'll be launched? When it'll be live?

[B]

Hopefully late 26.

[A]

Okay, well. Well, hurry up because I need that. Deb, you're great. Keep doing your thing.

[B]

Thank you. You too. Be well. This is great.

[A]

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