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EPISODE 10 / Jul 15, 2025

Disgust, Morality, and Kinship with Deb Lieberman

Deb Lieberman·2h 32m·26 sections
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The conversation, in brief.

In this episode of the podcast, hosts Dave Pietraszewski and David Pinsof are joined by veteran evolutionary psychologist Deb Lieberman to discuss evolutionary psychology, kin detection, and the complex mechanisms of disgust and morality. Lieberman shares her academic origins, the collaborative community surrounding Leda Cosmides and John Tooby, and her editorial tenure at Evolution and Human Behavior. The conversation explores how humans detect genetic relatives through cues like co-residency and maternal association, preventing inbreeding. Furthermore, the speakers examine how disgust functions not merely as disease avoidance, but as a potent social weapon and moral signal that delineates political and coalitional boundaries. Finally, they touch upon free will, moral responsibility, and the evolutionary function of tears.

QUESTIONS TO KEEP IN MIND

  • How do early childhood co-residency and maternal association cues drive human kin detection and inbreeding avoidance?
  • In what ways does disgust operate as a potent social and moral weapon compared to anger?
  • How does evolutionary psychology approach the study of culture and cognitive programs?
  • What role do sexual disgust and reproductive strategies play in shaping political coalitional differences?
  • How do tears function as an evolutionary signaling mechanism for individuals with lower physical leverage?

Ideas to take with you.

  • Deb Lieberman notes that sibling categorization and kin detection are influenced by observing maternal breastfeeding and experiencing long-term co-residency. 25:45
  • Disgust acts as a signal of low social value that helps coalitional systems marginalize targets by leveraging contamination logic. 31:23
  • Unlike anger, which can often be easily alleviated through an apology, disgust leaves a persistent emotional stain that is extremely difficult to remove. 36:40
  • David Pinsof suggests that political orientation differences regarding disgust sensitivity are primarily driven by sexual disgust reflecting underlying reproductive strategies. 1:14:09
  • Tears can function as a specialized signal communicating extreme positive or negative value, particularly for individuals with lower physical leverage. 2:21:41

Through the conversation.

26 sections
01
0:00 – 7:30

Introduction and Guest Academic Background

Hosts Dave Pietraszewski and David Pinsof introduce the podcast and their guest, veteran evolutionary psychologist Deborah Lieberman. They discuss her academic origins, including how a class by David Sloan Wilson at Binghamton University shifted her trajectory from pre-med and neurosurgery toward evolutionary psychology and the Center for Evolutionary Psychology.

Deborah Lieberman discusses taking an influential evolution course with David Sloan Wilson during her undergraduate studies.

“And then I took a course by David Sloan Wilson entitled Evolution in Human Behavior.” 4:02
02
7:30 – 12:03

Attraction to Scientific Controversy and Frontiers

The hosts and Deb Lieberman explore why evolutionary psychology appeals to researchers, highlighting the attraction to scientific controversy, tackling challenging intellectual frontiers, and the siege mentality of early evolutionary behavioral sciences.

Deb Lieberman reflects on being drawn to evolutionary psychology because of its controversial nature and the intellectual challenge of pushing science forward.

“So I saw a controversy and I just kind of ran straight into that.” 9:19
03
12:03 – 18:00

Early Memories and the Evolutionary Psychology Community

Hosts Dave Pietraszewski and David Pinsof chat with guest Deb Lieberman about her early experiences in the field, reminiscing about the familial, collaborative environment at Leda Cosmides and John Tooby's house, and discussing how the social atmosphere and public perception of evolutionary psychology have shifted over time.

it was unique and it was special and and I enjoy it

“it was unique and it was special and um and I enjoy it” 15:44

the temperature has come down quite a bit

“I would say the temperature has come down quite a bit.” 17:04
04
18:01 – 24:06

Field Health, Training, and Evolutionary Cognitive Science

Deb Lieberman discusses the current health and future challenges of evolutionary psychology, emphasizing the need for better training in evolutionary cognitive science and task analysis. The speakers also touch upon Lieberman's research on kin detection, disgust, and incest avoidance.

I think the field is quite healthy in its teenage years

“I think the field is quite healthy in its teenage years” 18:01

you gotta go there in order to zoom back out

“you gotta go there in order to zoom back out and have a better handle on macro” 22:34
05
24:06 – 28:32

Kinship Detection Cues and Evolutionary Analysis

Dave Pietraszewski and Deb Lieberman discuss how humans and animals detect genetic relatives without language, highlighting cues such as maternal association and co-residency duration. Lieberman explains how these inputs drive inbreeding avoidance and how the research spans multiple levels of analysis from biological programming to cultural variations.

Lieberman notes that the two cues influencing sibling categorization are observing the mother breastfeeding another infant and long-term parental investment through co-residency duration.

“the two cues that we've at least found that influence and affect how you” 25:45

Lieberman highlights that incest avoidance and kin detection systems can be examined systematically through all levels of biological and cultural analysis.

“you can take it through each of its different kinds of questions” 27:43
06
28:33 – 36:10

Disgust, Coalitional Psychology, and Morality

David Pinsof and Deb Lieberman explore the bridge between inbreeding aversion and moral condemnation, discussing how disgust acts as a signal of low social value that rallies coalitions and exploits contamination logic to deprive targets of social support.

Lieberman explains that disgust signals low social value, serving as a loud bell for coalitional systems to marginalize and go after individuals.

“disgust just happens to be one of those emotions that signals it's like a really” 31:23

Pinsof suggests that the contamination logic of disgust prevents targets from mobilizing allies because association with them is also avoided.

“because disgust elicits this contamination psychology, it makes it particularly useful” 34:56
07
36:10 – 40:06

The Persistence of Disgust Versus Anger

Dave Pietraszewski, David Pinsof, and guest Deb Lieberman discuss the psychological differences between anger and disgust, noting that while anger can be easily resolved through apologies, disgust is much harder to wash away or alleviate, making it a powerful and potent social weapon in human relationships and cultural examples.

it's kind of hard to get out the stain of disgust. Like with anger, it's very easy to, you know, alleviate someone's anger, just apologize.

“it's kind of hard to get out the stain of disgust. Like with anger, it's very easy to” 36:40

there's basically no way to alleviate disgust once it's been activated. Or it's it's really hard to do. Um, it's a much more potent and powerful social weapon to wield against your enemies.

“there's basically no way to alleviate disgust once it's been activated” 39:43
08
40:06 – 48:11

Moral Psychology, Coalition Signaling, and Leadership

Deb Lieberman explains how moral psychology uses disgust to track personal norms, assess others' moral campaigns, and signal coalition allegiance. The speakers explore individual differences in moralization, political ambition, and how leaders use moral and disgust narratives to solve complex alliance coordination problems.

disgust can be used and strategically in order to say, I'm with you, not against you.

“disgust can be used and strategically in order to say, I'm with you, not against you” 41:15

people who are really prone to carving up the world into good and evil are especially likely to seek positions of leadership and and and political power

“people who are really prone to carving up the world into good and evil are especially likely to seek” 46:35
09
48:12 – 55:41

Disgust Psychology and Legal Decision Making

Hosts Dave Pietraszewski and David Pinsof converse with guest Deb Lieberman about studying the intersection of disgust psychology, morality, and the legal system. Lieberman discusses ongoing research examining how disgust influences juror coordination and judgment, and touches upon historical work exploring how innate aversion mechanisms and family co-residence cues relate to perceptions of incest.

how you take the Ash style paradigm, right? And bring people around a table

“how you take the Ash style paradigm, right? And bring people around a table” 51:01

how morally wrong you found incest in general was predicted by how grossed out

“how morally wrong you found incest in general was predicted by how grossed out” 53:33
10
55:42 – 1:00:13

Case Studies on Incest, Aversion, and the Law

Deb Lieberman shares real-world case studies involving legal briefs and inquiries regarding adult siblings reared apart who formed relationships without developing sibling aversion. The speakers examine the disconnect between evolved biological cues of co-residence, subjective feelings of disgust, and rigid legal frameworks governing familial relationships and consent.

explicit knowledge doesn't change necessarily how you feel about someone

“explicit knowledge doesn't change necessarily how you feel about someone” 57:24
11
1:00:13 – 1:04:12

Development of Moral Psychology and Disgust in Children

Dave Pietraszewski, David Pinsof, and guest Deb Lieberman discuss the developmental emergence of moral psychology and disgust in children around seven or eight years of age, illustrating how children begin to monitor social norms and label unconventional behaviors as disgusting.

the development of this kind of moral system is really interesting.

“the development of this kind of moral system is really interesting” 1:02:06

Like when kids start turning on their that moral psychology, like seven, eight kind of thing

“like when kids start turning on their that moral psychology, like seven, eight kind of thing” 1:02:12
12
1:04:14 – 1:12:13

Pandemic Responses, Disgust Sensitivity, and Alliance Theory

The hosts and Deb Lieberman examine psychological reactions during the COVID-19 pandemic, questioning whether disgust sensitivity shifted across the population and discussing how coalitional dynamics and political belief systems manifested during the global health crisis.

I don't know that I saw anything that convinced me that the pandemic caused shifts in disgust sensitivity across the board.

“I don't know that I saw anything that convinced me that the pandemic caused shifts in disgust sensitivity across the board” 1:05:46

More jarring to me during COVID was the coalitional stuff and just how just how nasty people got.

“More jarring to me during COVID was the coalitional stuff and just how just how nasty people got” 1:07:24
13
1:12:14 – 1:15:20

Sexual Disgust and Political Coalitions

Dave Pietraszewski, David Pinsof, and Deb Lieberman discuss how disgust sensitivity relates to the political spectrum. David Pinsof argues that correlations between political orientation and disgust are primarily driven by sexual disgust and underlying reproductive strategies, reflecting conservative coalition interests rather than general disease avoidance.

I think most of that is driven by sexual disgust. And sexual disgust in turn is a marker of one's reproductive strategy.

“I think most of that is driven by sexual disgust. And sexual disgust in turn is a marker of one's reproductive strategy.” 1:14:09

that is a fundamental part of the uh uh conservative political coalition.

“that is a fundamental part of the uh uh conservative political coalition.” 1:14:37
14
1:15:21 – 1:24:17

Editing Evolution and Human Behavior

The hosts talk with guest Deb Lieberman about her long tenure as editor of the journal Evolution and Human Behavior. They explore special issues, publishing trends, anthropology contributions, debates on topics like the evolution of war, and the future potential for applied evolutionary psychology.

my goal really as the editor was to start more conversations and to get people engaged in talking back and forth.

“my goal really as the editor was to start more conversations and to get people engaged in talking back and forth.” 1:20:10

taking that model of full psychology and looking at how we can actually get out there into the real world, um, I think is important.

“taking that model of full psychology and looking at how we can actually get out there into the real world” 1:23:07
15
1:24:17 – 1:31:29

Editorial Standards and Journal Gatekeeping in Evolutionary Psychology

Host Dave Pietraszewski and guest Deb Lieberman discuss editorial strategy and quality control at an academic journal. Lieberman explains her adaptationist criteria for manuscript selection, the rejection of poorly reasoned or outdated theories, and how she balances personal scientific biases with allowing the broader history of science to evaluate incremental research.

I get I get nervous about uh poorly designed studies

“I get nervous about uh poorly designed studies.” 1:25:09

I am an adaptationist, and so and I am, and so I realize that's There's an adaptationist running the journal

“I'm an adaptationist, and so and I am, and so I realize that's There's an adaptationist running the journal.” 1:26:44
16
1:31:30 – 1:36:18

Cognitive Architecture and Explaining Culture in Evolutionary Science

The speakers examine the challenges facing junior evolutionary psychologists, emphasizing the need for greater engagement with cognitive programs and information processing. Lieberman expresses frustration with vague invocations of culture and learning as explanatory catchalls, arguing that evolutionary psychology should instead serve as the rigorous cognitive science of culture.

the next generation of scientists, of evolutionary psychologists, it's really critical they understand the level of cognitive program

“the next generation of scientists, of evolutionary psychologists, it's really critical they understand the level of cognitive program” 1:32:30

evolutionary psychology is the field of culture and learning. And we specify how all that happens

“evolutionary psychology is the field of culture and learning. And we specify how all that happens.” 1:34:33
17
1:36:18 – 1:43:06

Evolutionary Psychology and the Modern Cognitive Synthesis

Dave Pietraszewski, David Pinsof, and guest Deb Lieberman discuss the foundational role of anthropology and evolutionary psychology in social science, emphasizing the importance of cognitive programs, levels of explanation, and honoring the legacy of John Tooby through theory-first adaptationism.

the universality is going to happen at the layer of the cognitive programs, right? Not at the layer of whatever is manifest.

“universality is going to happen at the layer of the cognitive programs, right?” 1:37:27

you don't accept the built-in assumptions of the world that are delivered by our folk psychology.

“you don't accept the uh built-in assumptions of the world that are delivered by our folk” 1:41:37
18
1:43:06 – 1:48:20

Disgust, Morality, and Field Traditions

Deb Lieberman shares her intellectual journey investigating the functions of disgust—particularly pathogen, sexual, and moral disgust—and how she shifted her approach to studying social value and cooperation, concluding with reflections on memorializing foundational figures in evolutionary psychology.

when you start to write about the moral disgust, I was like in the same like nitty-gritty information processing way... and I came to a complete blank.

“when you start to write about the moral disgust, I was like in the same” 1:44:28

morality is cooperation. I want to start with, I don't want to start there. I want to start with how come we're not killing and eating each other?

“morality is cooperation. I want to start with, I don't want to start there.” 1:46:21
19
1:48:20 – 1:53:26

Theoretical Writings and the Nature of Consciousness

Host Dave Pietraszewski, David Pinsof, and guest Deb Lieberman discuss scientific edge writing styles, theoretical contributions to journals like Evolutionary Human and Behavior, and explore consciousness conceptualized as a data format.

My favorite part of the the Tubi Cosmide's writing is they'll have a list of examples to illustrate a point

“My favorite part of the the Tubi Cosmide's writing is they'll have a list of examples to illustrate a point” 1:49:42
20
1:53:26 – 2:00:22

Responsibility, Blame, and Causal Determinism

The speakers examine whether moral concepts like blame and responsibility are merely coordination points or if they reflect evolutionary mechanisms for identifying actionable leverage points in human behavior.

we have evolved entries for the kinds of things that if we do intervene upon, we can change outcomes.

“we have evolved entries for the kinds of things that if we do intervene upon, we can change outcomes.” 1:57:00
21
2:00:22 – 2:09:57

Responsibility Attribution, Incentives, and Free Will

Dave Pietraszewski, David Pinsof, and guest Deb Lieberman discuss how attributions of responsibility and free will relate to tracking causality, reasons responsiveness, and coordinating group behavior.

the idea like they couldn't choose, and it's like that prevents them from coordinating.

“they couldn't choose, and it's like that prevents them from coordinating.” 2:09:29

what free will is, is sort of a representational entry. It's not an objective feature of the world.

“what free will is, is sort of a representational entry. It's not an objective feature of the world.” 2:05:22
22
2:09:57 – 2:12:26

Evolutionary Psychology and Philosophical Traditions

The hosts discuss how evolutionary psychology provides a new framework for examining long-standing philosophical concepts like free will and associationism, contrasting them with older historical models.

A passage from this discussion.

“And I think that just free will is one of those things that allows you to it's just like,” 2:10:49
23
2:12:26 – 2:20:19

Expanding Evolutionary Psychology into Philosophy and Social Sciences

Dave Pietraszewski, David Pinsof, and Deb Lieberman discuss the future directions of evolutionary psychology, emphasizing its integration with philosophy of mind, political science, and economics. They explore how understanding the evolutionary origins of human intuitions can help resolve long-standing philosophical puzzles and broaden the scope of evolutionary reasoning.

Anything that stems from a human is ultimately within the the purview of evolutionary psychology. Humans are animals, they're products of the Darwinian process.

“Anything that stems from a human is ultimately within the the purview of evolutionary psychology.” 2:16:54
24
2:20:20 – 2:24:27

The Evolutionary Function of Tears as a Signaling Mechanism

The hosts and Deb Lieberman explore the evolutionary purpose of tears, proposing that they act as a specialized signal communicating extreme positive or negative value, particularly functioning as an amplifier for individuals with lower physical leverage or formidability.

basically, the idea is that, you know, what are tears? You know, we kind of never really had an evolutionary idea of what tears were, but it's like the it's the opposite of the scream and the yell, which can be used for good and bad, but tears can be the kind of signal positive and negative sorts of things.

“what are tears? You know, we kind of never really had an evolutionary idea of what tears were” 2:21:41

the idea is that everything ranges from negative to positive value for me psychologically. And what tears are is signaling uh the tails of that distribution, the two extremes, either extreme positive value or extreme negative value.

“what tears are is signaling uh the tails of that distribution, the two extremes” 2:22:33
25
2:24:27 – 2:28:21

Social Emotions, Weeping, and Extreme Value

Dave Pietraszewski, David Pinsof, and guest Deb Lieberman discuss social emotions, contrasting pathogen disgust with social expressions like crying, and examine how weeping functions as a costly signal of extreme value and low leverage between individuals who value each other's welfare.

The hosts and guest discuss how weeping operates as a low-leverage signal of extreme value.

“weepiness is a kind of thing for the is typically left for the lower leverage.” 2:24:35

They note that a crying signal only works on a recipient who cares about the signaler's welfare.

“to the extent that you value my welfare at all. So you won't care if you don't value my welfare at all.” 2:26:37
26
2:28:21 – 2:31:36

Reflections on Mentorship and Podcast Wrap-Up

The hosts reflect on academic mentorship inspired by John Tooby, thank guest Deb Lieberman for her foundational contributions to evolutionary psychology, and conclude the episode with humorous banter about listener reviews, Patreon incentives, and podcast fundraising goals.

The hosts joke about using podcast support incentives and potential singing as a listener deterrent.

“If you don't give on Patreon, I'll start singing. That's that's the there.” 2:31:18