The Behavioral Immune System with Josh Tybur

Hosts Dave Pietraszewski and David Pinsof introduce guest expert Josh Tybur, discussing his expertise in disgust and disease psychology. Tybur shares his personal and academic journey moving from the US to Amsterdam during the financial crisis, reflecting on differences between American and European universities and experiencing pandemic lockdowns in an urban setting.

Josh Tybur discusses his empirical research tracking psychological variables related to pathogen avoidance, disgust sensitivity, and outgroup attitudes during the COVID-19 pandemic in the Netherlands, providing insights into how human behavior and contact comfort changed when infectious disease threats became highly salient.

Dave Pietraszewski, David Pinsof, and guest Josh Tybur discuss a multi-year longitudinal study tracking behavioral immune system responses during the COVID-19 pandemic. Tybur explains that despite widespread reflective disease worries, measures of disgust sensitivity, anti-immigrant bias, and contact comfort remained stable over time due to high individual-level consistency.

Dave Pietraszewski, David Pinsof, and guest Josh Tybur examine the evolutionary logic of the behavioral immune system, highlighting pioneering work by Mark Schaller and others. They discuss how ancient parasite pressures shaped human psychology across domains like eating and social interaction, and how local ecological adaptations may inform prejudice toward outgroups.

Josh Tybur and Dave Pietraszewski discuss skepticism surrounding the hypothesis that the mind evolved to treat out-group membership as a cue to pathogens. Tybur highlights counterevidence from social psychology, including minimal group paradigms and coalition detection, suggesting that intergroup biases track assumptions of interdependence rather than ecological origins.

The speakers examine how people detect real infection cues versus relying on general relationship valuation. They discuss experimental findings showing that individuals use visual and acoustic signals of immune activation and calibrate pathogen avoidance tendencies based on how much they value specific social partners.

Host Dave Pietraszewski and guest Josh Tybur discuss how the behavioral immune system interacts with social valuation and intergroup attitudes. Tybur explains that tolerance for infection risk depends heavily on interpersonal value and traits like honesty rather than outgroup status alone. They also examine how immigrant assimilation affects disgust responses and anti-immigrant attitudes.

Guest Josh Tybur and the hosts discuss the relationship between pathogen avoidance and political conservatism, exploring whether this connection is mediated by sexual strategies rather than direct outgroup hostility. They review replicability issues in psychophysiological threat reactivity measures and summarize the broad impact of the behavioral immune system on social and mating psychology.

In this section, the speakers discuss how pathogen avoidance mechanisms and disgust sensitivity are modulated in the context of parenting and mating. Josh Tybur and the hosts explore research on parental tolerance for infant waste, the methodological complexities of priming studies in sexual contexts, and whether the behavioral immune system operates with targeted precision rather than blunt generalization.

The speakers examine how sophisticated adaptations within the behavioral immune system account for social rituals, physical affection, and cross-cultural sexual practices. David Pinsof and Josh Tybur discuss costly signaling theories, exploring why behaviors involving pathogen exposure or physical risk—such as contact rituals and BDSM—may function as hard-to-fake signals of social affiliation and sexual arousal.

Host David Pinsof and guest Josh Tybur discuss how people perceive research on disgust and pathogen avoidance. They examine whether the field faces resistance, comparing it to ideological pushback in other areas of evolutionary psychology, and discuss whether apparent disgust toward physical abnormalities or obesity is better explained by social value or infection cues.

The speakers explore the cultural phenomenon of zombies through the lens of evolutionary psychology, discussing them as supernormal stimuli representing severe pathogen risk and zoonotic infection, while contrasting fictional representations of mobile infected individuals with real-world infectious diseases.

Host Dave Pietraszewski, David Pinsof, and guest Josh Tybur discuss how evolutionary biology explains disease vectors and the virulence-spreadability trade-off. They examine how pathogens balance incapacitating their hosts with the need to spread through vectors like mosquitoes or fleas, referencing historical perspectives from Paul Ewald's work on infectious disease.

Guest Josh Tybur shares his critical perspective on the concept of evolutionary mismatch in evolutionary psychology. He argues that mismatch is often overextended, poorly tested, and conflates behavioral ecology with evolutionary psychology, while discussing examples like junk food preferences, ancestral ecologies, and error management theory.

The hosts and guest discuss the concept of evolutionary mismatch, examining whether it serves as a useful analytical tool for evolutionary psychologists or functions merely as an intuitive, lazy narrative shortcut. They also touch upon early pathogen and disgust research, considering how initial broad models have evolved toward greater specificity.

The speakers evaluate whether pathogen sensitivity relates to phenomena like conformity, noting that findings have been shaky. They then pivot to discuss the relationship between disgust and moral judgment, exploring Jonathan Haidt's work on moral foundations, emotional intuitions, and moral dumbfounding through classic vignettes.

Guest Josh Tybur discusses historical research on disgust and moral priming, addressing subsequent criticisms and a meta-analysis questioning the effect. With hosts Dave Pietraszewski and David Pinsof, Tybur explores empirical distinctions between disgust and anger in moral violations, highlighting how victim identity, perpetrator value, and behavioral motivations shape distinct emotional responses and aggression tendencies.

Josh Tybur shares empirical findings from studies using vegetarian populations to test whether personal disgust toward consuming meat predicts moral condemnation of meat-eaters. He explains how self-disgust uniquely predicts negative evaluations of specific norm violations independently of moral motivations, contrasting these results with other emotions like fear and defending the relevance of disgust to moral psychology.

Josh Tybur and the hosts discuss how feelings of disgust influence the moralization of behaviors such as incest and homosexuality. They explore theories on how cultural evolution, individual costs, and social coordination shape cross-cultural taboos, noting how attitudes toward homosexuality have shifted dramatically over time compared to other moral rules.

The speakers debate whether moralizing disgust requires direct exploitation benefits, such as opportunities to exclude or dominate others, rather than merely incurring no personal cost. They consider how resource scarcity and zero-sum contexts might drive the emergence of disgust-based moral rules in human societies.

Dave Pietraszewski, David Pinsoff, and Josh Tybur discuss how moral condemnation and disgust can function as strategic tools for acquiring status without necessarily excluding others. They explore religious framing, political signaling, and how coalition-building and social contagion parallel physical pathogen avoidance.

The speakers examine the similarities and differences between physical pathogen disgust and moral disgust. Josh Tybur and David Pinsoff consider how gossip and behavioral motivations function to manage reputation and protect individuals from unwanted inferences of alliance with norm violators.

Dave Pietraszewski and Josh Tybur discuss the shared phenomenology between pathogen disgust and moral disgust, drawing an analogy to the representation of opportunity costs in mental versus physical effort. They explore whether commonalities reflect contagion or valuation.

In the concluding segment, host Dave Pietraszewski and guest Josh Tybur briefly experience a connection glitch before summarizing the conversation about high-level commonalities in organism affordances, wrapping up the interview as it grows late for Josh.