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Recent papers

New! Does pride incentivize you to achieve acts or traits that other people value? Do people in East-Asian cultures lack a psychology of “self-enhancement,” as some theories in cultural psychology suggest? What dictates how socially valuable you are to those around you, culturally-specific norms or a human-universal grammar of social valuation? To find out, see Cross-cultural regularities in the cognitive architecture of pride by Daniel Sznycer, Laith Al-Shawaf, Yoella Bereby-Meyer, Oliver Curry, Delphine De Smet, Elsa Ermer, Sangin Kim, Sunhwa Kim, Norman Li, Florencia Lopez Seal, Jennifer McClung, Jiaqing O, Yohsuke Ohtsubo, Tadeg Quillien, Max Schaub, Aaron Sell, Florian van Leeuwen, Leda Cosmides, and John Tooby in Proceedings of the National Academy of Sciences, 2017. (Supplementary Information). Click here for the press release.

Is shame a maladaptive emotion with destructive consequences, as prominent theories claim? Or is it like pain—an evolved defense? We tested the hypothesis that shame evolved as a defense against being devalued by others. See Shame closely tracks the threat of devaluation by others, even across cultures by Daniel Sznycer, John Tooby, Leda Cosmides, Roni Porat, Shaul Shalvi, & Eran Halperin in Proceedings of the National Academy of Sciences, 2016. (Supplementary Information). Click here for the press release and here for more information.

Is punishing third parties an act of altruism? Or does third-party punishment result from a deterrence psychology for defending personal interests? To find out, see our new article in Psychological Science: Looking under the hood of third-party punishment reveals design for personal benefit by Max Krasnow, Andrew Delton, Leda Cosmides, & John Tooby.

Differences in political opinions: an occasion for calm reflection or a signal that people belong to rival gangs? A new study shows that political opinions engage an evolved system that tracks who is allied with whom, categorizing people by their coalitional alliances. When race does not predict political alliances, this alliance detection system categorizes people as members of rival political parties and starts to ignore race. What's more, racial categorization decreases, but categorization by sex and age do not. This is what you would expect if the mind treats race as an alliance cue...and nothing more. See Constituents of Political Cognition, by David Pietraszewski, Oliver Curry, Michael Bang Petersen, John Tooby, and Leda Cosmides. Click here for the press release and here to read the article.

Using a series of computer-based simulations, Max Krasnow, Andrew Delton, Leda Cosmides, and John Tooby demonstrate that individual selection pressures will give rise to and maintain punishment behavior given biologically plausible assumptions based on the social ecology and psychology of ancestral humans. Their findings appear in the journal PLosONE. Click here to read the article.

Research conducted by Aaron Sell at Griffith University in Australia and John Tooby and Leda Cosmides at UCSB have identified the functional advantages that caused the specific appearance of the anger face to evolve. Their findings appear in the journal Evolution and Human Behavior. Click here to read the press release and for more information.

Topics of Interest

For our previous research on how intergroup conflict decreases racial categorization and FAQ, see this:

Do space aliens need to attack Earth for people to unite across social boundaries? David Pietraszewski, John Tooby, and Leda Cosmides demonstrate that peaceful cooperation has the same effect as intergroup conflict in erasing social boundaries connected to race. See The content of our cooperation, not the color of our skin: An alliance detection system regulates categorization by coalition and race, but not sex. Click here for the press release and here to read the full article.

Is it possible to prevent people from automatically categorizing others by race? Years of psychological research suggest that race is always encoded in the process of impression formation, but the idea that the mind would have evolved mechanisms to identify racial categories is implausible given that our hunter-gatherer ancestors rarely to never encountered people of different races. See Can race be erased?: Coalitional computation and social categorization by Robert Kurzban, John Tooby, and Leda Cosmides in Proceedings of the National Academy of Sciences, 98(26), 15387-15392. Click here for FAQ and more

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For other recent CEP research on the psychology of coalitions and other kinds of group cooperation, see the following:

Humans cooperate in groups, but what is it about the human mind that makes this possible? To find out whether the mind has an evolved concept for identifying free riders-- individuals who take the benefits of group cooperation without contributing--see Delton, A. W., Cosmides, L., Guemo, M., Robertson, T. E., & Tooby, J. (2012). See The psychosemantics of free riding: Dissecting the architecture of a moral concept, by Delton, A. W., Cosmides, L., Guemo, M., Robertson, T. E., & Tooby, J. Journal of Personality and Social Psychology, 2012. Advance online publication. (Supplemental)

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Is there a relationship between men's strength and their sense of entitlement--and does it follow an ancestral logic? See these...

Do humans view issues of economic redistribution through the lens of cognitive adaptations for contests over resources? To find out, see The ancestral logic of politics: Upper-body strength regulates men’s assertion of self-interest over economic redistribution. by Michael Bang Petersen, Daniel Sznycer, Aaron Sell, Leda Cosmides, and John Tooby in Psychological Science, 2013.

Why does anger exist, what is its evolved function, and why are some people more anger prone than others? See Formidability and the logic of human anger by Aaron Sell, Leda Cosmides, and John Tooby, in Proceedings of the National Academy of Sciences, September 2009. Click here for more

Theories of animal conflict predict that humans should have an evolved specialization for assessing fighting ability. See Human adaptations for the visual assessment of strength and fighting ability from the body and face by Aaron Sell, Leda Cosmides, John Tooby, Daniel Sznycer, Christopher von Rueden, and Michael Gurven in Proceedings of the Royal Society London, (Biological Sciences), October 2008. Click here for more

Cross cultural research demonstrates that the male voice contains cues of fighting ability and upper body strength.  See Adaptations in humans for assessing physical strength from the voice by Aaron Sell, Gregory Bryant, Leda Cosmides, John Tooby, Daniel Sznycer, Christopher von Rueden, Andre Krauss, and Michael Gurven in Proceedings of the Royal Society London, (Biological Sciences), 277, 3509-3518. 

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How does two-person cooperation work? For recent work, see the following:

Natural selection builds brains and bodies to mesh with the structure of ancestral environments. What implications does this have for debates on the evolution of cooperation? To find out, see Meeting now suggests we will meet again: Implications for debates on the evolution of cooperation by Max Krasnow, Andrew Delton, John Tooby, and Leda Cosmides in Nature Scientific Reports. And for evidence that people use evolved heuristics for long-term, cooperative partner choice to calibrate their generosity toward partners in an ultimatum game, see Evidence of partner choice heuristics in a one-shot bargaining game by Adar Eisenbruch, Rachel Grillot, DarioMaestripieri, and James Roney in Evolution and Human Behavior.

What explains our strong inclination to track the reputations of others and to punish their bad behavior? We report new empirical tests that suggest these features of human nature are adaptations for deriving benefits from small-scale interactions, not from inter-group competition. See What are punishment & reputation for? by Max Krasnow, Leda Cosmides, Eric Pedersen, and John Tooby in PLOS ONE, 2012. (UCSB Press Release; Supplemental)

What explains why humans are so generous, even in one-shot interactions?  We show how the inherent uncertainty of social decision making, in combination with selection for direct reciprocity, leads to striking amounts of generosity. Our work reveals that natural selection creates motivation to be generous even in situations where generosity appears economically irrational. See The evolution of direct reciprocity under uncertainty can explain human generosity in one-shot encounters by Andrew W. Delton, Max M. Krasnow, Leda Cosmides, and John Tooby in Proceedings of the National Academy of Sciences, 2011. Click here for more

Click here to see our reply to a recent commentary on our article.

Click here to see a Science letter by Delton, Krasnow, Cosmides, and Tooby on alternative approaches to the evolution of cooperation.

Just how specialized is the cheater detection mechanism?  New research shows that it is activated only when the search for rule violations has the potential to reveal someone’s character—their propensity to cheat. It does not search for violations of social exchange rules when these are accidental, when they do not benefit the violator, or when the situation would make cheating difficult.  See Adaptive specializations, social exchange, and the evolution of human intelligence by Leda Cosmides, Clark Barrett, and John Tooby in Proceedings of the National Academy of Sciences, May 2010.  click here for more

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Will the second wave of the cognitive revolution tackle motivation? To find out, see Evolutionary psychology: New perspectives on cognition and motivation by Leda Cosmides and John Tooby in Annual Review of Psychology.

What explains the origins of personality trait covariation? To find out, see Testing an Adaptationist Theory of Trait Covariation: Relative Bargaining Power as a Common Calibrator of an Interpersonal Syndrome, by Aaron W. Lukaszewski in the Eurpoean Journal of Personality. 

What creates individual differences in personality? Does adaptively-patterned personality variation arise via specific gene polymorphisms (as predicted by evolutionary genetic models) or universal mechanisms of facultative calibration (as predicted by adaptationist models)? See The origins of extraversion: Joint effects of facultative calibration and genetic polymorphism by Aaron W. Lukaszewski and James R. Roney in Personality and Social Psychology Bulletin, March 2011.

Do our minds have cognitive systems that evolved for foraging, hunting, and avoiding predators? See:

Cross-cultural evidence for a domain specific adaptation in human spatial cognition for plant food gathering. See Cognitive adaptations for gathering-related navigation in humans by Max Krasnow, Danielle Truxaw, Steven Gaulin, Joshua New, Hiroki Ozono, Shota Uono, Taiji Ueno, and Kazusa Minemoto in Evolution and Human Behavior, January 2011.

Spatial Adaptations for Plant Foraging: Women Excel and Calories Count by Joshua New, Max Krasnow, Danielle Truxaw, and Steven J.C. Gaulin in the Proceedings of the Royal Society, Biological Sciences, 2007. Click here for more, including Krasnow, Truxaw, New & Gaulin's response to Brumfield et al. in Science...

Category-Specific Attention for Animals Reflects Ancestral Priorities, not Expertise” by Joshua New, Leda Cosmides, and John Tooby in the October 16, 2007 Proceedings of the National Academy of Sciences. Click here for discussion

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How do our minds detect which individuals in the social world are siblings? Does a kin detection mechanism regulate altruism and sexual aversion toward siblings?

The Architecture of Human Kin Detection by Debra Lieberman, John Tooby, and Leda Cosmides in Nature, 445, 727-731 (Feb 15, 2007). Click here for more



The Center for Evolutionary Psychology has a sister center in Japan, the Center for the Sociality of Mind, at Hokkaido University.

Interview with Leda Cosmides (El Mercurio, October 28, 2001) Click here

Interview with Leda Cosmides (Psychology Today, August 12, 2013) Click here