Evolution & Human Behavior RSS feed: Current Issue. Evolution and Human Behavior is an interdisciplinary journal, presenting research reports and theory in which evolutionary perspectives are brought to bear on the study of human behavior. It is primarily a scientific journal, but submissions from scholars in the humanities are also encouraged. Papers reporting on theoretical and empirical work on other species will be welcome if their relevance to the human animal is apparent. http://www.ehbonline.org/?rss=yesElsevier Inc.en © 2010 Elsevier Inc. All rights reserved. Evolution & Human Behavior1090-5138312March 2010 © 2010 Elsevier Inc. All rights reserved. healthpermissions@elsevier.comhttp://www.ehbonline.org/article/PIIS1090513809000622/abstract?rss=yesAbstract: Humans behave altruistically in one-shot interactions under total anonymity. In search of explanations for such behavior, it has been argued that at least some individuals have a general tendency to behave altruistically independent of profitability. In fact, a stable altruistic trait would be adaptive if it were recognizable. Then, altruists could choose each other in order to retain benefits through mutual cooperation. Previous research has shown that individuals can predict the degree of altruistic behavior of strangers by reading signs of emotions evoked in significant social decisions. However, the identification of benevolent emotional states is no guarantee of the existence of permanent altruistic traits, though permanent traits are the preferable criterion for selection of good interaction partners. In this study, we tested whether individuals are able to identify altruistic traits. Judges watched 20-s silent video clips of unacquainted target persons and were asked to estimate the behavior of these target persons in a money-sharing task. As the videotapes of the target persons had been recorded in a setting unrelated to altruistic behavior, the judges could not base their estimates on situational cues related to the money-sharing task but instead had to draw on stable signals of altruism. Estimates were significantly better than chance, indicating that individuals can identify permanent altruistic traits in others. As this mechanism raises opportunities for selective interactions between altruists, our findings are discussed with respect to their relevance for explaining the evolution of altruism through assortment.Not only states but traits — Humans can identify permanent altruistic dispositions in 20 sDetlef Fetchenhauer, Ton Groothuis, Julia Pradel10.1016/j.evolhumbehav.2009.06.009Evolution & Human Behavior 31, 2 (2010)2009-09-09Evolution & Human Behavior2009-09-09312S1090-5138(10)X0002-2Original Articles8086http://www.ehbonline.org/article/PIIS1090513809000932/abstract?rss=yesAbstract: Previous research has suggested that the spontaneous display of positive emotion may be a reliable signal of cooperative tendency in humans. Consistent with this proposition, several studies have found that self-reported cooperators indeed display higher levels of positive emotions than non-cooperators. In this study, we defined cooperators and non-cooperators in terms of their behavior as the proposer in an ultimatum game, and video-taped their facial expressions as they faced unfair offers as a responder. A detailed analysis of the facial expressions displayed by participants revealed that cooperators displayed greater amounts of emotional expressions, not limited to positive emotional expression, when responding to unfair offers in the ultimatum game. These results suggest that cooperators may be more emotionally expressive than non-cooperators. We speculate that emotional expressivity can be a more reliable signal of cooperativeness than the display of positive emotion alone.Emotional expressivity as a signal of cooperationJoanna Schug, David Matsumoto, Yutaka Horita, Toshio Yamagishi, Kemberlee Bonnet10.1016/j.evolhumbehav.2009.09.006Evolution & Human Behavior 31, 2 (2010)2009-11-09Evolution & Human Behavior2009-11-09312S1090-5138(10)X0002-2Original Articles8794http://www.ehbonline.org/article/PIIS1090513809000695/abstract?rss=yesAbstract: In the present study, the costly signaling theory (CST) is used to examine the effect of an offer of charity on social recognition. On behalf of a charitable organization, 186 students enrolled in 16 different courses were asked to offer support to unfamiliar persons in need. In accordance with our predictions, the results show that significantly more subjects are willing to give assistance if they make charity offers in the presence of their group members than when the offers are made in secret. In accordance with CST—but not with the prevailing explanations in social psychology—the likelihood of charity service was strongly influenced by the expected cost of altruistic behavior. Publicly demonstrated altruistic intentions yielded long-term benefits: Subjects who were willing to participate in a particular charity activity gained significantly higher sociometry scores (as a sign of social recognition) than did others. The cost of volunteerism correlated with social recognition in the case of a charity act judged as the most expensive (giving assistance to mentally retarded children), but not for the other categories of charity offer. Our results suggest that public generosity towards strangers as a costly signal may convey reliable information about subjects' personality traits, such as cooperativeness, but our data do not support the hypothesis that the signaling mechanism is related to sexual selection and mate choice.Altruism towards strangers in need: costly signaling in an industrial societyTamas Bereczkei, Bela Birkas, Zsuzsanna Kerekes10.1016/j.evolhumbehav.2009.07.004Evolution & Human Behavior 31, 2 (2010)2009-10-23Evolution & Human Behavior2009-10-23312S1090-5138(10)X0002-2Original Articles95103http://www.ehbonline.org/article/PIIS1090513809000701/abstract?rss=yesAbstract: Understanding the ultimate and proximate mechanisms that favour cooperation remains one of the greatest challenges in the biological and social sciences. A number of theoretical studies have suggested that competition between groups may have played a key role in the evolution of cooperation within human societies, and similar ideas have been discussed for other organisms, especially cooperative breeding vertebrates. However, there is a relative lack of empirical work testing these ideas. Our experiment found, in public goods games with humans, that when groups competed with other groups for financial rewards, individuals made larger contributions within their own groups. In such situations, participants were more likely to regard their group mates as collaborators rather than competitors. Variation in contribution among individuals, either with or without intergroup competition, was positively correlated with individuals' propensity to regard group mates as collaborators. We found that the levels of both guilt and anger individuals experienced were a function of their own contributions and those of their group mates. Overall, our results are consistent with the idea that the level of cooperation can be influenced by proximate emotions, which vary with the degree of intergroup competition.Cooperation in humans: competition between groups and proximate emotionsMaxwell N. Burton-Chellew, Adin Ross-Gillespie, Stuart A. West10.1016/j.evolhumbehav.2009.07.005Evolution & Human Behavior 31, 2 (2010)2009-09-16Evolution & Human Behavior2009-09-16312S1090-5138(10)X0002-2Original Articles104108http://www.ehbonline.org/article/PIIS1090513809000919/abstract?rss=yesAbstract: To test the hypothesis that sensitivity to monitoring drives people to act altruistically toward members of their own community, two experiments investigated whether an eye-like painting promotes altruism toward in-group members, but not toward out-group members. Participants played the role of dictator in a dictator game with another participant (a recipient) who was from the minimal in-group or out-group. Participants knew whether their recipient was an in-group member or an out-group member, but were informed that their recipient did not know the group membership of the dictator. In-group favoritism occurred only when participants were facing a computer desktop which displayed a painting of eyes, but did not occur in the absence of eyes. These findings demonstrate that the eye painting displayed on the participant's computer screen worked as a cue for monitoring and thus enhanced the participant's altruistic behavior.Altruism toward in-group members as a reputation mechanismNobuhiro Mifune, Hirofumi Hashimoto, Toshio Yamagishi10.1016/j.evolhumbehav.2009.09.004Evolution & Human Behavior 31, 2 (2010)2009-12-02Evolution & Human Behavior2009-12-02312S1090-5138(10)X0002-2Original Articles109117http://www.ehbonline.org/article/PIIS1090513809000877/abstract?rss=yesAbstract: Several studies have indicated that people are able to memorize the face of a cheater more accurately than that of a noncheater, but some contradictory findings have also been reported. Because most previous studies focused on memory for the faces of cheaters who break social contracts, the consequence for the subjects of their cheating was unclear. In our study, participants were asked to decide whether they trusted persons depicted in photographs to give them money using two sessions of the Faith Game. The participants tended to not increase their trust in the individuals, depicted in photographs, who had altruistically given money to them previously. However, participants recognized nonaltruists who had not shared money and, during the second session, rescinded the trust that they had previously placed in them. This suggests that bias in face recognition is not restricted to the recognition level, as previous studies have suggested, but also operates at the behavioral level and functions to facilitate the avoidance of persons who have caused some disadvantage in a previous interaction, rather than to facilitate new relationships with altruists by enhancing recognition of their faces.Biased face recognition in the Faith GameRyo Oda, Shun Nakajima10.1016/j.evolhumbehav.2009.08.005Evolution & Human Behavior 31, 2 (2010)2009-11-16Evolution & Human Behavior2009-11-16312S1090-5138(10)X0002-2Original Articles118122http://www.ehbonline.org/article/PIIS1090513809000841/abstract?rss=yesAbstract: Theoretical work predicts that individuals should strategically increase their reliance on social learning when individual learning would be costly or risky, or when the payoffs for individually learned behaviors are uncertain. Using a method known to elicit cumulative cultural evolution in the laboratory, we investigated the degree of within-group similarity, and between-group variation, in design choices made by participants under conditions of varying uncertainty about the likely effectiveness of those designs. Participants were required to build a tower from spaghetti and modeling clay, their goal being to build the tower as high as possible. In one condition, towers were measured immediately on completion and, therefore, participants were able to judge the success of their design during building. In the other condition, participants' towers were measured 5 min after completion, following a deliberate attempt to test the tower's stability, making it harder for participants to judge whether an innovative solution was liable to result in a good score on the final measurement. Cultural peculiarity (i.e., the extent to which a design could be identified as belonging to a particular chain) was stronger in the delayed measure condition, indicating that participants were placing greater reliance on social learning. Furthermore, in this condition, there was only very weak evidence of successive improvement in performance over learner generations, whereas in the immediate measure condition there was a clear effect of steadily increasing scores on the goal measurement. Increasing the risk associated with learning for oneself may favor the development of arbitrary traditions.Conservatism in laboratory microsocieties: unpredictable payoffs accentuate group-specific traditionsChristine A. Caldwell, Ailsa E. Millen10.1016/j.evolhumbehav.2009.08.002Evolution & Human Behavior 31, 2 (2010)2009-11-09Evolution & Human Behavior2009-11-09312S1090-5138(10)X0002-2Original Articles123130http://www.ehbonline.org/article/PIIS1090513809000853/abstract?rss=yesAbstract: The Wason selection task, a standard test of conditional reasoning, has featured prominently in experimental studies of cognitive adaptations for cooperation. The most prominent of these is Cosmides' investigations of cheater detection on social contract versions of the Wason selection task [Cognition 31 (1989) 187–276]. Subsequent to Cosmides' initial investigations, several researchers [Evol Hum Behav 21 (200) 25–37; Manage Decis Econ 19 (1998) 467–480; J Genet Psychol 163 (2002) 425–444; Evol Hum Behav 27 (2006) 366–380] have argued that people also are competent at detecting altruism on the Wason selection task, suggesting that there is nothing privileged about the detection of cheaters. However, an analysis of the selection tasks on which these claims are based suggests that participants may have solved these altruism-detection tasks correctly because the scenarios explicitly or implicitly provide the answer to the task in the scenario [Evol Hum Behav 21 (200) 25–37; Manage Decis Econ 19 (1998) 467–480; J Genet Psychol 163 (2002) 425–444], or due to confounds in the cheater-detection tasks leading to the (misleading) appearance of enhanced altruist-detection performance [Evol Hum Behav 27 (2006) 366–380]. We tested our conjecture by giving participants selection tasks with and without the answer embedded in the scenario. Performance dropped significantly on the altruism-detection tasks when the embedded answers were removed, whereas performance on cheater-detection versions was unaffected by the manipulation. A reanalysis of the findings of Oda et al. suggested that participants performed significantly worse on their altruism-detection problems than their cheater-detection problems — a finding that we replicate after removing confounds from the cheater-detection tasks of Oda et al. The results reaffirm the specificity of cheater-detection.Giving it all away: altruism and answers to the Wason selection taskLaurence Fiddick, Nicole Erlich10.1016/j.evolhumbehav.2009.08.003Evolution & Human Behavior 31, 2 (2010)2009-12-11Evolution & Human Behavior2009-12-11312S1090-5138(10)X0002-2Original Articles131140http://www.ehbonline.org/article/PIIS1090513809000683/abstract?rss=yesAbstract: This study tests the folk psychological belief that we find things funny because we think they are true. Specifically, it addresses the relationship between implicit preferences and laughter. Fifty-nine undergraduate Rutgers University students (33 females and 26 males) from ethnically diverse backgrounds were videotaped while watching a white stand-up comedian for 30 min. Positive emotional expression associated with laughter was later scored using the facial action coding system (FACS). Computer-timed Implicit Association Tests (IATs) were used to measure a subject's implicit preferences for traditional gender roles and racial preferences (blacks vs. whites). Results show that participants laughed more in response to jokes that matched their implicit preferences (e.g., those with stronger implicit preferences for whites laughed more at racially charged material). Implications for the evolution of humor, and laughter as a hard-to-fake signal of preferences, are discussed.It's funny because we think it's true: laughter is augmented by implicit preferencesRobert Lynch10.1016/j.evolhumbehav.2009.07.003Evolution & Human Behavior 31, 2 (2010)2009-10-05Evolution & Human Behavior2009-10-05312S1090-5138(10)X0002-2Original Articles141148http://www.ehbonline.org/article/PIIS1090513809000646/abstract?rss=yesIn a recent article in this journal (Pollet and Nettle, 2009), we reported that women with higher-income partners reported more frequent orgasms in the data from the Chinese Health and Family Life Survey (CHFLS). We also reported, using a stepwise model selection strategy implemented in SPSS 15.0 (SPSS, Chicago, IL, USA), that partner income was a better predictor of reported orgasm frequency than a number of control variables. However, in an accompanying commentary, Herberich et al. show that the model-fit statistics produced in SPSS are not properly comparable between models. This led us to choose an incorrect model as the best-fitting one. As they show, the effect of partner income is no longer significant once the control variables have been accounted for. We therefore wish to correct the conclusions of our article. The association in the CHFLS data between partner wealth and self-reported orgasm frequency is best explained by the fact that women with higher-income partners are healthier, happier, younger, and more educated than women with lower-income partners. The data do not support a direct effect of partner income on self-reported orgasm frequency, once other variables have been controlled for.Correction to Pollet and Nettle (2009): “Partner wealth predicts self-reported orgasm frequency in a sample of Chinese women”Thomas V. Pollet, Daniel Nettle10.1016/j.evolhumbehav.2009.06.011Evolution & Human Behavior 31, 2 (2010)2010-03-01Evolution & Human Behavior2010-03-01312S1090-5138(10)X0002-2Discussions149149http://www.ehbonline.org/article/PIIS1090513809001317/abstract?rss=yesPollet and Nettle (; henceforth, P&N) used ordinal regression models to investigate the effect of indicators of male quality, height and income, on self-reported female orgasm frequency. The strategy was as follows: in the first step the two key variables, male height and male income, were included. Subsequently, height was removed as it proved not to be a significant predictor at 5% level. Then, using an information theoretic approach, the authors examined whether model fit could be improved by adding control variables and stopped when the model could not be further improved as assessed by the Akaike Information Criterion (AIC) and the Bayesian Information Criterion (BIC). P&N concluded that the best-fitting model contained partner income as a predictor.A re-evaluation of the statistical model in Pollet and Nettle 2009Esther Herberich, Torsten Hothorn, Daniel Nettle, Thomas V. Pollet10.1016/j.evolhumbehav.2009.12.003Evolution & Human Behavior 31, 2 (2010)2010-03-01Evolution & Human Behavior2010-03-01312S1090-5138(10)X0002-2Discussions150151http://www.ehbonline.org/article/PIIS1090513809000865/abstract?rss=yesIt seems these days that female sexuality is one of the hot topics, whether you are a psychologist, biologist, sex researcher, anthropologist, sociologist or feminist. A plethora of books (both academic and popular press) have been published from The Secrets of Female Sexuality: Unapologetic Brutally Honest Truth About Sex That Women Secretly Wish You Knew But Can't Tell You (2007) by David Shade to The Case of The Female Orgasm: Bias in the Science of Evolution (2006) by Elizabeth Lloyd to the soon-to-be-published Why Women Have Sex: Understanding Sexual Motivations From Adventure to Revenge (And Everything in Between) (2009) by Cindy Meston and David Buss.Catherine Salmon10.1016/j.evolhumbehav.2009.08.004Evolution & Human Behavior 31, 2 (2010)2009-09-22Evolution & Human Behavior2009-09-22312S1090-5138(10)X0002-2Book Reviews152153http://www.ehbonline.org/article/PIIS1090513809000920/abstract?rss=yes“Are these the Nazis, Walter?”“No, Donny, these men are nihilists, there's nothing to be afraid of.”Dialogue from The Big Lebowski,Generation X and, even more so, the generation following it (those born 1984–2000) have grown up an extremely nihilistic generation. I do not mean nihilistic in the way The Big Lebowski means it (where they care about nothing), but instead in what I believe to be the mantra of nihilism: de omnibus dubitandum (“everything is to be doubted”). Many people associate this saying with Descartes, but I believe it is Nietzsche that understood the real impact of the term.Blog posting from the website “The Christian Watershed”Timothy Ketelaar10.1016/j.evolhumbehav.2009.09.005Evolution & Human Behavior 31, 2 (2010)2009-10-09Evolution & Human Behavior2009-10-09312S1090-5138(10)X0002-2Book Reviews154156