Explaining unconditional cooperation, such as donations to charities or contributions to public goods, continues to present a problem. One possibility is that cooperation can pay through developing a reputation that makes one more likely to be chosen for a profitable cooperative partnership, a process termed competitive altruism (CA) or reputation-based partner choice. Here, we show, to our knowledge, for the first time, that investing in a cooperative reputation can bring net benefits through access to more cooperative partners. Participants played a public goods game (PGG) followed by an opportunity to select a partner for a second cooperative game. We found that those who gave more in the PGG were more often selected as desired partners and received more in the paired cooperative game. Reputational competition was even stronger when it was possible for participants to receive a higher payoff from partner choice. The benefits of being selected by a more cooperative partner outweighed the costs of cooperation in the reputation building phase. CA therefore provides an alternative to indirect reciprocity as an explanation for reputation-building behaviour. Furthermore, while indirect reciprocity depends upon individuals giving preference to those of good standing, CA can explain unconditional cooperation.

Previous research has shown that political leanings correlate with various psychological factors. While surveys and experiments provide a rich source of information for political psychology, data from social networks can offer more naturalistic and robust material for analysis. This research investigates psychological differences between individuals of different political orientations on a social networking platform, Twitter. Based on previous findings, we hypothesized that the language used by liberals emphasizes their perception of uniqueness, contains more swear words, more anxiety-related words and more feeling-related words than conservatives’ language. Conversely, we predicted that the language of conservatives emphasizes group membership and contains more references to achievement and religion than liberals’ language. We analysed Twitter timelines of 5,373 followers of three Twitter accounts of the American Democratic and 5,386 followers of three accounts of the Republican parties’ Congressional Organizations. The results support most of the predictions and previous findings, confirming that Twitter behaviour offers valid insights to offline behaviour.

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Punishing group members who parasitize their own group's resources is an almost universal human behavior, as evidenced by multiple cross-cultural and theoretical studies. Recently, researchers in social and behavioral sciences have identified a puzzling phenomenon called "antisocial punishment": some people are willing to pay a cost to "punish" those who act in ways that benefit their shared social group. Interestingly, the expression of antisocial punishment behavior is regionally diverse and linked to the sociopsychological dimensions of local cultural values. In this review, we adopt an ecological perspective to examine why antisocial punishment might be an advantageous strategy for individuals in some socioeconomic contexts. Drawing from research in behavioral economics, personality and social psychology, anthropology, we discuss the proximate mechanisms of antisocial punishment operating at an individual level, and their consequences at the group and cultural levels. We also consider the evolutionary dynamics of antisocial punishment investigated with computer simulations. We argue that antisocial punishment is an expression of aggression, and is driven by competition for status. Our review elucidates the possible socioecological underpinnings of antisocial punishment, which may have widespread repercussions at a cultural level.

In an attempt to explain gender differences in risk taking from an evolutionary perspective, this study examined the attractiveness of risk taking in potential mates. Questionnaire data from a sample of 352 primarily undergraduate students at Liverpool University, U.K., provided participants' ratings of physical, social and financial risk-taking and risk-avoiding profiles in terms of attractiveness for long-and short-term relationships. As well as showing a considerable variation in the ratings of different types of risk, we found that the relationship type affected male and female preferences in a similar fashion. Both genders rated risk avoiders as more attractive than risk takers in the context of long-term relationships. In contrast, for short-term relationships men and women preferred risk takers over risk avoiders.