Coping with strangers: how familiarity and active interactions shape group coordination in Corydoras aeneus

Social groups composed of familiar individuals exhibit better coordination than unfamiliar groups; however, the ways familiarity contributes to coordination are poorly understood. Prior social experience probably allows individuals to learn the tendencies of familiar group-mates and respond accordingly. Without prior experience, individuals would benefit from strategies for enhancing coordination with unfamiliar others. We used a social catfish, Corydoras aeneus , that uses discrete, observable tactile interactions to assess whether active interactions could facilitate coordination, and how their role might be mediated by familiarity. We describe this previously understudied physical interaction, ‘nudges’, and show it to be associated with group coordination and cohesion. Furthermore, we investigated nudging and coordination in familiar/unfamiliar pairs. In all pairs, we found that nudging rates were higher during coordinated movements than when fish were together but not coordinating. We observed no familiarity-based difference in coordination or cohesion. Instead, unfamiliar pairs exhibited significantly higher nudging rates, suggesting that unfamiliar pairs may be able to compensate for unfamiliarity through increased nudging. By contrast, familiar individuals coordinated with comparatively little nudging. Second, we analysed nudging and cohesion within triplets of two familiar and one unfamiliar individual (where familiar individuals had a choice of partner). Although all individuals nudged at similar rates, the unfamiliar group-mate was less cohesive than its familiar group-mates and spent more time alone. Unfamiliar individuals that nudged their group-mates more frequently exhibited higher cohesion, indicating that nudging may facilitate cohesion for the unfamiliar group-mate. Overall, our results suggest that nudges can mitigate unfamiliarity, but that their usage is reduced in the case of familiar individuals, implying a cost is associated with the behaviour.

Sense of fairness: Not by itself a moral sense and not a foundation of a lot of morality

Baumard et al. make a good case that a sense of fairness evolved and that showing this requires reciprocity games with choice of partner. However, they oversimplify both morality and the evolution of morality. Where fairness is involved in morality, other things are, too, and fairness is often not involved. In the evolution of morality, other things played a role. Plus, the motive for being fair originally was self-interest, not anything moral.

Bachelor Farmers in France

This article uses some evolutionary psychological micro hypotheses to explain the high number of bachelor farmers in France. The authors argue that three factors are responsible for farmers remaining single: their low average income, the migration of females away from rural areas and a steady rise in the divorce rate. According to the theory of sexual selection, the authors can expect females for whom wealth is a criterion in their choice of partner to migrate where the average income is higher. Growth in the number of divorces further increases the scarcity of younger females. The authors then show that when the divorce rate is high, young farmers are even more affected by the phenomenon of bachelorhood.

Partner Referral by HIV-Infected Persons to Partner Counseling and Referral Services (PCRS) - Results from a Demonstration Project

Objective: The objectives of this article are to determine factors associated with refusal and agreement to provide partner information, and evaluate the effectiveness of referral approaches in offering PCRS. Methods: Index clients from 5 sites that used 3 different PCRS approaches were interviewed to obtain demographic and risk characteristics and choice of partner referral method for PCRS. Logistic regression was used to assess factors associated with providing partner information. Results: The percentage of index clients who refused to provide partner information varied by site (7% to 88%). Controlling for PCRS approach, index clients who were older than 25 years, male, or reported having male-male sex in the past 12 months were more likely (p <0.01) to refuse to provide partner information. Overall, 72% of named partners referred by index clients were located and offered PCRS. The proportion of partners who were located and offered PCRS differed by referral approach used, ranging from 38% using contract referral (index clients agree to notify their partners within a certain timeframe, else a disease intervention specialist or health care provider will notify them) to 98% using dual referral (index clients notify their partners with a disease intervention specialist or provider present). Conclusion: Success in obtaining partner information varied by the PCRS approach used and effectiveness in locating and notifying partners varied by the referral approach selected. These results provide valuable insights for enhancing partner services.