Behavior evolution

Discipline was implemented by mothers and alloparent spotted dolphins (Stenella frontalis) mothers and alloparents on Little Bahama Bank, Bahamas. Disciplinarians were significantly more likely to be adults than juveniles. Although most disciplinarians were female, males were also observed to perform discipline. The recipients of discipline were male and female, and significantly more likely to be calves than juveniles. Pursuit, contact, and display behaviors were used in discipline, however pursuit behaviors were most often observed. Variables such as age class, sex, and parity were not found to influence how discipline was implemented. The durations of all disciplinary pursuits were under thirty seconds, and successful pursuits had slightly shorter duration than unsuccessful pursuits. Disciplinarian success was not significantly influenced by age class, sex, parity, or behavior used.

Economic game theory has been a challenge to traditional models of selfish human nature. Resource acquisition games, such as the dictator game, which have been primarily played by adults, have revealed that humans are inclined to share even when it is not in their best interest to do so. Few studies have been conducted on the development of resource distribution in children, and fewer still have explored the effect of context and level of involvement of a second player in such games. In the current study, 179 children from kindergarten, first, and second grades participated in a modified dictator game with another player. Children were randomly assigned to one of four conditions; a control condition, where they played individually with an anonymous player, or one of three experimental conditions with two players who each played with varying levels of involvement with the second player. It was found that kindergarteners shared significantly less across conditions than first and second graders, with first and second graders sharing similar amounts. The presence of another player significantly increased the amount of sharing for all grades. Additionally, second players shared significantly less than first players. Developmental and contextual patterns of sharing are discussed.