Punishments for norm violations are hypothesised to be a crucial component of the maintenance of cooperation in humans but are rarely studied from a comparative perspective. We investigated the degree to which punishment systems were correlated with socioecology and cultural history. We took data from the Standard Cross-Cultural Sample database and coded ethnographic documents from a sample of 131 largely non-industrial societies. We recorded whether punishment for norm violations concerned adultery, religion, food, rape or war cowardice and whether sanctions were reputational, physical, material or execution. We used Bayesian phylogenetic regression modelling to test for culture-level covariation. We found little evidence of phylogenetic signals in evidence for punishment types, suggesting that punishment systems change relatively quickly over cultural evolutionary history. We found evidence that reputational punishment was associated with egalitarianism and the absence of food storage; material punishment was associated with the presence of food storage; physical punishment was moderately associated with greater dependence on hunting; and execution punishment was moderately associated with social stratification. Taken together, our results suggest that the role and kind of punishment vary both by the severity of the norm violation, but also by the specific socio-economic system of the society.

Infanticide is considered a conspicuous expression of sexual conflict amongst mammals, including bottlenose dolphins. Although reported previously in this species, confirmed cases of infanticide and associated epimeletic behaviour are very rare and their socio-behavioural context remains poorly understood. Here, we provide evidence of epimeletic and infanticide behaviours in free-ranging bottlenose dolphins in Galicia, NW Spain. After describing the observed events, we include a complete description of the post-mortem examinations (where the carcasses were recovered) in order to confirm the cause of death. With evidences of blunt trauma in two of the presented cases, we confirm that the calves were intentionally killed by adult individuals. The aggressive interaction between adult individuals and the neonates together with the observed ante-mortem injuries bore a strong resemblance to the behaviours and traumatic injuries described in other cases of violent dolphin interactions in other parts of the world. The circumstances under which these infanticides occurred at our site fit the conditions proposed under the sexual selection hypothesis. The difficulties for researchers to observe this type of behaviour in the field and to find carcasses in good enough condition to determine the cause of death, emphasizes the importance of this type of study.

Socioecology has traditionally assumed that differences in social form between species derive from selected responses to particular evolutionary environments, while differences within a species reflect plastic responses to contemporary differences in ecology. The issue of behavioural or social plasticity is particularly salient for primatologists as it ties into conceptualizations of the evolution of cognitive capacity. In this regard, savanna baboons Papio hamadryas have provided a focus for research by virtue of their ecological plasticity and a problem for researchers by virtue of marked social differences in one subspecies – hamadryas baboons P. h. hamadryas – that cannot be explained solely by reference to current ecology. It is argued that the problem extends beyond hamadryas and that at least some differences between other populations also reflect selected responses to restricted, local evolutionary conditions. Of particular importance to the understanding of contemporary differences in baboon sociality is the extent to which evolutionary environments have constrained group size and perturbed adult sex ratios and, thereby, structured responses to the ever-present threat of infanticide. The view that there is much to be gained from a phylogenetic approach to population differences in behaviour is endorsed.