Conflict is rife in group-living species and exerts a powerful selective force. Group members
face a variety of threats from extra-group conspecifics, from individuals looking for …

In human societies, social behaviour is strongly influenced by threats of punishment, even
though the threats themselves rarely need to be exercised. Recent experimental evidence …

Group living is predicted to arise only when the fitness benefits outweigh the costs of
sociality. Group-living species—including cooperatively breeding and family-living birds and …

Market-like situations emerge in nature when trading partners exchange goods and
services. However, how partner choice option contributes to the expression of social …

Delayed dispersal is a key step in the evolution of familial animal societies and cooperative
breeding. However, no consensus has been reached on the ecological and social …

In social mammals, grooming is used not only for hygienic purposes; it also serves social
functions. We examined the grooming patterns of dominant males in groups of cooperatively …

Numerous studies in group-living animals with stable compositions have demonstrated the
complex and dynamic nature of social behaviour. Empirical studies occasionally provide …

Newborn infants can affect female social dynamics, and provide ideal conditions to test the
biological market theory and its assumptions. In infant markets, infants are the desired …

Highlights•We induced conflict in fish social groups by temporarily removing a group
member.•Aggression towards the returning group member increased with social density.•An …

Access to one's newborn infant is a commodity that can be traded for other benefits such as
grooming in nonhuman primates. According to the biological market paradigm, the price …