Infants use relative numerical group size to infer social dominance

Significance The ability to detect dominance relationships is essential for survival because it helps individuals weigh the potential costs and benefits of engaging in a physical competition. Here we show that infants as young as 6 mo of age are capable of detecting dominance relations when provided with an ecologically relevant cue such as social group size. Furthermore, infants can infer the social dominance relationship between two competing individuals based on the size of the group to which they belong, and expect individuals from a numerically larger group to get their way. These findings reveal that infants may have an evolutionarily ancient cognitive capacity to represent social dominance relations that is shared with other species within the animal kingdom.