Cues to kinship and close relatedness during infancy in white-faced capuchin monkeys, Cebus capucinus

The ability to recognize kin has important impacts on fitness because it can allow for kin-biased affiliative behaviours and avoidance of mating with close kin. While the presence and effects of kin biases have been widely studied, less is known about the process by which animals recognize close kin. Here we investigate potential cues that white-faced capuchin monkeys, Cebus capucinus, may use to detect half siblings and closer kin. We focus on the first year of life in a sample of 130 infant (N = 65 infant females) wild capuchins from the Lomas Barbudal population in Costa Rica. We show that (1) infant relatedness to juvenile and adult males at the level of half sibling and higher can be predicted by male alpha status, spatial proximity and age proximity, and that (2) infant relatedness to juvenile and adult females at the level of half sibling or higher can be predicted by spatial proximity (but not age proximity). Furthermore, (1) the identities of infants' fathers can also be predicted by male alpha status and the spatial proximity between infants and adult males, and (2) age proximity (but not spatial proximity) is predictive of paternal sibship. These results suggest that infant capuchins have access to multiple cues to close relatedness and paternal kinship, although whether infants use these cues later in life remains to be explored in future research.