Social contact influences the response of infant marmosets towards novel food

To reduce the risks involved in investigating potential food, individuals may use social information from more experienced conspecifics. Infants of generalist foragers are those most often confronted with unknown food items. To investigate the extent to which the response of infant common marmosets, Callithrix jacchus towards novel food is influenced by the presence of experienced adults, we confronted six infants with novel and familiar food, either in their family group or in the absence of adults. In the absence of adults, the infants either refused to eat the unknown items or ate only small amounts, waiting longer and investigating the food more before feeding than when food was familiar. When adults were present during food presentation, differences in the treatment of familiar and novel food were much less pronounced, suggesting that social facilitation helped to overcome neophobia in the infants. Short approach latencies and high exploration rates indicate that the infants simultaneously showed high levels of both neophobia and neophilia, as predicted for individuals living in complex and variable environments that hold substantial foraging risks. Food transfers from adults to infants made up 17.5% of the food ingested by the infants and were usually initiated by the infants. Infants were more likely to take the first piece of food from an adult when it was novel than when it was familiar. The mean number of food transfer attempts and the proportion of ingested food that was acquired socially were higher for novel than for familiar food. Such effects of novelty suggest that food transfers function to transmit information.