Bonobos, Pan paniscus, chimpanzees, Pan troglodytes, and marmosets, Callithrix jacchus, prefer to feed alone

Many primates share food, but the motives behind this food sharing are mostly not known. We investigated individualsʹ preference to feed either alone or together with a tolerant partner. Subjects (chimpanzees who are highly competitive around food, bonobos who are more tolerant around food and common marmosets who are cooperative breeders and share food actively with some partners) were tested with a door-opening paradigm. In a 2 × 2 design with the factors ‘food’ and ‘partner’, subjects had the opportunity to eat piles of sharable food, if present, and/or to open the door, thereby allowing the partner, if present, to join the subject. While food had a main effect on the subjectʹs behaviour, the presence of the partner did not. Individuals of all species opened the door much more often if there was no food available. These results suggest that regardless of their differing social organizations, chimpanzees, bonobos and marmosets do not voluntarily co-feed, but do not mind having company if there is no food present.