But our study focused on social interactions. The cases we reviewed involved 88 primate species and their interactions with 127 other animal species. Some interactions happen where primates and other animals spend time together because of shared foraging opportunities or protection from predators. For example, tropical primates form associations with other primate species and jointly forage in the tree canopy. In these cases, social interactions, such as grooming or play, may simply emerge from repeated contact and social familiarity.