Fission-fusion social organization is characteristic of spider monkeys groups. They live in large groups that split into smaller groups during the day. Males are philopatric and male-male associations play an important role in their social organization. This is related with strong bonds between males. Therefore, the knowledge of male social relationships is of great value in the study of this species.

The aim of this work was to study social interactions between males, considering time and frequency of affinitive and aggressive male-male interactions in a community of spider monkeys in the Lacandona Rainforest. Data were collected  using the focal sampling method. Results showed there were differences in time and frequency between aggressive and affiliative male-male interactions. Also, there were significant differences for the distinct affiliative behaviors considered. Moreover, there was a particular pair of males that showed a series of affinitive behaviors that were completely different from the other males affinitive interactions. This set of affiliations lasted more than expected and looked like a consortship behavior, so when this behavior was performed, the interaction involved a copulation. In this case, the observation suggest an evidence of homosexuality in this species.