According to researchers at Imperial College London, male monkeys regularly have gay sex and are behaviourally bisexual. The study found that same-sex sexual behavior among monkeys made them better friends, and more likely to back each other up in conflicts. This study focused on 236 males within a wild colony of 1,700 rhesus macaques on a Puerto Rican island over three years. The findings suggest that “same-sex sexual behaviors” (SSB) have evolved and could be a common feature of primate reproduction, challenging beliefs that this is rare in non-human animals.