We humans love our pets, but we aren’t the only great apes who buddy up with other species. The data pool sources 303 cases across available scientific literature, 66 primatologists surveys, and 58 media accounts describing cross-species interactions involving humans’ close relatives. Situations included tufted gray langurs (Semnopithecus priam) petting squirrels in Sri Lanka, snub-nosed monkeys (Rhinopithecus bieti) playing with domesticated pigs in China, and even one case of capuchin monkeys (Sapajus libidinosus) in Brazil raising an infant marmoset for months. Beyond a better understanding of positive inter-species relationships among apes and monkeys, the researchers say further analysis could also benefit mixed animal facilities at wildlife sanctuaries and zoos. “Humans have long been considered unique in forming close social relationships with other species,” said Grueter.