An unprecedented review led by the University of Oxford, published in September 2026, identified that care and friendship behaviors between different species are not exclusive to humans. By analyzing 427 interactions between primates and other animals, scientists found valuable clues about how the willingness to create emotional bonds with pets may have very ancient evolutionary roots.
What did the study find about the interactions between monkeys and other species?
The researchers analyzed hundreds of records, including videos and expert reports, involving 88 species of primates and 127 types of partner animals, such as dogs, cats and birds. They found that primates often take the initiative to interact in a friendly way. Among the most common behaviors are playing, caressing and even sharing food. In rarer and more surprising situations, what scientists call adoption has been observed, where one species takes care of another’s baby as if it were its own, protecting and feeding the animal.
What real examples of friendship between animals were highlighted in the research?
One of the most emblematic cases occurred here in Brazil, where a group of capuchin monkeys adopted a marmoset baby, caring for it for at least ten months with the group’s total tolerance. Another example cited took place in a zoo in Israel, where a crested monkey began to take protective care of a chicken. These episodes show that the ability to go beyond the boundaries of one’s own species to offer care or seek companionship is not a trait that emerged only with modern human beings, but something present in our evolutionary relatives.
How do these behaviors help explain the origins of pets?
Science seeks to understand why humans are the only species that systematically keeps pets. Research suggests that, before we domesticated dogs for hunting or cats to protect grain, we already had in our biological heritage the “ingredients” necessary for this bond: curiosity, tolerance and the desire to play with different beings. The habit of having pets would, therefore, be a much more sophisticated and continuous version of a natural tendency of primates to establish physical and social proximity with other living creatures.
Are there differences between the relationship between primates and our relationship with animals?
Yes, and the authors make an important warning about this. Although interactions between monkeys and other species are positive, they are often brief and fleeting. The human relationship with pets presupposes lifelong coexistence and a constant investment of time, resources and feelings. Furthermore, in the wild, the approximation may occur for practical reasons, such as the search for protection or simple exploration of the environment, while in captivity, forced coexistence in enclosures can induce behaviors that would not occur in nature.