Friends With Benefits. (cover story)

The article explores the concept of friendship in nonhuman animals, noting that long-term cooperative relationships with unrelated animals have been observed in many animal social interactions. Various examples are provided of research studies on animal species that exhibit friendship behaviors, including dolphins, horses, and baboons. Scientists have investigated explanations for animal friendship such as reciprocal altruism, mutual defense, and the evolution of social behaviors to benefit reproductive fitness, longevity, and the regulation of stress. Also discussed is the importance of understanding animal friendships in the study of human relationships.