It has literally astounded me that some researchers continue to ponder if animals have fun and form friendships. Ample evidence shows they do. I recently wrote a review essay on the evolution of fun, especially in animal play, and view fun in the way that the Nobel laureate ethologist Niko Tinbergen suggested that we study various behavior patterns. Specifically, Tinbergen suggested that we ask questions about the evolution, adaptative value, causation, and development of various behavior patterns. Later, University of Tennesee psychologist Gordon Burghardt suggested that we also ask about the subjective experiences of animals as they perform different behavior patterns or find themselves in various social situations. So, concerning fun, we can ask: Why did it evolve? How does it promote individual reproductive fitness? What causes fun? How does fun develop? We can also ask what is the emotional side of fun or what is the personal experience of animals while they are having fun?
In mammals, because of evolutionary continuity, there is every reason to believe that the same neural mechanisms are important in nonhuman and human animal fun. Surely, having something be fun is a good way to keep the behavior in an individual's repertoire. It's also relaxing to just let it all hang out whenever you can. For some wild animals it's a rare experience to simply have fun. Many animals do things just for fun and it's about time we recognize this and study when, how, and why they seek out fun and why fun has evolved. What an exciting area of research this is, and it also would be ... fun.