Playful fun in dogs

out how someone else would feel, given what is described: if you can’t, it’s not funny. As yet, the ‘what?’ question has not been explored systematically, but anecdotes of play suggest that some species may have cognitive abilities beyond those we credit them with. Baboons have been observed teasing cattle, pulling their tails when the cow was safely behind a wire fence and could not hurt the baboon (B. Smuts, personal communication). Teasing is fun for us because we realize how the victim feels [8]: does this mean that baboons have some as-yetunrecognized theory of mind ability? Young elephants regularly chase other animals, not just predators like jackals that might present some small threat to them, but also totally harmless species like wildebeest and egrets (personal observation). It would surely be a stretch to claim that elephants need such games to perfect their chasing skills or develop their chasing repertoire; so why is this fun for an elephant? Chimpanzees use objects as tools in many different ways, and it is therefore no surprise to find that they often play with objects (Figure 2). But when an adult chimpanzee, slowly consuming the brain of a monkey it has helped hunt, carefully places small pieces of skull onto a nearby liana, one-byone in a neat row just like we might place plum stones on the edge of a plate, it raises a question: how does a chimpanzee think about objects, such that this neat pattern is fun to make? In the future, the analysis of the specific content of animal fun, in addition to its distribution and functionality, may have the power to help us understand much more about how animals see their world.