Q. Do animals play games? If so, why?

A. Many immature mammals practice hunting and fighting skills in preparation for the real thing. Anyone who has raised a litter of kittens has observed their almost continuous cycles of pursuit and evasion, capture and attempted evisceration, and sometimes even a mock version of the killing bite. Fortunately, the rules of the game seem to stop a killer kitten short of committing real bodily harm to a littermate.

To the human observer, it looks like fun, but there is an underlying evolutionary utility to such romps. At least one researcher has suggested that such games, if games they are, are not just physical practice, but a way of preparing animals for mental and emotional reaction to unexpected perils.

The avian world also includes examples of what appears to be play. Absent the more detailed brain research done in mammals, this is a hard hypothesis to test conclusively. But some scientists believe that birds do things for pure pleasure, not just to practice useful skills, and that birds have the necessary brain receptors for reward and pleasure, as do mammals.

As for other animals, there is at least anecdotal evidence that some turtles and octopuses engage in play-like activities.