Play is important to the development of both humans and animals. In animals evolutionary psychologists believe there must be a reason for the benefit of play especially because there seem to be so many reasons to avoid it. The reasons to avoid it are because of the tendency for injury, expending valuable energy and distraction from predators. Yet play seems to be a normal activity with animals who occupy the higher strata of their own hierarchy of needs. On the end, animals on the lower strata, for example stressed and starving animals, generally do not play.

One play theory is "play as preparation". This was developed through observation that play often mimics adult themes of survival. In predators such as lions, bears and wolves, they play by chasing, pouncing, pawing, wrestling, and biting, as they learn to stalk and kill prey. Prey animals such as deer and zebras play by running and leaping as they nee speed and agility to escape the predators. Hoofed mammals also practice kicking their hind legs to learn to ward off attacks from predators. Playmates don't generally injure each other because attacking actions such as kicking and biting are not completely fulfilled. Also in social animals, playing might also help to establish dominance rankings. This is used among the young in order to avoid conflicts as adults.

It has also been discovered that the amount of time spent at play for many mammals peaks around puberty, and then drops off. This discovery corresponds to the development of the cerebellum, suggesting that play is not so much about practicing exact behaviors, as much as building general connections in the brain. Also as young animals tend to have an overabundance of brain cells in their cerebrum which is the outer areas of the brain, play has been shown to help the brain clean up this excess of cells. The result of this is a more efficient cerebrum at maturity.
The video below shows a turtle at play with a football.