it took gordon burkhardt to figure that out he studies animal behavior from an evolutionary perspective highly primarily a reptile if ologist reptile behavior person and i've always like snakes and lizards and turtles and years ago articles came out about plating and i thought well i'm a remote sauna if you know and sort of play in a. scientists have known for a long time that mammals and birds play recognizing play in an animal that moves slowly it's a lot trickier. it's a dog's waiting its tail or monkeys or chips responded to tickling and so want some we can easily identify hey that's it's playful pleasurable fun for the animal it's hard to do that with a turtle. so we need more objective criteria. and i came up with 5 different groups and it's a 5 criteria of play. to qualify as playing a behavior must be done for no apparent reason 2. it has to be done over and over again. sometimes in an exaggerated way. in spontaneous. and the animal has to be doing it when it's not stressed. burghardt came up with his criterion after discovering reptiles are capable of play . girl. i was going t