In April 2013, on board the unmanned spacecraft BION-M, a thick-toed gecko wriggled out of its polyurethane collar. In microgravity, the object floated away, then floated back toward the animal, then away again, approaching another gecko, and then a third. The animals got curious. One pushed the collar with its snout. Another tried inserting its head into it. Yet another pinned the thing down to the floor. As the spacecraft orbited Earth, the geckos started to play.
Russian scientists described this particular instance of reptile play in 2015, after observing the astronaut-geckos with cameras inside the spacecraft. The experiment, designed to study general behavior of reptiles in weightlessness, added to growing evidence that it’s not just kittens and baby chimps that play, but also birds, reptiles, fish and even invertebrates, including spiders and wasps. We have reports of octopuses fooling around with Lego blocks and Komodo dragons waging tug of war with their keepers. In 2015, a study of tooth marks on fossils showed that the bones may have served as a toy for a tyrannosaurid more than 65 million years ago. Play in non-mammalian species offers us novel insights into the activity’s function and evolution. Until recently, however, researchers doubted these diverse species were even capable of the behavior.
For decades, if not centuries, scientists rejected the notion that animals other than mammals actually play, even when faced with observational reports of frolicking fish or apparently fun-loving birds. “People tried to find every possible explanation,” says Gordon Burghardt, a behavioral biologist at the University of Tennessee, Knoxville. “They thought maybe the animals just tried to knock parasites off their bodies, even though there was no evidence they were doing that. Or they’d say that the animals were so stupid they didn’t know the thing they were playing with wasn’t edible, even though you wouldn’t say that about a cat playing with a rubber mouse.”
At the close of the 20th century, as extensive use of video and computers allowed scientists to analyze animal behavior in detail, the consensus began to change. Consider the case of Pigface, a Nile soft-shelled turtle who spent nearly his entire life alone in an enclosure at the National Zoo in Washington, D.C. In the 1980s, when Pigface was already in his 40s, he began biting himself and clawing at his face. “He used to self-mutilate so bad he’d get fungal growth on his skin,” recalls Burghardt. “So the reptile curator thought, ‘Hey, maybe he’s bored?’ No one back then thought that reptiles could get bored.”
