Isabel Behncke is a (hot) primatologist at Oxford - she specializes in play among wild bonobos. Play is defined as the ability to do things spontaneously and socially that induce pleasure. The bonobos spend most of their time playing; whereas chimpanzees will groom one another constantly as part of conflict resolution, bonobos will simply fool and mess around. Bonobos will engage in sex as a means of cementing friendships and social relations - bisexual sex is common. Behncke notes that in all social animals play continues into adulthood - think about it, all our friendships are built around play, whether it be sporting, joking, gossiping, sexual, or gaming based play. Without play, social relationships cannot be maintained - that joviality and relaxedness is in a way what society is based upon. We make friends at work because of the banter not because of the work. Play is a way of using our imagination, of doing things without inhibitions. There is nothing magical about this - Behncke suggests the adaptive joker hypothesis: we know that variability - the ability to deal with new strange situations in novel ways - is adaptive. Play, in bonobos and humans, is seen as kind of a hypothesis-tester, a way of practising your variability, to stay flexible. I would argue that children’s play - often involving dens, camping, building things, painting new ideas, manipulating objects, learning social roles in ‘house’, medicine in nurses and doctors - could be viewed as an adaptive training ground for our future lives. This just shows the importance of learning through play … young children are not taught to play, they invent their own world and their own games. Bonobos do the same.
I suggest you watch the talk, short but fascinating. She’s a clever woman.