layfulness is what makes us human. Doing pointless, purposeless things, just for fun. Doing things for the sheer devilment of it. Being silly for the sake of being silly. Larking around. Taking pleasure in activities that do not advantage us and have nothing to do with our survival. These are the highest signs of intelligence. It is when a creature, having met and surmounted all the practical needs that face him, decides to dance that we know we are in the presence of a human. It is when a creature, having successfully performed all necessary functions, starts to play the fool, just for the hell of it, that we know he is not a robot.

I'm not so sure about this. theadvancedapes, we know that other primates are also "silly" and that they use play as a way of developing motor skills etc. So, this isn't unique to humans.

All at once, it was clear. The bush people, lounging about after dark in their family shelter, perhaps around a fire – basically just hanging out—had been amusing themselves doing a bit of rock art. And perhaps with some leftover red paste, a few of the younger ones had had a competition to see who could jump highest and make their fingermarks highest up the overhang.

I wonder, theadvancedapes are there examples of other primates competing solely for the sake of competition?