Why do male chicks play more than females? Study finds answers in distant ancestor

Play is widespread, but far from ubiquitous, across the animal kingdom. Especially common in mammals, play is also known to occur in taxa as diverse as birds, fish, octopuses, and even insects. But what is its function, given that natural selection never selects fun for its own sake? One prominent hypothesis is that play is beneficial to individuals because it allows them to practice skills needed later in life.