Magazine issue 2943.
If we consider the contribution of play to children's development as learners, and the harm caused by starting formal learning at 4 to 5 years old, the evidence for a later start is very persuasive.
This evidence comes from anthropological, psychological, neuroscientific and educational studies. For example, research on children's play in extant hunter-gatherer societies, and evolutionary psychology studies of other mammalian young, have identified play as an adaptation that enabled early humans to become powerful learners and problem-solvers.