Is a prolonged middle childhood the secret to the success of the human species?

The New York Times “The Hormone Surge of Middle Childhood”

I think that what’s particularly interesting about the research described in this article is the role of play in human development: the middle childhood period seems to be a period rich with playful experimentation and learning. It is feasible that this “luxury” allowed adult Homo sapiens to outwit their hominid cousins, leaving the playful human as the last bipedal cooperative social species standing.