There's a fascinating (but – I must warn you – long) story at The Chronicle of Higher Education about the nature of boyhood. It's very interesting, and it tries to answer the questions about developmental gaps between young boys and young girls.
I loved this insight in this quote: "People look at the adult world and say, 'Men are still in charge.' So they look down at boys and say, 'They are small men, so they must be on the way to success'. It's still a man's world. People make the mistake of thinking it's a boy's world."