Language, it is usually supposed, developed among the males of the human species in order to facilitate hunting-shooting-fishing activities of the "Pass us that spear, mate." "What? Oh, right ..." sort. But if that's the case then why, Robin Dunbar wants to know, is two-thirds of human conversation taken up with matters of social import, otherwise known as gossip? Because, he suggests, language evolved among women and was developed, not as an instrument of war, but as a tool which could bind individuals and societies together.
It's an intriguing theory, and Dunbar backs it up with lots of weird, wonderful and absolutely accessible science.