Men work more than their needs require only when forced to.
The result of this would be the formation of a new species. Here, then, I had at last got a theory by which to work. Taking the broad view of history, Diamond takes us from our primate heritage to the present ecological crisis, linking the two through entertaining and thoughtful discussions of numerous dimensions of human evolution in the context of a wide-ranging knowledge of birds and a great sensitivity to the natural world. He is particularly interested in the vagaries of sexual selection, arguing for Zahavi's handicap principle , a theory of honest signals in sexual advertizing. An illuminating series of interviews about formulating which questions to ask.