"The word 'passion' describes attachments that are this strong. As I came to learn how such attachments are generated, it became the mission of this book to expose the hidden physical roots of the unique human capacity for passionate and creative work. It is now abundantly clear to me that these roots are more than deep and more than merely ancient. They reach down, and backward in time, past the dawn of human history to the beginning of primate life on this planet," p. 6.

"Washburn quite specifically insisted that the modern human brain came into being after the hominid hand became 'handier' with tools, maintaining that the brain was the last organ to evolve. It is a daring idea, one which requires us to look very closely at the evolutionary background of this hand, and at the changes that brought it its present anatomic configuration and functional capabilities...