In spite of recent advances in the study of evolution, scholars have shied away from the most intriguing problem of all--how and why animal nature became human nature. In confronting this problem, Peter Wilson leads his readers on a fascinating exploration. What made it possible, he asks, for one genus of the order Primates, living in Africa in the Plio-Pleistocene era, to become human and to develop culture? Continuing the tradition of bold speculation...