The title is misleading, for Darwin's anthropological reflections do not occupy the center of the stage and Gruber is generally less interested in content than in creative process. His focus is on the interaction of the thinker with the intellectual and social milieu in which he worked. He then reconstructs the way in which an ensemble of ideas were related to each other until a new scientific paradigm emerged. A more aggressive formulation of the theme would be ""How Does One Create a Scientific Revolution?"" This study reveals that scientific creativity is neither a straightforward advance nor a sudden act. It is not the charismatic visionary who revolutionizes a scientific field. The true revolutionist is, like Darwin, a rather cautious fellow. Through subtle changes he eventually enforces a shifting of the foundations of science. This insight into creative thought patterns alone makes the book worthwhile. For the historian of ideas there is the added bonus of Darwin's manuscripts.