Geologist David B. Kitts negatively reviewed the book commenting that all of "Grassé's arguments have been marshaled against Darwinian theory before and, in the opinion of most Darwinians, have been adequately countered." Grassé stated that evolution was driven by an internal factor. Regarding the identification of this factor, Kitts quotes Grassé as saying "perhaps in this area of biology can go no further: the rest is metaphysics". Kitts found this statement unacceptable commenting that "the fundamental issues raised by Grassé's theory of evolution do not even belong to biology, but to some other discipline."