This book is the result of a noble dream, one of the many results made possible by the grant of Dwight H. Terry, whose object was “not the promotion of scientific investigation and discovery but rather assimilation and interpretation of that which has been or shall be hereafter discovered and its application to human welfare.”

Gaylord Simpson, Curator of Fossils, Mammals and Birds at the American Museum of Natural History, successfully carries out the Terry aim.

Any book written on the topic of evolution must, if accurate, be interesting. The topic is so embracing and unifying that it can give the reader a greater understanding of man's place in the scheme of things than any system of metaphysics ever could.

Often it (the study) fails to integrate well because of the vastness of the components of the study—paleontology and genetics, ontology,