Rushton's book was like Darwin's Descent of Man for this age. Structured as a complete thesis should be. Starting at the foundations, each stage meticulously evidenced and proceeding logically from the former. Everything explained, nothing left out. The fundamentalist left reacted with seething hostility. Critics attacked it with everything they could, but their best wasn't good enough. His best critics were actually other race realists. Since the publication of this book, further data has come to light which refines and updates his thesis. For an overview of these refinements I recommend Edward Dutton's book Making Sense of Race.

One of the most fascinating sections of the book is comparative anatomy between races. Blacks have smaller brains, smaller skulls, prognathic jaws, larger teeth and more teeth. They have larger and more muscles controlling the jaw. What makes this interesting is how it mirrors evolutionary trends in the Homo genus. As the ancestral species of Homo sapiens evolved, larger brains had to be compensated with a reduction in jaw and tooth size. The muscles of the jaw reduced in size. In numerous anatomical markers, Negroes have a greater resemblance to archaic Homo species.

Each race actually carries DNA from previous Homo species. Europids carry a small amount of neantherdal DNA, which is lacking in Negroids. Negroids carry DNA from an unknown archaic species that predates neanderthals. It does appear that Negroids are "less evolved" for lack of a better term.

These anatomical differences pose a problem for left's one and only attack on race realism; poverty did it. Does poverty make your teeth bigger? Does poverty make you have more teeth? The deniers can only respond with "it just so happens." It just so happens they have smaller brains. It just so happens they have smaller craniums. It just so happens they have more teeth. And so on down the line. If these people were detectives investigating a murder they would say "it just so happens he had the murder weapon in his car, it just so happens he had the blood of the victim on his coat, it just so happens he was seen fleeing the scene of the crime, it just so happens he wrote a message saying he was going to kill the guy."