After Dachau and Eliminating Competition

More on the theme of elimination competition. This is an excerpt from "After Dachau." In that book the Nazis had successfully purged the human race of the mongrel races and the only race left was the Aryan race. Here is one of characters describing the inevitability of the Aryan's success:

"The story of human evolution doesn't follow the same pattern as the evolution of other creatures. When reptiles emerged from the amphibians, they didn't destroy the amphibians. When mammals emerged from the reptiles, they didn't destory the reptiles. But the same is not true for humans. Among humans, each emerging species apparently destroyed the species from which it emerged. This explains why none of those earlier species survived to the present time. In fact, most biologists feel this accounts for the tremendous speed with which humans evolved from lower forms. So we Aryans were only doing what humans have done from the beginning. [Daniel Quinn, Pg.125, After Dachau]