Since the “races” are different, some MUST be more evolved than others, according to the theory.
Therefore, some races are SUPERIOR to others.
This was the assertion of the biology book in question in the Scopes trial.
Are there many races?.. -OR- are all decended from "Adam and Eve".. meaning theres merely ONE race..
Not necessarily superior, but more suited for the environment in which they were naturally selected. Humans are more isolated from nature today so these environmental pressures are not as apparent.
For example, extremely deep-sea fish did not evolve to have eyes but this is not inferior for their pitch-black environment.
Rapid changes can force a formerly adapted species to die out entirely. Dodo birds did not fly but this was not inferior in a predator free environment. Once their environment rapidly changed and included humans, flightless birds instantly became inferior.