QUOTE : Human beings have evolved to be extremely good at identifying other individual humans. The race's survival depends on it. A guard lets the wrong person through the gate, and a whole settlement is wiped out. There are a million ways to tell two human beings apart. Not just appearance, either. Gait, odor, pheromones, speech patterns, dialect, nervous habits... even the way people breathe. Even parents of identical twins have little difficulty telling them apart, despite the fact that they are genetically identical and were raised in exactly the same environment, because of tiny differences in appearance and behavior that accrue as the result of differing experiences. The ability of one human to recognize another by appearance is especially acute when it comes to heterosexual males observing nubile females. There is nothing on Earth men pay more attention to than the appearance of sexually attractive young women.