It was most important to early humans to readily distinguish between friend and foe, and that's why we're so good at recognizing faces. And to be that good, we concentrate on the quirks and on what stands out, because it'd be wholly inefficient to remember features common to many. Which is why we tend to classify people according to outlier characteristics, and not commonalities. But again, biology is no justification for bigotry.
Source By TallSkin