In todays’s new York Times, an evolutionary explanation of the active intellect:
“On a very basic level, judging people by appearance means putting them quickly into impersonal categories, much like deciding whether an animal is a dog or a cat. ‘Stereotypes are seen as a necessary mechanism for making sense of information,’ said David Amodio, an assistant professor of psychology at New York University. ‘If we look at a chair, we can categorize it quickly even though there are many different kinds of chairs out there.’
Eons ago, this capability was of life-and-death importance, and humans developed the ability to gauge other people within seconds.”
This is the article in the NYT.