The Dark Light Years — Brian W. Aldiss

A strange alien species forces us to question our definition of civilization in this biting satire from the Grand Master of Science Fiction.

What would intelligent life�'forms on another planet look like? Would they walk upright? Would they wear clothes? Or would they be hulking creatures on six legs that wallow in their own excrement? Upon first contact with the Utod -- intelligent, pacifist beings who feel no pain -- mankind instantly views these aliens as animals because of their unhygienic customs. This leads to the slaughter, capture, and dissection of the Utod. But when one explorer recognizes the intelligence behind their habits, he must reevaluate what it actually means to be “intelligent.”