I just used this quote in another answer, but it fits very well here - another of Mark Twain's quotes was: "Man is the only animal that blushes - or needs to."

Mark Twain also said, "Evolution is the law of policies: Darwin said it, Socrates endorsed it, Cuvier proved it and established it for all time in his paper on ''The Survival of the Fittest.'' These are illustrious names, this is a mighty doctrine: nothing can ever remove it from its firm base, nothing dissolve it."

Twain routinely ridiculed mankind for its undeserved pride in itself. The quote intends to place man and monkey on a similar status, rather than the typical view people have of the human race as being sublime and perfect. In modern terms, Twain might have said that people were just Monkey v1.01