Once you incorporate that nonhomogeneous view of the humans a lot of (near or distant) historical events, trends, cultural stuff, etc makes a lot more sense (sadistic & opportunistic behavior is significantly more dominant and accepted than we pretend it to be, despite constant evidence) - to the extend that "evil" might not even be completely/fully the right word for it (lacks the quality of destructive-parasitic in it's most mondaine sense?).
We sure aren't a typical mammal, but we don't deviate all that much in single traits - we just concentrated a bunch of specific ones.