Groups of people who did not have a generous sprinkling of “sociopaths” were killed or absorbed by those tribes that did.

…or it’s tough for a tribesmen who feels “compassion” for others or Empathy, identifying with another human being as being like themselves, to stand in the shield wall and shove the spearpoint into the face on the other side of the shields.

Achilles was a sociopath,  so was Lancelot.

If it comes to Civil War again in this country,  I plan on being a good little sociopath.