Well, truth is that back in the days before socialism, when human beings "evolved" instead of "becoming socialists", us humans would go out every night with the intent of whupping up and/or killing everyone in sight and sometimes even possibly cooking and eating them! So we've developed inborn mechanisms (some more than others) to attack and fight.

But we're not the only ones: all other animals do the same. Only now, that we've turned into Democrats, is there hope for our kind, now that we know every life is precious and irreplaceable.