Would you undergo major surgery to benefit someone you don’t know, and will likely never meet? Who would do that — and what motivates a person to be so selfless? According to the theory of evolution, such selflessness should’ve died out long ago; it’s a voluntary, costly behavior that benefits another but not the good-doer. Yet altruism still exists.
And just as impossible to comprehend is the extreme opposite: those who go out of their way to harm others with no sense of compassion. What divides these two extremes?