Humans have a lot of pro-social tendencies.

It is well known that apes in the wild offer spontaneous assistance to each other, defending against leopards, say, or consoling distressed companions with tender embraces.

I have often noticed how primate groups in their entirety enter a similar mood. All of a sudden, all of them are playful, hopping around. Or all of them are grumpy. Or all of them are sleepy and settle down. In such cases, the mood contagion serves the function of synchronizing activities.

The more self-aware an animal is, the more empathetic it tends to be.

If I were God, I'd work on the reach of empathy.

If both parties have a stake in the other, the chances of them killing each other are going to be reduced.

In humans, the family prevents infanticide. Next to language, the core family, consisting of a mother, a father and children, is the greatest difference between us and other primates.