Good stuff. I want to comment particularly on:

> the first of our ancestors to empathize and read facial expressions had a striking advantage.

This is a point made in a lot of detail in the book "A General Theory of Love" by three San Francisco psychiatrists. But humans are not the only animals to have developed this ability! I think the authors claim it arose with mammals in general. I know my cats can perceive and react to the emotional states of other cats -- and of humans! Actually, birds send out distress signals too. Other examples?