Families survive the Terrible Twos because toddlers aren't strong enough to kill with their hands and aren't capable of using lethal weapons. A 2-year-old with the physical capacities of an adult would be terrifying.

Part of the satisfaction of tattling surely comes from showing oneself to adults as a good moral agent, a responsible being who is sensitive to right and wrong. But I would bet that children would tattle even if they could do so only anonymously. They would do it just to have justice done.

Only the strong survive

Modern science tells us that the conscious self arises from a purely physical brain. We do not have immaterial souls.

Maybe one of the most heartening findings from the psychology of pleasure is there's more to looking good than your physical appearance. If you like somebody, they look better to you. This is why spouses in happy marriages tend to think that their husband or wife looks much better than anyone else thinks that they do.

Empathy has some unfortunate features - it is parochial, narrow-minded, and innumerate. We're often at our best when we're smart enough not to rely on it.