Chimpanzees are incredibly intelligent. They can learn more than 400 signs of American Sign Language. They have memories for spatial distribution, like numbers on a TV screen, way better than ours. You come onto the emotions: happiness, sadness, fear, and despair - all the things for which I was accused of being anthropomorphic when I ascribed them to chimpanzees.

We can learn to suppress our feelings for other reasons.

Words can be said in bitterness and anger, and often there seems to be an element of truth in the nastiness. And words don't go away, they just echo around.

I believe that we have more capability than any other creature to control our biological inheritance - and we do so most of the time.

Certainly, if you look at human behavior around the world, you have to admit that we can be very aggressive.

I was the sort of person who didn't care about hairdressing and clothes and parties and boyfriends. I really wanted to be in the wild.

If you consciously say 'I won't do it!' to yourself, then you have a good chance that you won't.