Maternal behavior helps when you have to be patient with nonverbal creatures.

Even in chimps there is true altruistic behaviour; behaviour that doesn't fit into the sociobiological model that says you either help a close relative and thereby your own genes, or you help somebody else now in return for their help in the future. When a very high-ranking male chimpanzee rescues a little orphan, saving his life, that kind of explanation doesn't work.

Studying chimps, I came to the conclusion that being evil is something that only humans are capable of. A chimp would never plan to pull another's nails out. The chimps' way of aggression is quick and brutal. I compare them to gang attacks.

I started as - well, I wanted to be Poet Laureate. And I wanted to be a naturalist. That's how I began. I didn't have any desire to go and be a scientist. Louis Leakey channeled me there. I'm delighted he did. I love science. I love analyzing and making sense of all these observations. So, it was the perfect rounding off of who I was into who I am.

We find animals doing things that we, in our arrogance, used to think was "just human".

If only we can overcome cruelty, to human and animal, with love and compassion we shall stand at the threshold of a new era in human moral and spiritual evolution - and realize, at last, our most unique quality: humanity.

At some point, my body will collapse. But I hope that my brain will still be working so that I can carry on with writing.