What makes us human, I think, is an ability to ask questions, a consequence of our sophisticated spoken language.

Well, in some ways we're not successful at all. We're destroying our home. That's not a bit successful.

Farm animals feel pleasure and sadness, excitement and resentment, depression, fear, and pain. They are far more aware and intelligent than we ever imagined...they are individuals in their own right.

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

War had always seemed to me to be a purely human behavior. Accounts of warlike behavior date back to the very first written records of human history; it seemed to be an almost universal characteristic of human groups.

Louis [Leakey] was anxious to initiate a scientific study of these chimpanzees. It would be difficult, he emphasized, for nothing was known; there were no guidelines for such a field study; and the habitat was remote and rugged. Dangerous wild animals would be living there, and chimpanzees themselves were considered at least four times stronger than humans. I remember wondering what kind of scientist he would find for such a herculean task.

Some people say, therefore, that violence and war are inevitable. I say rubbish: Our brains are fully capable of controlling instinctive behavior.