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.

It's easy to become hopeless. So people must have hope: the human brain, the resilience of nature, the energy of young people and the sort of inspiration that you see from so many hundreds of people who tackle tasks that are impossible and never give up and succeed.

Of course we're all programmed genetically to some extent. But the "selfish gene" thesis doesn't explain everything.

I became intensely aware of the being-ness of trees. The feel of rough sun-warmed bark of an ancient forest giant, or the cool, smooth skin of a young and eager sapling, gave me a strange, intuitive sense of the sap as it was sucked up by unseen roots and drawn up to the very tips of the branches, high overhead.

We learn the social norms of our society and modify our behaviour accordingly.

I see that within each human being there are two extremes: there's the loving, the passionate, altruistic side that has evolved with us, and then there's the violent, brutal side that has evolved with us. The question for each individual is: which side is going to come out on top?

If everybody on the planet today had the same standard of living as the average European or American, we would need three new planets. But we don't even have one new planet. We have this one, and with the way we're polluting it, the shrinking water resources, the climate change, the experimentation with plants... the outlook is grim.