But does that mean that war and violence are inevitable? I would argue not because we have also evolved this amazingly sophisticated intellect, and we are capable of controlling our innate behavior a lot of the time.

Here we are, arguably the most intelligent being that's ever walked planet Earth, with this extraordinary brain ... and yet we're destroying the only home we have.

If you look through all the different cultures. Right from the earliest, earliest days with the animistic religions, we have sought to have some kind of explanation for our life, for our being, that is outside of our humanity.

I don't even think of chimps as animals. I think of them as beings.

The hardest part of returning to a truly healthy environment may be changing the current totally unsustainable heavy-meat-eating culture of increasing numbers of people around the world. But we must try. We must make a start, one by one.

When I go back to Gombe it's to be in that timeless world where it's soft and where life is entwined and you actually see the pattern of nature. I always feel this great spiritual power which I believe is around.

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