If you watch animals objectively for any length of time, you're driven to the conclusion that their main aim in life is to pass on their genes to the next generation.

I'm no longer sceptical. I no longer have any doubt at all. I think climate change is the major challenge facing the world.

Steve Irwin did wonderful conservation work but I was uncomfortable about some of his stunts. Even if animals aren't aware that you are not treating them with respect, the viewers are.

If we were all to reduce our demands for energy, it would make an enormous amount of difference.

Climate change will affect the whole of humanity, while terrorist attacks will only affect a small section of humanity. Of course, you wouldn't say that if you were related to someone who had been beheaded or blown up or murdered.

I suppose happiness is something one enjoys, but I suspect that happiness is not a state but rather a transition.

To suggest that God specifically created a worm to torture small African children is blasphemy as far as I can see. The Archbishop of Canterbury doesn't believe that.