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. But humanity is facing a very big, slow, long, drawn-out threat, and that is to do with the way the weather is changing and the size of the population.

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

I often get letters, quite frequently, from people who say how they like the programmes a lot, but I never give credit to the almighty power that created nature.

Sentimentalising is anathema, as far as I am concerned. It leads you into ethical problems about violence and killing and eating meat. The whole world becomes topsy-survy if you impose moralities that were evolved within human society on what a blowfly or what a parasite does... there are lots of emotions you can deduce from an animal's behaviour that are correct, but when you start saying it's feeling guilty or thinking or a loved one or mourning, you must be very careful of those feelings.

I have no doubt that the fundamental problem the planet faces is the enormous increase in the human population

I've been to Nepal, but I'd like to go to Tibet. It must be a wonderful place to go. I don't think there's anything there, but it would be a nice place to visit.

The World is full of wonders, but they become more Wonderful, not less Wonderful when Science looks at them.