In the West, that's what's happening. The birth rate has been dropping steadily and still is. But there is still a vast amount of the world where that's not the case. And that is where the big population growth is taking place.

Clearly we could devastate the world... as far as we know, the Earth is the only place in the universe where there is life. Its continued survival now rests in our hands

I've been bitten by a python. Not a very big one. I was being silly, saying: 'Oh, it's not poisonous' Then, wallop! But you have fear around animals.

It seems to me that the natural world is the greatest source of excitement; the greatest source of visual beauty; the greatest source of intellectual interest. It is the greatest source of so much in life that makes life worth living.

Can a growing human population still leave space for wildlife?

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.

You'll find people where their conditions aren't changing in any way, its rather rare for them to be happy.