You can only get really unpopular decisions through if the electorate is convinced of the value of the environment. That's what natural history programmes should be for.

All our environmental problems become easier to solve with fewer people and harder - and ultimately impossible to solve - with ever more people.

How could I look my grandchildren in the eye and say I knew what was happening to the world and did nothing.

It's extraordinary how self-obsessed human beings are. The things that people always go on about is, 'tell us about us', 'tell us about the first human being'. We are so self-obsessed with our own history. There is so much more out there than what connects to us.

I think the most alarming animals I have encountered are really poisonous snakes.

I like animals. I like natural history. The travel bit is not the important bit. The travel bit is what you have to do in order to go and look at animals.

Human beings, because we're so clever, have removed every single one of those population limiting factors... So nothing controls our increase in numbers except our own wish. Since I first started making television programs, the population of the world has increased three times. That's an extraordinary notion. Can it increase four times? Can it increase five times? The Earth is a finite size. So a point will eventually come when we run out of food, when we run out of space and when we will have destroyed most of the natural world. So ought we to do something about it before that happens?