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

‎Using his burgeoning intelligence, this most successful of all mammals has exploited the environment to produce food for an ever increasing population. Instead of controlling the environment for the benefit of the population, perhaps it's time we controlled the population to allow the survival of the environment.

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?

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

Life is not all high emotion. Some of the most interesting things are when its not highly emotional: little details of relationships and body language.

Dealing with global warming doesn't mean we have all got to suddenly stop breathing. Dealing with global warming means that we have to stop waste, and if you travel for no reason whatsoever, that is a waste.

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.