This last chapter .. may have given the impression that somehow man is the ultimate triumph of evolution, that all these millions of years of development have had no purpose other than to put him on earth. There is no scientific evidence whatever to support such a view and no reason to suppose that our stay here will be any more permanent than that of the dinosaur.

It's a moral question about whether we have the right to exterminate species.

I'm a humanist. I'm neither one side nor the other.

We really need to kick the carbon habit and stop making our energy from burning things. Climate change is also really important. You can wreck one rainforest then move, drain one area of resources and move onto another, but climate change is global.

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 can mention many moments that were unforgettable and revelatory. But the most single revelatory three minutes was the first time I put on scuba gear and dived on a coral reef. It's just the unbelievable fact that you can move in three dimensions.

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