Few people produce a new book in their hundredth year; fewer still at that age produce a book containing original ideas. But if anyone was going to do it, it surely had to be James Lovelock. He has been having good ideas for at least seventy-five of the past hundred years and is best known for one that occurred to him half a lifetime ago – the concept, which he named the Gaia hypothesis, that the Earth is a living organism. His new book, written with Bryan Appleyard, looks forward to the future of that organism, a future in which humankind is unlikely to play a major role, having fulfilled its ‘purpose’ by ushering in an era of artificial intelligence, the Novacene.

I should at this point declare an interest. I have known Lovelock for more than half my life, and nearly half of his, and have written a biography (now clearly in need of updating) covering a large part of his life. I come to praise Caesar, not to bury him. That said, if his latest book had contained the ramblings of a once great mind in its dotage, I would as a friend have ignored it. But because it is as important and accessible as anything he has written, if shorter than one might have hoped, I can recommend it with a clear conscience.

Underpinning Lovelock’s book is his conviction that as a home of intelligent life our planet is probably unique, at least in our galaxy, if not in the universe as a whole. This may seem to fly in the face of the