The idea that we might create machines more intelligent than ourselves is not new. Myths and folk stories abound with creations such as the bronze automaton Talos, who patrolled the island of Crete in Greek mythology. These stories reflect a deep, atavistic fear that there could be other minds that bear the same relationship to us as we do to the animals we eat or keep as pets. With the arrival of artificial intelligence, the idea has re-emerged with a vengeance.

We are condemned to understand new phenomena by analogy with things we already understand, just as the anatomists of old named parts of the brain after fruit and nuts — the amygdala (almonds) and the olives, to name but two. Although Hippocrates, in the fourth century BC, had firmly placed the brain at the centre of human thought and feeling, most early medical authorities had little use for it.

Aristotle thought it was a radiator for cooling the blood. The importance of the brain, for Galen 500 years later, were the fluid cavities — the ventricles — in its centre, and not the tissue of the organ itself. With the rise of scientific method in the 17th century, the brain started to be explained in terms of the latest modern technology. Descartes described the brain and nerves as a series of hydraulic mechanisms. In the 19th century the brain was explained in terms of steam engines and telephone exchanges.