There's a story told about French philosopher René Descartes and his daughter. He boards a ship for a voyage over the North Sea with a large wooden box which he insists be handled with such great care that the sea captain's curiosity is aroused. When Descartes is out of his cabin the sea captain opens the box and is horrified to find a life sized automaton inside. He's so shocked he throws the "daughter" overboard.

Descartes championed a view of nature in which everything happened because of the physical forces acting between its constituent parts: nature as a machine. It was a coolly rational vision that caught the scientific spirit of the seventeenth century. He was fascinated by automata and what they tell us about what it is to be human.

Philip Ball tells the story of Descartes and his "daughter" and his writings about humans and machines. He finds out more about the thirst for mechanical wonders and what it said about theories of the human body in Descartes' time, from historian of science Simon Schaffer of Cambridge University. And Kanta Dihar of the Centre for the Future of Intelligence also at Cambridge University talks about current research into AIs, driven purely by some mechanism of formal logic, that can mimic the capabilities of the human mind, and how contemporary culture explores our fears about them.