The story of science: power, proof and passion. Part 6, Who are we.

Presented by Michael Mosley, this is the last in a six-part series looking at the history of scientific discovery. In this part, Mosley focuses on brain anatomy and psychology. He begins by looking at the world of Ancient Egypt in which attitudes to the afterlife provide evidence of an understanding of what separates humans from other animals, however the brain was not thought to be what makes us human and it was discarded from the corpse prior to mummification. We hear about Rene Descartes' philosophical doubt and about the studies of brains performed by Thomas Willis in the 17th century. Studies on apes brought to the UK during the Victorian era fascinated Darwin, because of the similarities between the emotions he saw in apes with those of humans: tenderness, shame, joy. Mosley visits Salpetriere and charts its history, leading to an account of Charcot's vital work to separate and categorise different forms of mental illness, to use hypnosis as a treatment and to begin to hint at the presence of the unconscious mind. Mosley allows himself to be hypnotised and is surprised by the effects. Charcot influenced Freud and, later, psychology rose to prominence in the study of who we are. New technologies and systems of communication led to different metaphors to describe the workings of the mind. Mosley revisits the life and work of Santiago Ramón y Cajal who, through his art and photography, made a breakthrough discovery about neurons in the brain.