5. The Spark of Being

Dr Geoff Bunn's ten-part history is a journey through 5000 years of our understanding of the most complex thing in the known universe.

From Neolithic times to the present day, Geoff journeys through the many ideas of what the brain is for and how it fulfils its functions.

What soon becomes obvious is that our understanding of this most inscrutable organ has in all periods been coloured by the social and political expedients of the day no less than by the contemporary scope of scientific or biological exploration.

In this episode, the focus is on electricity and communication, within the brain and between the brain and the rest of the body.

When John Walsh showed, in 1776, that an eel could generate electricity, it became possible that human consciousness also relied on sparks fizzing within the brain.

It came at a time when Benjamin Franklin - an acknowledged expert on electricity - was signing the Declaration of Independence which asserted that all men are created equal.

This generated a new perspective on the workings of the brain - with the old hierarchical model discarded in favour of the doctrine of equipotentiality.

Featuring the voices of:

* Paul Bhattacharjee
* Jonathan Forbes
* Hattie Morahan

Producer: Marya Burgess

First broadcast on BBC Radio 4 in November 2011.