This is a podcast from the archives of the BBC Reith Lectures.

This lecture in the series The Future of Man, given by Sir Peter Medawar, was originally broadcast in 1959.

The Future of Man. The BBC presents P.B. Medawar with the last of six wreath lectures.

In this series, Professor Medawar has discussed some problems involved in thinking about the biological future of humanity.

In the final lecture, he describes how it is that the human brain has given man his special status.

In this last lecture, I shall discuss the origin in human beings of a new,

a non-genetical system of heredity and evolution,

based upon certain properties and activities of the brain.

The existence of this non-genetical system of heredity

is something you're perfectly well aware of.

It wasn't biologists who first revealed to an incredulous world that human beings have brains,

that having brains makes a lot of difference, and that a man may influence posterity by other than genetic means.

Yet, much of what I've read in the writings of biologists seems to say no more than this.

I feel a biologist should contribute something towards our understanding of the distant origins

of human tradition and behaviour, and this is what I shall now attempt.

It'll make my argument clearer if I build it on an analogy.

I'd like you to consider an important difference between a jukebox and a gramophone, or if you

like, between a barrel organ and a tape recorder. A jukebox is an instrument which contains one or more gramophone records,

one of which will play whatever is recorded upon it if a particular button is pressed.

The act of pressing the button I shall describe as the stimulus.

The stimulus is specific.

To each button that corresponds one record and vice versa,

...