Presented by John Maddox
The new formulation of the theory of continental drift was put forward in the early 1960s. The general picture has been confirmed by a decade of observations. DR D. p. MCKENZIE of the Geodesy and Geophysics Department of Cambridge University discusses the fine details of the processes of plate tectonics that are now being untangled.
How do we become immune to a disease we have never had before? Does the body have a system that can cope with all the foreign chemicals it encounters? PROFESSOR N. A. MITCHISON of the Department of Zoology at University College, London, talks about the genetic basis of immunity.
Producer DAVID PATERSON