This year's Reith lecturer is the Professor of Zoology and Comparative Anatomy at University College London, Peter Brian Medawar. His work on graft rejection and the discovery of acquired immune tolerance has been fundamental to the practice of tissue and organ transplants. In his Reith lecture series entitled 'The Future of Man', Professor PM Medawar considers how humans will continue to evolve in the future. In his sixth lecture entitled 'The Future of Man', Professor PM Medawar discusses the possibility of a new, non-genetic, system of inheritance. He predicts that certain properties and activities of the brain will affect our evolution in the future.