Running with the Red Queen: reflections on 'Sex versus non-sex versus parasite'

The scientific output of W. D. Hamilton can be broadly split into two parts ; the first dealing with inclusive fitness and the evolution of social beha viour while the second part focused on the role of parasites in the evoluti on of sex. This change in research interest was marked by a classic paper p ublished in this journal in 1980, 'Sex versus non-sex versus parasite'. To mark Hamilton's death I consider the historical background and influence of this paper.