The evolution of virulence in primate malaria parasites based on Bayesian reconstructions of ancestral states

► The ancestor of recent primate-infecting malaria parasites caused little harm to its hosts. ► The acquisition of a harmful host exploitation strategy is likely to be a current evolutionary event. ► Parasites causing severe symptoms are closely related genetically, thus virulence evolution is phylogenetically constrained. ► Such phylogenetic constraints may emerge due to the role of virulence genes that are inherited from ancestors.