Hermaphrodites are generally seen as species adapted to conditions of low mate availability. This is primarily because hermaphrodites can adjust allocation of resources to each sex function in response to current conditions, making reproduction more efficient. Adaptation to low density is further enhanced because many have the ability to self-fertilize and because the encounter rate of potential mates is twice as high for a hermaphroditic than for a gonochoric species. Yet, many hermaphrodites often occur at consistently high densities. Herein I review the consequences of high density on hermaphrodite sexual behaviour and show that this approach can explain the presence of a number of obvious adaptations known from hermaphrodites. These adaptations cannot be explained by assuming that low density has been the rule in their evolutionary past.