An evolutionary understanding of the complex mating systems of megapodes has been impaired by a historical and simplistic classification system that assumed all species to be monogamous. This approach has been challenged by behavioural ecology theories that emphasize the primacy of the individual attempt to maximize its own fitness. From this point of view the remarkable incubation techniques and the recently described behaviours of some clearly promiscuous species can be more clearly understood. In particular, the influence of the type of incubation-heat source on the mating system is paramount.