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Cooperative breeding, where only a subset of individuals reproduce within a social group, is widespread among invertebrates, birds and mammals. Curiously, cooperative breeding is completely absent in reptiles and amphibians and restricted to a handful of cichlid species in fishes. The absence of cooperative breeding in ectothermic vertebrates is remarkable, especially because many species live in stable aggregations that are often comprised of close kin. Moreover, parental care is present in some species of reptiles, amphibians and fish, albeit mainly in the form of guarding of eggs or juveniles. In this project, together with Mike Thompson (School of Biological Sciences, University of Sydney), I explore the possible reasons for the absence of cooperative breeding from ectothermic vertebrates.