Tiliquin lizards as a model vertebrate system for understanding the emergence of societies

The Tiliquini skinks are a clade of lizards that include multiple species that live in long-lasting, territorial groups. Memberships among group-living species range from simple nuclear families to larger, more complex groups containing multiple generations of offspring and sometimes, unrelated adults. We detail the factors that favour the formation of societies in one model species, the White’s skink, Liopholis whitii , in which groups typically consist simply of a nuclear family (parents plus one generation of offspring), although some groups expand into what can be called incipient societies in that they can contain multiple generations of offspring and unrelated adults. Conversely, two other species (Cunningham’s skink, Egernia cunninghami , and the gidgee skink, Egernia stokesii) live in much larger groups and their behaviour is more consistent with being societal. We suggest that the mechanism whereby individuals can gain entrance into a new group is through repeated exposure at the periphery of the group’s territory, which in turn generates familiarity and tolerance. We argue that lizards provide a valuable model for understanding the origins and maintenance of societal formation in vertebrates.