Trends Ecol Evol 2020 09 27;35(9):834-847. Epub 2020 May 27.
Department of Anthropology, Queens College, City University of New York, Flushing, NY 11367-1597, USA; New York Consortium in Evolutionary Primatology, New York, NY 11367, USA; Anthropology, Biology and Psychology Programs, CUNY Graduate Center, 365 Fifth Avenue, New York, NY 10016, USA; Department of Archaeology, University of Cape Town, Rondebosch, 7701, Cape Town, South Africa.
Multilevel societies (MLSs), stable nuclear social units within a larger collective encompassing multiple nested social levels, occur in several mammalian lineages. Their architectural complexity and size impose specific demands on their members requiring adaptive solutions in multiple domains. The functional significance of MLSs lies in their members being equipped to reap the benefits of multiple group sizes. Here, we propose a unifying terminology and operational definition of MLS. To identify new avenues for integrative research, we synthesise current literature on the selective pressures underlying the evolution of MLSs and their implications for cognition, intersexual conflict, and sexual selection. Mapping the drivers and consequences of MLS provides a reference point for the social evolution of many taxa, including our own species.