title: Transitions in individuality.
abstract: The evolution of multicellular organisms is the premier example of the integration of lower levels into a single, higher-level individual. Explaining the evolutionary transition from single cells to multicellular organisms is a major challenge for evolutionary theory. We provide an explicit two locus genetic framework for understanding this transition in terms of the increase of cooperation among cells and the regulation of conflict within the emerging organism. Heritability of fitness and individuality at the new level emerge as a result of the evolution of organismal functions that restrict the opportunity for conflict within and ensure cooperation among cells. Conflict leads, through the evolution of adaptations that reduce it, to greater individuality and harmony for the organism.
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Arizona, Tucson 85721, USA. michod@ccit.arizona.edu
authors.forename: R E
authors.initials: RE
authors.lastname: Michod
authors.forename: D
authors.initials: D
authors.lastname: Roze
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D005075:Biological Evolution; D006238:Haploidy; D007206:Individuality; D008957:Models, Genetic; D012641:Selection, Genetic