VI. Earth Life Emergence: Development of Body, Brain, Selves and Societies
D. An Enhancement of Autonomous Individuality
West, Stuart, et al. Major Evolutionary Transitions in Individuality. Proceedings of the National Academy of Sciences. 112/10112, 2015. A paper for the 2014 NAS Sackler Colloquium entitled Symbioses Becoming Permanent: The Origins and Evolutionary Trajectories of Organelles about confirmations of life’s communal emergence as due to pervasive symbiotic unions. In accord with Eors Szathmary’s presentation at this meeting (search), this nested, manifest scale could be seen as regnant, liberated persons in relative communities. See also in the Science journal Evolving New Organisms via Symbiosis by Toby Kiers and Stuart West (348/392, 2015) and How Single Cells Work Together by Jonathan Zehr (349/1163, 2015).
The evolution of life on earth has been driven by a small number of major evolutionary transitions. These transitions have been characterized by individuals that could previously replicate independently, cooperating to form a new, more complex life form. For example, archaea and eubacteria formed eukaryotic cells, and cells formed multicellular organisms. However, not all cooperative groups are en route to major transitions. How can we explain why major evolutionary transitions have or haven’t taken place on different branches of the tree of life? We break down major transitions into two steps: the formation of a cooperative group and the transformation of that group into an integrated entity. We show how these steps require cooperation, division of labor, communication, mutual dependence, and negligible within-group conflict. We find that certain ecological conditions and the ways in which groups form have played recurrent roles in driving multiple transitions. In contrast, we find that other factors have played relatively minor roles at many key points, such as within-group kin discrimination and mechanisms to actively repress competition. More generally, by identifying the small number of factors that have driven major transitions, we provide a simpler and more unified description of how life on earth has evolved. (Abstract)
Zimmer, Carl. Expressing Our Individuality, the Way E. Coli Do. New York Times. April 22, 2008. A Science Tuesday report that even for the simplest forms of life such as microbial colonies, individual bacteria are not insensate clones but seem to possess an ability to respond and act in their own, independent ways.