Rinkevich, Baruch. “The Apex Set-Up for the Major Transitions in Individuality.” Evolutionary Biology 46, no. 3 (2019): 217-228.
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Morphological and functional hierarchies occurring in contemporary biological entities are amalgamated via a small number of progressive key-steps termed as Major Transition in Evolution (MTE) that encompass steps of Major Transition in Individuality (MTI). Literature views MTE/MTI in nature as a sequential increase in complexity, and has contributed insights into the emergence of genuine MTI candidates that actually build higher order individuals from simpler entities and into their specific properties. The theory- By considering a novel MTI trajectory termed the ‘MTI continuum’ (independent of the tree of life that contemplates taxonomic correlations), I found no literature consensus for this continuum’s apex. Next, I consider the properties of biological entities termed as ‘superorganism’ (eusocial insects, humans), also considered as highly-developed MTIs. I classify ‘superorganism’ as being on the level of ‘miscellaneous transitions’ that have not yet developed into real MTIs and that do not meet the ‘individual’ physiognomy. Then I assign the emergence of three new MTI diachronic-classes, the colonial-organisms, chimerism and multi-chimerism, suggesting that they represent highly complex MTIs that belong at the apex of the MTI continuum. These novel MTIs are neither fraternal, nor egalitarian, deprived of ‘kinship’ and ‘fairness’ considerations, yet still generate genuine and distinct libertarian entities. I posit that these MTIs embody the qualities of real units of selection.