PhilInBioMed series: Tyler Brunet

Constructive Neutral Evolution (CNE) is a theory for explaining the origin and maintenance of complexity in biological systems without the necessary input of adaptive Evolution by Natural Selection (ENS). CNE was originally developed to explain a few comparatively obscure cases of complexity in molecular biology, including spliceosomal splicing, trypansomal gene editing, scrambled genes in ciliates, and duplicate gene retention. However, since its conception, CNE has been extended and applied to a number of other cases – both novel molecular cases, and cases at cellular, organismal and ecological levels of organization. At the same time, CNE is not the only theory for explaining biological complexity that differs from ENS. For example, prior to the coinage of CNE the theory of Generative Entrenchment (GE) was also used to explain complexity without reliance on ENS alone; many authors in molecular evolution have since deployed a related, similar theory, here called Contingency and Entrenchment (CE). This talk will define and examine cases of CNE, using examples from molecular, cell and organismal biology, then compare it to other theories of complexity. I present CNE as a more general theory of the evolution of complexity which, alongside traditional adaptive explanations employing ENS, can account for a wide range of complex structures and relationships in biology.