Extended Evolutionary Synthesis: Neither Synthesis Nor Extension

Abstract

The extended evolutionary synthesis (EES) intends to offer a new framework for understanding evolution based mainly on empirical and theoretical findings of current studies, including heredity and evolutionary developmental biology. In this essay, we present and develop the following objections about the terminology associated with the EES literature: (1) despite using the term "extension," EES protagonists claim new evolutionary processes, reformulate conceptual networks, and modify central assumptions of the evolutionary synthesis (ES). Therefore, the difference between ES and EES should not be described in terms of a set-subset relationship (that is, as an extension); (2) despite using the term "synthesis," the EES leads, at least in the short term, to a pluralism of approaches in evolutionary biology. Thus, we argue that the EES should not be described as a synthesis, but as a broad and plural interpretative framework encompassing different approaches. These objections are not directed to the proposed changes, but to the interpretation of these changes as a mere expansion of the previous evolutionary framework, as well as to the interpretation of the EES as a synthesis. Based on these objections, we seek to present some explanations for the use of the term "extended synthesis" among its protagonists.