The Organism in Evolutionary Explanation: From Early Twentieth Century to the Extended Evolutionary Synthesis

Abstract

In recent years there have been a number of calls for integrating developmental and organismal phenomena into evolutionary theory. This so-called Extended Evolutionary Synthesis (EES) argues that evolutionary theory should not primarily explain certain evolutionary phenomena by highlighting genes and populations but organisms instead, in particular how their development and behavior biases and drives evolutionary change. Here, we offer a new historiography that focuses less on the differences between the EES and the Modern Synthesis but seeks to provide a better understanding about which theoretical and explanatory traditions the organism-centered framework of the EES draws on. This concerns especially three currently resurfacing explanatory roles granted to organisms in evolution: organisms should allow (1) contextualizing parts in development, especially genes, (2) focusing on reciprocal organism-environment relations (in contrast to, e.g., gene-environment interactions), and (3) understand the role of agency in evolution. Through this analysis, we show that the EES advances a revival of older explanatory roles granted to the organism in evolutionary research, which became marginalized in the second half of the twentieth century. This new perspective helps to re-center contemporary theoretical debates towards relevant questions of explanatory standards in evolutionary biology.