Types and the Geoffroy-Cuvier debate: a crossroads in evolutionary morphology

Abstract

Several interrelated terms and concepts — the type, archetype, unity of the type, unity of plan — used for groups of organisms united on the basis of common anatomical design, held sway among pre-Darwinian morphologists. In recognizing equivalences of structures, these early morphologists used the type or archetype, rather than any notion of descent from a common ancestor, to explain morphological similarities in apparently unrelated organisms. Gradually, embryological criteria became increasingly important in this quest, leading through evolutionary morphology to evolutionary developmental biology. This chapter establishes the groundwork for these concepts by providing a brief overview of the type concept (sections 3.1 and 3.2), addressing the perceived dichotomy between form and function by examining Geoffroy’s exposition of idealistic morphology (section 3.3), the subsequent debate between Geoffroy and Cuvier (section 3.4) and the ramifications of that debate for evolutionary morphology and for the establishment of evolutionary developmental biology (section 3.5).

What is the essence of life — organization or activity? (Russel, 1916, p. v)