Online research in philosophy

Homology is among the most important comparative concepts in biology. Today, the evolutionary reinterpretation of homology is usually conceived of as the most important event in the development of the concept. This paradigmatic turning point, however important for the historical explanation of life, is not of crucial importance for the development of the concept of homology itself. In the broadest sense, homology can be understood as sameness in reference to the universal guarantor so that in this sense the different concepts of homology show a certain kind of “metahomology”. This holds in the old morphological conception, as well as in the evolutionary usage of homology. Depending on what is (or was) taken as a guarantor, different types of homology may be distinguished (as idealistic, historical, developmental etc.). This study represents a historical overview of the development of the homology concept followed by some clues on how to navigate the pluralistic terminology of modern approaches to homology.

Homology continues to be a concept of central importance in the study of phylogenetic relations, but its relation to ontogenetic processes remains problematical. A definition of homology in terms of equivalent morphogenetic processes is defined and applied to the comparative study of tetrapod limbs. This allows for a consistent treatment of relations of similarity and difference of appendage structure in vertebrates, and the distinction between fishes fins and tetrapod limbs in terms of the concept of equivalence is described. The role of genes can also be clarified in this context, in particular the influence of the Hox 4 complex in determining digit character and the homeotic transformations that arise from changes in their expression patterns. It is argued that these observations are not compatible with the notion of homology between individual digits (I, II, III, etc.) across the tetrapods, and that homology cannot be consistently identified with gene action. The relations between homology and the properties of the morphogenetic limb field are discussed.

The study of evolutionary developmental biology (“evo‐devo”) has recently experienced a dramatic surge in popularity among researchers and theorists concerned with evolution. However, some biologists and philosophers remain skeptical of the claims of evo‐devo. This paper discusses and responds to the recent high profile criticisms of evo‐devo presented by biologists Hopi E. Hoekstra and Jerry A. Coyne. I argue that their objections are unconvincing. Indeed, empirical research supports the main tenets of evo‐devo, including the claim that morphological evolution is the result of cis ‐regulatory change and the distinction that evo‐devo draws between morphological and physiological traits. *Received January 2008; revised March 2009. †To contact the author, please write to: Department of Philosophy, University of Cincinnati, Cincinnati, OH 45221; e‐mail: craiglr@email.uc.edu.

Evolutionary developmental biology (evo-devo) offers both an account of developmental processes and also new integrative frameworks for analyzing interactions between development and evolution. Biologists and philosophers are keen on evo-devo in part because it appears to offer a comfort zone between, on the one hand, what some take to be the relative inability of mainstream evolutionary biology to integrate a developmental perspective; and, on the other hand, what some take to be more intractable syntheses of development and evolution. In this article, I outline core concerns of evo-devo, distinguish theoretical and practical variants, and counter Sterelny's recent argument that evo-devo's attention to development, while important, offers no significant challenge to evolutionary theory as we know it.

In the evolutionary biology of the Modern Synthesis the study of patterns refers to how to identify and systematise order in lineages, looking for hierarchies or for branching/splitting events in the tree of life, whereas the resulting order is supposed to be due to underlying processes or mechanisms. But patterns and processes play distinct roles in evo-devo: four different views on the role of patterns and processes in descriptions and explanations of development and evolution: A) transformational; B) generative; C) processual; and D) complex are reviewed in this paper. Then, this discussion is related to two issues in evo-devo: homology and variation.

_The emerging discipline of evolutionary developmental biology has opened up many new _ _lines of investigation into morphological evolution. Here I explore how two of the core _ _theoretical concepts in ‘evo-devo’ – modularity and homology – apply to evolutionary _ _psychology. I distinguish three sorts of module - developmental, functional and mental _ _modules and argue that mental modules need only be ‘virtual’ functional modules. _ _Evolutionary psychologists have argued that separate mental modules are solutions to _ _separate evolutionary problems. I argue that the structure of developmental modules in _ _an organism helps determine what counts as a separate evolutionary problem for that _ _organism. I suggest that homology as an organizing principle for research in _ _evolutionary psychology, has been severely neglected in favor of analogy (adaptive _ _function). I consider some arguments suggesting that determining homology is less _ _epistemically demanding than determining adaptive function and argue that _ _psychological categories defined by homology are, in fact, more suitable objects of _ _psychological - and particularly neuropsychological - investigation than categories _ _defined by analogy. _.

Richard Owen has been condemned by Darwinians as an anti-evolutionist and an essentialist. In recent years he has been the object of a revisionist analysis intended to uncover evolutionary elements in his scientific enterprise. In this paper I will examine Owen's evolutionary hypothesis and its connections with von Baer's idea of divergent development. To give appropriate importance to Owen's evolutionism is the first condition to develop an up-to-date understanding of his scientific enterprise, that is to disentagle Owen's contribution to the modernization of typology and morphology. I will argue that Owen's Platonic essentialism is rhetorical and incongruous. On the contrary, an interpretation of the archetype based on Aristotle's biological works makes possible a new conception of type, based on a homeostatic mechanism of stability. The renewal of morphology hinges on homological correspondences and a homeostatic process is also the origin of serial and special homology. I will argue that special homology shows an evolutionary orientation insofar as it is a typically inter-specific character while serial homology is determined through an elementary usage of the categories of developmental morphology.

This article reviews the recent reissuing of Richard Owen’s On the Nature of Limbs and its three novel, introductory essays. These essays make Owen’s 1849 text very accessible by discussing the historical context of his work and explaining how Owen’s ideas relate to his larger intellectual framework. In addition to the ways in which the essays point to Owen’s relevance for contemporary biology, I discuss how Owen’s unity of type theory and his homology claims about fins and limbs compare with modern views. While the phenomena studied by Owen are nowadays of major interest to evolutionary developmental biology, research in evo-devo has largely shifted from homology (which was Owen’s concern) towards evolutionary novelty, e.g., accounting for fins as a novelty. Still, I argue that questions about homology are important and raise challenges even for explanations of novelty.

This article reviews the recent reissuing of Richard Owen’s On the Nature of Limbs and its three novel, introductory essays. These essays make Owen’s 1849 text very accessible by discussing the historical context of his work and explaining how Owen’s ideas relate to his larger intellectual framework. In addition to the ways in which the essays point to Owen’s relevance for contemporary biology, I discuss how Owen’s unity of type theory and his homology claims about fins and limbs compare with modern views. While the phenomena studied by Owen are nowadays of major interest to evolutionary developmental biology, research in evo-devo has largely shifted from homology (which was Owen’s concern) towards evolutionary novelty, e.g., accounting for fins as a novelty. Still, I argue that questions about homology are important and raise challenges even for explanations of novelty.

This article reviews the recent reissuing of Richard Owen’s On the Nature of Limbs and its three novel, introductory essays. These essays make Owen’s 1849 text very accessible by discussing the historical context of his work and explaining how Owen’s ideas relate to his larger intellectual framework. In addition to the ways in which the essays point to Owen’s relevance for contemporary biology, I discuss how Owen’s unity of type theory and his homology claims about fins and limbs compare with modern views. While the phenomena studied by Owen are nowadays of major interest to evolutionary developmental biology, research in evo-devo has largely shifted from homology (which was Owen’s concern) towards evolutionary novelty, e.g., accounting for fins as a novelty. Still, I argue that questions about homology are important and raise challenges even for explanations of novelty.