The importance of homology for biology and philosophy

Abstract

Homology is one of the most important concepts in biology (de Beer 1971;Donoghue 1992).Having been introduced in pre-Darwinian comparative biology, it continues to be fundamental to taxonomy, phylogeny, and evolutionary biology. In recent times it has come to play an important role in molecular and developmental biology. In addition to figuring prominently in biological practice, the notion of homology is the subject of extensive theoretical reflection among biologists (Bock and Cardew 1999; Hall 1994;Wagner 2001b).Curiously though, homology has been discussed only sparsely by philosophers.3 The contributions to this special issue attempt to highlight the importance of homology for philosophy as well as biology. Homology is germane to such philosophical issues as the individuation of biological natural kinds, and the patterns of inductive reasoning in the life sciences. Given the possibility of individuating cognitive kinds and mental phenomena in terms of homology (rather than their evolutionary function), the idea of homology has implications for the philosophy of mind and cognitive science, implications that are explored in the contributions of Marc Ereshefsky and Mohan Matthen.While species have been extensively discussed by philosophers and have served as the prime examples of biological natural kinds, homology is an equally important notion of natural kindhood in the biological sciences (Brigandt 2002, in press;Rieppel 2006;Wagner 1996, ( ), Brigandt (2002, Griffiths (1994Griffiths ( , 1996Griffiths ( , 2006, Matthen (1998Matthen ( , 2000, and Sober (1999). THE IMPORTANCE OF HOMOLOGY FOR BIOLOGY AND PHILOSOPHY 2001a). Biologists partition an organism into homologues which are presumed to represent natural units of biological organization because they can be reidentified in other organisms and other species (Griffiths, this issue). A homologous character shares many biological properties in the different organisms in which it occurs, and there is a causal basis for this sharing of properties (common ancestry and shared developmental mechanisms). These two features, a cluster of properties and a causal basis for the co-occurrence of those properties, are the two hallmarks of natural kinds (Boyd 1991;Hacking 1991; Wilson et al., in press). In the course of evolution, a character typically undergoes modification, so that homologues are Over the past few decades there has been an intensification of interest in the concept of homology. Its scope of application has increased and new theoretical interpretations of homology have been proposed. In addition to traditional morphological characters, processes and functions can be homologised (Amundson and Lauder 1994;Gilbert and Bolker 2001;Gilbert et al. 1996;Lauder 1994), and behavioural patterns and cognitive features are increasingly recognized as homologous across species (see Ereshefsky, this issue; Matthen, this issue). Following the rise of molecular biology, genes and proteins came to be homologized, leading to the field of molecular evolution and the practice...

Explanation in Biology: Reduction, Pluralism, and Explanatory Aims

“…A phenotypic difference, which is due to a difference in one allele according to classical genetics, can by the lights of molecular genetics be brought about by causes that are different in kind and not connected to one another other: a point mutation within a molecular gene's coding region, a mutation in regulatory region preceding the gene, or a mutation elsewhere in the genome. A morphological structure that is recognized as the same structure in different species can develop by means of quite different developmental processes and the involvement of different genes in these species (Brigandt and Griffiths 2007;Laubichler and Wagner 2001). As a result, an explanation in terms of the concepts of a higher level discipline can be more unified (encompassing many instances, possibly different species) and addresses the relevant natural kinds / categorizations underlying the phenomenon to be explained, while describing the situation in terms of a lower level science would require different accounts for some instances, where these accounts are not systematically related.…”

Evolutionary remnants as widely accessible evidence for evolution: the structure of the argument for application to evolution education

“…Unfortunately, in addition to the complexities with which the term "homology" is historically fraught (e.g., De Beer 1971;Hall 1994Hall , 2003Mindell and Meyer 2001;Wagner 2002;Brigandt and Griffiths 2007;Rieppel and Kearney 2007;McCune and Schimenti 2012;Baum, 2013;Minelli and Fusco 2013), this definition has the weakness of being tautological if we are seeking to use particular features as evidence for common ancestry (Gilbert 2003;Griffiths 2007). In this context, DWM is the explanation for homology, not its definition.…”

The Paradox Of Portal Metastases In HCC Patients

“…The terms "homology" and "homologous" here and further are used only in a sense of a historical concept of homology (Brigandt and Griffiths, 2007;Minelli and Fusco, 2013): "Homology, as classically defined, refers to a historical continuity in which morphological features in related species are similar in pattern or form because they evolved from a corresponding structure in a common ancestor." (Shubin et al, 2009).…”