Note: The titles below are hyperlinked to downloadable articles.
Journal of Molecular Evolution, 2016
(w Ford Doolittle)
The concept of homology has a long history, during much of which the issue has been how to reconcile similarity and common descent when these are not coextensive. Although thinking molecular phylogeneticists have learned not to say "percent homology" the problems are deeper than that, and unresolved.
Making Sense of Molecular Homology: A Context-Sensitive Causal Account
(w Ford Doolittle and Rich Campbell)
Homology is an indispensable but elusive concept in biology. We argue that current accounts of gene homology are problematic because they face a reductio ad absurdum objection. We offer a novel account that avoids this objection: the context-sensitive causal account. This account consists of two claims. First, for two or more genes to be homologous, there must be causal continuity along the lineages leading from a common ancestor to each homolog. Second, what additional facts are relevant to membership in a homologous kind in a specific case is determined by the research context and research question: homology is context- sensitive, though not arbitrary. Our discussion also illuminates the neglected relationship between concepts of gene homology and morphological homology.