Some biogenetic considerations for historical linguistics: Phyletic comparison

Both biology and language clearly evidence analogous processes for transmitting information through time. One of these processes is the replication of information from parent to offspring and from predecessor to successor. Another is the entropy that ensures that such replication will be imperfect, leading to speciation in the case of evolution and to linguistic change in the case of speech communities. Starting with a review of various notions employed in "historical" biology, we then prospect them for analytic tools in historical linguistics. While illustrating adaptation as a tool for family level historical linguistics, we also review, detail and demonstrate exaptation as an analytic tool, especially for long-range and/or phyletic linguistic comparison. Indeed, as linguistic relationships grow more distant (e.g. Avestan vs. Sanskrit and then, say, Sogdian vs. Sanskrit; Greek vs. Armenian and then, say, Armenian vs. English), it seems that one increasingly has to rely on exaptation rather than adaptation to achieve adequate developmental histories. We explain this trend as an inevitable result of the tendency toward opacity of derivational morphology when compounded through generations; a primary case in point being the emergence of English than as detailed here. We also note that in some exceptional cases exaptation can be used in recent change, as in the formation of acronyms.