Being exacting about exapting
For historical linguists, exaptation is an attractive notion, offering an overt link with biological evolution. Nonetheless, one can ask whether it represents something substantive about linguistic change or is merely an appealing metaphor. I critically assess exaptation, using case studies suggesting that speakers in crafting new “grammar” simply make use of material on hand. Whether it is “junk” (Lass 1990) or not is immaterial to the speaker; what matters is a model’s availability, often a very “localised” one. Through these examples, I argue that “exaptation” reduces to regular and well-understood processes of diachronic morphology, particularly analogy, not limited to any component of grammar. The material forming the model for innovation can be highly restricted and can itself be an irregular bit of the grammar. Similarly, any parallels with “grammaticalization” derive from these developments all being ways that speakers creatively make connections among elements in their language and act on them.