Where does exaptation collide?

Gould and Vrba (1982), in Exaptation: a missing term in the science of form, named a trait that now serves a function natural selection did not originally shape it to perform: the feature either arose for a different use or for no use at all, and was later co-opted for its current role. Bird feathers, argued to have first aided temperature regulation before being used for flight, are the stock example. The referent is a biological character in an organism, judged by its evolutionary history against its present use, and it is not a reused piece of grammar or a repurposed technology.[1]

Unit

A single character of an organism, classed by whether its current function matches what shaped it

Recovery means

Not applicable

Measured by

Inferred from comparative anatomy, the fossil record, and phylogenetic reconstruction of when a trait arose versus when its current use appeared

Lass (1990), in How to do things with junk: exaptation in language evolution, borrowed the term for grammatical or morphological material that has lost its original job and is then recruited for a new grammatical function rather than discarded. His cases were old inflectional endings that no longer marked what they once did, put back to work marking something else. Whether this truly parallels the biological process is debated, since language change involves no natural selection. The referent is a linguistic form given a second life inside a grammar, not an organism's trait or a firm's product.[2]

Unit

A grammatical or morphological form, classed by its former function and its new one

Recovery means

Not applicable

Measured by

Traced through historical texts and diachronic corpora showing a form losing one function and taking on another

Dew, Sarasvathy, and Venkataraman (2004), in The economic implications of exaptation, carried the term into economics to describe a technology or product put to a use it was not designed for, and Andriani and Cattani (2016) later developed it as a source of novelty in firms and markets. Microwave technology, first built for radar and later used to cook food, is a common illustration. Because human designers can intend a new use, this reading strains the original criterion that the new function was not selected for. The referent is a repurposed artifact or capability in an economy, not a biological trait or a grammatical remnant.[3][4]

Unit

A technology or product, classed by its designed use against its later adopted use

Recovery means

Not applicable

Measured by

Identified from case histories and patent or product records tracing an artifact's shift to an unintended application