exaptation

plural exaptations

1. countableuncountableevolutionary theorybiologyThe use of a biological structure or function for a purpose other than that for which it initially evolved.

   Birds initially developed wings and feathers as a means of heat regulation. The use of wings for flight is an example of exaptation.

   3 more examples

   I believe that Stephen Gould and Elizabeth Vrba were correct in proposing exaptation as a missing term in evolutionary biology. I want to make a distinction between adaptation and exaptation here. Again it is about mechanistic differences. An exaptation can be viewed as the acquisition of a new and useful function once the novelty has spread and once the environment has changed.

   2000, Gabriel A. Dover, Dear Mr. Darwin: Letters on the Evolution of Life and Human Nature, University of California Press, page 226

   These presumed exaptations can be assigned to major categories associated with theories of movement (Nathan et al. 2008). In table 1.2, we list five categories of exaptations that we believe make resident birds possessing them preadapted for migration.

   2013, John H. Rappole, The Avian Migrant: The Biology of Bird Migration, Columbia University Press, page 22

   An interesting consequence of this way of characterizing exaptations is that whether or not a trait counts as an exaptation depends upon how we describe it. Human legs are adaptations for locomotion, but exaptations for walking.

   2013, Heather Dyke, James MacLaurin, “30: Evolutionary Explanations of Temporal Experience”, in Adrian Bardon, Heather Dyke, editors, A Companion to the Philosophy of Time, Paperback edition, Wiley, published 2016, page 522

2. broadlycountableuncountablehuman sciencesThe promotion of meaningless or redundant material so that it does new grammatical (morphosyntactic or phonological) or semantic work.

   The process Haiman focuses on is exaptation, which he defines as "the promotion of meaningless or redundant material so that it does new grammatical (morphosyntactic or phonological) or semantic work" (p52).

   2017, Eric Haeberli, Review of Ledgeway & Roberts (eds.) (2017), Cambridge Handbook of Historical Syntax, Journal of Historical Syntax, Volume 3, Article 4, 2019, PDF edition page 2