exaptation

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exaptation

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Blend of ex- +‎ adaptation. Coined 1982 by palaeontologists Stephen Jay Gould and Elisabeth Vrba to avoid the perceived teleological baggage of the existing term preadaptation.^[1]

exaptation (countable and uncountable, plural exaptations)

1. (biology, evolutionary theory) The 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.

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

     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.

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

     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, 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:

     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.

2. (linguistics, by extension) The promotion of meaningless or redundant material so that it does new grammatical (morphosyntactic or phonological) or semantic work.
   • 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

     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).

• preadaptation

• Paul McGarr, Stephen Rose, editors (2006), The Richness of Life: The Essential Stephen Jay Gould, Jonathan Cape, →ISBN