exaptation

noun

ex·​ap·​ta·​tion ˌeg-ˌzap-ˈtā-shən 

: a trait, feature, or structure of an organism or taxonomic group that takes on a function when none previously existed or that differs from its original function which had been derived by evolution

As for exaptations, we need look no further than feathers. It is now argued that feathers were not originally evolved for flight, but emerged in the reptilian ancestors of today's birds, where they served for temperature regulation.

—Steven Rose

also : the condition or circumstance of possessing one or more such traits, features, or structures

In fact, it's hard to say just how much of the brain's power is a result of exaptation rather than adaptation.

—Tom Siegfried

Note: The word exaptation was proposed by Stephen Jay Gould and Elizabeth Vrba in the 1980s as an alternative to preadaptation, which was felt to imply that such traits, features, or structures were destined for a future function. While exaptation has been widely adopted, preadaptation continues to be acceptable in current usage with both terms showing comparable frequency of usage.

Examples of exaptation in a Sentence

Recent Examples on the Web

According to Sander’s evolutionary cascade model, sauropods started out small, but became giants through a combination of exaptation and key innovation. —Guest Blogger, Discover Magazine, 30 Oct. 2013

According to the new findings, the eventual, crucial role the feathers played in flight was an exaptation: essentially, an evolutionary re-purposing of an existing trait. —Gemma Tarlach, Discover Magazine, 2 July 2014

In 1982, Stephen Jay Gould and Elisabeth Vrba gave a name to this phenomenon: exaptation. —Quanta Magazine, 4 Sep. 2013

Feathers are a marvelous example of exaptation, or the process of acquiring functions for which they were not originally adapted. —Kate Morgan, CNN, 12 Dec. 2017

Word History

Etymology

ex- entry 1 + (ad)aptation

Note: The term was apparently introduced in a presentation Gould gave as the annual Tinbergen Lecturer at a meeting of the Association for the Study of Animal Behaviour in London in December, 1981. Formal publication of the word was in the article "Exaptation—a missing term in the science of form" by Gould and Elizabeth S. Vrba, Paleobiology, vol. 8, no. 1 (December, 1982), pp. 4-15.

First Known Use

1981, in the meaning defined above