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An "exaptation" is just one example of a characteristic that evolved, but that isn't considered an adaptation. Evolutionary biologists Stephen Gould and Elizabeth Vrba proposed vocabulary to let biologists talk about features that are and are not adaptations:

  • Bat echolocation
    Adaptation — a feature produced by natural selection for its current function (such as echolocation in bats, right).
  • Exaptation — a feature that performs a function but that was not produced by natural selection for its current use. Perhaps the feature was produced by natural selection for a function other than the one it currently performs and was then co-opted for its current function. For example, feathers might have originally arisen in the context of selection for insulation, and only later were they co-opted for flight. In this case, the general form of feathers is an adaptation for insulation and an exaptation for flight.

Flight feather


Evo examples
Learn more about exaptation in context: Quick bites and quirky adaptations, a news brief with discussion questions.

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