Exaptation as source of creativity, innovation, and diversity: introduction to the Special Section

Exaptation is one of the most important and, yet, little studied evolutionary mechanisms in the history of species, ecosystems, and artifacts (e.g., technologies). Many, if not most, of all biological traits and human artifacts that were developed for particular functions started as something different: feathers were most likely selected for thermal insulation, bones originated as excess calcium repositories, microwave ovens started life as radar magnetrons. Exaptation thus describes a discontinuous evolutionary process resulting from a functional shift of an existing trait or artifact. Despite the importance of the concept, even the term exaptation still remains largely unknown outside the field of evolutionary biology. The main purpose of this special section is to introduce the concept of exaptation to a broader audience, discuss its significance, and expose its contribution to the (possible) solution of long-standing, yet unresolved, questions about the emergence of novelty, particularly radical innovation.