  Rediscovering a new function for something can be just as important as the
discovery itself. In 1982, Stephen Jay Gould and Elisabeth Vrba named this
phenomenon Exaptation to describe a radical shift in the function of a specific
trait during biological evolution. While exaptation is thought to be a
fundamental mechanism for generating adaptive innovations, diversity, and
sophisticated features, relatively little effort has been made to quantify
exaptation outside the topic of biological evolution. We think that this
concept provides a useful framework for characterising the emergence of
innovations in science. This article explores the notion that exaptation arises
from the usage of scientific ideas in domains other than the area that they
were originally applied to. In particular, we adopt a normalised entropy and an
inverse participation ratio as observables that reveal and quantify the concept
of exaptation. We identify distinctive patterns of exaptation and expose
specific examples of papers that display those patterns. Our approach
represents a first step towards the quantification of exaptation phenomena in
the context of scientific evolution.
