But if the decision-making capacity of a human and a lamprey are so different, why are the basal ganglia of lampreys and humans so strikingly similar? Grillner and Stephenson-Jones propose an explanation: an evolutionary process called exaptation. As opposed to adaptation, which is the process of developing new traits—such as air-breathing lungs or a four-chambered heart—exaptation takes something that already exists and finds a new function for it; for example, expanding the basal ganglia’s decision-making jurisdiction to govern other, more advanced types of decisions. Grillner and
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it is not obvious to me why there needs to be a distinction between adaptation and exaptation.
