Evolution and redeployment
Part of understanding the functional organization of the brain is understanding how it
evolved. The current study suggests that while the brain may have originally emerged as
an organ with functionally dedicated regions, the creative re-use of these regions has
played a significant role in its evolutionary development. This would parallel the
evolution of other capabilities wherein existing structures, evolved for other purposes, are
re-used and built upon in the course of continuing evolutionary development
(“exaptation”: Gould and Vrba, 1982). There is psychological support for exaptation in
cognition (Cosmides, 1989; Cruse, 2003; Glenberg and Kashak, 2002; Gould, 1991;
Lakoff and Nunez, 2000; Riegler, 2001; Wilson, 2001), and neuroanatomic evidence that
the brain evolved by preserving, extending, and combining existing network components,
rather than by generating complex structures de novo (Sporns and Kotter, 2004).
However, there has been little evidence that integrates these two perspectives, bringing
such an account of the evolution of cognitive function into the realm of cognitive
neuroscience (although see, e.g., Barsalou 1999).
One recent hypothesis along these lines—that combines a story about the evolution of the
brain based on the re-use and extension of existing elements with an exaptive account of
cognitive functions—is the massive redeployment hypothesis (Anderson, 2006;
Anderson, in press). The massive redeployment hypothesis suggests that cognitive
evolution proceeds in a way analogous to component reuse in software engineering
(Heinemann and Councill, 2001), whereby existing components—originally developed to
serve some specific purpose—are used for new purposes and combined to support new