0.7 Music, biological evolution, and the brain  (Page 22/30)

Before closing, it is worth asking what distinguishes TTM theory from the concept of exaptation, or a trait whose evolutionary origin is not related to its current use (Gould and Vrba, 1982). Feathers are an oft-cited example of an exaptation, as it has been theorized that these structures originated in the context of thermoregulation and were only later put to use (and directly shaped by natural selection) for flight (Gould and Vrba, 1982). Since TTM theory views music as an invention based on diverse nonmusical brain functions, each of which may have been shaped by natural selection, it considers music a type of exaptation. However, exaptation is not a specific enough term to capture the idea of a transformative technology. This is because exaptation (a term coined before our modern understanding of neural plasticity) does not connote the power of a novel trait to shape the biological systems from which it arose (cf. Lewontin, 2000). Furthermore, exaptation allows the notion of secondary adaptation (as in the feather example above), whereas TTM theory holds that that there has been no evolutionary modification of the brain aimed at supporting musical behavior.

Darwin himself was not an ultra-adaptationist; that is, he did not believe that every characteristic of an organism was a product of natural selection. (He differed from his contemporary Alfred Russell Wallace in this regard [Gould, 1980].) For example, in The Descent of Man , Darwin wrote that “many cases could be advanced of organs and instincts originally adapted for one purpose, having been utilized for some distinct purpose” (p. 1208). That is, he implicitly recognized the concept of exaptation long before the term was coined by later evolutionary biologists. What Darwin did not foresee, however, was that human inventions could substantially influence the structure and function of the brain, albeit within the course of a lifetime. This remarkable fact lays the foundation for a biological approach to music and other human cultural phenomena (Wilson, 1998; Becker, 2004; Edelman, 2006; Smail, 2008). Understanding the biology of human inventions involves understanding how our evolved neural organization shapes those inventions and how our inventions in turn shape our brains within individual lifetimes. In exploring this fascinating dialectic, music is a particularly promising area of research.

Acknowledgments

Supported by Neurosciences Research Foundation as part of its research program on music and the brain at The Neurosciences Institute, where ADP is the Esther J. Burnham Senior Fellow. I am grateful to the following individuals for their insightful comments: Jennifer Burton, John Iversen, Sebastian Kirschner, Richard Lewontin, Bruno Repp, Oliver Sacks, Robert Sapolsky, Thom Scott-Phillips, Daniel Smail, Lauren Stewart, William Forde Thompson, and Ellen Winner. I also thank Melissa Bailar for thoughtful editing, and Fred Moody for his prompt and helpful input throughout the publication process.