Harnessed: How Language and Music Mimicked Nature and Transformed Ape to Man
by Mark Changizi. BenBella Books, 2011
Once upon a time, humans could not hold conversations or sing songs together. Now we chatter incessantly, not only with speech but also through text messages, tweets and status updates. How we transformed into the highly social species we are today remains the subject of many theories.
Two competing hypotheses center on whether our capacity for language is an innate skill that grew stronger through natural selection or whether we lacked any such ability and instead trained our brains to collect new information using objects and sounds in our environment. In his new book Harnessed, Mark Changizi stakes out the middle ground: cultural—not natural—selection explains our language ability.
Generating controversial theories is not new to this evolutionary neurobiologist. In his previous book, The Vision Revolution, he argued that writing evolved from the shapes our ancestors saw in nature. In Harnessed he extends that logic to claim that the most common sounds we hear in nature—of objects making contact or sliding across one another, such as the patter of footsteps or the hiss of a hunted animal dragged across the ground by a predator—occur more frequently and consistently in human language than chance would allow. People evolved auditory systems that process natural noises efficiently, although we are capable of producing a range of sounds broader than those found in nature. Changizi proposes that our culture—that is, language and music, among other artifacts—evolved around, or “harnessed,” the sounds we already process best.
The tricky part, however, is that Changizi’s theory is almost impossible to test. The bulk of his evidence consists of correlations he observes between sounds in nature and those in language, and he devotes much of the book to acoustical analyses of the two. But the examples he cites are just that—correlations, not causes. In addition, Changizi never explains why other apes, which heard the same sounds as early humans, did not develop language.
Nevertheless, the idea of culture as an actor in the evolutionary process, rather than its by-product, provides an interesting way to frame the question of how we learned to communicate through language.