The Musical Mind
If song has no purpose, why is it deep-wired in the brain?
Music means nothing to Isabelle Peretz's patients. The University of Montreal psychologist studies people who have suffered brain damage from a stroke or surgery and lost the ability to make sense of the simplest tune. To the most seriously affected, "Happy Birthday to You" is a meaningless jumble of notes, and a Mozart sonata sounds no better or worse when it is played off key.
Their plight seems bizarre. But the bigger mystery, scientists are coming to realize, is that music speaks so powerfully to the rest of us. It's found in every culture and has probably been with us as long as we have been fully human. Yet unlike other basic skills, such as language and toolmaking, it doesn't seem to help us survive and reproduce. It doesn't even mimic the real world, as some art and games do. As David Huron, a musicologist at Ohio State University, puts it, "Music is weird."
The more scientists learn, the weirder it seems, because this seemingly useless taste is deeply embedded in our brains, and maybe even in our genes. Some of the latest evidence comes from scientists in Germany, who have found that even in people with no training in music, the brain is capable of sophisticated musical analysis. The faint magnetic signals emitted as neurons fire show that the brain gives a little start of surprise when a passage of music takes an unexpected turn. Other researchers have recently mapped a broad network of brain regions that separately analyze pitch, melody, timing, and emotion.
Choosing dessert. It all shows that listening to music "is a very sophisticated thing to do," says Robert Zatorre, a neuroscientist at McGill University in Montreal. Some researchers argue that we do it simply because music, like wine or a rich dessert, tickles pleasure circuits that evolved for other, more useful purposes. "Auditory cheesecake," neuroscientist Steven Pinker of the Massachusetts Institute of Technology has called it. Other scientists think our musical brain evolved because it gave our ancestors some as-yet-unidentified evolutionary advantage. And still others theorize that music came along for the ride as we evolved the brain circuits needed to decipher speech or natural sounds.
Despite the competing theories, few would disagree with Zatorre when he says, "There's something about the brain that predisposes us to learn about music." He thinks our brains are prewired for the task, enabling us to learn music as fast and effortlessly as we learn to talk. Others go further and argue that a sophisticated ear for music may be inborn. Sandra Trehub of the University of Toronto teaches babies 6 to 10 months of age to listen to snippets of music played over and over again and to react when they hear a change. Those experiments have shown that Everybaby is, if not a little Mozart, at least a natural music lover with abilities "incredibly similar to adults."
Like adults, babies perceive a tune as the same when it is shifted in key, yet if the pitch of a note or two is changed they instantly know something is wrong. The tunes that adults find most pleasing, in which successive notes differ in pitch by specific intervals--octaves and so-called perfect fifths, for example--are the ones that delight babies as well. Babies are much better at remembering tuneful snippets than less melodic tunes.
It's possible, Trehub concedes, that by 6 months, babies have already heard enough lullabies and stray melodies to have cultivated an ear for music. Yet others have seen the same abilities in newborns, she notes, and the babies she has tested don't prefer music that is specifically Western--the kind they are most likely to have heard. Instead, they seem to respond most strongly to scales and intervals found even in unfamiliar, non-Occidental music.
Trehub speculates that we are born with a musical brain because music provides a special communication channel between parent and child. Lullabies are found in every culture, she points out, and so is parents' habit of speaking to babies in singsong, musical baby talk: "Music is a child-caring tool."
Or maybe, says Huron, music evolved because it provided a crucial social glue in humanity's evolutionary past. Campfire songs, hymns, and marches help unify groups today; tunes piped on Ice Age flutes may have given our Paleolithic ancestors the social cohesion they needed to hunt, forage, and do battle.
Many people trying to explain the musical brain favor a different idea, however: that even if music itself did not give our ancestors a survival advantage, it is closely tied to something that did, namely language. Some of the same mental faculties that let us appreciate Mozart also come into play in conversation, after all. "Much of the information that's transmitted during speech is transmitted by pitch and timing," two of the crucial elements of music, says neurologist Mark Tramo of Harvard University. Think of the little upturn at the end of a sentence that signals a question.
Double duty. Brain-imaging studies show that parts of the right brain that are sensitive to pitch in music play the same role in speech. And the left brain, sensitive to the split-second differences in timing that make, say, pa and ba sound different, is also busy when we listen to music. Work published by German researchers this spring shows that Broca's area, a patch of brain that analyzes language syntax, seems to do a similar job in music. Its activity spikes in response to inappropriate chords just as it does for a verbal incongruity.
Yet even if music shares some mental equipment with speech, it is much more than just an offshoot of the spoken word. Indeed, brain-imaging studies suggest that some neurological wiring is unique to music. Equally compelling evidence comes from Peretz's "amusic" patients. Even though music is beyond their ken, their ability to speak and understand seems unaffected. Indeed, says Zatorre, "they are completely intact in every way--one is a real estate developer, one is a nurse." The music has stopped for them, but they carry on.
And that brings back the deep strangeness of music, seemingly so central to our lives--and so irrelevant.
This story appears in the August 13, 2001 print edition of U.S. News & World Report.