Over on my web site I've posted an article I've just written for the Sunday Telegraph Magazine in England about an eerie brain disorder called musical hallucinosis. You've probably had a tune stuck in your head for an hour at least once in your life. Now imagine that the tune played all day and night--and imagine that it sounded as real as if a marching band was standing by your window.
Here's how it starts:
Janet Dilbeck clearly remembers the moment the music started. Two years ago she was lying in bed on the California ranch where she and her husband were caretakers. A mild earthquake woke her up. To Californians, a mild earthquake is about as unusual as a hailstorm, so Dilbeck tried to go back to sleep once it ended. But just then she heard a melody playing on an organ, "very loud, but not deafening," as she recalls. Dilbeck recognized the tune, a sad old song called When You and I Were Young, Maggie.
Maggie was her mother's name, and when Dilbeck (now 70) was a girl her father would jokingly play the song on their home organ. Dilbeck is no believer in ghosts, but as she sat up in bed listening to the song, she couldn't help but ask, "Is that you, Daddy?"
She got no answer, but the song went on, clear and loud. It began again from the beginning, and continued to repeat itself for hours. "I thought, this is too strange," Dilbeck says. She tried to get back to sleep, but thanks to the music she could only doze off and on. When she got up at dawn, the song continued. In the months to come, Dilbeck would hear other songs. She heard merry-go-round calliopes and Silent Night. For a few weeks, it was The Star-Spangled Banner.
Go here to read the rest.
Brain disorders always grab our attention because they have the power to warp the fabric of reality, or at least our experience of it. But they can tell us even deeper things about ourselves--specifically, how the human mind was assembled over the course of evolution. Autistic people, for example, lack what psychologists call a theory of mind--an intuition of what other people are thinking. In an article I wrote last year for Science, I detailed research that shows how the evolution of a theory of mind was key to the rise of social intelligence in humans, perhaps even making language possible.
Musical hallucinations may offer some clues to another important feature of human evolution: our capacity for music. Like language, music in humans has no real counterpart elsewhere in the animal kingdom. Birds and whales sing, but their songs have little of the flexibility and creativity that marks human music. And music, researchers are finding, is processed by a complicated network of regions in the brain. Musical hallucinations may emerge when that network is cut off from the outside world by deafness, and it seizes on stray impulses in the brain, cranking them up into the perception of real tunes. But how did this special faculty for music evolve? Scientists I've spoken to don't think there's a good explanation out there yet. When a good explanation does come along, it will have to account for music either as an adaptation in itself or as a byproduct of other adaptations--or some combination of both. The building blocks of music seem to be nested within our ability to understand language and other complex noises--detecting pitch, tempo, and so on. One could argue that proto-music gave our ancestors some reproductive advantage. Perhaps songs gave bands of hominids a powerful sense of solidarity. Or perhaps it is nothing but a fortunate fluke, its pleasure deriving from reward networks that evolved for other functions long before anyone hummed a tune.
Update: 3/9/04 1:20 Theory of mind link fixed