Gray and company note that humpback composers employ many of the same tricks human songwriters do. In addition to using similar rhythms, humpbacks keep musical phrases to a few seconds, creating themes out of several phrases before singing the next one. Whale songs in general are no shorter than human ballads and no longer than symphony movements, perhaps because they have a similar attention span. Even though they can sing over a range of seven octaves, the whales typically sing in key, spreading adjacent notes no farther apart than a scale. They mix percussive and pure tones in pretty much the same ratios as human composers¿and follow their ABA form, in which a theme is presented, elaborated on and then revisited in a slightly modified form.

Perhaps most amazing, humpback whale songs include repeating refrains that rhyme. Gray and her colleagues say that whales might use rhymes for exactly the same reasons we do: as devices to help them remember. As a recent study showed, whale songs are often rather catchy. When a few humpbacks from the Indian Ocean strayed into the Pacific, some of the whales they met there quickly changed their tunes¿singing the new whales' songs within three short years.

Back on land, birds, too, make music much like people. "When birds compose songs they often use the same rhythmic variations, pitch relationships, permutations and combinations of notes as human composers," Gray and her colleagues write, citing work done by their late co-author Luis Baptista. "Thus, some bird songs resemble musical compositions; for example, the canyon wren's trill cascades down the musical scale lie the opening of Chopin's 'Revolutionary' Etude." That same bird sings in the chromatic scale, which divides the octave into 12 semitones, and the hermit thrush sings in the so-called pentatonic scale. It is perhaps because these birds pitch their songs to the same scale as Western music that people find them so attractive.

Why would such different creatures¿with such different physical means for making sound¿all adopt such astonishingly uniform patterns for their melodies? Gray and her colleagues conclude that the similarities "tempt one to speculate that the platonic alternative may exist¿that there is a universal music awaiting discovery." But in fact, there is currently considerable debate over the purpose of music, and whether it was adaptive for humans in evolution or not.

"Auditory Cheesecake" or Evolutionary Advantage?

Linguist Steven Pinker of the Massachusetts Institute of Technology has proposed that music is merely "auditory cheesecake," or "an evolutionary accident piggy-backing on language," as Daniel J. Levitin at McGill University explained in a recent issue of the journal Cerebrum. But many scientists¿Levitin among them¿don't agree. "Some researchers are finding that listening to familiar music activates neural structures deep in the ancient primitive regions of the brain, the cerebellar vermis," Levitin writes. "For music so profoundly to affect this gateway to emotion, it must have some ancient and important function."

Geoffrey Miller of University College London has proposed that musical ability¿like broad shoulders or showy plumes¿may serve to demonstrate fitness to a potential mate. After all, singing or playing an instrument well requires dexterity and good memory. Another suggestion Levitin makes is that music functions as communication, perhaps mimicking the rhythm and contour of our species' primitive calls. So, too, he proposes that perhaps music conveys an advantage through stimulating our primitive timing mechanisms.

Most interesting, he suggests that music stimulates our drive to find patterns in the environment. "Our brain is constantly trying to make order out of disorder, and music is a fantastic pattern game for our higher cognitive centers," he writes. "From our culture, we learn (even if unconsciously) about musical structures, tones and other ways of understanding music as it unfolds over time; and our brains are exercised by extracting different patterns and groupings from music's performance." It is this very kind of pattern recognition¿which is extremely important for making sense of the world around us¿that Keith Devlin suggests in his book The Math Gene gave rise to language and stands behind mathematical ability as well. To be certain, researchers won't agree on the purpose of music anytime soon¿which fortunately shouldn't stop any of us from enjoying it.

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