How Whales Write Number One Hits
| By Elizabeth Pennisi ScienceNOW Daily News 22 March 2006 Humpback whales have long been celebrities for their intricate songs; tracks of their melodic moans, whistles, and clicks could fill a dozen CDs. How in the world do they do it? According to a new study, whales compose their ballads by stringing together these sounds into a grand series of repetitive patterns. Although the findings aren't proof of a cetacean language, they do indicate that the sea-faring giants use a kind of syntax, a feature thought to be unique to humans.Each year, male humpbacks devise new songs. And each year, a number one hit emerges that catches on among the whales. Because the songs are so complex, researchers have spent decades trying to figure out how whales compose new ones every year--and how they manage to remember them. One idea, first proposed 30 years ago, is that whale sounds are grouped into short units, which in turn form the components of longer phrases. To test for such an underlying structure, Ryuji Suzuki, a neuroscience graduate student at the Massachusetts Institute of Technology in Cambridge, wrote a computer program to detect individual combinations of sounds. The program translates sound combinations into symbols--"AAABBB" or "ABACC", for example--that enable both the computer and human analysts to pick out specific patterns. Based on these patterns, the program derived "rules" of whale-song writing. The sets are arranged in a hierarchy of ever-larger repeating segments. It's a bit like human music: If you consider the seconds-long sets of whistles and clicks as musical notes, the notes combine into melodies, and the melodies into veritable sonatas, Suzuki and his colleagues report this month in the Journal of the Acoustical Society of America. This hierarchical structure allows for mixing and matching elements on several levels for easy repackaging and memorization of a tune, he says. "What this tells me is that humpback whales have evolved a surprisingly sophisticated way of remembering the complexity of structure in their songs," says Phillip Clapham, a marine biologist at the National Marine Mammal Laboratory in Seattle, Washington. "The results challenge the idea that some of the properties of human language are unique to humans." This was seized 4 u at Science Magazine |
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