Whales' Songs May Have
Grammatic Structure
By Amanda Onion
NEW YORK - For centuries people believed whales lived in silence as they lurked deep in ocean waters.
But ever since the Cold War, when the U.S. began lowering microphones into the ocean to detect enemy ships and submarines, we have understood that whales are not silent. In fact, the military mics picked up a wide array of loud, eerie noises that turned out to be the complex songs of the humpback whale.
The songs, which can go on for as long as 25 minutes and repeat for up to 24 hours, are so intricate that some have speculated they may be the workings of some kind of otherworldly, marine language. But because it's too easy to subjectively ascribe human characteristics such as speech to an animal, a team of electrical engineers is using a mathematical theory to analyze the songs. So far they have found what appears to be a complex structure - perhaps even a form of grammar - in the songs.
"Our data suggests that the humpback whale song does have a kind of hierarchical structure," said John Buck, a professor of electrical engineering at the University of Massachusetts at Dartmouth. "That doesn't necessarily mean it's grammar or a language, but hierarchical structure is one of several requirements for language."
To analyze two 45-minute songs recorded off the coast of Hawaii in 1977, Buck's student, Ryuji Suzuki, applied the information theory, devised by Claude Shannon in 1948. Shannon revolutionized the field of communications when he suggested that information can be calculated as a quantity. To do that he distinguished repetition in a phrase as a low-information structure and randomness as high-information entropy.
A baby crying "Mama, mama, mama," for example, offers very little information in his cries. But the structure of the baby's speech - repetition of one word - is very predictable. On the other hand, an adult carrying on a conversation uses several words in sentences that abide by some structure, but on the whole are very unpredictable.
"If I say to you either the sun will shine or it will rain," explained Buck. "As soon as you hear me say 'either,' you know there's going to be an 'or' down the road, but you don't know how many words it's going to take me to get there."
In a similar way, the moans, clicks, whistles, pulses, and grunts that make up the various units of a male humpback whale song, appear to be assembled in a hierarchical grammar. Just as words in human language can link back to words much earlier in a sentence, a "moan" in the humpback whale song can agree with a "click" much earlier in the song. Suzuki's findings support a pattern that two biologists, Roger Payne and S. McVay, first detected in 1977 while studying the sound charts of the humpback whale song.
"It appears that a group of these units will often appear in a regular order to make up a phrase. The phrases then make up a theme and that theme is arranged to make up a song," said Buck.
Although the mathematical analysis of the humpback whale song carries exciting implications, there remains a significant stumbling block to fully understanding the songs of these massive sea creatures. Unlike terrestrial animals like chimpanzees and birds, it's nearly impossible to conduct thorough behavioral studies on whales.
"We see only about 8-15 percent of whale behavior " when they're on the surface," said Kurt Fristrup, assistant director of bioacoustics at Cornell University. "That's when they come to breathe and breathing is not particularly interesting social behavior. We miss an awful lot of what's going on."
Ideally, scientists need to control the environment of the animal to match the syntax of an animal's sounds with its behavior. By introducing visual and audio stimulants to chimpanzees in a controlled environment, for example, scientists can isolate how they use different forms of communication. Designing a controlled environment for a humpback whale that can measure up to 50 feet in length and weigh up to 60 tons, is more or less out of the question.
In fact, Buck holds little hope that scientists will ever be able to get adequate behavioral studies of humpback whales to fully understand what their songs may be communicating.
"We can examine the syntax of sounds, but getting from syntax to language is a very big gulf," he said. "I don't know if we'll ever manage to do that."
If nothing else Buck and Suzuki's work indicates there may be much more to understand about the not so quiet, underwater world of the humpback whale. Courtesy of The Virtual Whale Project