Researchers studying thousands of recorded calls have discovered a kind of “sperm whale phonetic alphabet” embedded in their strings of “click” sounds. The finding suggests these whales have a communication system considerably more complex than previously thought.
For sperm whales, bursts of clicks known as a codas come in different varieties and form the building blocks of speech, just as human language emerges from the different vocal sounds we combine to form words and sentences.
The whales shape these codas into some 300 types by varying their duration, rhythm and tempo, and sometimes by adding an extra click. The researchers describe their discovery in a study published Tuesday in the journal Nature Communications.
“The very important caveat to add here is that we still don’t know whether you want to think of a coda as being a word, or like a sentence, or like an individual vowel or consonant,” said Jacob Andreas, an associate professor in electrical engineering and computer science at MIT who is one of the authors of the new study.
“The big payoff here, the way you figure out what they’re actually talking about, how this communication system works and what things mean,” he added, is by trying to link the specific calls to a whale’s behavior. “And that is something we’re actively working on now.”
Robert Seyfarth, an emeritus professor of psychology at the University of Pennsylvania who was not involved in the research, called the study novel and important. “It is also a technological achievement, because studying whale communication poses problems not encountered when studying terrestrial species that are easy to observe,” he said.
Clicking to communicate
Sperm whales do not sing like humpback whales. They make clicks to detect prey as well as communicate using their phonic lips, organs composed of fat and connective tissue located at the opening of the nose. The phonic lips open very briefly and slap back together, creating a loud click that is then amplified in the nasal complex.
The sperm whale clicks reach the equivalent of about 170 decibels in the ocean, as loud as a shotgun blast. Sounds above 120 decibels can cause immediate damage to the human ear, according to the Centers for Disease Control and Prevention.
As they roam the ocean, sperm whales will dive more than 3,200 feet below the surface in pursuit of squid and other prey.
“They come up 45 minutes later, and you don’t know where they are going to come up,” said Gasper Begus, assistant professor of linguistics at the University of California at Berkeley. Begus works with the nonprofit Project CETI, which was instrumental in the research, but he did not participate in the Nature Communications study.
Under such challenging conditions, Project CETI researchers have been recording a community of about 60 sperm whales in the eastern Caribbean Sea, near the island of Dominica. Staff in boats must get close enough to the whales to use long plastic rods to attach a suction tag with a recording device.
For the new study, scientists from Project CETI, MIT and the Dominica Sperm Whale Project used algorithms to group the recorded sperm whale codas. They found 18 different rhythms, five tempos and two different types of extra clicks, which they call ornaments.
“These ornaments come at critical times in the exchange. A lot of times when an ornament is made, another whale joins the conversation, or there’s an end in the conversation,” said Pratyusha Sharma, another of the paper’s authors and a graduate student in the MIT Computer Science and Artificial Intelligence Laboratory.
Researchers also found three different types of what they call rubato, a slight change in the duration of codas. They plan to use their analysis to produce tools that can be used in machine learning.
The many ways animals ‘speak’
Research into communications among animals and insects dates back to the work of the Austrian scientist Karl von Frisch, who in the 1940s studied the honeybee waggle dance. He discovered that bees used the dance to communicate to nestmates the distance and direction of food sources. For his honeybee studies, von Frisch shared the 1973 Nobel Prize in physiology or medicine.
Scientists have since found that birds, nonhuman primates, elephants and Egyptian fruit bats, among many other animals, have their own systems of communication.
Con Slobodchikoff, author of the 2012 book “Chasing Doctor Dolittle: Learning the Language of Animals,” spent 35 years studying prairie dog speech and found that they use distinct calls to communicate the type, size and color of a potential predator. They also added a segment when one potential predator — a man — fired a shotgun in the air.
After reading the sperm whale paper, Slobodchikoff said, “I think it’s great that they’re finding for a marine mammal the kinds of things that we found for land animals.”
Just a few weeks ago, Slobodchikoff and other researchers discussed the potential for decoding the communication systems of other species using artificial intelligence and machine learning at an internet seminar hosted by the nonprofit Santa Fe Institute and the think tank Interspecies Internet.
“AI can really help us out because it is good at detecting patterns,” Slobodchikoff said.
Though he no longer goes out in the field to study prairie dogs, he is now the founder and chief scientist for a company called Zoolingua, which is building a dog translator. He said the device would be a cellphone app with a built-in AI program, “which would tell you [when the dog] says something like, ‘I’m hungry’ or ‘I really need to go for a pee.’”
