Scientists document remarkable sperm whale 'phonetic alphabet'
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[May 08, 2024]
By Will Dunham
(Reuters) - The various species of whales inhabiting Earth's oceans
employ different types of vocalizations to communicate. Sperm whales,
the largest of the toothed whales, communicate using bursts of clicking
noises - called codas - sounding a bit like Morse code.
A new analysis of years of vocalizations by sperm whales in the eastern
Caribbean has found that their system of communication is more
sophisticated than previously known, exhibiting a complex internal
structure replete with a "phonetic alphabet." The researchers identified
similarities to aspects of other animal communication systems - and even
human language.
Like all marine mammals, sperm whales are very social animals, with
their calls an integral part of this. The new study has provided a
fuller understanding of how these whales communicate.
"The research shows that the expressivity of sperm whale calls is much
larger than previously thought," said Pratyusha Sharma, a Massachusetts
Institute of Technology doctoral student in robotics and machine
learning and lead author of the study published on Tuesday in the
journal Nature Communications.
"We do not know yet what they are saying. We are studying the calls in
their behavioral contexts next to understand what sperm whales might be
communicating about," said Sharma.
Sperm whales, which can reach about 60 feet (18 meters) long, have the
largest brain of any animal. They are deep divers, feeding on giant
squid and other prey.
The researchers are part of the Project CETI (Cetacean Translation
Initiative) Machine Learning Team. Using traditional statistical
analysis and artificial intelligence, they examined calls made by about
60 whales recorded by the Dominica Sperm Whale Project, a research
program that has assembled a large dataset on the species.
"Why are they exchanging these codas? What information might they be
sharing?" asked study co-author Shane Gero, Project CETI's lead
biologist and Dominica Sperm Whale Project founder, also affiliated with
Carleton University in Canada.
"I think it's likely that they use codas to coordinate as a family,
organize babysitting, foraging and defense," Gero said.
Variations in the number, rhythm and tempo of the clicks produced
different types of codas, the researchers found. The whales, among other
things, altered the duration of the codas and sometimes added an extra
click at the end, like a suffix in human language.
"All of these different codas that we see are actually built by
combining a comparatively simple set of smaller pieces," said study
co-author Jacob Andreas, an MIT computer science professor and Project
CETI member.
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The fluke of a sperm whale sticks out of the sea as it dives in the
sea near Rausu, Hokkaido, Japan, July 1, 2019. REUTERS/Kim Kyung-Hoon/File
Photo
People combine sounds - often corresponding to letters of the
alphabet - to produce words that carry meaning, then produce
sequences of words to create sentences to convey more complex
meanings.
For people, Sharma said, "There are two levels of combination." The
lower level is sounds to words. The higher level is words to
sentences.
Sperm whales, Sharma said, also use a two-level combination of
features to form codas, and codas are then sequenced together as the
whales communicate. The lower level has similarities to letters in
an alphabet, Sharma said.
"Every communication system is tailored to the environment and
animal society in which it has evolved," Sharma added.
The communication system used by sperm whales differs, for example,
from the "songs" of humpback whales - and, for that matter, from the
whistles, chirps, croaks and assorted other vocalizations by various
animals.
"Human language is unique in many ways, yes," Gero said. "But I
suspect we will find many patterns, structures and aspects thought
to be unique to humans in other species, including whales, as
science progresses - and perhaps also features and aspects of animal
communications which humans do not possess."
If scientists can decipher the meaning of what the sperm whales are
"saying," should people try to communicate with them?
"I think there's a lot more research that we have to do before we
know whether it's a good idea to try to communicate with them, or
really even to have a sense of whether that will be possible,"
Andreas said.
"At the same time, I'm optimistic that we're going to be able to
learn a lot more about what information is actually encoded in these
vocalizations that we're listening to, what sort of information is
contained in these clicks and these codas, as we start to understand
the behavioral context in which this occurs," Andreas added.
(Reporting by Will Dunham in Washington; Additional reporting by
Matthew Stock in London; Editing by Rosalba O'Brien)
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