Science News

Do Dolphins Speak in Sentences? U.S. Scientists Debunk Claims

A team of researchers with Russia's Karadag Scientific Station–Nature Reserve of RAS has used specially developed underwater microphones to capture for the first time what they claim to be a human-like conversation between two Black Sea bottlenose dolphins.

In their paper uploaded to the open access site St. Petersburg Polytechnical University Journal: Physics and Mathematics, the team, led by Vyacheslav Ryabov, describe the pulses generated by the sea creatures and why they believe what they heard was an actual conversation.

Humans have suspected for centuries that dolphins have more advanced communications than other animals—tales of their conversational abilities have been reported by sailors from around the globe. More recently, scientists have been listening to sounds the underwater mammals produce and trying to decipher their meaning—some have claimed they have found that certain pulsed clicks and whistles correspond to certain activities or observations, but to date, none have been able to prove that the dolphins actually carry on conversations. In this new effort, the researchers believe they have come close.

Not So Fast

According to a responding article appearing on the National Geographic website, the claims may no be what they seem.

“Dolphin clicks are highly directional, with the energy focused in front of the animal, much like a flashlight,” Marc Lammers, an expert in dolphin acoustics and an associate research professor at the Hawaii Institute of Marine Biology told National Geographic.

“It is complete bull, and you can quote me,” Richard Connor, a marine biologist at the University of Massachusetts-Dartmouth and a researcher of dolphin social interactions for more than 30 years told National Geographic.

“The biggest problem,” says Connor, “is that now when people make real scientific discoveries on dolphin communication, the public, having been exposed to this nonsense, will not be impressed because they will think Russian researchers already showed that they have language.”

He explained that because dolphin clicks are focused directly in front of them, but were measured at a 90 degree angle while their heads were at the surface of a tank, the sounds recorded do not accurately represent the amplitudes and frequencies projected by the dolphins. He compares it to “recording a conversation by people in the other room speaking into pillows.”

The Russian Claims

According to the researchers, “Many species of dolphins produce long frequency-modulated (FM) acoustic signals containing a large number of harmonics . . . Such signals have come to be called whistles because this is how humans perceive them . . . Most species of dolphins producing whistle signals are gregarious animals and live in large groups, so it was suggested that whistles play an important role in their social communication.”

The researchers calculated that the whistling signals can be heard at a distance of about 10.5 km.

To gain a better perspective on dolphin communication, the researchers developed a two-channel hydrophone recording system in the frequency band up to 220 kHz with a dynamic range of 81 dB meant specifically to capture all the sounds produced by a pair of dolphins (named Yasha and Yana) housed in a research pool. They began by recording sounds from just one of the dolphins at a time to match the pulses made to each individual animal—capturing their unique voices. Then they recorded the two animals as they appeared to hold a conversation near the side of the pool. They noted that the animals took turns "speaking" while the other listened—back and forth emitting short pulses of clicks that varied in pitch and volume, which the researchers suggest were similar to words used in human communication—they describe the conversation as eerily reminiscent of two people having a chat.

So Long, and Thanks for All the Fish

The researchers were not able to decipher the messages the dolphins relayed to one another, of course, but suggest their recordings indicate that dolphins are able to communicate in a highly developed spoken language.

They conclude that the dolphin language, “can be ostensibly considered a highly developed spoken language, akin to the human language. This claim is supported by the fact that dolphins have possessed brains that are somewhat larger and more complex than human ones for more than 25 million years. Humans must take the first step to establish relationships with the first intelligent inhabitants of the planet Earth by creating devices capable of overcoming the barriers that stand in the way of using languages and in the way of communications between dolphins and people.”

They also suggest the existence of a “similar highly developed spoken language in toothed whales (Odontoceti), based on the similarity of their acoustic signals and morphology.”

Responding to the, Lammers told National Geographic that, “The Ryabov paper effectively ignores most of what is currently known about the properties of dolphin clicks, how to measure them correctly, and how they are used by animals in various contexts, and instead lays out the author's own ideas for how dolphin communication might work by weaving together some simple observations with various disconnected notions of acoustics, cognition, and language research.”

For his part, Ryabov stands by the work and mostly deflects his critics by saying he doesn’t believe they read his paper closely enough.

In the U.S., researchers at the Wild Dolphin Project has had some small success creating a dolphin language translator called Cetacean Hearing and Telemetry (CHAT), through which they have taught dolphins to translate a word made up in their dolphin language. However, teaching dolphins words in a lab setting is not proof that they use such words or data in the wild, according Denise Herzing, research director for the Wild Dolphin Project.

Sources

Vyacheslav A. Ryabov, The study of acoustic signals and the supposed spoken language of the dolphins, St. Petersburg Polytechnical University Journal: Physics and Mathematics (2016). DOI: 10.1016/j.spjpm.2016.08.004

Douglas Adams, So Long, and Thanks for All the Fish, Hitchhikers Guide to the Galaxy (Book 4) Del Rey, 1994.

Jason Bittel, Dolphins Recorded Having a ‘Conversation?’ Not So Fast, National Geographic

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