Dolphins use individual signature whistles like humans use names

Researchers determined that dolphins use signature whistles that they establish in their first months of life in order to recognize each other. This is the first non-human species observed to use representational labeling behavior.

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Summary

In a recent paper, Cross-modal perception of identity by sound and taste in bottlenose dolphins, researchers described their efforts to demonstrate that dolphins can identify each other by signal whistles that are established in a dolphin's first months of life. According to the abstract, this is significant because, "only humans are known to label concepts to use them in mental simulations or predictions".

The work is further described at TheConversation.Com, in Dolphins use signature whistles to represent other dolphins – similarly to how humans use names. In that article, one of the authors describes the significance like this:

For behavioral biologists like us, this is an incredibly exciting result. It is the first time this type of representational naming has been found in any other animal aside from humans.

You can click through for embedded audio files with two of the dolphin's signature whistles.

The Researchers

The work was performed by Jason Bruck, Assistant Professor of Biology, at the Stephen F. Austin State University, Vincent Janik, Director of the Scottish Oceans Institute at the Univesity of St. Andrews, and Sam Walmsley also at the University of St. Andrews.

Bruck earned a PhD from the University of Chicago in 2013, Janik earned a PhD from University of St Andrews in 1998, and Walmsley appears to be a current or recently completed graduate student.

Lead author, Bruck, describes his research work like this

I focus on the interplay of evolution, cognition and sociality in animals. Specifically I examine how complex social systems in cetaceans, primates and other vertebrates drive the evolution of complex learning and memory skills. Animals with fluid, complex social dynamics have a greater need to remember many social partners over unpredictable lengths of time. Therefore animals with complex social systems like humans, dolphins, chimps, elephants, corvids and some parrots for example should display something called long-term social recognition, which allows them to remember many social partners, sometimes for life.

What they did

It has been known for some time that young dolphins establish unique signature whistles in their early months of development, and that they use these whistles to announce their presence to a group or to greet each other. It was not known, however, what depth of recognition is associated with the whistles of familiar dolphins. The team set out to answer that question.

In order to accomplish this, the team needed another test for recognition that the whistle could be compared to. For this, they used dolphin urine. Dolphins have been observed swimming through each other's waste, and the team wondered if that could be used as a form of recognition. So they trained the dolphins to follow cups of urine that were poured into the dolphin's habitat. By comparing the dolphin's response to familiar and unfamiliar urine samples, they were able to determine that the dolphins did, indeed, recognize each other's urine.

After establishing the baseline, they paired the urine distribution with audio tracks of the dolphin's signature whistles and they observed the dolphin's behavior when exposed to both sets of stimuli. In fact, the dolphins investigated the samples for an average of 30 seconds when the whistle and urine were paired correctly, but only for 20 seconds when the pair was mismatched.

What it shows

Of course, this shows that dolphins can recognize each other, but that's really not news. The groundbreaking part of this research is that the dolphins are able to recognize each other by using an abstract label that they invented themselves. The article at The Conversation closes with this summary:

Signature whistles represent the most language-like aspect of dolphin communication currently known. However, the scientific community knows little about dolphin non-signature calls or the functions of their other acoustic signals. With further research into how dolphins communicate with sound – as well as with chemicals – it may be possible to better understand the minds of these mammals.

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Thank you for your time and attention.

As a general rule, I up-vote comments that demonstrate "proof of reading".

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Steve Palmer is an IT professional with three decades of professional experience in data communications and information systems. He holds a bachelor's degree in mathematics, a master's degree in computer science, and a master's degree in information systems and technology management. He has been awarded 3 US patents.

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^{Pixabay license, source}

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