A paper recently published in the Proceedings of the Royal Society on dolphin communication got some public attention in Science last week because the studies inferred that dolphins could learn names of individuals in their social group and use these names referentially under certain circumstances.
On the face of it this may not sound that remarkable. Symbolic or representational gestures are found in many other animals, identifying predators, foods, or situations with call types or even specific sounds (names). What makes this study somewhat novel is the referential context − implying a reflexive consciousness.
Dolphins use two different types of vocalizations; the ultrasonic signals used for bio-sonar, and lower-frequency whistles (audible to humans) which they use in social settings. As much as 50% of these vocalizations are the individual dolphins announcing their own “signature whistle” presumably letting their community know who and where they are. These signature whistles are “invented” by the owner. The significance of the other social sounds remains unknown but could be expressions of emotional fitness or proximity (akin to jingling your bicycle bell as you move up to pass another rider).
The study took place over quite a few years taking note of the signals that captive dolphins produced when sequestered for health monitoring exams. In these settings many of the dolphins did not annunciate their own signature whistle; rather they mimicked the signature whistles of a closely affiliated individual; perhaps like saying “Bob, help me out here” when they wanted to get the attention of a pal.
In their typical social settings mimicking another’s signature whistle would be confusing and counterproductive. But using them under a stressful situation implies the referential consciousness required to call in an ally under specific conditions. This is not like the alarm calls found in many animals – alerting the entire community that there is a problem; rather this is an individual animal announcing that they are in a situation that they need to convey to another specific individual.
This probably doesn’t sound all that surprising for an animal that we know has complex cognitive abilities and even more complex signal processing capabilities. We’ve known for decades that dolphins create and learn their own signature whistles. It is just that trying to sort out “who is making what whistle when” when the animals are in tightly coupled social settings is hard to do to the satisfaction of science.
There is evidence that the more complex dolphin communication happens in the ultrasonic range of their bio-sonar. They can “eavesdrop” on the target echoes produced by the sonar signals of others. So while dolphins can “keep tabs” on each other with their lower frequency social whistles, they may strategize foraging and hunting maneuvers by inhabiting a mutually-created ultrasonic sound-field. This form of communication is probably less like “talking” and more like everyone having flashlights in the dark woods.
While there is evidence of this, until we can understand how to mimic the sonar signals that a dolphin receives we are a long way from understanding it to the satisfaction of science.