Department of Animal Speech

News reports from a few weeks ago told of researchers at St. Andrew’s University in Scotland who have discovered that bottlenose dolphins use signature whistles, to identify themselves to others in their pod. In typical fashion, the news reports played this up, saying that dolphins had "names" for one another and some even going so far as stating that this is proof of animal use of language.

First, the news that dolphins use signature calls is not new; we’ve known that since the 1960s. And it is hardly unique in the animal world; it is common among birds, for example. Nor is it truly a name–there’s no evidence of one dolphin calling another by its signature; instead the calls are used for self-identification. What is new is that Dr. Vincent Janik of St. Andrews has determined that the key to the signature is the pattern of frequency variation over time. Janik was able to make dolphins respond by artificially playing the frequency pattern belonging to another in their pod, with other aspects of the sound, like harmonics or "tone" and the clicks that dolphins also make, removed. So, we’ve learned something new about the structure of dolphin signature whistles. It’s interesting, but hardly earth-shattering. We’re not going to be rewriting the linguistic textbooks because of this discovery. (For a linguist’s opinion on the matter, see Mark Liberman’s post on languagelog.com.)

We’ve been through this before, perhaps most famously with apes who have allegedly been taught sign language. The most famous of these is probably the chimp Washoe, who starting in 1967 was taught American Sign Language (ASL) by Allen and Beatrice Gardner of the University of Nevada. Washoe and the other apes who have been "taught" ASL did learn a large number of signs and could apparently communicate simple concepts to their trainers. Their degree of mastery of ASL is disputed– independent observers have difficulty interpreting the signs and have noted that many of the responses given by the apes are actually prompted by the trainers. None of the apes ever learned the grammar or syntax of ASL. And claims that the apes have created new words, have attempted to sign to other apes as opposed to their human trainers, and have taught other apes to sign are undocumented. Finally, the apes have never been seen using ASL to solicit information from their trainers. Their use of signs is entirely reactive.

Part of the issue with the press confusing animal communications with language is a failure to grasp the essentials of how language is distinguished from other forms of communication. Many animals communicate, but only humans have language.

Linguist Charles Hockett devised a system of thirteen criteria for comparing different forms of communication. Human speech has all thirteen and by looking what criteria various forms of animal communication have, we can determine how close that communication is to speech.

The thirteen criteria are:

  • Arbitrariness. The elements of the signal are not analogous to the real-world situation. Phonemes and words are arbitrary–the sound / kæt / has no real-world analog for a feline. The orientation and speed of the dance of a honey bee, on the other hand, is analogous to the direction and distance of the food source and is not arbitrary.
  • Auditory-vocal channel. Sound is the medium for the message. This is true of all human languages, with the exception of sign languages for the deaf. Many animal communications, however, are visual, tactile, or auditory but not vocal (e.g., a beaver slapping the water with its tail as a warning).
  • Broadcast transmission & directional reception. Any receiver within earshot can hear the signal and determine where the source is. Many animal communication methods share this criterion with language.
  • Discreteness. The set of elements that compose the potential elements are limited in number and contrast with one another. Animal grunts and growls fail this criterion, but there are some animal communication systems that possess it.
  • Displacement. It is possible to communicate about events remote in time and space. With a few exceptions, such as the dance of the honey bee, most animal communications do not possess this characteristic, although it is difficult to determine this for sure.
  • Duality of patterning. The elements have no intrinsic meaning but can be combined into larger structures (e.g., words) that do have meaning. Generally, animal communications also lack this. Although some, like bird song, might possess it.
  • Interchangeability. The message is the same regardless of who delivers it. Many animal communication systems, such as courtship signals, depend on who delivers the message–a female cannot meaningfully deliver the male courtship signal, for example. Some primate systems, like the calls of gibbons, are interchangeable.
  • Productivity. There is a virtually infinite capacity to combine elements into new meanings. This varies. Some animal communications systems are productive, bee dancing for example. Others, such as warning or courtship signals, are not.
  • Rapid fading. The signal is transitory. This is true of many animal communications systems, but not all such as that of marking territory with scent. Note the human writing and modern human recording media do not possess this either.
  • Semanticity. The elements of the signal have stable meanings associated with them. Some animal signals have stable semantic content, such as the elements bee’s dance, others do not, such as a dog’s bark which has different meanings depending on the context.
  • Specialization. The medium (sound waves in the case of language) has no purpose other than carrying the message. Again, this varies with some animal systems possessing it and others not.
  • Total feedback. The sender can also hear the message and make corrections. Another mixed bag here.
  • Traditional communication. The method of communication is taught to succeeding generations rather than being instinctual. Generally animal communications lack this, although some may be taught.

Where does dolphin "naming" fit into this?

  • Arbitrary: Yes. The "names" have no real-world analogs.
  • Auditory-vocal: Yes.
  • Broadcast: Yes,
  • Discrete: No. Janik’s demonstration that it is frequency modulation that is the key makes this system non-discrete.
  • Displacement: No.
  • Duality of patterning: Yes.
  • Interchangeability: Yes and no. Dolphins use only their own names, not those of others.
  • Productivity: Limited. There are an infinite number of possible dolphin names, but these are just names and other messages cannot be communicated. (It may be that dolphin "names" are only part of a larger system of communications that we don’t yet understand. In which case productivity may be generally characteristic of dolphin communications.)
  • Rapid fading: Yes.
  • Semanticity: Yes.
  • Specialization: Yes.
  • Total feedback: Yes.
  • Traditional communication: Apparently no. Young dolphins appear to instinctually "name" themselves.

So, while dolphin naming shares many characteristics with human languages, it differs from language in several key aspects.

(Source: The Cambridge Encyclopedia of Language, 2nd Edition, David Crystal, ed., Cambridge University Press, 1997)

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