By Richard Karel

Croaking toads, barking dogs, and chirping birds are sending a message, but unless you've listened_carefully_to Eugene Morton, Ph.D., you probably won't get it.

Morton, the senior wildlife biologist at the National Zoo, presented the 1996 Zigmond M. Lebensohn Lecture last month in Washington, D.C., titled "Communication Within Species: Do Animals Talk? If Not, What Do They Do?"

Despite the radical differences between communication in human and nonhuman animals, there is an overwhelmingly significant common root, according to Morton. Whatever the differences between cultures and species, "the whole basis for communication" is as a substitute for aggression, he contends.

"The fact that we can communicate and resolve differences in a statelike way is a great example. Most of it goes on, of course, at an individual level. That's what communication in the sense of individuals is all about."

In nonhuman animals the perpetuation of one's genetic legacy is the biological definition of success, which leads to "a sort of selection for Machiavellian intelligence," Morton noted.

But the human definition for success is, of course, more complex. "On the one hand we're doing the same thing, we're trying to get ahead, but on the other hand, we're trying to keep the society that nurtures us intact," observed Morton. "And this is a great bind we're all in biologically, but in terms of human social [interaction] it's perfect. It means that communication replaces fighting most of the time. Because fighting is a last resort."

From the perspective of evolutionary biology, fighting ultimately accomplishes nothing, said Morton. Because bigger animals tend to win fights, fighting tends to select for excessive size. But the fossil record shows that size is usually an evolutionary liability, particularly among carnivores, which must expend great energy merely to eat enough to stay alive. Dinosaurs are the prime example.

In the long run, smaller size confers greater adaptability and enhances survival. Sound communication, by replacing overt aggression, has allowed birds and animals "to adjust their sizes better to the environment in which they find themselves," said Morton. "If you can win the same resources [through sound communication] as you would through combat, that's very adaptive."

But a glance at today's headlines reminds us that communication is not always a successful substitute for physical aggression. Humans, observed Morton, "haven't been around very long. . . .There's a great test going on right now; I wish we knew the answer. But I think that aspect of communication_that it might substitute for fighting in its very origins_is a useful one to keep in mind."

In speaking about animal communication, said Morton, biologists no longer talk about "information transfer and communication." Rather, they say that "the animal that makes the sounds is attempting to manage the behavior of the animal that perceives them. And the perceiver assesses these sounds and makes its own response based upon its own needs at the time."

Follow this to its logical conclusion, he said, and "you will realize that the animal that's making the sounds is not in control of the situation as much as it might think, or like to be; but in fact, it's the listener who is controlling most of communication at its evolution. Because only if the listener, or the assessor, makes changes in its behavior appropriate for what the manager or the signaler wants will that manager continue to make that sound, both on a proximate, and even more importantly on an ultimate, long evolutionary time scale."

In other words, you may shout, but if it doesn't bring results, you probably won't continue.

Although most bird sounds and animal vocalizations are structurally innate, learning is involved in their specific expression, said Morton. But understanding the neurophysiology of communication, so often the focus of animal studies, provides an incomplete picture. If you don't understand why these sounds were useful to the bird or animal both in the past and at present "in that they add fitness to the individuals giving them, you can make mistakes in your interpretation of them," Morton cautioned.

In animal social behavior "the form of the vocalization is directly related to its function_they ain't arbitrary," Morton noted. Hence the sound form of the deep growl always functions as a signal of aggression and dominance. In evolutionary terms, deep tones are associated with large size, which in turn symbolizes success in combat. But the sound, in most cases, permits avoidance of combat through its symbolic conferring of victory on the animal that is able to emit the deepest growl, explained Morton.

"This [relationship between form and function] is the main difference between animal communication and human communication," he noted.

Morton played a tape of a Carolina wren giving three sounds conveying different emotional states. The first was an aggressive sound, which he described as a "growl." The second was a high-toned "appeasement sound." The third he described as "barks."

The bark, if analyzed on a spectroscope, is structured like "a chevron" with both higher and lower pitched sounds making the code ambiguous. This conforms perfectly to the rule of form following function, he said.

"A bark simply is given whenever an animal sees something, or perceives something, that is of interest to it, biological interest, immediate interest, but it does not denote any further action such as 'attack it' or 'run away from it' at that instant."

Such sounds can be varied and combined, "but the general message is that the structure of the sound is incredibly important for its function. There's no known record of an animal growling when it's trying to get closer to another one or be appeasing or vice versa."

Recent work on human speech has started to examine its affective nature, rather than structure and syntax. "In this case they are really looking at what speaking really is. They're not looking at its grammatical structure; they're looking at how people really use it" and are finding that people use "a lot of vocal intonations," said Morton.

Linguists have identified "universals" found in all human languages that seem "to relate to the animal origins of size and sound symbolism," he continued. "For instance, in every language if you ask a question of someone, the last word rises in pitch. . . .If you demand something or want something of someone, you lower your voice at the end of the sentence."

Uniquely among animals, humans simultaneously use both vocal, that is, laryngeal sounds, and nonvocal sounds, involving movements of tongue and lips.

In animals, nonvocal sounds, such as the hiss of a threatened goose, are used when the animal is faced with conflicting motives. "The goose wants to attack a fox that's coming at her nest. On the other hand, the fox can be very dangerous to her, so she's got this 'protect the eggs or protect myself' problem," explained Morton. If the beleaguered goose vocalized in that situation, that is, used her syrinx (the bird's equivalent of our larynx), she would probably emit a sound that didn't work for her. So they hiss. And the hiss is a very ancient and primitive way of voiding the motivation that's tied into most vocally produced sounds in animals."

But the goose, or any creature other than man, cannot simultaneously employ vocal and nonvocal sounds. Animals use vocal sounds that are "very honest; they can't fake them very well," said Morton. "So human speech is rather interesting in that it almost seems to be designed to be as deceitful as possible. So think about that. Primates produce a lot of fricatives or consonants, but they don't put them in vocal sounds. They lip smack or go 'ooohh'. . .but they don't combine them into intricate little signals that we call words" in the arbitrary way that humans do.

(Psychiatric News, October 18, 1996)