Work in animal behavior, and in particular cognitive ethology, has shown that most of the differences in kind once thought to distinguish humans from other animals are actually differences in degree. The one behavior where a huge gap still seems to exist is language.
Language is best defined as a communication system that employs arbitrary signals to refer to things distant in time or space. It is not simply a way of advertising a creature’s species and sex—the role of the vast majority of animal communication. Thus, the flashing of fireflies, olfactory signaling of moths, croaking of frogs, and mate attraction calls of birds are specific here-and-now signals; they are no more a matter of language than are body shapes or the movements involved in locomotion.
One scenario for the evolution of language is that it developed from preexisting systems of animal communication. This hypothesis suggests that the previous communication systems would have needed multiple signals to give evolution a start. In social animals, including animals that are social only during reproduction and the rearing of young, there are generally many innate calls or other signals that permit the necessary coordination of effort. Monogamous birds, for instance, have approximately two dozen unique calls used during pairing, incubation, and feeding of nestlings. Social primates have roughly the same number.
True language is found in two highly social species: honeybees and humans. In bees, the foragers communicate to potential recruits the direction, distance, and quality of a food source; the language is also used for pollen, water, and nesting sites. In two species, the dances occur on vertical surfaces in the darkness of the hive, out of sight of the food (up to several thousand meters away) and minutes or even hours after visiting the site.
The arbitrary conventions involve taking vertical in the hive to correspond to the direction of the sun and considering each “waggle” and sound burst in the dance to correspond to a specific distance flown. “Up” could just as easily have been referenced to the direction the hive faces or to the north; at least these directions do not change with time and would not have required the elaborate time compensation system by which the dance angle is changed to reflect the unseen motion of the sun outside. The arbitrariness of the distance convention is particularly clear; different subspecies of honeybees have different waggle-to-meters dialects.
Impressive as it is, the honeybee language is both wholly innate and closed; that is, no new arbitrary conventions (words or grammar) can be added to the system. At the same time, we now know that human language depends on enormous amounts of inborn help; consonants are innately recognized, vowel categories are innately sorted (although culturally defined), specific brain areas (generally on a particular side) are present from birth, a default word-order grammar is in place, a “deep structure” for encoding and decoding is built in, and strong drives exist to categorize, learn grammatical rules, and acquire a vocabulary.
Perhaps the wealth of innate circuitry should not have been a surprise. Language is, after all, a species-specific human behavior that develops in all normal children at a characteristic age independent of active teaching or error correction. On the other hand, the intellectually trivial skill of multiplication is never learned spontaneously and always requires error correction.
Comparing humans with primates, the obvious candidate for the initial components of language is the set of innate calls, which could correspond to consonants. In certain species such as vervet monkeys, some of these calls have highly specific meanings such as a predatory bird, snake, or leopard in ambush. Like most human language, these calls are “inflected”; that is, alteration of the beginning, duration, or ending add meaning to the signal. The right-angle bend from spine to head engendered by walking erect created the two separate chambers necessary to produce vowels and, thus, created a huge number of syllables when combined with approximately three dozen consonants. But how this potential was turned into the elaborate mix of innate and acquired features that is human language remains a mystery.
References:
- Gould, J. L. (1982). Ethology: The mechanisms and evolution of behavior. New York: Norton.
- Gould, J. L., & Gould, C. G. (1995). The honey bee (2nd ed.). New York: Freeman.
- Pinker, S. (1994). The language instinct. New York: William Morrow.
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