THE EVOLUTION OF VERBAL BEHAVIOR

Evolutionary theory has always been plagued by scantiness of evidence. We see the products of ev olution but not much of the process. Most of the story happened long ago, and little remains of the early stages. Especially few traces of behavior remain; only recently were there artefacts that could endure. Verbal behavior left no artifacts until the appearence of writing, and that was a very late stage. We shall probably never know precisely what happened, but we ougth to be able to say what might have happended - that is what kind of variations and what kind of contingencies of selection could have brought verbal behavior into existence. Speculation about natural selection is supported by current research on genetics; the evolution of a social enviroment or culture is supported by the experimental analysis of behavior. Strictly speaking, verbal behavior does not evolve. It is the product of a verbal enviroment or what linguistics call a language, and it is the verbal enviroment that evolves. Since a verbal enviroment is composed of listeners, it is understandable that linguistics emphasize the listener. A question often asked, for example, is "How is it possible for a person to understand a potentially infinite number of sentences"? In contrast, a behaviorial analysis asks, "How is it possible for a person to say a potentially infinite number of se ntences? This paper, then, is about the evolution of a verbal enviroment as the source of the behavior of the speaker. The plausibility of a reconstruction depends in part upon the size of the variations thar are assumed to have occurred; the smaller the variations, the more plausible the explanation. Web-making in the spider, for example, could scarcely have appeared all at once in its present form as a variation. More plausible is a series of small steps. The excretion that eventually became silk may have begun as a coating for effs. It worked better when it took the form of fibers with wich eggs could be wrapped rather than coated. The fibers helped the spiders keep from falling as they worked and did so more effectively as they grew stronger. The spiders might have begun to lift and lower themselves with the fibers, and strands that were left behind might have cought insects, winch the spiders ate. The more strands left, the more insects cought. Some patterns of strands cought more than others. And so on. That may not be exactly what happen, but it is easier to believe than the appearance of web-making as sudden, single variation. The evolution of behavior is also more plausibly regarded as the product of a series of small variations and selections. It is rather like the shaping of operant