Combinatoriality within the Word: Sign Language Evidence
In human languages, spoken and signed, words or signs are products of combinatorial systems that combine meaningless smaller units in different ways to yield different words or signs with different meanings. In spoken languages those smaller units are the sounds of speech (phonemes). In sign languages, they are handshapes, movements, and the places on the body where signs are made. The question is how the combinatorial systems that combine them evolve.
Word-internal combinatoriality evolved in spoken languages too long ago to be traced, but in sign languages that evolution is much more recent. We argue that signs originated as holistic gestures and show how the life cycle of one sign in American Sign Language (ASL) mirrors the evolution from iconic gestures to products of a combinatorial system, tracing the intervening stages in some detail.
We show that grouping the smaller units together based on similarities in how they are made limits how much signs can vary from one signer to another. Formerly iconic gestures have evolved into signs governed by formal constraints that can obliterate a sign’s original iconic basis.
We briefly present evidence that chimpanzees exposed to ASL for years learned only a small number of holistic gestures, not the combinatorial system learned by signers of ASL. This is explained if the combinatorial abilities needed to learn the vocabulary of a human language evolved in humans after the human and chimpanzee lineages diverged.
We conclude by suggesting that the evolutionary path proposed here for signs of iconic origin could provide an appropriate working model of the parallel evolution of non-iconic signs in sign languages and of the spoken words of spoken languages.