Integration Hypothesis: A Parallel Model of Language Development in Evolution

Abstract

There are generally two views of how language emerged in evolution: emergent and gradual. The emergent view holds that language appeared relatively rapidly within the last 100,000 years, possibly due to some minor mutation. The gradualist view postulates stages of “protolanguage” that began as a simple system that progressively developed into ever-complex systems until language as we know it emerged. The original protolanguage may have been singing, as Darwin conjectured, or lexical in nature as proposed by a number of linguists. Human language is enormously rich and complex, which makes it difficult to imagine that all the components of it emerged somehow out of the blue in recent evolutionary time, yet there is no evidence for such a system earlier in evolution. The Integration Hypothesis holds that language is an integration of two independently occurring systems in nature that underlie communication. One system, exemplified by the alarm calls of primates, is the lexical system, which is composed of isolated units of utterance that typically have a specific referent, such as “leopard,” “snake,” and “eagle,” we see in the calls of vervet monkeys. The expression system, associated with birdsong, creates patterns without the use of lexical items. Each system has developed over a long span of time, millions and possibly hundreds of millions of years. At some point in recent evolutionary time, the two systems, L and E, integrated uniquely in humans to give rise to language, which gives the appearance of rapid emergence. I will speculate on how the integration may have been triggered.