Functions of early language
Discussion
Taking the different motivations distinguished in (4) as the basis of evaluation, there is seemingly no clear evidence in favor of either the cognition or the communication hypothesis. To be sure, two of the factors would seem to lend support to the latter hypothesis: To act in accordance with or to impose social norms (4c) requires some kind of communicative context, and this also applies to (4d): To talk in such a way that you are noticed implies that talking relates to people other than the speaker. On the other hand, (4a) and (4b), which are the ones most frequently observed in grammaticalization, can be reconciled with both hypotheses.
But there is another perspective on this issue. Newmeyer (2004) observes that parts of speech and units of word formation are almost always definable semantically, and he therefore concludes that grammatical categories tend to have a closer relation to cognitive categories than to communicative ones. While this is an important observation, it is also possible to argue the other way round, namely that parts of speech and units of word formation arose because of their relevance to communication and that cognition was simply an aiding factor. Human linguistic communication is mostly about actions, events, and states, it involves people acting or experiencing actions, objects acted upon, places, time, circumstances, etc. These are entities evolving naturally in human interaction, hence there is reason to assume that the categories used to encode these entities, such as the semantic roles agent and patient (or undergoer), or the corresponding parts of speech, are motivated by communicative needs. On this view, the cognitive machinery that is used for representing these entities in linguistic discourse is derivative of their communicative functions (Givo ´n 1979a, 1979b, 1979c, 1984, 1995).
How does this perspective relate to the motivations underlying grammaticalization that we listed in (4)? As we noted above, (4a) and (4b) are compatible with both hypotheses. There is abundant evidence in the literature on semantic and grammatical change to show that describing abstract and less easily accessible concepts in terms of concrete and easily accessible concepts—in accordance with (4a)—constitutes an important strategy of linguistic communication, and so does (4b): Describing complex or less clearly delineated contents with reference to less complex, more readily intelligible concepts is also a salient strategy to be regularly observed in human day-to-day interaction (see, e.g. LakoV and Johnson 1980; LakoV 1987). Accordingly, an interpretation of (4a) and (4b) with reference to the communication hypothesis is at least as plausible as one with reference to the cognition hypothesis.
This leaves us with the remaining motivations that we identified in (4): All of them are incompatible with the cognition hypothesis. We are thus left with the following situation: Since all motivations can be reconciled with the communication hypothesis, and none is exclusively in support of the cognition hypothesis, the only reasonable conclusion is that the communication hypothesis is the one that has to be adopted, while cognition may be defined as an auxiliary function in structuring early linguistic communication.
This conclusion is in accordance with the circumstantial evidence that has been adduced in favor of the communication hypothesis: A number of authors, most of all Givo ´n (2002a, 2005), argue that communication in early language was characterized predominantly by manipulative speech-acts and that the shift towards declarative speech-acts may constitute a later development in the evolution of human language. The evidence for his hypothesis is taken from both primate communication and from early child communication: Both are said to be predominated by manipulative speech-acts, while the bulk of the grammatical machinery of modern languages is invested in the coding of declarative speech-acts (Givo̒n 2002b: 32).
Accordingly, the most plausible scenario proposed so far on this issue is that of Pinker and Jackendoff (2005: 223), according to whom the language faculty evolved gradually in response to the adaptive value of more precise and efficient communication in a knowledge-using, socially inter dependent lifestyle, where ‘‘later stages had to build on earlier ones in the contingent fashion characteristic of natural selection’’ (see also Haspelmath 1999c; Croft 2000), even if it is still largely unclear what exactly the nature of the selection pressure leading to adaptation in language evolution was.
