The Evolution of Human Communication and Language
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CHAPTER 14 The evolution of human communication and language James R. Hurford 14.1 Introduction territorial songs, and by vervet monkey alarm calls. We are not yet sure exactly what is conveyed Human language stands out in a number of ways by whale songs, but a reasonable default hypoth- from the topics of almost all of the other chapters esis would seem to be that they convey messages of in this book. Although every communication sys- the same expressive power as complex birdsongs. tem can claim in some way to be unique, human We may be wrong about this, but the current belief language is spectacularly unique in its complexity is thus that any human language is capable of com- and expressive power. municating the sum total of all that any animal spe- Complexity is hard to measure, but a clue is cies can communicate, and more. More, because we given by the fact that The Cambridge Grammar of alone, as far as we know, can tell each other about the English Language (Huddleston & Pullum, 2002), ctional or abstract objects, and about events far which is just a description of Modern Standard distant in time and space. English, weighs in at over 1700 pages. The head- In the bulk of this chapter, I will list and discuss ings of the rst half-dozen descriptive chapters, some of the most important differences and simi- out of eighteen, are: The verb, The clause: comple- larities between human languages and nonhuman ments, Nouns and noun phrases, Adjectives and communication systems, with an evolutionary adverbs, Prepositions and preposition phrases, perspective, in particular drawing on results from and The clause: adjuncts. No non-human com- comparative psychology pertaining to our closest munication system demands anything like this relatives, the non-human primates (see related dis- degree of detail to describe it. And English is just cussion on language in Chapter 13). one of over 6,000 human languages, all of compa- rable complexity. As for expressive power, this is also hard to meas- 14.2 Diversity ure. We can’t see far into the minds of nonhuman animals to know what exactly they can commu- We must rst make the vital distinction between nicate with each other, but it seems a fair bet that Language, the biologically given universal human any factual information, and any affective content1 capacity, and languages, such as English, Swahili, that can be conveyed by an animal communication Cantonese, Dyirbal and Navajo, which are cultur- system can also be conveyed, or at least satisfacto- ally developed systems enabled by the biological rily paraphrased, in any human language. We can, capacity. Noone speaks Language; Language (with we believe, concisely summarize the information a capital L) is not a language. This contrasts with given by honeybee waggle dances, by chaf nch animal communication systems. True, different chaf nch, and other songbird, dialects exist, but 1 A glossary of terms routinely used by linguists about their range is far less than that among human language is given at the end of this chapter. l a n g u a g e s . 249 114-Dettore-Chap14.indd4-Dettore-Chap14.indd 224949 33/11/2008/11/2008 110:55:060:55:06 AAMM 250 SOCIOBIOLOGY OF COMMUNICATION By the usual count, there are over 6,000 different long as they put the words in the same order to human languages. De ning the difference between convey who did what to whom, and use the same a language and a dialect is ultimately not possible, conventional in9 ections to convey such details as but a rough criterion is that different languages the timing of the event reported and the speaker’s are mutually unintelligible, whereas there is some attitude to it, the language works. So languages are degree of mutual intelligibility among different fairly free to evolve different grammars and sound dialects of the same language. By this criterion, systems within the limits imposed by the commu- there are in fact several different Chinese lan- nicative needs of the group. guages, of which Mandarin and Cantonese are two, A contentious issue within linguistics is the but Norwegian and Swedish actually count as the degree to which language learning, and therefore same language. In the past, many other languages linguistic diversity, is further constrained by biol- existed, but are now extinct. It seems likely that ogy. One can certainly imagine crazy languages the peak number of languages spoken by humans that would be impossible to learn. A frequently occurred some time in the last few millennia, when given example is a language which expressed ques- the earth was as yet sparsely populated by small tions by completely inverting the word order of the groups of humans living in relative isolation. Now, corresponding statements. In such a language, you languages are being lost, and we are in an age of would ask the way to the station by saying Station mass linguistic extinction, with predictions that the to way the me tell can you?. The strain on short- about half the world’s languages will die out in term memory in computing how to express ques- the next century. The great diversity of human lan- tions in such a language rules it out as a possible guages is made possible by the fact that they are natural language. The contention within linguistics learned, rather than biologically transmitted from arises because there may be some such constraints generation to generation via the DNA. The fact that on language-learnability which are not attribut- languages are learned is not, however, suf cient to able to nonlinguistic factors such as short-term account for their great diversity. memory, but operate only in the speci c domain of The diversity of biological species arises through language. Here is a candidate for such a Language- accumulated genetic copying errors, geographical speci c constraint. Beware, like all such examples, isolation, and selective adaptation to new niches. it involves ‘thinking the impossible’, something Copying errors in learning and geographical iso- that linguists are skilled at. Consider the following lation are also responsible for the great diversity pair of sentences. of human languages. As early humans spread out The man built the house. The house fell down. over the planet, their group languages accumu- lated changes which were not constrained by any We can make a single sentence, expressing the need to communicate with the groups they had left same information, thus: behind, and these languages struck out on their The house that the man built fell down. own. But adaptation to new niches is not a factor affecting the diversity of languages, aside from the So far, so good. The compressed sentence was relatively simple matter of vocabulary—languages formed by making a relative clause (underlined) out of African pygmies have no unborrowed word of the rst sentence, and attaching it to the shared for snow. In matters of grammatical structure noun phrase, the house. The original right-hand and structure of their sound systems, there is no sentence The house fell down is wrapped around the correlation between languages and the physical outside of this underlined relative clause. Now let’s environments of their speakers. try it again, with this last complex sentence as one A factor permitting the diversi cation of lan- of the inputs to the process: guages is the ‘arbitrariness of the sign’1. A rose by The house that the man built fell down. The man escaped. any other name would smell as sweet. So long as people tacitly agree to use the same words for the Here again, there is a shared noun phrase, the man. same things, a language works. In grammar, as So in principle, it ought to be possible to use the 114-Dettore-Chap14.indd4-Dettore-Chap14.indd 225050 33/11/2008/11/2008 110:55:060:55:06 AAMM THE EVOLUTION OF HUMAN COMMUNICATION AND LANGUAGE 251 same relative clause-forming process. If we do, we grammar, the result of the Norman Conquest of get: England in 1066 and centuries of contact ever since. Many languages are of such hybrid types, owing *The man that the house that built fell down escaped. their structure to multiple sources. The possibility This is an impossible sentence, as indicated by the of such hybridization adds to the overall diversity linguist’s conventional asterisk. And generally, of languages. across languages, we nd that sentences like this, Summarizing the factors contributing to linguis- and their analogues, adjusting for the differences tic diversity, (1) the fact that languages are learned, between languages, such as word order, are also not rather than coded into the genes, (2) the arbitrari- well-formed. The interesting question is ‘Why?’ Is it ness of the sign, and (3) the prevalence of hori- due to a constraint speci c to Language, a putative zontal transmission allow for great diversity, but ‘Law of Language’, that sentences such as this do this is signi cantly constrained by (4) biological not occur in languages? Or is this fact due to a more factors such as memory and processing limitations, general constraint on processing any kind of serial which may or may not be speci c to the Language information, linguistic or otherwise? Both opinions domain. are held in the eld, probably with a swing under way to the general non- domain-speci c explana- 14.3 Learning tion. The original discoverer of this family of con- straints, known as ‘Syntactic Island Constraints’ Human languages are learned. Many animals are was J.R.Ross (Ross, 1967, 1986), in the early heyday also adept at learning.