14 July 2008

The speed of change

In 2003, Morten Christiansen and Simon Kirby edited a volume called Language Evolution (Oxford University Press), which is an excellent, and quite comprehensive account of the main lines of research in the field of the origin of language and language evolution. (You can find more information about this book and an excerpt here).

The authors who contributed articles to this volume are among the leading researchers in the area, e.g. Steven Pinker, Derek Bickerton, Michael Tomasello, Philip Lieberman or James Hurford. They come from a variety of scientific backgrounds (linguistics, archaeology, psychology, anthropology, etc.) and they’re mainly concerned with the evolution of the language human capacity, rather than the evolution of particular languages or language groups. However, from time to time they use data from historical linguistics (mainly from Indo-European studies, which is the best-known, most studied language group) in order to develop their own theories. They’re no experts in historical linguistics, so they naturally turn to the main theories and most recent developments in this area. What they find at the beginning of the 21st century is not much different from what they would have found fifty years earlier, especially in the field of Indo-European studies: traditional chronology and traditional assumptions about language change. I have variously shown in this blog that these ideas are quite dated and basically wrong. But they are still the generally accepted framework, which means that they lead other authors, who are not specialists in historical linguistics, to assume wrong things about the history of languages. In Christiansen and Kirby’s volume I have found some examples of these induced errors. Let’s take a look at them:

- Frederick Newmeyer, What can the Field of Linguistics tell us about the Origins of Language? (op. cit., pp. 58-76).
(p. 62): “The problem is that languages change so fast that (by most estimates) the method allows a time depth for reconstruction of about 6,000-8,000 years (...). So if Proto-World coincided with the appearance of Homo Sapiens, let us say arbitrarily 200,000 years ago, then the intervening 192,000-194,000 years would have been more than enough time to obliterate any signs of what it might have looked like”.

- Michael Tomasello, On the Different origins of Symbols and Grammar, (ibid, pp. 94-110).
(p. 103): “... grammaticalization and syntacticization is somewhat speculative - (...) for example, the main diversification of the Romance languages took place during some hundreds of years - and thus there is no reason why they could not also work to make a simpler language more complex syntactically in some thousands of years”.

- Michael Arbib, The Evolving Mirror System: A Neural Basis for Language Readiness, (ibid, pp. 182-200).
(p. 182): “The immense diversity of the Indo-European languages (...) took about 6,000 years. How can we imagine what has changed in ‘deep time’ since the emergence of Homo sapiens some 200,000 years ago, or in 5,000,000 years of prior hominid evolution?”.

- Robin Dunbar, The origin and Subsequent Evolution of Language (ibid, pp. 219-234).
(p. 230): “Ancestral Indo-European, the language spoken by a small group of (probably Anatolian) agro-pastoralists around 6,000 BC, has given rise to around 150 descendant languages (...) over an 8,000-year period. Interpolating these values into the standard Gaussian logistic growth equation for biological population growth suggests that the Indo-European language family has evolved at a rate equivalent to the budding off of a new language from each existing language, on average, about once every 1,600 years”.

It is clear from these examples that the traditional chronology for Indo-European (IE) creates the wrong impression that IE languages changed at a very high speed. According to the Paleolithic Continuity Theory, which is a new paradigm in historical linguistics, these dates are wrong. IE languages took many more millennia to develop and change than commonly accepted. Language change is not an inherent or measurable feature in languages, it depends on historical, social factors, which means that there are certain circumstances which accelerate the process of change. In the absence or of these factors, human languages tend to remain unchanged. This conservatism of languages is beneficial in terms of communication effectiveness and learnability and it can easily be observed in all human communities. As I said, there are many factors which trigger language change. It is obvious, for example, that the Neolithic revolution is one of them. Another one is the migration of human groups or the invasion and colonization of territories. But these are relatively recent phenomena in the history of humanity. Let’s think about the Paleolithic period, which lasted more than a hundred thousand years and where the socioeconomic and demographic characteristics of human populations were quite different from the ones we know today. The main factor in language change is hybridization, that is, when there is contact between speakers of different languages. It is obvious that in a Paleolithic environment there were fewer opportunities for mobility and for exchange between human communities than in the Neolithic or Metal Age periods, and therefore fewer opportunities for language contact. On the other hand, Paleolithic societies were not highly stratified, which means that pressure from elite groups was not a relevant factor in language.

As we have seen, the assumption that language change happens at a given rate, or that it can be understood regardless of external factors, is a serious mistake that has pervaded historical linguistics for centuries. Evidence for this comes from a variety of sources, e.g. the fact that (relatively) isolated populations, like the ones we find in islands, speak languages with markedly archaic traits if compared to other related languages. This can be seen in Icelandic, for example. There is no internal clock in languages signalling the moment for divergence. In fact, the idea of divergence from the common tree is also very poor when applied to historical linguistics. Languages are not like animal or plant species that can be distributed along a genealogical tree in the form of branches or sub-branches that are the consequence of mutations and adaptation. Languages are something quite different.

Further reading:
- ALINEI, Mario. (1996). Origini delle lingue d'Europa. Vol. I: la Teoria della Continuità. Bologna: Il Mulino.
- ALINEI, Mario (2000). Origini delle lingue d'Europa. Vol. II: Continuità dal Mesolitico all'età del Ferro nelle principali aree etnolinguistiche. Bologna: Il Mulino.
- DIXON, R. M. W. (1997). The Rise and Fall of Languages. Cambridge: CUP.

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