Glottochronology
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Glottochronology refers to methods in historical linguistics used to estimate the time at which languages diverged, based on the assumption that the basic (core) vocabulary of a language changes at a constant average rate. This assumption, originally put forward by Morris Swadesh, is based on an analogy with the use of carbon dating for measuring the age of organic materials, in that a "lexical half-life" is estimated. The method estimates the length of time since two or more languages diverged from a common earlier proto-language, by counting the number of words that have been replaced in each language. This then yields an estimated date of origin for those languages. Glottochronology is an adjunct to lexicostatistics, with which it has been sometimes confused.
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[edit] History
The concept of language change is old and its history is reviewed in Hymes (1973) and Wells (1973). Glottochronology itself dates back to the mid-20th century (see Lees 1953; Swadesh 1955, 1972) An introduction to the subject is given in Embleton (1986) and in McMahon and McMahon (2005).
Glottochronology has long been controversial, partly owing to issues of precision, as well as the question of whether its basis is sound (see e.g. Bergsland 1958; Bergsland and Vogt 1962; Fodor 1961; Chretien 1962; Guy 1980). These concerns have been addressed by Dobson et al (1972), Dyen (1973) and Krustal, Dyen and Black (1973). The assumption of a single-word replacement rate can distort the divergence-time estimate when borrowed words are included; but more realistic models have been used.
Chretien purported to disprove the mathematics of the model. At a conference at Yale in 1971 his criticisms were shown to be invalid.
[edit] Methodology
[edit] Word List
The original method presumed that the core vocabulary of a language is replaced at a constant (or near constant) rate across all languages and cultures, and can therefore be used to measure the passage of time. The process makes use of a list of lexical terms compiled by Morris Swadesh assumed to be resistant against borrowing (originally designed as a list of 200 items; however, the refined 100 word list in Swadesh (1955) is much more common among modern day linguists). This core vocabulary was designed to encompass concepts common to every human language (such as personal pronouns, body parts, heavenly bodies, verbs of basic actions, numerals 'one' and 'two', etc.), eliminating concepts that are specific to a particular culture or time. It has been found that this ideal is not in fact possible and that the meaning set may need to be tailored to the languages being compared.
The percentage of cognates (words that have a common origin) in these word lists is then measured. The larger the percentage of cognates, the more recently the two languages being compared are presumed to have separated.
[edit] Glottochronologic Constant
Lees obtained a value for the "glottochronological constant" of words by considering the known changes in 13 pairs of languages using the 200 word list. He obtained a value of 0.806 +/-0.0176 with 90% confidence. For the 100 word list Swadesh obtained a value of 0.86, the higher value reflecting the elimination of borrowed words. This constant may be related to the retention rate of words by:-
- L = 2ln(r)
where L is the rate of replacement, ln is the logarithm to base e, and r is the glottochronological constant
[edit] Divergence Time
The basic formula of glottochronology in its shortest form is:-
where t = a given period of time from one stage of the language to another, c = proportion of wordlist items retained at the end of that period, and L = rate of replacement for that word list.
By testing historically verifiable cases where we have knowledge of t through non-linguistic data (e. g. the approximate distance from Classical Latin to modern Romance languages), Swadesh arrived at the empirical value of approximately 0.14 for L (meaning that the rate of replacement constitutes around 14 words from the 100-wordlist per millennium).
[edit] Results
Glottochronology was found to work in the case of Indo-European, accounting for 87% of the variance.[citation needed] It is also said to work for Hamito-Semitic (Fleming 1973), Chinese (Munro 1978) and Amerind (Stark 1973; Baumhoff and Olmsted 1963). For the latter correlations have been obtained with radiocarbon dating and blood groups as well as archaeology.
[edit] Controversy
[edit] Mainstream rejection
Since its original incarnation, glottochronology has been rejected by many linguists who view it as having been falsified by many counterexamples, some of which are discussed below. However some of these claims are not justified. Many claim that evidence suggests varied rates of language change. For instance, a language's literature may have a stabilizing effect on a literate culture's language[citation needed]. Another argument is that language change arises from socio-historical events which are unforeseeable and uncomputable, and which do not affect language at a constant rate.
There are, moreover, no basic or qualitative differences between features of different rank in the word lists.[citation needed] It is highly likely that the chance of replacement is in fact different for every word or feature ("each word has its own history").[citation needed] Glottochronology uses instead an average rate, with an error estimate.[citation needed]
[edit] Pseudo-Falsification
Some of the more common examples used to discredit glottochronology are actually based on an incorrect understanding of the method. Glottochronology does not presume that language as a whole always changes at a stable rate (including its phonology or grammar), nor does it deny the possibility of rapid lexical loss in the "cultural" layer of the lexicon under specific circumstances. Instead, it focuses on a small, strictly defined list of the most basic items that, according to proponents of the method, do turn out to be resistant to rapid change.
For example, English did not replace about 50 % of its originally Germanic vocabulary 'by time', but by Norman dominance after the battle of Hastings, besides a long-lasting educational background of Latin. Nevertheless. Within the Swadesh 100-wordlist there is only one item that entered English after the Norman conquest ("mountain"), meaning that in terms of a short list of basic lexicon these effects can be all but neglected.
Another example is Albanian, which changed 90% of its Indo-European heritage, while neighbouring Greek did not. Nevertheless, Albanian and modern Greek share approximately the same number of cognates from the 100-wordlist, and 25-26% with English.Template:Fact=March 2007 This indicates that the basic lexicon of Albanian has shifted far less dramatically than more culturally specific items.
[edit] Real Falsification
Much more problematic for glottochronology was the critique addressed at its true foundation, when the method turned out to be falsifiable by using Swadesh's own rules. Thus, in Bergsland & Vogt (1962), the authors make an impressive demonstration, on the basis of actual language data verifiable by extra-linguistic sources, that the "rate of change" for Icelandic constituted around 4% per millennium, whereas for Riksmal (Literary Norwegian) it would amount to as much as 20%. (Swadesh's proposed "constant rate" was supposed to be around 14% per millennium).
This and several other similar examples effectively proved that Swadesh's formula would not work on all available material—a serious accusation considering that evidence that can be used to "calibrate" the meaning of L (i. e. language history recorded during prolonged periods of time) is not overwhelmingly large in the first place. As a consequence, many linguists turned away from glottochronology entirely, rejecting it as falsified once and for all.
[edit] Improvements to Swadesh's Model
Various improvements have been made to Swadesh's simple model. Inhomogenieties in the replacement rate were dealt with by Van der Merwe (1966) by spliting the word list into classes each with their own rate. While Dyen, James and Cole (1967) allowed each meaning to have its own rate. Simultaneous estimation of divergence time and replacement rate was studied by Krustal, Dyen and Black.
Brainard (1970) allowed for chance cognation and drift effects was introduced by Gleason (1959). Sankoff (1973) suggested introducing a borrowing parameter and allowed synonyms.
A combination of these various improvements is given in Sankoff's "Fully Parameterised Lexicostatistics". In 1972 Sankoff in a biological context had developed a model of genetic divergence of populations. Embleton (1981) derives a simplified version of this in a linguistic context. She carries out a number of simulations using this which are shown to give good results.
[edit] Starostin's Method
Somewhere in between the original concept of Swadesh and the rejection of glottochronology in its entirety lies the idea that glottochronology as a formal method of linguistic analysis becomes valid with the help of several important modifications. In particular, an attempt to introduce such modifications was performed by the Russian linguist Sergei Starostin, who had proposed that
- systematic loanwords, borrowed from one language into another, are a disruptive factor and have to be eliminated from the calculations; the one thing that really matters is the "native" replacement of items by items from the same language. The failure to notice this factor was a major reason in Swadesh's original estimation of the replacement rate at under 14 words from the 100-wordlist per millennium, when the real rate is, in fact, much slower (around 5 or 6). Introducing this correction effectively cancels out the "Bergsland & Vogt" argument, since a thorough analysis of the Riksmal data shows that its basic wordlist includes about 15-16 borrowings from other Germanic languages (mostly Danish) - exclusion of these elements from the calculations brings the rate down to the expected rate of 5-6 "native" replacements per millennium;
- the rate of change is not really constant, but actually depends on the time period during which the word has existed in the language (i. e. chances of lexeme X being replaced by lexeme Y increase in direct proportion to the time elapsed – the so called "aging of words", empirically understood as gradual "erosion" of the word's primary meaning under the weight of acquired secondary ones);
- individual items on the 100 wordlist have different stability rates (for instance, the word "I" generally has a much lower chance of being replaced than the word "yellow", etc.).
The resulting formula, taking into account both the time dependence and the individual stability quotients, looks as follows:
In this formula, -Lc reflects the gradual slowing down of the replacement process due to different individual rates (the less stable elements are the first and the quickest to be replaced), whereas the square root represents the reverse trend - acceleration of replacement as items in the original wordlist "age" and become more prone to shifting their meaning. The formula is obviously more complicated than Swadesh's original one, but, as shown in Starostin's work, yields more credible results than the former (and more or less agrees with all the cases of language separation that can be confirmed by historical knowledge). On the other hand, it shows that glottochronology can really only be used as a serious scientific tool on language families the historical phonology of which has been meticulously elaborated (at least to the point of being able to clearly distinguish between cognates and loanwords).
[edit] Time-Depth Estimation Conference
The problem of time-depth estimation was the subject of a conference held by the McDonald Institute in 2000. The published papers (Renfrew, McMahon and Trask, 2002) give an idea of the views on glottochronology at the time. These vary from "Why linguists dont do dates" to the one by Starostin discussed above.
[edit] Bibliography
- Arndt, Walter W. (1959). The performance of glottochronology in Germanic. Language, 35, 180-192.
- Bergsland, Knut; & Vogt, Hans. (1962). On the validity of glottochronology. Current Anthropology, 3, 115-153.
- Brainerd, Barron (1970). A Stochastic Process related to Language Change. Journal of Applied Probability 7, 69-78.
- Callaghan, Catherine A. (1991). Utian and the Swadesh list. In J. E. Redden (Ed.), Papers for the American Indian language conference, held at the University of California, Santa Cruz, July and August, 1991 (pp. 218-237). Occasional papers on linguistics (No. 16). Carbondale: Department of Linguistics, Southern Illinois University.
- Campbell, Lyle. (1998). Historical Linguistics; An Introduction [Chapter 6.5]. Edinburgh: Edinburgh University Press. ISBN 0-7486-0775-7.
- Chretien, Douglas (1962). The Mathematical Models of Glottochronology. Language 38, 11-37.
- Gudschinsky, Sarah. (1956). The ABC's of lexicostatistics (glottochronology). Word, 12, 175-210.
- Gleason, H (1959). Counting and Calculating for Historical Reconstruction. Anthropological Linguistics 1, 22-32.
- Haarmann, Harald. (1990). "Basic vocabulary and language contacts; the disillusion of glottochronology. In Indogermanische Forschungen 95:7ff.
- Hockett, Charles F. (1958). A course in modern linguistics (Chap. 6). New York: Macmillan.
- Hoijer, Harry. (1956). Lexicostatistics: A critique. Language, 32, 49-60.
- Holm, Hans J. (2003). The Proportionality Trap. Or: What is wrong with lexicostatistical Subgrouping. Indogermanische Forschungen, 108,38-46.
- Holm, Hans J. (2005). Genealogische Verwandtschaft. Kap. 45 in Quantitative Linguistik; ein internationales Handbuch. Herausgegeben von R.Köhler, G. Altmann, R. Piotrowski, Berlin: Walter de Gruyter.
- Hymes, Dell H. (1960). Lexicostatistics so far. Current Anthropology, 1 (1), 3-44.
- Lees, Robert. (1953). The basis of glottochronology. Language, 29 (2), 113-127.
- McWhorter, John. (2001). The power of Babel. New York: Freeman. ISBN.
- McMahon, April and McMahon, Robert (2005) Language Classification by Numbers. Oxford: Oxford University Press (in particular p. 95).
- Nettle, Daniel. (1999). Linguistic diversity of the Americas can be reconciled with a recent colonization. in PNAS 96(6):3325-9.
- Sankoff, David (1972). Reconstructing the History and Geography of an Evolutionary Tree. American Mathematical Monthly 79, 596-603.
- Sankoff, David (1973). Mathematical Developments in Lexicostatistic Theory in Current Trends in Linguistics, Ed T Sebock V11, 93-113.
- Sjoberg, Andree; & Sjoberg, Gideon. (1956). Problems in glottochronology. American Anthropologist, 58 (2), 296-308.
- Starostin, Sergei. Methodology Of Long-Range Comparison. 2002. pdf
- Swadesh, Morris. (1955). Towards greater accuracy in lexicostatistic dating. International Journal of American Linguistics, 21, 121-137.
- Swadesh, Morris (1972). What is glottochronology? In M. Swadesh, The origin and diversification of languages (pp. 271–284). London: Routledge & Kegan Paul.
- Tischler, Johann, 1973. Glottochronologie und Lexikostatistik [Innsbrucker Beiträge zur Sprachwissenschaft 11]; Innsbruck
- Time Depth in Historical Linguistics (2000). Ed. by Colin Renfrew, April McMahon & Larry Trask. The McDonald Institute for Archaeological Research, Cambridge, England.
