VIEWPOINT Language Boundaries Driven by Surface Tension A new model of language evolution assumes that changes in the spatial boundaries between dialects are controlled by a surface tension effect. by Andrew D. M. Smith uman language is unique among communication systems in being a cultural system characterized by prodigious and pervasive variation and ﬂux H on many dimensions [1, 2]. Until the advent of global communication, linguistic varieties were predomi- nantly localized to spatially bound areas, and much research in dialectology has been devoted to understanding the shape and distribution of these dialect regions and how linguistic change spreads through them. In a new paper , James Burridge from the University of Portsmouth, UK, presents Figure 1: These maps show a simulation of three language an innovative statistical-mechanics model, in which the evo- variants that are initially distributed throughout Great Britain in a lution of the boundaries between dialects is driven by a kind random pattern. As time passes (left to right), the boundaries of “surface tension” that minimizes the boundary lengths. between language variants tend to shorten in length. One can also By accounting for the inﬂuence of external topographical see evidence of boundary lines xing to river inlets and other features like the shape of coastlines and the positioning of coastal indentations. (J. Burridge, Phys. Rev. X (2017)) cities, Burridge shows that his model reproduces established features in the distribution of dialects in Great Britain, Ger- many, and elsewhere. novations jump between areas in order of population size, reaching sparsely populated areas later than densely popu- The dynamics of linguistic variation and the mechanisms lated ones, even when they are geographically closer to the by which linguistic changes are propagated through com- original source. Later work , however, showed that diffu- munities have long been important issues for both historical sion patterns can vary dramatically for different linguistic linguists and sociolinguists wanting to explain the origin features, depending on the social value attached to them. and evolution of languages. Traditional models of language For example, adoption of a new word by a “popular ” social dynamics used evolutionary trees to represent historical group can sometimes help it spread more quickly [7, 8]. linguistic relationships, highlighting abrupt points of dif- These models can be tested by looking for signatures in ference between languages but ignoring both the gradual the spatial distribution of dialects. For example, the gravity nature of their divergence and any ongoing contact and mu- model predicts that speciﬁc variants will be clumped around tual inﬂuence. An alternative “wave” model of linguistic big cities. The spatial distribution of linguistic features was diffusion  posited that linguistic innovations radiate from ﬁrst noted by 19th-century dialectologists, who drew maps a central focus and vary in their adoption with distance from with boundary lines, or isoglosses, around the perimeter this source. Few examples of pure wave-like diffusion are of areas using the same form for a linguistic item. Tra- found, however, and other researchers  instead proposed ditional dialect boundaries may therefore be seen on these a hierarchical “gravity” model of diffusion to reﬂect the im- maps where multiple isoglosses for different forms coincide. portance of population density in the spread of linguistic In practice, however, few dialect boundaries are precisely behavior. In this theory, innovations begin in heavily popu- deﬁned. Rather, they reﬂect transition zones of signiﬁcant lated centers with greater interaction and cascade gradually linguistic variability between distinct dialect regions . A through the system. Rather than a single wave, linguistic in- famous example is the so-called Rhenish fan in the dialect map of Germany. The main isogloss divides the country University of Stirling, Stirling FK9 4LA, United Kingdom in half, with Low German in the north and High German physics.aps.org 2017 American Physical Society 17 July 2017 Physics 10, 80 in the south, but this boundary separates into at least eight of space between language users, however, can be seen both different lines as it approaches the country’s western fron- positively and negatively. On the plus side, it allows for a tier—reﬂecting the signiﬁcant linguistic variability among clear understanding of how minor changes in topology can the large industrial centers situated along the river Rhine. yield very different dialect distributions in a qualitatively In his new study, Burridge presents a deliberately mini- plausible way, and it opens the door for easy application mal model of language change, which focuses on explaining of the model to other scenarios. But the model omits phys- dialect distribution solely in terms of topographical features ical factors that contribute to a more nuanced view of the and speaker interaction. The model assumes the existence of cultural “space” between groups of people in a community multiple linguistic variants for multiple linguistic variables, . These include prestige factors, through which linguis- which effectively deﬁne different dialects. In determin- tic propagation is driven by the association of variants with ing whether a given speaker adopts a speciﬁc variant, the different social groups [7, 8], and network factors that are model does not consider “social value” factors. Instead, it known to profoundly affect the diffusion of change through assumes that speakers interact predominantly with people different kinds of social networks . living in their local environment (deﬁned by some radius around their home), and that they will conform to the speech This research is published in Physical Review X. patterns of the majority of people in that geographic vicin- ity. Such local linguistic alignment favors the emergence of distinct dialect areas, with dialect boundaries tending to shorten in length in a way that mimics how surface tension REFERENCES minimizes the surface area of a water droplet (see Fig. 1).  N. Evans and S. C. Levinson, ``The Myth of Language Uni- In a region with uniform population density, this language- versals: Language Diversity and its Importance for Cognitive based surface tension will cause the boundary between two Science,'' Behav. Brain Sci. 32, 429 (2009). dialects to form straight lines. Densely populated areas,  A. D. M. Smith, ``Dynamic Models of Language Evolution: The however, interfere with boundary straightening by repelling Linguistic Perspective,'' in The Palgrave Handbook of Eco- boundaries and effectively creating new dialect areas around nomics and Language, edited by V. Ginsburgh and S. Weber themselves. Furthermore, topography can have an imprint (Palgrave MacMillan, New York, 2016), p. 61. on dialect spatial distributions. In systems with irregular  J. Burridge, ``Spatial Evolution of Human Dialects,'' Phys. Rev. perimeters, Burridge shows that boundary lines tend to mi- X 7, 031008 (2017).  L. Bloomeld, Language (Holt, Rinehart & Winston, New York, grate to places where they emerge perpendicular from the 1933). edge of the system, such as indentations in coastlines.  P. Trudgill, ``Linguistic Change and Diffusion: Description and The paper presents several artiﬁcial systems designed to Explanation in Sociolinguistic Dialect Geography,'' Lang. Soc. reﬂect speciﬁc real-life topographies, with the results com- 3, 215 (1974). pared to known dialect-distribution effects. For example,  G. Bailey, T. Wikle, J. Tillery, and L. Sand, ``Some Patterns Of the model shows how two large indentations on the En- Linguistic Diffusion,'' Lang. Var. Change 5, 359 (1993). glish coast—a square-shaped bay called the Wash in the  R. A. Blythe and W. Croft, ``S-Curves and the Mechanisms of east and the Severn estuary in the southwest—can explain Propagation in Language Change,'' Language 88, 269 (2012). the major boundary between northern and southern English  T. Gong, L. Shuai, M. Tamariz, and G. Jäger, ``Studying Lan- dialects. Over time, multiple isoglosses migrated to these in- guage Change Using Price Equation and Pólya-urn Dynam- ics,'' PLoS One 7, e33171 (2012). dentations, thus reinforcing the differences between the two  D. Britain, ``Space and Spatial Diffusion,'' in The Handbook of regions. The model is also able to simulate a Rhenish fan Language Variation and Change, edited by J. K. Chambers, P. structure in an artiﬁcial system with a cluster of cities near Trudgill, and N. Schilling-Estes (Blackwell, Oxford, 2002), p. the mouth of a river. Burridge’s model successfully and feasibly reproduces  J. Milroy and L. Milroy, ``Linguistic Change, Social Network and several kinds of dialect distributions simply through local Speaker Innovation,'' J. Linguist. 21, 339 (1985). linguistic alignment in distinct topological circumstances. The author ’s focus on a purely localized and geometric view 10.1103/Physics.10.80 physics.aps.org 2017 American Physical Society 17 July 2017 Physics 10, 80
Physics – American Physical Society (APS)
Published: Jul 17, 2017
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