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Evolution within a language : Environmental differences contribute to divergence of dialect groups

Honkola, Terhi; Ruokolainen, Kalle; Syrjänen, Kaj J.J.; Leino, Unni Päivä; Tammi, Ilpo; Wahlberg, Niklas LU and Vesakoski, Outi (2018) In BMC Evolutionary Biology 18(1).
Abstract

Background: The processes leading to the diversity of over 7000 present-day languages have been the subject of scholarly interest for centuries. Several factors have been suggested to contribute to the spatial segregation of speaker populations and the subsequent linguistic divergence. However, their formal testing and the quantification of their relative roles is still missing. We focussed here on the early stages of the linguistic divergence process, that is, the divergence of dialects, with a special focus on the ecological settings of the speaker populations. We adopted conceptual and statistical approaches from biological microevolution and parallelled intra-lingual variation with genetic variation within a species. We modelled the... (More)

Background: The processes leading to the diversity of over 7000 present-day languages have been the subject of scholarly interest for centuries. Several factors have been suggested to contribute to the spatial segregation of speaker populations and the subsequent linguistic divergence. However, their formal testing and the quantification of their relative roles is still missing. We focussed here on the early stages of the linguistic divergence process, that is, the divergence of dialects, with a special focus on the ecological settings of the speaker populations. We adopted conceptual and statistical approaches from biological microevolution and parallelled intra-lingual variation with genetic variation within a species. We modelled the roles of geographical distance, differences in environmental and cultural conditions and in administrative history on linguistic divergence at two different levels: between municipal dialects (cf. in biology, between individuals) and between dialect groups (cf. in biology, between populations). Results: We found that geographical distance and administrative history were important in separating municipal dialects. However, environmental and cultural differences contributed markedly to the divergence of dialect groups. In biology, increase in genetic differences between populations together with environmental differences may suggest genetic differentiation of populations through adaptation to the local environment. However, our interpretation of this result is not that language itself adapts to the environment. Instead, it is based on Homo sapiens being affected by its environment, and its capability to adapt culturally to various environmental conditions. The differences in cultural adaptations arising from environmental heterogeneity could have acted as nonphysical barriers and limited the contacts and communication between groups. As a result, linguistic differentiation may emerge over time in those speaker populations which are, at least partially, separated. Conclusions: Given that the dialects of isolated speaker populations may eventually evolve into different languages, our result suggests that cultural adaptation to local environment and the associated isolation of speaker populations have contributed to the emergence of the global patterns of linguistic diversity.

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author
organization
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type
Contribution to journal
publication status
published
subject
keywords
Cultural adaptation, Dialect divergence, Environmental variation, Human ecology, Linguistic diversity, Linguistic microevolution, Multiple regression on distance matrices, Variation partitioning
in
BMC Evolutionary Biology
volume
18
issue
1
publisher
BioMed Central
external identifiers
  • scopus:85052663315
ISSN
1471-2148
DOI
10.1186/s12862-018-1238-6
language
English
LU publication?
yes
id
ae45eeca-8974-4a35-b118-74978a1cbed5
date added to LUP
2018-09-25 12:13:46
date last changed
2019-02-20 11:27:39
@article{ae45eeca-8974-4a35-b118-74978a1cbed5,
  abstract     = {<p>Background: The processes leading to the diversity of over 7000 present-day languages have been the subject of scholarly interest for centuries. Several factors have been suggested to contribute to the spatial segregation of speaker populations and the subsequent linguistic divergence. However, their formal testing and the quantification of their relative roles is still missing. We focussed here on the early stages of the linguistic divergence process, that is, the divergence of dialects, with a special focus on the ecological settings of the speaker populations. We adopted conceptual and statistical approaches from biological microevolution and parallelled intra-lingual variation with genetic variation within a species. We modelled the roles of geographical distance, differences in environmental and cultural conditions and in administrative history on linguistic divergence at two different levels: between municipal dialects (cf. in biology, between individuals) and between dialect groups (cf. in biology, between populations). Results: We found that geographical distance and administrative history were important in separating municipal dialects. However, environmental and cultural differences contributed markedly to the divergence of dialect groups. In biology, increase in genetic differences between populations together with environmental differences may suggest genetic differentiation of populations through adaptation to the local environment. However, our interpretation of this result is not that language itself adapts to the environment. Instead, it is based on Homo sapiens being affected by its environment, and its capability to adapt culturally to various environmental conditions. The differences in cultural adaptations arising from environmental heterogeneity could have acted as nonphysical barriers and limited the contacts and communication between groups. As a result, linguistic differentiation may emerge over time in those speaker populations which are, at least partially, separated. Conclusions: Given that the dialects of isolated speaker populations may eventually evolve into different languages, our result suggests that cultural adaptation to local environment and the associated isolation of speaker populations have contributed to the emergence of the global patterns of linguistic diversity.</p>},
  articleno    = {132},
  author       = {Honkola, Terhi and Ruokolainen, Kalle and Syrjänen, Kaj J.J. and Leino, Unni Päivä and Tammi, Ilpo and Wahlberg, Niklas and Vesakoski, Outi},
  issn         = {1471-2148},
  keyword      = {Cultural adaptation,Dialect divergence,Environmental variation,Human ecology,Linguistic diversity,Linguistic microevolution,Multiple regression on distance matrices,Variation partitioning},
  language     = {eng},
  month        = {09},
  number       = {1},
  publisher    = {BioMed Central},
  series       = {BMC Evolutionary Biology},
  title        = {Evolution within a language : Environmental differences contribute to divergence of dialect groups},
  url          = {http://dx.doi.org/10.1186/s12862-018-1238-6},
  volume       = {18},
  year         = {2018},
}