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Genetic and linguistic coevolution in Northern Island Melanesia.

Hunley K, Dunn M, Lindström E, Reesink G, Terrill A, Healy ME, Koki G, Friedlaender FR, Friedlaender JS - PLoS Genet. (2008)

Bottom Line: There we found some of the strongest recorded correlations between genetic, linguistic, and geographic distances.We also found that, throughout the region, linguistic features have generally been less likely to diffuse across population boundaries than genes.The results from our study, based on exceptionally fine-grained data, show that local genetic and linguistic exchange are likely to obscure evidence of the early history of a region, and that language barriers do not particularly hinder genetic exchange.

View Article: PubMed Central - PubMed

Affiliation: Department of Anthropology, University of New Mexico, Albuquerque, NM, USA. khunley@unm.edu

ABSTRACT
Recent studies have detailed a remarkable degree of genetic and linguistic diversity in Northern Island Melanesia. Here we utilize that diversity to examine two models of genetic and linguistic coevolution. The first model predicts that genetic and linguistic correspondences formed following population splits and isolation at the time of early range expansions into the region. The second is analogous to the genetic model of isolation by distance, and it predicts that genetic and linguistic correspondences formed through continuing genetic and linguistic exchange between neighboring populations. We tested the predictions of the two models by comparing observed and simulated patterns of genetic variation, genetic and linguistic trees, and matrices of genetic, linguistic, and geographic distances. The data consist of 751 autosomal microsatellites and 108 structural linguistic features collected from 33 Northern Island Melanesian populations. The results of the tests indicate that linguistic and genetic exchange have erased any evidence of a splitting and isolation process that might have occurred early in the settlement history of the region. The correlation patterns are also inconsistent with the predictions of the isolation by distance coevolutionary process in the larger Northern Island Melanesian region, but there is strong evidence for the process in the rugged interior of the largest island in the region (New Britain). There we found some of the strongest recorded correlations between genetic, linguistic, and geographic distances. We also found that, throughout the region, linguistic features have generally been less likely to diffuse across population boundaries than genes. The results from our study, based on exceptionally fine-grained data, show that local genetic and linguistic exchange are likely to obscure evidence of the early history of a region, and that language barriers do not particularly hinder genetic exchange. In contrast, global patterns may emphasize more ancient demographic events, including population splits associated with the early colonization of major world regions.

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Genetic and language trees.(A) Language tree. (B) Genetic tree. (C) Revised language tree after removing outliers. The symbols and colors associated with the population names are the same as those used in Figure 1. Bootstrap values for the language tree and revised language tree are listed next to each branch. Because there was insufficient room to list the numeric values next to many of the small branches in the genetic tree, bootstrap values in those cases are indicated by the branch color. The outlier populations identified from the observed vs. expected genetic distance plots (Figure 5) are highlighted with yellow circles. These populations are absent from the revised language tree. The genetic tree contains more populations than the language tree because biological samples were collected from several populations that spoke the same language (e.g., the genetic sample contains two Anêm-speaking populations).
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pgen-1000239-g004: Genetic and language trees.(A) Language tree. (B) Genetic tree. (C) Revised language tree after removing outliers. The symbols and colors associated with the population names are the same as those used in Figure 1. Bootstrap values for the language tree and revised language tree are listed next to each branch. Because there was insufficient room to list the numeric values next to many of the small branches in the genetic tree, bootstrap values in those cases are indicated by the branch color. The outlier populations identified from the observed vs. expected genetic distance plots (Figure 5) are highlighted with yellow circles. These populations are absent from the revised language tree. The genetic tree contains more populations than the language tree because biological samples were collected from several populations that spoke the same language (e.g., the genetic sample contains two Anêm-speaking populations).

Mentions: The language and genetic trees in Figure 4 reinforce this scenario. Neither tree completely separates the Oceanic- from the Papuan-speaking populations. Instead, the trees tend to group populations from the same island. The island grouping is particularly strong for the genetic tree, which also clusters geographic neighbors within islands better than the language tree, e.g., it contains the Mamusi/Nakanai-S/Ata cluster from inland New Britain. The language tree does not contain this cluster, but instead groups the geographically distant Ata and Anêm together, both of which speak Papuan languages. Overall, the language tree has a stronger tendency than the genetic tree to group Papuan-speaking populations separately from Oceanic-speaking populations, suggesting that structural linguistic features are more resistant to exchange than genes between the major language groups, or that linguistic exchange has been comparatively more common within the language groups than between them. The results may also reflect relatively low information content in the linguistic data. The bootstrap values of the language tree are low, and the linguistic data contain only 108 features compared to the 6,437 alleles for the microsatellite loci.


Genetic and linguistic coevolution in Northern Island Melanesia.

Hunley K, Dunn M, Lindström E, Reesink G, Terrill A, Healy ME, Koki G, Friedlaender FR, Friedlaender JS - PLoS Genet. (2008)

Genetic and language trees.(A) Language tree. (B) Genetic tree. (C) Revised language tree after removing outliers. The symbols and colors associated with the population names are the same as those used in Figure 1. Bootstrap values for the language tree and revised language tree are listed next to each branch. Because there was insufficient room to list the numeric values next to many of the small branches in the genetic tree, bootstrap values in those cases are indicated by the branch color. The outlier populations identified from the observed vs. expected genetic distance plots (Figure 5) are highlighted with yellow circles. These populations are absent from the revised language tree. The genetic tree contains more populations than the language tree because biological samples were collected from several populations that spoke the same language (e.g., the genetic sample contains two Anêm-speaking populations).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2570610&req=5

pgen-1000239-g004: Genetic and language trees.(A) Language tree. (B) Genetic tree. (C) Revised language tree after removing outliers. The symbols and colors associated with the population names are the same as those used in Figure 1. Bootstrap values for the language tree and revised language tree are listed next to each branch. Because there was insufficient room to list the numeric values next to many of the small branches in the genetic tree, bootstrap values in those cases are indicated by the branch color. The outlier populations identified from the observed vs. expected genetic distance plots (Figure 5) are highlighted with yellow circles. These populations are absent from the revised language tree. The genetic tree contains more populations than the language tree because biological samples were collected from several populations that spoke the same language (e.g., the genetic sample contains two Anêm-speaking populations).
Mentions: The language and genetic trees in Figure 4 reinforce this scenario. Neither tree completely separates the Oceanic- from the Papuan-speaking populations. Instead, the trees tend to group populations from the same island. The island grouping is particularly strong for the genetic tree, which also clusters geographic neighbors within islands better than the language tree, e.g., it contains the Mamusi/Nakanai-S/Ata cluster from inland New Britain. The language tree does not contain this cluster, but instead groups the geographically distant Ata and Anêm together, both of which speak Papuan languages. Overall, the language tree has a stronger tendency than the genetic tree to group Papuan-speaking populations separately from Oceanic-speaking populations, suggesting that structural linguistic features are more resistant to exchange than genes between the major language groups, or that linguistic exchange has been comparatively more common within the language groups than between them. The results may also reflect relatively low information content in the linguistic data. The bootstrap values of the language tree are low, and the linguistic data contain only 108 features compared to the 6,437 alleles for the microsatellite loci.

Bottom Line: There we found some of the strongest recorded correlations between genetic, linguistic, and geographic distances.We also found that, throughout the region, linguistic features have generally been less likely to diffuse across population boundaries than genes.The results from our study, based on exceptionally fine-grained data, show that local genetic and linguistic exchange are likely to obscure evidence of the early history of a region, and that language barriers do not particularly hinder genetic exchange.

View Article: PubMed Central - PubMed

Affiliation: Department of Anthropology, University of New Mexico, Albuquerque, NM, USA. khunley@unm.edu

ABSTRACT
Recent studies have detailed a remarkable degree of genetic and linguistic diversity in Northern Island Melanesia. Here we utilize that diversity to examine two models of genetic and linguistic coevolution. The first model predicts that genetic and linguistic correspondences formed following population splits and isolation at the time of early range expansions into the region. The second is analogous to the genetic model of isolation by distance, and it predicts that genetic and linguistic correspondences formed through continuing genetic and linguistic exchange between neighboring populations. We tested the predictions of the two models by comparing observed and simulated patterns of genetic variation, genetic and linguistic trees, and matrices of genetic, linguistic, and geographic distances. The data consist of 751 autosomal microsatellites and 108 structural linguistic features collected from 33 Northern Island Melanesian populations. The results of the tests indicate that linguistic and genetic exchange have erased any evidence of a splitting and isolation process that might have occurred early in the settlement history of the region. The correlation patterns are also inconsistent with the predictions of the isolation by distance coevolutionary process in the larger Northern Island Melanesian region, but there is strong evidence for the process in the rugged interior of the largest island in the region (New Britain). There we found some of the strongest recorded correlations between genetic, linguistic, and geographic distances. We also found that, throughout the region, linguistic features have generally been less likely to diffuse across population boundaries than genes. The results from our study, based on exceptionally fine-grained data, show that local genetic and linguistic exchange are likely to obscure evidence of the early history of a region, and that language barriers do not particularly hinder genetic exchange. In contrast, global patterns may emphasize more ancient demographic events, including population splits associated with the early colonization of major world regions.

Show MeSH