Population History and Anthropometric Variation of West Coast Irish Islands.

Objectives: Previous research using anthropometric data from the west coast of Ireland in the late 19th century showed that two island populations, the Aran Islands and Inishbofin, were phenotypically divergent from the mainland and more similar to England, a pattern consistent with historical evidence for English admixture. The present study extends these analyses by including data from two other island populations in the region that do not have a history of English admixture.

Materials and methods: Data were taken from published sources for six west coast Irish populations measured in the 1890s: two mainland groups (Connemara and Erris) and four island populations (the Aran Islands, Clare Island, Inishbofin, and the Inishkea Islands). The anthropometric data consist of 13 measures on 317 males. Mahalanobis distances among the six populations were derived as well as distances to a mean based on English anthropometric data.

Results: The two island populations with a history of likely English admixture following the garrisoning of English soldiers in previous centuries were the most divergent from the Irish mainland and most similar to the English mean. The other two island populations (Clare Island and the Inishkea Islands) did not have a history of English admixture and were most similar to the Irish mainland.

Discussion: The different patterns of anthropometric similarity among the four island populations show different population histories and support earlier studies suggesting differential English admixture as a factor in the population structure of the region.