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Rocker jaw: Global context for a Polynesian characteristic

Scott, GR, Stull, KE, Sbei, AN, McKinney, M, Boling, SR and Irish, JD (2020) Rocker jaw: Global context for a Polynesian characteristic. The Anatomical Record. ISSN 1932-8486

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Abstract

Our goal is to describe the global distribution of the ‘rocker jaw’ variant in human populations. Rocker jaw refers to mandibles that lack the antegonial notch, making them unstable on a flat surface. Data were collected by C.G. Turner II on 9207 individuals from Asia, Europe, the Pacific, and the Americas, and by J.D. Irish on 3526 individuals from North and South Africa. With a focus on Polynesia, where the trait is most common, frequencies are presented for subdivisions of Oceania, Australasia, Eurasia, the Americas, and Africa. While the rocker jaw is a Polynesian characteristic, the trait is found throughout the world. Within major geographic regions, there are interesting contrasts, e.g. (1) the similarity of Jomon and Ainu and their difference from modern Japanese; (2) Aleuts and Northwest Coast Indians are similar and both are distinct from the Inuit and other Native Americans; and (3) North and Sub-Saharan Africans show a regional difference that parallels genetic and dental distinctions. Skeletons in South America that exhibit the rocker jaw have been interpreted as Polynesian voyagers who ventured to the west coast of South America. The rarity of rocker jaw in South American natives supports this view. The rocker jaw can be attributed to the unique basicranium morphology and large upper facial height of Polynesians, which highlights the integrated growth of a functional module (i.e., mastication) of the craniofacial complex. The unusually high frequency of the trait in Polynesians is a product of both function and founder effect/genetic drift.

Item Type: Article
Uncontrolled Keywords: 06 Biological Sciences, 11 Medical and Health Sciences
Subjects: Q Science > QM Human anatomy
Q Science > QP Physiology
Divisions: Biological & Environmental Sciences (new Sep 19)
Publisher: Wiley
Date Deposited: 27 Jan 2021 12:16
Last Modified: 27 Jan 2021 12:16
DOI or Identification number: 10.1002/ar.24566
URI: https://researchonline.ljmu.ac.uk/id/eprint/14313

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