Nonmetric dental characteristics of the early modern population of Okinawa Island in Nansei Islands, Japan

Manabe, Yoshitaka; Oyamada, Joichi; Kitagawa, Yoshikazu; Igawa, Kazunari; Kato, Katsutomo; Matsushita, Takayuki; Rokutanda, Atsushi

doi:10.1002/oa.1174

Cited by 7 publications

(3 citation statements)

References 44 publications

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“…Because a differentiation between the Ryukyu and mainland population has also been demonstrated [11], the Amami Islanders are suggested to belong predominantly to the Ryukyu population. Previous dental morphological studies found that the modern inhabitants of Tanegashima Island, just south of Kyushu, are most similar to the mainland Japanese (Figure 1) [24], [25]. Thus, we suggest a genetic boundary between the Amami Islands and Tanegashima Island, which should be further verified (Figure 1).…”

Section: Discussionsupporting

confidence: 58%

Detailed Analysis of Japanese Population Substructure with a Focus on the Southwest Islands of Japan

et al. 2012

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Uncovering population structure is important for properly conducting association studies and for examining the demographic history of a population. Here, we examined the Japanese population substructure using data from the Japan Multi-Institutional Collaborative Cohort (J-MICC), which covers all but the northern region of Japan. Using 222 autosomal loci from 4502 subjects, we investigated population substructure by estimating FST among populations, testing population differentiation, and performing principal component analysis (PCA) and correspondence analysis (CA). All analyses revealed a low but significant differentiation between the Amami Islanders and the mainland Japanese population. Furthermore, we examined the genetic differentiation between the mainland population, Amami Islanders and Okinawa Islanders using six loci included in both the Pan-Asian SNP (PASNP) consortium data and the J-MICC data. This analysis revealed that the Amami and Okinawa Islanders were differentiated from the mainland population. In conclusion, we revealed a low but significant level of genetic differentiation between the mainland population and populations in or to the south of the Amami Islands, although genetic variation between both populations might be clinal. Therefore, the possibility of population stratification must be considered when enrolling the islander population of this area, such as in the J-MICC study.

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Section: Discussionsupporting

confidence: 58%

Detailed Analysis of Japanese Population Substructure with a Focus on the Southwest Islands of Japan

et al. 2012

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“…This difference is qualitatively comparable to the facial shift from the Jomon to the modern Japanese in Honshu, and may result from a southward population influx from the main islands of the Japanese archipelago during medieval times (e.g. Asato, 1996;Doi, 2003;Higa et al, 2003;Manabe et al, 2008Manabe et al, , 2011. Nevertheless, the results indicate that the early-modern Okinawans had facial features seen in both Okinawa Jomon/ Yayoi and early-modern Honshu Japanese, as plausibly illustrated by the PCA result ( Figure 6A).…”

Section: Discussionmentioning

confidence: 58%

“…However, both morphological and genetic findings have also emphasized differential traits of the Ryukyuans (including the Okinawans) from the Jomon/Ainu cluster, cautioning against a simple model that regards the modern Ryukyuans as direct descendants of the prehistoric Jomon, and suggesting considerable population influx from surrounding regions into the Ryukyu area during medieval times (Dodo et al, 1998(Dodo et al, , 2000Asato and Doi, 1999;Hatta et al, 1999;Pietrusewsky, 1999Pietrusewsky, , 2004Pietrusewsky, , 2010Higa et al, 2003;Fukumine et al, 2006;Manabe et al, 2008Manabe et al, , 2011. Dodo et al (2000) compared facial skeletons among many Japanese groups from different periods and regions, and found that the early-modern Okinawans did not exhibit some facial characteristics that are manifested in both Jomon and Ainu (e.g.…”

Section: Introductionmentioning

confidence: 99%

Facial characteristics of the prehistoric and early-modern inhabitants of the Okinawa islands in comparison to the contemporary people of Honshu

Fukase

Wakebe

Tsurumoto

et al. 2012

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Modern inhabitants of the Okinawa islands have been supposed to represent a relatively close genealogical connection to the prehistoric Jomon and the indigenous Ainu, when compared with people living on Japan's main island (Honshu). However, several previous studies have also clarified some morphological facial traits discernible between the early-modern Okinawans and the Jomon of Honshu. In the present study, to further evaluate the Jomon-Okinawan relationship, we compared facial forms between skeletal samples from the Okinawa islands and Honshu, both in the Jomon and early-modern periods. Results of the comparisons showed that the Okinawa Jomon tended to possess a flatter interorbital region than the Honshu Jomon, but most measurements did not significantly differ between the two Jomon groups. This confirms that people sharing both Jomon culture and fundamental facial features lived throughout almost the entire Japanese archipelago, including the Okinawa islands. Results also demonstrated that the early-modern Okinawans had a significantly lower and broader face with transversely broader and flatter interorbital region than the early-modern Honshu Japanese. Such facial characteristics of the early-modern Okinawans qualitatively matched those of the Okinawa Jomon. However, compared with the Okinawa Jomon, the early-modern Okinawans exhibited an absolutely taller/narrower face and a further flatter nasal root. This could stem in part from a certain amount of population flow from surrounding regions during historic periods, as suggested by many earlier studies. Nevertheless, the results obtained in this study indicate that, comparatively, modern Okinawan people have retained physical traits including facial forms of the Jomon who survived in the same southernmost islands of the Japanese archipelago. Geographical variations of modern Japanese phenotypes should also be accounted for partly by those of the ancestral Jomon characteristics that were manifested by the end of the Jomon period.

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Mirror, mirror? An evaluation of identical twin mirroring in tooth crown morphology

McCrary,

Hughes,

Brook

et al. 2024

The Anatomical Record

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It has been estimated that 25% of monozygotic (“identical”) twin pairs exhibit reverse asymmetry (RA) or “mirroring” of minor anatomical features as a result of delayed zygote division. Here, we examine whether identical twin mirroring accounts for patterns of dental asymmetry in a sample of monozygotic and dizygotic (“fraternal”) twins. We focus on crown morphology to approach the following question: is there an association between dental RA frequency and twin type suggestive of the presence of mirror image twins in our sample? Data were collected from 208 deciduous and 196 permanent dentitions of participants of the University of Adelaide Twin Study using Arizona State University Dental Anthropology System standards. RA frequencies were compared across morphological complexes (deciduous, permanent), twin types (monozygotic, dizygotic), and traits. Fisher's exact tests were performed to formally evaluate the association between twin type and dental RA. Across the entire dataset, RA rates failed to exceed 8% for any twin type. In monozygotic twins, deciduous mirroring totaled 5.3% of observed cases, while permanent mirroring totaled 7.8% of observed cases. We found no statistically significant association between RA and twin type for any morphological character (p‐value range: 0.07–1.00). Our results suggest the timing of monozygotic twin division does not explain the structure of asymmetry for our morphology dataset and that published estimates of identical twin mirroring rates may be inflated or contingent upon phenotype. Instead, rates reported for this sample more closely align with the proposed etiology of this condition.

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Nonmetric dental characteristics of the early modern population of Okinawa Island in Nansei Islands, Japan

Cited by 7 publications

References 44 publications

Detailed Analysis of Japanese Population Substructure with a Focus on the Southwest Islands of Japan

Detailed Analysis of Japanese Population Substructure with a Focus on the Southwest Islands of Japan

Facial characteristics of the prehistoric and early-modern inhabitants of the Okinawa islands in comparison to the contemporary people of Honshu

Mirror, mirror? An evaluation of identical twin mirroring in tooth crown morphology

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