Influence of size and placement of developing teeth in determining anterior corpus height in prehistoric Jomon and modern Japanese mandibles

Fukase, Hitoshi; Suwa, Gen

doi:10.1537/ase.090513

Cited by 10 publications

(15 citation statements)

References 70 publications

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“…Significant differences in UFH between the Jomon and the post-Jomon adolescents are apparent based on the differences in the growth trajectory between the two groups ( Figure 2B). This pattern of ontogenetic acquisition of group differences was consistent with that of nasal height, although symphyseal height showed a unique change with advancing age cohorts of relative ranking of population means (Table 2), which could be related to the difference in the spatial size for anterior teeth formation between the Jomon and Early Modern groups (Fukase and Suwa, 2010). In contrast, no significant differences in growth trajectory were found for maxillary breadth or bigonial breadth among the chronologically defined groups ( Figure 2C).…”

Section: Facial Heightsupporting

confidence: 68%

Developmental variation in facial forms in Japan

Okazaki

Nakahashi

2011

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Significant differences in facial form between the Jomon and the post-Jomon series of the Yayoi, Medieval, and Early Modern period have been interpreted in terms of the gene flow from the Asian continent or the reduction of masticatory stress through the Jomon to the Early Modern period. However, the developmental process that produced these differences in facial form between the two groups has remains unknown. In this study we examined the factors contributing to differences in facial form by studying the developmental patterns of facial form using data from 311 subadult individuals from the middle-late Jomon (c. 5000-2500 BP) to the Early Modern period (1900( -1950. We found statistically significant differences in facial form among the temporally defined groups at early stages of development. Differences in upper facial height between the Jomon and the post-Jomon series were significant during both childhood (3-6 years, P < 0.05) and adolescence (12-20 years, P < 0.01). Differences in simotic index and bigonial breadth between the Jomon and the post-Jomon series were significant, beginning in childhood (P < 0.05), and differences in symphyseal height between the series were significant during both infancy (0-3 years, P < 0.05) and adolescence (P < 0.01). Based on previous ethnographical data, studies on the wear of the deciduous dentition in the Jomon and post-Jomon populations, and stable isotope analyses for reconstructing weaning diets in Jomon and Medieval children, it seems to be the first-stage juvenile stage (6-9 years) when the differences in masticatory load among the chronological groups become conspicuous enough to act on the functional adaptation of facial bones. Therefore, the patterns of group differences which begin in infancy or childhood and become remarkable in adolescence do not contradict the former explanation that the gene flow from the Asian continent largely contributed to the change of facial form during the transition between the Jomon and Yayoi periods.

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Section: Facial Heightsupporting

confidence: 68%

Developmental variation in facial forms in Japan

Okazaki

Nakahashi

2011

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“…The Jomon materials span a chronological age of approximately 5000-2350 BP, and the 'modern' Japanese are from the anatomy department collections formed at the end of the 19th/early 20th century. Further details of the samples are available in Fukase and Suwa (2010).…”

Section: Methodsmentioning

confidence: 99%

Mandibular tooth root size in modern Japanese, prehistoric Jomon, and Late Pleistocene Minatogawa human fossils

Suwa

Fukase

Kono

et al. 2011

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Although dental size and morphology have contributed to population history studies in Japan, little attention has been paid to root size and dimensions. We report here computer tomography (CT)-based metrics of mandibular tooth roots in modern Japanese, Holocene Jomon, and Late Pleistocene Minatogawa human fossils (15000-20000 BP). Our results confirmed that, in terms of both mesiodistal cervical diameters and root lengths, the Jomon is overall smaller-toothed, with summed mesiodistal cervical diameters 4% smaller than in the modern Japanese. However, no significant differences were found in the M 1 , in both cervical diameter and root length. These results are comparable to the crown size differences reported in the two populations. There were no significant differences in root proportions (root length relative to cervical diameter) between the Jomon and the modern Japanese in each tooth element from I 1 to M 1 , while an allometric root length reduction was observed in the M 2 and M 3 of the modern Japanese. This reflects distinct patterns of dental reduction in the two populations. The Late Pleistocene Minatogawa fossils were found to have larger cervical diameters and root lengths than either the modern Japanese or the Jomon, in some respects approximating the largetoothed Australian and/or earlier Late Pleistocene Homo sapiens conditions. This indicates a largely conservative dental system retained in the Minatogawa fossils, distinct from the Jomon condition.

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“…Spatial requirements for housing and supporting the anterior teeth have been proposed as one potential nonmechanical factor that may determine symphyseal size and shape (e.g., Wolpoff, 1975;Wood, 1978;Chamberlain and Wood, 1985;Dean and Beynon, 1991;Taylor, 2002;Plavcan and Daegling, 2006;Coquerelle et al, 2010Coquerelle et al, , 2011Fukase and Suwa, 2010;Cobb and Panagiotopoulou, 2011;Fukase, 2011). However, the symphyseal contours of adult great apes exhibit much less variation between sexes than among species (Daegling, 1993b(Daegling, , 2001Sherwood et al, 2005;Guy et al, 2008).…”

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confidence: 99%

“…These results indicate that eventual canine size has a limited influence on intra-species symphyseal shape variation, and may refute a simple relationship between the sizes of the symphysis and teeth. However, arguments from earlier studies were mostly based on external dimensions of the adult mandible and teeth, and recent ontogenetic studies using CT data have substantially indicated that certain aspects of symphyseal configurations can develop from the spatial demands of the forming incisor and canine crypts (e.g., Coquerelle et al, 2010Coquerelle et al, , 2011Fukase and Suwa, 2010;Cobb and Panagiotopoulou, 2011;Fukase, 2011).…”

mentioning

confidence: 99%

“…Using a finite elements analysis, the authors also inferred that the absence of trabecular bone due to the presence of tooth crypts impacts on the mechanical function of the symphysis. Furthermore, our previous study (Fukase and Suwa, 2010) compared the size and placement of the developing anterior teeth between two human populations, prehistoric Jomon and modern Japanese. Results showed that the modern Japanese had an overall smaller mandible and concomitant narrower inter-canine space throughout growth than the Jomon, whereas the incisor and canine crypts of the modern Japanese grew faster and became larger by the time of incisor emergence.…”

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confidence: 99%

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Interspecies difference in placement of developing teeth and its relationship with cross‐sectional geometry of the mandibular symphysis in four primate species including modern humans

Fukase

2011

American J Phys Anthropol

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The form of the anthropoid mandibular symphysis has recently been addressed in association with spatial requirements for the forming anterior teeth. To evaluate potential relationships between the symphyseal shape and teeth further, the growth patterns of the symphyseal region and the positioning of the tooth crypts were examined using CT data, comparing four primate species (modern humans, chimpanzees, Japanese monkeys, and hamadryas baboons) with varied symphyseal curvature and tooth size. First, results showed that interspecies differences in overall mandibular shape including symphyseal inclination and bicanine width are consistently expressed throughout postnatal ontogeny, although local symphyseal configurations related to the superior transverse torus (STT) tended to change considerably during growth in chimpanzees. Second, the four species were found to exhibit differentiated formation positions of the incisor and canine crypts. In particular, I2 developed between I1 and C in humans with a broad bicanine space and small teeth, whereas it was positioned posterior to I1 and above C in the cercopithecines with an extremely narrow bicanine space. In chimpanzees, despite the large bicanine width, I1 and I2 grew with a large antero-posterior overlap owing to their large size. These results indicate that the dental positioning is determined in concert with the size balance of the available mandibular space and forming teeth. Finally, the positions/contours of I2 crypt were shown to correspond strongly with the STT across the taxa. This suggests that interspecies differences in symphyseal shape should be interpreted partially by the species-specific positional relationships of the developing anterior teeth.

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Influence of size and placement of developing teeth in determining anterior corpus height in prehistoric Jomon and modern Japanese mandibles

Cited by 10 publications

References 70 publications

Developmental variation in facial forms in Japan

Developmental variation in facial forms in Japan

Mandibular tooth root size in modern Japanese, prehistoric Jomon, and Late Pleistocene Minatogawa human fossils

Interspecies difference in placement of developing teeth and its relationship with cross‐sectional geometry of the mandibular symphysis in four primate species including modern humans

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