Shifts in subsistence type and its impact on the human skull's morphological integration

Paschetta, Carolina; Azevedo, Soledad de; González, Marina Fernanda; Quinto‐Sanchez, Mirsha; Cintas, Celia; Varela, Hugo; Gómez-Valdés, Jorge; Sánchez‐Mejorada, Gabriela; González‐José, Rolando

doi:10.1002/ajhb.22746

Cited by 15 publications

(7 citation statements)

References 72 publications

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“…The semilandmarks must be slid along a tangential direction so as to remove tangential variation because contours should be homologous from subject to subject, whereas their individual points need not be (Perez et al, ). Therefore, we projected an asterisk (Figure A) on each face of the centrum in order to allocate semilandmarks, following similar approaches to those published in Maddux and Franciscus () and Paschetta et al (). The projection was positioned so its center would coincide with the anatomical landmark on the center of the centrum face (Figure A, Table ).…”

Section: Methodsmentioning

confidence: 99%

Morphology of the vertebral centra in dolphins from the southwestern South Atlantic: A 3D morphometric approach and functional implications

Marchesi

Boy

Dans

et al. 2019

Marine Mammal Science

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In dolphins, centrum shape is one of the features that allows determination of stable and flexible regions in the vertebral column. The Commerson's (Cephalorhynchus commersonii; n = 37), Peale's (Lagenorhynchus australis; n = 24), dusky (Lagenorhynchus obscurus; n = 29), and hourglass dolphins (Lagenorhynchus cruciger; n = 10) are closely related species inhabiting the Southern Hemisphere that have diverse prey and habitat preferences. We applied 3D geometric morphometrics to describe differences in centrum shape along the vertebral columns of these species, and hypothesize how these differences may affect swimming. On each column, we chose a maximum of eight vertebrae and digitized 18 landmarks on each centrum with a Microscribe G2X. We explored shape differences amongst regions employing principal components analyses and computing Mahalanobis distances. We describe differences in centrum shape in relation to functional regions and among species; and analyze shape changes in relation to particular biomechanical requirements. The species studied here may be partially sympatric in the Southern Hemisphere, but they have important differences in foraging ecology and habitat preferences that could be related to differences in centrum shape along the vertebral column.

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Section: Methodsmentioning

confidence: 99%

Morphology of the vertebral centra in dolphins from the southwestern South Atlantic: A 3D morphometric approach and functional implications

Marchesi

Boy

Dans

et al. 2019

Marine Mammal Science

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“…Mechanically, the more food is pre-processed, the lower the masticatory effort required to break it down and the lower the forces experienced by the facial bones [30, 35, 36]. In general terms, reduced strain on bones would result in a reduction in bone growth and this has been proposed as a relevant factor in skull variation among populations, particularly in the lower portion of the face, with the rest of the bones being subject to the influence of other agents of variation [37, 38]. In the case of modern individuals, who eat a soft, mechanically less demanding diet, mandibular prognathism would result from an excessive growth of the condyle cartilage; this has been proposed to be a response to masticatory loads of an individual’s mandible, the interaction between genes and environmental factors, which can increase the predisposition to develop such malocclusions [32].…”

Section: Introductionmentioning

confidence: 99%

Normal and altered masticatory load impact on the range of craniofacial shape variation: An analysis of pre-Hispanic and modern populations of the American Southern Cone

et al. 2019

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The reduction of masticatory load intensity resulting from dietary changes in human evolution has been proposed as an important factor that alters craniofacial shape in past and current populations. However, its impact on craniofacial variation and on the perceived differences among populations is unclear. The maxillomandibular relationship, which alters masticatory force direction, is a factor often neglected but it can contribute to variation in craniofacial morphology, particularly among modern/urban populations where the prevalence of dental malocclusions is greater than in prehistoric populations. This study investigates the influence of masticatory load intensity and maxillomandibular relationship as a proxy for force direction on the human craniofacial skeleton. By using 3D imaging and geometric morphometrics, we analyzed craniofacial shape variation among 186 individuals from pre-Hispanic and modern Chilean and Argentinean populations that differ in diet consistency (a proxy for masticatory load intensity) and maxillomandibular relationship. We predicted that masticatory load would have a subtle effect on the upper craniofacial bones and that this would be more marked in the maxilla. Our results showed no clear influence of masticatory load on craniofacial shape, particularly in modern/urban populations. Allometry, on the contrary, shows a stronger effect. The degree of integration between the upper craniofacial bones and the load-bearing maxilla depends on masticatory load intensity, decreasing from high to low but showing a conservative pattern of covariation among the groups. The degree of variation in the shape of the maxilla is greater than the upper craniofacial bones. These results suggest that masticatory load has a limited effect in determining differences in craniofacial morphology among populations. This effect is slightly greater for the maxillary region of the face. We propose that the reduction of functional constraints is key to greater shape variation found in modern/urban populations.

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“…Temporal changes in masticatory regions are well documented in human and nonhuman crania (Antón, ; Katz, Grote, & Weaver, ; Menegaz et al, ; Menéndez, Bernal, Novellino, & Perez, ; Noback & Harvati, ; Paschetta et al, ; Sardi, Novellino, & Pucciarelli, ). For instance, agriculturalists exhibit more inferiorly located superior temporal line, taller palatal vault, narrower dental arch (palate), and less vertical zygomatic arch than in hunter‐gatherers (Katz et al, ).…”

Section: Introductionmentioning

confidence: 99%

Changes in mandibular ramus shape from the Neolithic to modern periods in Korea

Jung

Woo

2019

Intl J of Osteoarchaeology

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The purpose of this study is to assess the mandibular ramus shape using geometric morphometrics, in order to examine secular changes in the shape from the Neolithic to modern period Koreans. Morphological data were collected from 151 adult mandibles representing four temporally different populations. Five landmarks on the mandibular ramus were subjected to a generalized Procrustes analysis. For statistical analysis, canonical variate analysis was conducted using shape coordinates. The Neolithic skeletal group had broader and shorter mandibular ramus shape, whereas the other archaeological and modern skeletal groups showed gracilization in mandibular ramus morphology. Possible causes for the observed secular changes are function‐induced variation and/or morphological integration in skull elements due to brachycephalization. This study can contribute to the discussion on temporal changes in mandibular morphology in relation to masticatory stress and/or morphological integration in skull elements.

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Shifts in subsistence type and its impact on the human skull's morphological integration

Abstract: The transition to softer diets increased morphological variation across cranial regions that are more exposed to masticatory strains effects.

Cited by 15 publications

References 72 publications

Morphology of the vertebral centra in dolphins from the southwestern South Atlantic: A 3D morphometric approach and functional implications

Morphology of the vertebral centra in dolphins from the southwestern South Atlantic: A 3D morphometric approach and functional implications

Normal and altered masticatory load impact on the range of craniofacial shape variation: An analysis of pre-Hispanic and modern populations of the American Southern Cone

Changes in mandibular ramus shape from the Neolithic to modern periods in Korea

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