Qian Wang

Mercer University

We tested hypotheses about sagittal suture morphology, strain regime, feeding behavior, and muscle activity relationships in robust Sapajus and gracile Cebus capuchin primates. Morphometrics of sinuosity in three regions of the sagittal suture were compared among museum specimens of Sapajus and Cebus, as well as in robust and gracile lab specimens....

Australopiths, a group of hominins from the Plio-Pleistocene of Africa, are characterized by derived traits in their crania hypothesized to strengthen the facial skeleton against feeding loads and increase the efficiency of bite force production. The crania of robust australopiths are further thought to be stronger and more efficient than those of...

Objectives: (1) To investigate sex differences in molar wear in known-age Cayo Santiago rhesus macaques (Macaca mulatta) and, (2) To explore sex differences in body weight and molar eruption timing as factors influencing sex differences in molar wear. Materials and methods: Data set I comprises wear scores, ages and body weights of 212 living mo...

Primate models are important for understanding human conditions, especially in studies of ageing, pathology, adaptation, and evolution. However, how to integrate data from multiple disciplines and render them compatible with each other for datamining and in-depth study is always challenging. In a long-term project, we have started a collaborative r...

Objectives: Odontogenic abscesses are one of the most common dental diseases causing maxillofacial skeletal lesions. They affect the individual's ability to maintain the dental structures necessary to obtain adequate nutrition for survival and reproduction. In this study, the prevalence and pattern of odontogenic abscesses in relation to age, sex,...

Australopiths exhibit a number of derived facial features that are thought to strengthen the face against high and/or repetitive loads associated with a diet that included mechanically challenging foods. Here, we use finite element analysis (FEA) to test hypotheses related to the purported strengthening role of the zygomatic root and “anterior pill...

This issue of the Anatomical Record is the second of a two-volume set on the zygoma (also called the cheek bone, the zygomatic bone, the malar, or the jugal, the latter term being used in vertebrates other than mammals). The zygoma is an important component of the craniofacial skeleton, in which the zygoma is a connection between the midfacial and...

This issue of The Anatomical Record is the first of a two-volume set on the zygoma (also called the cheek bone, the zygomatic bone, the malar, or the jugal, the latter term being used in vertebrates other than mammals). The zygoma is an important component of the craniofacial skeleton, in which the zygoma is a connection between the midfacial and t...

The internal and external anatomy of the primate zygoma is central to orofacial function, health, and disease. The importance of variation in its gross morphology across extinct and extant primate forms has been established using finite element analysis, but its internal structure has yet to be explored. In this study, mCT is used to characterize t...

Relatively few assessments of cranial biomechanics formally take into account variation in the material properties of cranial cortical bone. Our aim was to characterize the elastic properties of chimpanzee craniofacial cortical bone and compare these to the elastic properties of dentate human craniofacial cortical bone. From seven cranial regions,...

Supplementary Methods.

Strain and strain energy density results from simulated premolar bites. Maximum principal strain (MaxPrin), minimum principal strain (MinPrin), strain mode (Mode), maximum shear strain (Shear), von Mises strain, and strain energy density (SED) generated during simulated premolar (P3) biting in the ALL-HUM variants of “extreme” and “average” modern...

Principal strain orientations recorded during validation analysis: Sites 1, 2, and 3. Purple lines represent the orientation of minimum principal strain (compression), which is 90° to orientation of maximum principal strain. Black circles represent location of strain gages at the dorsal interorbital (site 1), working-side dorsal orbital (site 2), a...

Principal strain orientations recorded during validation analysis: Sites 4, 6, and 13. Blue lines represent the orientation of maximum principal strain (tension). Purple lines represent the orientation of minimum principal strain (compression), which is 90° to orientation of maximum principal strain. Black circles represent location of strain gages...

Cortical bone mechanical properties collected from two cadaveric human specimens. E3 and v23 refer to the elastic (Young’s) modulus and Poisson’s ratio in the axis of maximum stiffness, respectively. For modulus, factor and temperature data were used to distribute regionally variation mechanical properties throughout each of the ALL-HUM models (see...

Strain and strain energy density results from simulated molar bites. Maximum principal strain (MaxPrin), minimum principal strain (MinPrin), strain mode (Mode), maximum shear strain (Shear), von Mises strain, and strain energy density (SED) generated during simulated molar (M2) biting in the ALL-HUM variants of “extreme” and “average” modern human...

In vitro loading of human cranium. Illustration of the loading apparatus constructed for the current analysis within the INSTRON loading machine during loading of the left P3.

Principal strain orientations recorded during validation analysis: Sites 9 and 11. Blue lines represent the orientation of maximum principal strain (tension). Purple lines represent the orientation of minimum principal strain (compression), which is 90° to orientation of maximum principal strain. Black circles represent location of strain gages at...

The GRGL finite element model showing constraints and muscle loads applied following Wroe et al. (2010). We compared two variants of this “beamed” model to our original “boneloaded” model, one that only included muscle beams for the anterior temporalis, superficial masseter, deep masseter, and medial pterygoid muscles (A) and a second that also inc...

Results of sensitivity analysis: color maps of von Mises strain magnitudes. Panels show strain distributions during premolar (P3) biting in the (A) original “boneloaded” ALL-HUM model, (B) “beamed” model lacking a posterior temporalis, and (C) “beamed” model including a posterior temporalis. Scales are set to range from 0–300 μɛ White regions excee...

Beam forces used in sensitivity analysis. Total muscle forces, beam count, and force per beam for each muscle group assigned to the GRGL model in the sensitivity analysis. Forces are in Newtons (N).

Transparent view of the model under in vitro validation. The surface model is shown in the position it was constrained during muscle loading, as in Fig. S1.

Principal strain orientations recorded during validation analysis: Sites 8, 10, and 12 strain. Blue lines represent the orientation of maximum principal strain (tension). Purple lines represent the orientation of minimum principal strain (compression), which is 90° to orientation of maximum principal strain. Black circles represent location of stra...

Principal strain orientations recorded during validation analysis: Sites 5, 7, and 14. Blue lines represent the orientation of maximum principal strain (tension). Purple lines represent the orientation of minimum principal strain (compression), which is 90° to orientation of maximum principal strain. Black circles represent location of strain gages...

Results of sensitivity analysis: line plot of von Mises strain. Plot shows the microstrain generated during simulated premolar (P3) biting, recorded from 14 identical brick elements across the craniofacial skeletons of our original “boneloaded” model, a “beamed” variant with muscle forces and constraints modeled following Wroe et al. (2010), and a...

The evolution of the modern human (Homo sapiens) cranium is characterized by a reduction in the size of the feeding system, including reductions in the size of the facial skeleton, postcanine teeth, and the muscles involved in biting and chewing. The conventional view hypothesizes that gracilization of the human feeding system is related to a shift...

The evolution of the modern human (Homo sapiens) cranium is characterized by a reduction in the size of the feeding system, including reductions in the size of the facial skeleton, postcanine teeth, and the muscles involved in biting and chewing. The conventional view hypothesizes that gracilization of the human feeding system is related to a shift...

Australopithecus sediba has been hypothesized to be a close relative of the genus Homo. Here we show that MH1, the type specimen of A. sediba, was not optimized to produce high molar bite force and appears to have been limited in its ability to consume foods that were mechanically challenging to eat. Dental microwear data have previously been inter...

Supplementary Figures 1-6, Supplementary Tables 1-4 and Supplementary Reference

In a broad range of evolutionary studies, an understanding of intraspecific variation is needed in order to contextualize and interpret the meaning of variation between species. However, mechanical analyses of primate crania using experimental or modeling methods typically encounter logistical constraints that force them to rely on data gathered fr...

The African Plio-Pleistocene hominins known as australopiths evolved derived craniodental features frequently interpreted as adaptations for feeding on either hard, or compliant/tough foods. Among australopiths, Paranthropus boisei is the most robust form, exhibiting traits traditionally hypothesized to produce high bite forces efficiently and stre...

Recent biomechanical analyses examining the feeding adaptations of early hominins have yielded results consistent with the hypothesis that hard foods exerted a selection pressure that influenced the evolution of australopith morphology. However, this hypothesis appears inconsistent with recent reconstructions of early hominin diet based on dental m...

Background: Craniofacial sutures are major sites of bone expansion during postnatal skull growth (Opperman, 2000). It is generally thought that the growth and morphology of craniofacial sutures reflect their functional environment (Rafferty and Herring, 1999). Craniofacial sutures can be viewed weak bone " growth " sites characterized by very diff...

Craniofacial sutures are bone growth fronts that respond and adapt to biomechanical environments. Little is known of the role sutures play in regulating the skull biomechanical environment during patency and fusion conditions, especially how delayed or premature suture fusion will impact skull biomechanics. Tgf-β3 has been shown to prevent or delay...

The global biomechanical impact of cranial sutures on the face and cranium during dynamic conditions is not well understood. It is hypothesized that sutures act as energy absorbers protecting skulls subjected to dynamic loads. This hypothesis predicts that sutures have a significant impact on global patterns of strain and cranial structural stiffne...

The dentofacial complex has important functions related to vision, sound, and nutrition (Lieberman 2011 ). In addition to traditional attempts to estimate age in lieu of birth records in forensic and anthropological studies (i.e., Relethford et al 1982 ; Nuzzolese and Di Vella 2008 ), investigations of dental eruption in various past and present pr...

Understanding how the skull transmits and dissipates forces during feeding provides insights into the selective pressures that may have driven the evolution of primate skull morphology. Traditionally, researchers have interpreted masticatory biomechanics in terms of simple global loading regimes applied to simple shapes (i.e., bending in sagittal a...

The biomechanical significance of cranial sutures in primates is an open question because their global impact is unclear, and their material properties are difficult to measure. In this study, eight suture-bone functional units representing eight facial sutures were created in a finite element model of a monkey cranium. All the sutures were assumed...

Australopithecus africanus is an early hominin (i.e., human relative) believed to exhibit stress-reducing adaptations in its craniofacial skeleton that may be related to the consumption of resistant food items using its premolar teeth. Finite element analyses simulating molar and premolar biting were used to test the hypothesis that the cranium of...

The midfacial skeleton in the human lineage demonstrates a wide spectrum of variation that may be the consequence of different environmental and mechanical selective pressures. However, different facial configurations may develop under comparable selective regimes. For example, the Neanderthal high and projected face and the Inuit broad and flat fa...

Skeletal adaptations to reduced function are an important source of skeletal variation and may be indicative of environmental pressures that lead to evolutionary changes. Humans serve as a model animal to investigate the effects of loss of craniofacial function through edentulation. In the human maxilla, it is known that edentulation leads to signi...

This study reports the elastic material properties of cortical bone in the mandible of juvenile Alligator mississippiensis obtained by using an ultrasonic wave technique. The elastic modulus, the shear modulus, and Poisson's ratio were measured on 42 cylindrical Alligator bone specimens obtained from the lingual and facial surfaces of 4 fresh Allig...

The African Plio-Pleistocene hominins known as australopiths evolved a distinctive craniofacial morphology that traditionally has been viewed as a dietary adaptation for feeding on either small, hard objects or on large volumes of food. A historically influential interpretation of this morphology hypothesizes that loads applied to the premolars dur...

Understanding the mechanical features of cortical bone and their changes with growth and adaptation to function plays an important role in our ability to interpret the morphology and evolution of craniofacial skeletons. We assessed the elastic properties of cortical bone of juvenile and adult baboon mandibles using ultrasonic techniques. Results sh...

Cranial defect reconstruction presents 2 challenges: induction of new bone formation, and providing structural support during the healing process. This study compares quantity and quality of new bone formation based on various materials and support frameworks. Eighteen dogs underwent surgical removal of a significant portion of their cranial vault....

A re-examination of a human femur found at the Blind River Site, East London, South Africa: Its age, morphology, and breakage pattern Modern human femoral features might have appeared in the early Middle Stone Age (156 ka to 20 ka) in South Africa, as demonstrated by the recent re-examination of a human femur fossil found at the Blind River Site, E...

Insight into the ontogeny of sexual dimorphism is important to our understanding of life history, ecology, and evolution in primates. This study applied a three-dimensional method, Euclidean Distance Matrix Analysis, to investigate sexual dimorphism and its diachronic changes in rhesus macaque (Macaca mulatta) skulls. Twenty-one landmarks in four f...

Bones of the face and cranial vault meet at sutural boundaries. These sutures are of great importance for craniofacial growth. Although the effects that the sutures have on modulating craniofacial strains have been investigated, how sutural fusion influences primate craniofacial biomechanics and adaptation are less considered. Confounding this prob...

When a force is applied to an object, the resulting pattern of strain is a function of both the object's geometry and its elastic properties. Thus, knowledge of elastic properties in craniofacial cortical bone is indispensable for exploring the biomechanics and adaptation of primate skulls. However, elastic properties, such as density and stiffness...

Knowledge of elastic properties and of their variation in the cortical bone of the craniofacial skeleton is indispensable for creating accurate finite-element models to explore the biomechanics and adaptation of the skull in primates. In this study, we measured elastic properties of the external cortex of the rhesus monkey craniofacial skeleton, us...

Five of the bones that characteristically comprise the cranial vault articulate on the lateral aspect of the skull at or near the cephalometric landmark referred to as the pterion. The pattern of articulation in the sutures associated with these bones varies among and within primate species and has been used as a criterion for classification in tax...

The aim of this study was to determine regional variability of material properties in the dentate maxilla. Cortical samples were removed from 15 sites of 15 adult dentate fresh-frozen maxillas. Cortical thickness, density, elastic properties, and the direction of greatest stiffness were obtained. Results showed that cortical bone in the alveolar re...

This article reviews strain and stress and their relationship. It also discusses the various types of strain gages in detail.

The mandibular posterior 3-unit fixed partial denture (FPD) is a conventional prosthodontic therapy and presumably has an effect on the direction and magnitude of occlusal forces and, thus, on the biomechanical environment of the mandible, which may in turn affect bone structure. However, the impact of FPD therapy on mandibular biomechanics is unkn...

The influence of elastic properties on finite-element analysis was investigated using a finite-element model of a Macaca fascicularis skull. Four finite-element analyses were performed in which the model was assigned different sets of elastic properties. In analysis 1, elastic properties were modeled isotropically using published data obtained from...

The position of the minimum shaft breadth (MSB) of the femur was investigated in complete femora to test its value in the estimation of whole femoral length in two modern human populations, the European and the Xhosa, from the Dart skeletal collection in Johannesburg. The results show that the position of MSB widely varies from 22.1% to 54.9% in mo...

It has been established that modern humans were living in the Levant and Africa ca. 100ka ago. Hitherto, this has contrasted with the situation in China where no unequivocal specimens of this species have been securely dated to more than 30ka. Here we present the results of stratigraphic studies and U-series dating of the Tongtianyan Cave, the disc...