Results show that cervical vertebral morphology does not significantly covary with differences in joint mobility. Rather, they implicate the critical role of ligaments and muscles in facilitating head mobility. Results of the kinematics study show that the neck plays a role in maintaining head stability during locomotion. However, the kinematic data do not significantly correlate with morphological variation among primate species. Given the negative results of the extant morphological analyses, it is difficult to apply them to the fossil record. As such, the functional significance of the disparate morphologies found in the hominin fossil record remain ambiguous.
This study tested hypotheses using two diet categorizations: total consumption percent and food material properties (FMPs). The first hypothesis that cortical bone area (CA) and section moduli (bone strength) are positively correlated with masticatory loading tests whether CA and moduli measures were greatest anteriorly and decreased posteriorly along the arch. The results found these measures adhered to this predicted pattern in the majority of taxa. The second hypothesis examines sutural complexity in the zygomaticotemporal suture as a function of dietary loading differences by calculating fractal dimensions as indices of complexity. No predictable pattern was found linking sutural complexity and diet in this primate sample, though hard object consumers possessed the most complex sutures. Lastly, cross-sectional geometric properties were measured to investigate whether bending and torsional resistance and cross-sectional shape are related to differences in masticatory loading. The highest measures of mechanical resistance tracked with areas of greatest strain in the majority of taxa. Cross-sectional shape differences do appear to reflect dietary differences. FMPs were not correlated with cross-sectional variables, however pairwise comparisons suggest taxa that ingest foods of greater stiffness experience relatively larger measures of bending and torsional resistance. The current study reveals that internal and external morphological factors vary across the arch and in conjunction with diet in primates. These findings underscore the importance of incorporating these mechanical differences in models of zygomatic arch mechanical behavior and primate craniofacial biomechanics.
Many authors have written about the social and economic risk factors such as poverty, low educational attainment, and discrimination that contribute to global indigenous-nonindigenous disparity. In this work, we consider an additional immunological risk factor — T-helper 2 dominance — that appears to exacerbate the effects of social and economic factors on infectious disease outcomes in tropical zones. To this end, a critical review approach was used to extract published data on total serum IgE — an indicator of T-helper 2 dominance. We found a three-orders-of-magnitude differences in total serum IgE across climate zones (tropical vs. temperate), ecologies within the tropics (forests vs. urban/rural), and clinical conditions (HIGE, TPE, ABAP vs. atopy, and helminthiasis). Additionally, that the highest ever reported total serum IgE levels are reported for tropical regions - mainly, healthy members of forest-dwelling indigenous groups of South America, and patients diagnosed with clinical conditions such as onchocerciasis, tropical pulmonary eosinophilia, and hyper-IgE.