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Objectives: Due to the scarcity of the fossil record, in-vivo changes in the dentognathic system of early Homo are typically documented at the level of individual fossil specimens, and it remains difficult to draw population-level inferences about dietary habits, diet-related activities and lifestyle from individual patterns of dentognathic alterations. The Plio-Pleistocene hominin sample from Dmanisi (Georgia), dated to 1.77 million years ago, offers a unique opportunity to study in-vivo changes in the dentognathic system of individuals belonging to a single paleodeme of early Homo. Materials and Methods: We analyze dentognathic pathologies in the Dmanisi sample, and in comparative samples of modern Australian and Greenlander hunter-gatherer populations, applying clinical protocols of dentognathic diagnostics. Results: The Dmanisi hominins exhibit a similarly wide diversity and similar incidence of dentognathic pathologies as the modern human hunter-gatherer population samples investigated here. Dmanisi differs from the modern population samples in several respects: At young age tooth wear is already advanced, and pathologies are more prevalent. At old age, hypercementosis is substantial. Discussion: Results indicate that dentognathic pathologies and disease trajectories are largely similar in early Homo and modern humans, but that the disease load was higher in early Homo, probably as an effect of higher overall stress on the dentognathic system. Key words: aging, tooth wear, caries, periodontitisThe Plio-Pleistocene site of Dmanisi has yielded a large sample of hominin fossils associated with abundant and diverse faunal remains and Mode I stone artifacts (Gabunia et al. 2001;Ferring et al. 2011;Mgeladze et al. 2011). Occupation of the site began shortly after 1.85 Ma. The fossil hominin finds are dated to 1.77 Ma (Ferring et al. 2011). Dmanisi thus represents the earliest evidence of Homo outside of Africa. The well-preserved cranial, mandibular and postcranial remains of five individuals are unique in offering detailed insights into patterns of morphological variation within a paleodeme of early Homo, and into patterns of growth and aging Margvelashvili et al. 2013;Zollikofer et al. 2014). The craniomandibular morphology of the Dmanisi paleodeme has been described previously (Gabunia and Vekua 1995;Gabunia et al. 2000;Gabunia et al. 2001;Gabounia et al. 2002;Lordkipanidze et al. 2005;Lordkipanidze et al. 2006;Rightmire et al. 2006;Rightmire and Lordkipanidze 2010;Lordkipanidze et al. 2013;Margvelashvili et al. 2013). Cranial and mandibular morphological variation within the Dmanisi paleodeme is wide, but well within the range of variation seen in modern humans populations, and in populations of chimpanzee subspecies (Skinner et al. 2006;Lordkipanidze et al. 2013;Margvelashvili et al. 2013;Zollikofer et al. 2014). Variation in size, shape and dentognathic features among the Dmanisi mandibles has received special attention and has been studied to address questions of phylogeny, taxonomy, sexual dimorphism, die...
Objectives: Due to the scarcity of the fossil record, in-vivo changes in the dentognathic system of early Homo are typically documented at the level of individual fossil specimens, and it remains difficult to draw population-level inferences about dietary habits, diet-related activities and lifestyle from individual patterns of dentognathic alterations. The Plio-Pleistocene hominin sample from Dmanisi (Georgia), dated to 1.77 million years ago, offers a unique opportunity to study in-vivo changes in the dentognathic system of individuals belonging to a single paleodeme of early Homo. Materials and Methods: We analyze dentognathic pathologies in the Dmanisi sample, and in comparative samples of modern Australian and Greenlander hunter-gatherer populations, applying clinical protocols of dentognathic diagnostics. Results: The Dmanisi hominins exhibit a similarly wide diversity and similar incidence of dentognathic pathologies as the modern human hunter-gatherer population samples investigated here. Dmanisi differs from the modern population samples in several respects: At young age tooth wear is already advanced, and pathologies are more prevalent. At old age, hypercementosis is substantial. Discussion: Results indicate that dentognathic pathologies and disease trajectories are largely similar in early Homo and modern humans, but that the disease load was higher in early Homo, probably as an effect of higher overall stress on the dentognathic system. Key words: aging, tooth wear, caries, periodontitisThe Plio-Pleistocene site of Dmanisi has yielded a large sample of hominin fossils associated with abundant and diverse faunal remains and Mode I stone artifacts (Gabunia et al. 2001;Ferring et al. 2011;Mgeladze et al. 2011). Occupation of the site began shortly after 1.85 Ma. The fossil hominin finds are dated to 1.77 Ma (Ferring et al. 2011). Dmanisi thus represents the earliest evidence of Homo outside of Africa. The well-preserved cranial, mandibular and postcranial remains of five individuals are unique in offering detailed insights into patterns of morphological variation within a paleodeme of early Homo, and into patterns of growth and aging Margvelashvili et al. 2013;Zollikofer et al. 2014). The craniomandibular morphology of the Dmanisi paleodeme has been described previously (Gabunia and Vekua 1995;Gabunia et al. 2000;Gabunia et al. 2001;Gabounia et al. 2002;Lordkipanidze et al. 2005;Lordkipanidze et al. 2006;Rightmire et al. 2006;Rightmire and Lordkipanidze 2010;Lordkipanidze et al. 2013;Margvelashvili et al. 2013). Cranial and mandibular morphological variation within the Dmanisi paleodeme is wide, but well within the range of variation seen in modern humans populations, and in populations of chimpanzee subspecies (Skinner et al. 2006;Lordkipanidze et al. 2013;Margvelashvili et al. 2013;Zollikofer et al. 2014). Variation in size, shape and dentognathic features among the Dmanisi mandibles has received special attention and has been studied to address questions of phylogeny, taxonomy, sexual dimorphism, die...
The purpose of this review is to provide a synoptic, critical evaluation of the evidence of, and potential etiological factors contributing to, sex differences in the expression of enamel hypoplasia (EH). Specifically, this review considers theoretical expectations and empirical evidence bearing on two central issues. The first of these is the impact of a theorized inherent male vulnerability to physiological stress on sex differences in EH. The second issue is the potential contribution to sex differences in EH of intrinsic differences in male and female enamel composition and development. To address this first issue, EH frequencies by sex are examined in samples subject to a high degree of physiological stress. Based on the concept of inherent male vulnerability (or female buffering), males in stressful environments would be expected to exhibit higher EH frequencies than females. This expectation is evaluated in light of cultural practices of sex-biased investment that mediate the relationship between environmental stress and EH expression. Defects forming prenatally afford an opportunity to study this relationship without the confounding effects of sex-biased postnatal investment. Data bearing on this issue derive from previously conducted studies of EH in permanent and deciduous teeth in both modern and archaeological samples as well as from new data on Indian schoolchildren. To address the second issue, fundamental male-female enamel differences are evaluated for their potential impact on EH expression. A large sex difference in the duration of canine crown formation in non-human primates suggests that male canines may have greater opportunity to record stress events than those of females. This expectation is examined in great apes, whose canines often record multiple episodes of stress and are sexually dimorphic in crown formation times. With respect to the first issue, in most studies, sex differences in EH prevalence are statistically nonsignificant. However, when sex differences are significant, there is a slight trend for them to be greater in males than in females, suggesting a weak influence of greater male vulnerability. Cultural practices of sex-biased investment in children appear to have greater impact on EH expression than does male vulnerability/female buffering. With respect to the second issue, sex differences in the composition and development of enamel were reviewed and determined to have limited or unknown impact on EH expression. Of these factors, only the duration of crown formation was expected to affect EH expression by sex within the great apes. The data support an association between higher defect counts in the canines of great ape males relative to those of females that may be the result of longer crown formation times in the canines of great ape males. This review concludes with an assessment of the nature of the evidence currently available to examine these issues and suggests future avenues for research focused on elucidating them.
This paper presents new data on enamel hypoplasia in the deciduous canine teeth of great apes. The enamel defect under consideration is known as localized hypoplasia of primary canines (LHPC), and is characterized by an area of thin or missing enamel on the labial surface of deciduous canine teeth (Skinner [1986a] Am. J. Phys. Anthropol. 69:59-69). Goals of this study are: 1) to determine if significant differences in the frequency of LHPC occur among three genera of great apes, and 2) to evaluate variation in LHPC prevalence among great apes as evidence of differential physiological stress. Infant and juvenile apes with deciduous teeth were examined at the Cleveland Museum of Natural History (n = 100) and at the Smithsonian Institution, National Museum of Natural History (n = 36). Deciduous teeth were observed under oblique incandescent light, with the naked eye and with a 10x hand lens. Enamel hypoplasia was scored using Federation Dentaire International (FDI)-Defects of Dental Enamel (DDE) standards. Hypoplasias were recorded by drawing defect location and size on a dental chart, and by measuring defect size and location with Helios needlepoint dial calipers. The prevalence of LHPC is reported by genus and sex, using two approaches: 1) the frequency of affected individuals-those having one or more deciduous canine teeth scored positive for LHPC; and 2) the number of canine teeth scored positive for LHPC as a percentage of all canine teeth observed. Variation in defect size and location will be described elsewhere. Localized hypoplasia of primary canine teeth was found in 62.5% of 128 individual apes, and in 45.5% of 398 great ape deciduous canines. As in humans, LHPC is the most common form of enamel hypoplasia in deciduous teeth of great apes, while LEH is rare or absent. The distribution and pattern of expression of LHPC in great apes is similar to that described in humans: side differences are not significant, but mandibular canines exhibit the defect two to five times more often than maxillary canine teeth. Differences in LHPC prevalence by sex are small and not significant. Intergeneric differences are large and non-random: chimpanzees (Pan) exhibit a significantly lower frequency of LHPC (22%, n = 50) by individual count, than either the orangutan (Pongo, 88.0%, n = 25) or the gorilla (Gorilla, 88.7%, n = 53). Tooth count prevalences exhibit a similar pattern of variation and are also statistically significant. These findings suggest that large bodied great apes (gorilla and orangutan) may be under greater physiological stress during perinatal and early postnatal development than the chimpanzee. The size, position, and timing of LHPC lesions are currently under analysis and may yield more insight into the etiological origin of this enamel defect.
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