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This report documents greater variability in early hominin first molar dental trait frequencies than previous research indicated. Specifically, frequencies of several M1 dental traits that previously appeared to uniquely characterize Paranthropus are shown here to resemble those of the A. afarensis sample from Hadar. Like Paranthropus, A. afarensis from Hadar has a high frequency of cusp 6 and a low frequency of the protostylid. Paranthropus and A. afarensis are also not statistically significantly different in their frequencies of LM1 cusp 7, although this cusp is actually absent in the latter. Both groups differ significantly from A. africanus in their frequencies of these traits. Based on the developmental biology of molar cusp patterns, we suggest that the morphological similarities between Paranthropus and the Hadar sample may be homoplasies. 相似文献
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H. J. Keene 《Human Evolution》1994,9(3):231-247
Cusp six (C6) of the mandibular molars is well-represented in the Hominoid fossil record and occurs with irregular frequency
in the various geographic populations of modernHomo as well as in many of the extant non-human primates. The literature reveals considerable controversy and confusion related
to C6 anatomic location, definitions and scoring criteria, and a major problem exists in deciding what actually is the “real”
or “true” C6, especially relative to variable hypoconulid (C5) expression (i.e., reduction forms and the “divided hypoconulid”).
A method is proposed that involves dual 4-point ranking (absent, small, medium, large) and reporting of C5–C6 covariation
within a framework of 13 morphological expressivity categories. When applied to 3 different human populations, the method
provided a reasonably clear picture of the actual C5 and C6 covariation patterns observed in the mandibular molar dentition.
Data obtained from this exercise illustrated that inter- and intrapopulation differences in reported C6 frequencies could
be associated with variable scoring criteria as well as with different levels of occlusal attrition and age distribution of
the samples. 相似文献
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Colobines have been generally described as primates that use the anterior teeth minimally, but the posterior teeth extensively, to process leaves and related food items. However, variation among leaf monkeys in both anterior and posterior dental morphology has been recognized for decades. In this study, we turn to Hylander's (Science 189 (1975) 1095-1098) analysis of anterior incisor row length and Kay's (Adaptations for foraging in nonhuman primates, 1984) examination of relative molar crest length to test hypotheses proposed by them for Asian colobines. We present findings based on data from the largest Asian colobine sample measured to date. Our findings for incisor row length and molar cresting are not amenable to broad generalizations. In those instances when our morphological findings concur with those of Hylander (Science 189 (1975) 1095-1098) and Kay and Hylander (The ecology of arboreal folivores, 1978), the ecological evidence seldom supports the morphological predictions. The disassociation between diet and dental patterns may be a consequence of differential selection by fallback foods, anthropogenic disturbance or climatic shifts limiting preferred diets, or the use of food types as opposed to food mechanical properties for dietary categorization. We also found that in the case of both incisor row length and molar crest length, the patterns for males and females differed markedly. The reasons for these differences may in part be ascribed to the metabolic challenges faced by females and subsequent niche partitioning. We propose integrated analyses of the ingestive and digestive systems of our study taxa to clarify relationships among behavior, dental morphology, and diet in extant and extinct colobines. 相似文献
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Robert N. Staley James P. Vance Carney D. Loucks 《American journal of physical anthropology》1998,105(1):93-95
A Type II tooth cusp occurrence asymmetry proposed for human twins in 1974 but not observed until recently was described in a female monozygotic twin pair. Am J Phys Anthropol 105:93–95, 1998. © 1998 Wiley-Liss, Inc. 相似文献
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Kazunori Ikebe Tomohiro Hazeyama Taiji Ogawa Ryosuke Kagawa Ken‐ichi Matsuda Masahiro Wada Tomoya Gonda Yoshinobu Maeda 《Gerodontology》2011,28(3):192-196
Gerodontology 2010; doi: 10.1111/j.1741‐2358.2009.00357.x Subjective values of different age groups in Japan regarding treatment for missing molars Objective: To determine how patients and dentists in Japan value the outcomes of different treatment options for missing molars. Materials and methods: Elderly removable‐denture wearers and dentate persons (senior group), preclinical dental students (young group), and prosthodontists were presented with five possible treatment options for missing lower bilateral first and second molars. The participants indicated on a visual analogue scale how they would value the treatment (utility value: UV), if they had received each of the treatments. Two‐way repeated measures anova was used for statistical analyses. Results: The UV for the shortened dental arch (SDA) without replacement was the lowest in every group. The young group rated the value of cantilever fixed partial dentures (FPD) and implants significantly higher than removable partial dentures (RPD), while the senior group rated the value of FPD and RPD significantly higher than implants. Those having experience with removable dentures were likely to place a higher value on the acrylic RPD. The prosthodontists rated the value of implants significantly higher than any other options. Conclusions: The participants in every group placed the lowest value on the outcome from the SDA in Japan. The denture wearers preferred the RPD, while prosthodontists preferred implants. 相似文献
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Birgitte Sejrsen Jan Jakobsen Inger Kjr 《American journal of physical anthropology》1996,99(4):603-611
The purpose of this investigation was to measure postnatal lengthening and widening of the hard palate by use of nerve canal openings as references. The relationship of the dentition to the greater palatine foramina was also investigated. Thirty-nine medieval dry skulls were examined, 22 from children and 17 from adults. All crania were photographed at a 1:1 scale. The dimensions of the maxilla and the location of the dentition were determined from the photographs. The study showed that palatal growth in length in the sagittal plane takes place anterior to the greater palatine foramen. The growth increment in the area between the incisive foramen and the transverse palatine suture is more pronounced than the growth increment in the area between the transverse palatine suture and the greater palatine foramen. The distance from the greater palatine foramina to the posterior margin of the palate did not increase significantly with age. The growth in width seems to continue into adult life. The first permanent molars and the surrounding bone are moved forwards in relation to the greater palatine foramina during growth. The space for the developing maxillary premolars and molars therefore has to be obtained by growth in the transverse palatine suture. © 1996 Wiley-Liss, Inc. 相似文献
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Bailey SE 《Journal of human evolution》2004,47(3):183-198
This study explores the significance of shape differences in the maxillary first molar crowns of Neandertals and anatomically modern humans. It uses morphometric analysis to quantify these differences and to investigate how the orientation of major cusps, relative cusp base areas and occlusal polygon area influence crown shape. The aims of this study were to 1) quantify these data to test whether the tooth shapes of Neandertals and anatomically modern humans differ significantly and 2) to explore if either of the shapes is derived relative to earlier fossil hominins. Data were collected from digital occlusal photographs using image-processing software. Cusp angles, relative cusp base areas and occlusal polygon areas were measured on Neandertals (n=15), contemporary modern humans (n=62), Upper Paleolithic humans (n=6), early anatomically modern humans (n=3) and Homo erectus (n=3). Univariate and multivariate statistical tests were used to evaluate the differences between contemporary modern humans and Neandertals, while the much sparser data sets from the other fossil samples were included primarily for comparison. Statistically significant differences reflecting overall crown shape and internal placement of the crown apices were found. Neandertals are distinguished from contemporary humans by possessing maxillary first molars that 1) are markedly skewed; 2) possess a narrower distal segment of the occlusal polygon compared to the mesial segment; 3) possess a significantly smaller metacone and a significantly larger hypocone; and 4) possess a significantly smaller relative occlusal polygon area reflecting internally placed cusps. Differences in relative cusp base areas of the hypocone and metacone may contribute to the shape differences observed in Neandertals. However, early anatomically modern humans possessing a pattern of relative cusp base areas similar to Neandertals lack their unusual shape. That the morphology observed in non-Neandertal fossil hominins is more anatomically modern human-like than Neandertal-like, suggests that this distinctive morphology may be derived in Neandertals. 相似文献
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Palatine tonsils are continuously exposed to microorganisms and antigens and secrete antimicrobial peptides as a first line of defense. S100A7 is a protein with antimicrobial and chemotactic properties. Our aim was to investigate how the expression of S100A7 in human palatine tonsils is affected by inflammatory processes. Tonsils obtained from 109 patients undergoing tonsillectomy were divided into groups of infected and noninfected as well as allergic and nonallergic, based on the results from tonsillar core culture tests and Phadiatop analysis, respectively. Western blot and immunohistochemistry were used to assess protein expression and real-time PCR was used to quantify mRNA levels. To explore the induction of S100A7, tonsils were stimulated with lipopolysaccharide in vitro. The immunohistochemical staining for S100A7 was most intense in the tonsillar epithelium, but the protein was also detected in B- and T-cell regions, which was confirmed with Western blot on isolated B and T cells. The S100A7 expression appeared to be the highest in CD8+ T cells. Reduced mRNA levels of S100A7 were detected in infected tonsils as well as in tonsils from allergic individuals. In vitro stimulation of tonsils with lipopolysaccharide did not have any effect on the expression. The results suggest a role for S100A7 in recurrent tonsillitis and allergic disease. 相似文献
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对人类和动物的心理学研究证实,老年个体的视觉对比敏感度相对青年个体显著下降。为揭示其可能的神经机制,采用在体细胞外单细胞记录技术研究青、老年猫(Felis catus)初级视皮层(primary visual cortex,V1)细胞对不同视觉刺激对比度的调谐反应。结果显示,老年猫V1细胞对视觉刺激反应的平均对比敏感度比青年猫显著下降,这与灵长类报道的研究结果相一致,表明衰老影响视皮层细胞对视觉刺激反应的对比敏感度是灵长类和非灵长类哺乳动物中普遍存在的现象,并可能是介导老年性视觉对比敏感度下降的神经基础。另外,与青年猫相比,老年猫初级视皮层细胞对视觉刺激的反应性显著增强,信噪比下降,感受野显著增大,表明衰老导致的初级视皮层细胞对视觉刺激反应的对比敏感度下降伴随着皮层内抑制性作用减弱。 相似文献
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A severe palatine disorder caused by maloccluded molars was discovered in captive adult cheetahs at the San Diego Wild Animal Park. This defect has been labeled focal palatine erosion (FPE). Subsequently, a total of 59 cheetahs from several institutions have been examined to evaluate the occurrence and etiology of this disorder. Maloccluded lower molars contacting the palatal mucosa appear to be the primary source of irritation. Infection develops when decaying food and grass particles become lodged in the resulting defect. Eventually, complete palatine perforation results which can extend into the nasal passages and eventually lead to systemic disorders. Of 59 cheetahs studied, 15 displayed various stages of FPE. Examination of 26 museum skull specimens revealed four cases of palatine perforation. These four were from a group of eight animals that were zoo raised. Focal palatine erosion appears to be a result of dietary factors. All cheetahs with FPE received a commercially prepared soft diet while in captivity. The lack of normal biting, tearing, and pulling action associated with natural prey capture and consumption could result in malocclusion caused by atrophy from disuse of the masticatory apparatus. Improper occlusion could also stem from insufficient wear or unsynchronized development of the opposing dental arches. All but two cases of FPE were found in cheetahs imported from a limited area in southwest Africa in 1970, or their offspring. Since molar size and jaw structure can be inherited, there may be genetic factors involved but more data are needed to support this idea. Treatment includes changing diet, reducing the height of the offending molar, controlling infection, eliminating irritants, and in some cases, surgical reconstruction. 相似文献
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The dental awareness and needs of a population with Parkinson's disease were assessed by means of postal questionnaires sent to members of Parkinson's disease societies of Belfast and London. A total of 228 valid replies were received representing a response rate of 31%. Results showed that dental problems were reported often, xerostomia and burning sensation being at least twice that of the general population. Satisfaction with dental care was high although it was significantly reduced in those with loose dentures and burning sensation. The results of this study support a greater participation by dentists in the planning and provision of healthcare for sufferer of Parkinson's disease. 相似文献
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《Ethology, Ecology and Evolution》2012,24(3):247-254
This paper concerns the olfactory reaction of female domestic cats (Felis catus L.), distributed in four different groups on the basis of their reproductive state (pregnant, with kittens, in oestrous, in anoestrous), to sprayed urine from a strange, unrelated male cat. The behaviour of the animals, presented with an unscented cotton-wool bud, was compared with the behaviour of the same animals presented with a cotton-wool bud satured with the test urine. Furthermore, the behaviour of females belonging to different groups was compared to verify if the reaction to the scent source was influenced by their hormonal state. Female cats showed more olfactory investigation of the scent and of the environment in the presence of the urine. The latter response may reflect an attempt to check for the presence of an unknown male in the area. Although oestrus females showed most investigation when the urine was absent, pregnant and anoestrus females became the most active when it was introduced. Thus, the hormonal state of females influenced their reaction to the stimulus. All group of females showed habituation to the urine. 相似文献
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This report describes a case of amelogenesis imperfecta in the dentition of a female chimpanzee. Amelogenesis imperfecta is a group of rare genetic conditions that create severe enamel defects, which, although well researched in humans, has not yet been investigated in wild non‐human primates. 相似文献