Intraindividual and intragroup variability of buccal tooth striation pattern

Intrapopulational tooth striation variability has been studied in a sample of 99 individuals from the medieval agriculturalist population of La Olmeda (Palencia, Spain). The number, length, and orientation of all observed striations were recorded using a scanning electron microscope and an image analyzer system. Tooth striations were observed at 100 × magnification on the buccal surface of Pm4 and M1 teeth. The results obtained for the adult age group indicate that the buccal striation pattern is a characteristic trait which does not vary significantly among teeth for each individual. Agegroup variability suggests that buccal tooth striations accumulate over quite long periods of time. The characteristic striation pattern for the population is completely attained in the subadult age group. For the analyzed population, seasonal changes in dietary habits apparently did not affect the buccal striation pattern. Weaning of children in the population from La Olmeda seems to have occurred long before 2–5 years of age. Infants had a highly abrasive diet, and subadult and adult individuals would have had a slightly softer diet, perhaps due to a higher meat intake. The buccal striation pattern as a dietary indicator seems to be of great reliability, allowing for quantitative analysis of intrapopulation and interpopulation variability. © 1994 Wiley-Liss, Inc.     

Ecogeographic variation in Neandertal dietary habits: evidence from occlusal molar microwear texture analysis

In the late Middle and early Late Pleistocene, Neandertals inhabited a wide variety of ecological zones across western Eurasia during both glacial and interglacial times. To elucidate the still poorly understood effects of climatic change on Neandertal subsistence patterns, this study employs dental microwear texture analysis to reconstruct the diets of Neandertal individuals from various sites across their wide temporal and geographic ranges. The results of this study reveal environmentally-driven differences in the diets of Neandertal groups. Significant differences in microwear signatures, correlated with paleoecological conditions, were found among Neandertal groups that lived in open, mixed, and wooded environments. In comparison to recent hunter-gatherer populations with known, yet diverse diets, the occlusal molar microwear signatures of all the Neandertal groups indicate that their diet consisted predominantly of meat. However, the results of this study suggest that plant foods did form an important part of the diet of at least some Neandertal groups (i.e., those that lived in mixed and wooded habitats). Overall, the proportion of plant foods in the Neandertal diet appears to have increased with the increase in tree cover.     

Folivory or fruit/seed predation for Mesopithecus, an earliest colobine from the late Miocene of Eurasia?

Here we compare dental microwear textures from specimens of the fossil genus Mesopithecus (Cercopithecidae, Colobinae) from the late Miocene of Eastern Europe with dental microwear textures from four extant primate species with known dietary differences. Results indicate that the dental microwear textures of Mesopithecus differ from those of extant leaf eaters Alouatta palliata and Trachypithecus cristatus and instead resemble more closely those of the occasional hard-object feeders Cebus apella and Lophocebus albigena. Microwear texture data presented here in combination with results from previous analyses suggest that Mesopithecus was a widespread, opportunistic feeder that often consumed hard seeds. These data are consistent with the hypothesis that early colobines may have preferred hard seeds to leaves.     

牙齿微痕研究在古食性重建中应用的简述

在古食性研究中,牙齿微痕是指动物在咀嚼食物的过程中在牙齿咬合面上产生的微观磨损痕迹。不同食性的动物具有不同的牙齿微痕特征,因此可以通过研究牙齿微痕特征来重建灭绝动物的古食性,为探讨动物演化和古生态环境变化提供重要信息。本文主要介绍牙齿微痕作为一种简单而高效的古食性重建方法在古生物领域中的应用。本文主要内容包括牙齿微痕的发展历史,形成机理与应用,以及近年来被广泛应用的牙齿微痕定量化分析——表面纹理分析法,并在最后浅谈了牙齿微痕研究未来可能研究的方向。     

The assessment of jaw movement direction from dental microwear

In order to resolve several controversies about unusual jaw movements such as thegosis and orthal retraction, information about direction of jaw movement is essential. Ryan (1979a,b) proposed that asymmetry of microwear striations might provide such data. In vivo occurrences of asymmetric striations on chimpanzee molars are presented and analyzed. Results suggest that either thegosis contacts commonly occur on chimpanzee molars or that Ryan's model, as developed in vitro, does not accurately apply to naturally occurring molar microwear.     

Dental microwear texture analysis: technical considerations

Dental microwear analysis is commonly used to infer aspects of diet in extinct primates. Conventional methods of microwear analysis have usually been limited to two-dimensional imaging studies using a scanning electron microscope and the identification of apparent individual features. These methods have proved time-consuming and prone to subjectivity and observer error. Here we describe a new methodological approach to microwear: dental microwear texture analysis, based on three-dimensional surface measurements taken using white-light confocal microscopy and scale-sensitive fractal analysis. Surface parameters for complexity, scale of maximum complexity, anisotropy, heterogeneity, and textural fill volume offer repeatable, quantitative characterizations of three-dimensional surfaces, free of observer measurement error. Some results are presented to illustrate how these parameters distinguish extant primates with different diets. In this case, microwear surfaces of Cebus apella and Lophocebus albigena, which consume some harder food items, have higher average values for complexity than do folivores or soft fruit eaters.     

日本对虾对饵料摄食与吸收利用的研究

本文用￣１４Ｃ示踪法测定日本对虾糠－３幼体对褶皱臂尾轮虫,卤虫和亚心形扁藻的摄食率、吸收率和利用率;以￣３Ｈ－葡萄糖和￣１４Ｃ－苯丙氨酸作示踪剂研究人工配合饵料中葡萄糖和氨基酸在日本对虾体内转运和分布。实验结果表明褶皱臂尾轮虫是日本对虾糠－３幼体最适的动物性饵料之一。糠－３幼体对卤虫无节幼体摄食与利用率不高,但适量投放２３只／ｍｌ密度的卤虫无节幼体作补充饵料以满足幼体对食物日益增长的需要,有利于幼体的生长。虽然糠－３幼体食性以动物性为主,但单独投放适宜密度亚心形扁藻也能摄食。其利用率可达４０％左右。日本对虾的营养物质主要通过中肠被吸收,经血液循环被输送到组织器官。氨基酸更多参与对虾组织构成细胞的成分代谢活动,而葡萄糖则是对虾能量代谢活动的主要来源。     

Frequencies of oral pathologies in a sample of 767 non-human primates

In this work 767 skulls of both wild caught and captive non-human primates were studied and the following characteristics were analyzed: frequency of caries and osteolytic phenomena, presence of apical or radicular cysts, degree of bone atrophy and parodontal tissue alterations, neoplasies, supernumerary teeth, and cusps. Caries and osteolytic phenomena were more frequent in captive animals because of their “anthropic” diet, while frequency of dental fractures was higher in wild primates because of their higher environmental stress. The most frequent pathologies observed in non-human primates were tartar, parodontopathies, and condylar wear, while caries and osteolytic phenomena were minimal. Condylar wear was very frequent but not very marked and possibly due to “physiological” responses and not, as in humans, to a force unbalance which occurs in masticatory dynamics of the temporomandibular joint.     

Dental microwear texture analysis and diet in the Dmanisi hominins

Reconstructions of foraging behavior and diet are central to our understanding of fossil hominin ecology and evolution. Current hypotheses for the evolution of the genus Homo invoke a change in foraging behavior to include higher quality foods. Recent microwear texture analyses of fossil hominin teeth have suggested that the evolution of Homo erectus may have been marked by a transition to a more variable diet. In this study, we used microwear texture analysis to examine the occlusal surface of 2 molars from Dmanisi, a 1.8 million year old fossil hominin site in the Republic of Georgia. The Dmanisi molars were characterized by a moderate degree of surface complexity (Asfc), low textural fill volume (Tfv), and a relatively low scale of maximum complexity (Smc), similar to specimens of early African H. erectus. While caution must be used in drawing conclusions from this small sample (n = 2), these results are consistent with continuity in diet as H. erectus expanded into Eurasia.     

The mandibular corpus of female primates: taxonomic, dietary, and allometric correlates of interspecific variations in size and shape

Measurements were taken on skulls of 253 adult female anthropoid primates from 32 species, in order to determine patterns and possible causes for variation among species in the cross-sectional size and shape of the mandibular corpus under M1. When all 32 species are considered as a group, there is a tendency for corpus shape to become more robust with increasing body size. However, this does not hold for colobines or cercopithecines evaluated separately. When diets are classified into the general categories of folivory or frugivory, neither size-adjusted measurements of mandibular corpus breadth and height, nor estimates of the second moments of inertia or the polar moment of inertia of the mandibular cross section, show any relationship to dietary variation among species. Species reported to include hard nuts in their diets have larger mandibular cross sections than other species, and the size of the corpus is significantly correlated with size of the dentition and molar enamel thickness. A biomechanical model taking into account frictional effects of tooth-to-tooth contact indicates that mandibular corpus robusticity may not be related to a large horizontal component of force during mastication.     

Microwear, mechanics and the feeding adaptations of Australopithecus africanus

Recent studies of dental microwear and craniofacial mechanics have yielded contradictory interpretations regarding the feeding ecology and adaptations of Australopithecus africanus. As part of this debate, the methods used in the mechanical studies have been criticized. In particular, it has been claimed that finite element analysis has been poorly applied to this research question. This paper responds to some of these mechanical criticisms, highlights limitations of dental microwear analysis, and identifies avenues of future research.     

Evolutionary modifications of human milk composition: evidence from long-chain polyunsaturated fatty acid composition of anthropoid milks

Brain growth in mammals is associated with increased accretion of long-chain polyunsaturated fatty acids (LCPUFA) in brain phospholipids. The period of maximum accumulation is during the brain growth spurt. Humans have a perinatal brain growth spurt, selectively accumulating docosahexaenoic acid (DHA) and other LCPUFA from the third trimester through the second year of life. The emphasis on rapid postnatal brain growth and LCPUFA transfer during lactation has led to the suggestion that human milk LCPUFA composition may be unique. Our study tests this hypothesis by determining fatty acid composition for 11 species of captive anthropoids (n = 53; Callithrix jacchus, Cebus apella, Gorilla gorilla, Hylobates lar, Leontopithecus rosalia, Macaca mulatta, Pan troglodytes, Pan paniscus, Pongo pygmaeus, Saimiri boliviensis, and Symphalangus syndactylus). Results are compared to previously published data on five species of wild anthropoids (n = 28; Alouatta paliatta, Callithrix jacchus, Gorilla beringei, Leontopithecus rosalia, and Macaca sinica) and human milk fatty acid profiles. Milk LCPUFA profiles of captive anthropoids (consuming diets with a preformed source of DHA) are similar to milk from women on a Western diet, and those of wild anthropoids are similar to milk from vegan women. Collectively, the range of DHA percent composition values from nonhuman anthropoid milks (0.03–1.1) is nearly identical to that from a cross-cultural analysis of human milk (0.06–1.4). Humans do not appear to be unique in their ability to secrete LCPUFA in milk but may be unique in their access to dietary LCPUFA.     

The depth of the lingual fossa in permanent incisors of Norwegians. I. Method of measurement, statistical distribution and sex dimorphism

The depth of the incisor lingual fossa in permanent extracted incisors and plaster casts of Norwegians was examined. It was shown that plaster casts are well suited for measurements of lingual fossa depth, and that the measurements can be performed with great accuracy. Skewness values showed the symmetry of the distribution to decrease with decreasing mean lingual fossa depth. Kurtosis was found small in maxillary incisors, in mandibular outside the limits for normal theory. The distribution of the depth of the lingual fossa cannot generally be described as normal. No sex differences were found. The inheritance of this trait in Norwegians is probably not sex linked.     

Wear striations on the incisors of ceropithecid monkeys as an index of diet and habitat preference

Wear striations on the incisors of Old World monkeys were examined in order to determine associations between the distributions of striations, diet, and habitat preference. Significant differences exist between the Cercopithe-cinae and the Colobinae in respect to the orientation of incisor wear striations. In the Colobinae striations are oriented in a predominantly mesiodistal direction. In the Cercopithecinae striations usually have a labiolingual orientation. Comparisons of terrestrial and arboreal genera indicate that significant differences exist between the two groups in respect to the density of striations on the oc-clusal wear facets of maxillary central incisors. Arboreal and terrestrial monkeys also differ in the frequency of individual incisor wear facets completely devoid of wear striations.     

A functional consequence of an ossified mandibular symphysis

According to most recent workers, the presence of fused symphyses in some mammals is explained by the common view that muscle force is transmitted better across a fused, as opposed to an unfused, mandibular symphysis. Recent theoretical work has cast doubt on the importance of fusion for simple force transmission by suggesting that force can also be transmitted efficiently across an unfused symphysis, an expectation that has since been confirmed by a number of observational studies. Perhaps the real significance of symphyseal fusion is that, in animals with upper and lower incisor tooth rows that apply large forces to relatively small resistant food items, muscle force from both sides of the head is reliably available only when the symphysis is fused. Independent movement between the two sides of the lower incisor row, permitted by a patent symphysis, allows the possibility that one side of the lower row will come into contact with the upper incisor row, dissipating all of the muscle force from that side. The dissipation of approximately half of the available jaw muscle force, allowed by a patent symphysis, cannot be ignored when attempting to explain the presence of fused symphyses if one accepts the idea that strong incisor biting is an important element in the masticatory apparatus of those primates and other mammals with fused mandibular symphyses.     

Brief communication: interproximal tooth wear: a new observation.

Microscopic observations were made of wear on the proximal surfaces of tooth crowns of Australian Aboriginals and whites. Typical wear facets displayed well-defined borders within which vertical or near vertical furrows, ranging from about 0.1 to 0.5 mm in width, were noted. Furrows on the interproximal surface of one tooth seemed to "interdigitate" with those on the proximal surface of the adjacent tooth. These observations are not consistent with the commonly-held view that interproximal tooth wear results from a buccolingual movement of adjacent teeth that maintain contact through mesial migration. Vertical or near vertical movement of teeth, possibly including a tipping action, must be an important factor, although the precise nature of the movement requires further investigation.