Dental microwear variability on buccal tooth enamel surfaces of extant Catarrhini and the Miocene fossil Dryopithecus laietanus (Hominoidea)

Analyses of buccal tooth microwear have been used to trace dietary habits of modern hunter-gatherer populations. In these populations, the average density and length of striations on the buccal surfaces of teeth are significantly cor-related with the abrasive potential of food items consumed. In non-human pri-mates, tooth microwear patterns on both occlusal and buccal wear facets have been thoroughly studied and the results applied to the characterization of dietary habits of fossil species. In this paper, we present inter- and intra-specific buccal microwear variability analyses in extant Cercopithecoidea (Cercopithecus mitis, C. neglectus, Chlorocebus aethiops, Colobus spp., Papio anubis) and Hominoidea (Gorilla gorilla, Pan troglodytes, Pongo pygmaeus). The results are tentatively compared to buccal microwear patterns of the Miocene fossils Dryopithecus and Oreopithecus. Significant differences in striation density and length are found among the fossil taxa studied and the extant primates, suggesting that buccal microwear can be used to identify dietary differences among taxa. The Dryopithecus buccal microwear pattern most closely resembles that of abrasive, tough plant foods consumers, such as the gorilla, in contrast to stud-ies of dental morphology that suggest a softer, frugivorous diet. Results for Oreopithecus were equivocal, but suggest a more abrasive diet than that previously thought.     

Differences in the Striaton Pattern in individuals with Unilateral Buccal Pathologies

A sample of individuals with different unilateral pathologies affecting the masticatory apparatus has been studied. Replicas of the same teeth (first or second molar) on both sides have been obtained and observed by SEM. The number, length and orientation of buccal striations have been determined for each individual. Differences in the microwear pattern have been observed between pathological sides. Each individual displays a particular striation pattern, especially referred to the striation number variables. It is concluded that individuals exhibiting pathologies likely to affect mastication should be excluded from studies relating striation patterns to diet.     

Nonocclusal dental microwear analysis of 300,000-year-old Homo heilderbergensis teeth from Sima de los Huesos (Sierra de Atapuerca, Spain)

Casts of nonocclusal enamel surfaces of 190 teeth from the Middle Pleistocene site of Sima de los Huesos have been micrographed by scanning electron microscopy. Microscopic analyses of striation density and length by orientation show distinct patterns of intrapopulation variability. Significant differences in the number and length of the striations by orientation are found between maxillary and mandibular teeth. This probably reflects differences in the mechanical forces involved in the process of chewing food. Significant differences are present between isolated and in situ teeth that could be caused by postdepositional processes differentially affecting the isolated teeth. In addition, a distinct and very unusual striation pattern is observed in a sample of teeth that can be explained only by a strong nondietary, most probably postmortem abrasion of the enamel surfaces. These teeth have a very high density of scratches, shorter in length than those found on other teeth, that are not indicative of dietary habits. No known depositional process may account for the presence of such postmortem wear since heavy transportation of materials within the clayish sediments has been discarded for the site. Despite this, a characteristic dietary striation pattern can be observed in most of the teeth analyzed. Most likely the diet of the Homo heidelbergensis hominids from Sima de los Huesos was highly abrasive, probably with a large dependence on hard, poorly processed plant foods, such as roots, stems, and seeds. A highly significant sex-related difference in the striation pattern can also be observed in the teeth analyzed, suggesting a differential consistency in the foods eaten by females and males.     

Non-occlusal dental microwear variability in a sample of Middle and Late Pleistocene human populations from Europe and the Near East

Non-occlusal, buccal tooth microwear variability has been studied in 68 fossil humans from Europe and the Near East. The microwear patterns observed suggest that a major shift in human dietary habits and food processing techniques might have taken place in the transition from the Middle to the Late Pleistocene populations. Differences in microwear density, average length, and orientation of striations indicate that Middle Pleistocene humans had more abrasive dietary habits than Late Pleistocene populations. Both dietary and cultural factors might be responsible for the differences observed. In addition, the Middle Paleolithic Neanderthal specimens studied show a highly heterogeneous pattern of microwear when compared to the other samples considered, which is inconsistent with a hypothesis of all Neanderthals having a strictly carnivorous diet. The high density of striations observed in the buccal surfaces of several Neanderthal teeth might be indicative of the inclusion of plant foods in their diet. The buccal microwear variability observed in the Neanderthals is compatible with an overall exploitation of both plant and meat foods on the basis of food availability. A preliminary analysis of the relationship between buccal microwear density and climatic conditions prevailing in Europe during the Late Pleistocene has been attempted. Cold climatic conditions, as indicated by oxygen isotope stage data, seem to be responsible for higher densities of microwear features, whereas warmer periods could correspond to a reduced pattern of scratch density. Such a relationship would be indicative of less abrasive dietary habits, perhaps more meat dependent, during warmer periods.     

Dental microwear in anubis and hybrid baboons (Papio hamadryas, sensu lato) living in Awash National Park, Ethiopia

We describe dental microwear in baboons (Papio hamadryas sensu lato) from the anubis-hamadryas hybrid zone of Awash National Park, Ethiopia, outline its variation with sex and age, and attempt to relate the observed microwear pattern to environment and diet. Casts of the maxillary second molar of 52 adult and subadult individuals of both sexes were examined with a scanning electron microscope at x 500. Digitized micrographs were taken at a consistent location on facet 9, and microwear was recorded with an image analysis software package. Univariate and multivariate statistics were used to investigate the shape, size, and density of microwear features. The overall pattern of microwear exhibits an unusual combination of high feature density, with numerous small pits and relatively wide striations, and a high correlation between width of pits and striations across individuals. We interpret this pattern as predominantly the consequence of abrasion by relatively small-caliber environmental grit when accidentally ingested with tough foods such as dried seeds and fruits, as expected in a terrestrial omnivore living in a dusty habitat. Statistical analysis revealed no significant differences between groups defined by sex, age, or troop membership, a result consistent with qualitative observations of feeding habits in this population, and which lends no support to the hypothesis that the longer jaws of adult males should result in longer striations. A trend towards greater feature density in females, however, might be due to limited sexual dinichism, and merits further investigation.     

Buccal dental microwear variability in extant African Hominoidea: taxonomy versus ecology

Buccal microwear patterns on teeth are good indicators of the abrasiveness of foodstuffs and have been used to trace the dietary habits of fossil species, including primates and hominids. However, few studies have addressed the variability of this microwear. The abrasiveness of dietary components depends not only on the hardness of the particles ingested, but also on the presence of dust and other exogenous elements introduced during food processing. These elements are responsible for the microwear typology observed on the enamel surfaces of primate teeth. Here we analyzed the variability of buccal microwear patterns in African Great Apes (Gorilla gorilla and Pan troglodytes), using tooth molds obtained from the original specimens held in several osteological collections. Our results suggest that ecological adaptations at subspecies or population level account for differences in microwear patterns, which are attributed to habitat and ecological conditions within populations rather than differences between species. The findings from studies on the variability of buccal dental microwear in extant species will contribute to a better understanding of extinct hominids’ diet and ecology.     

Dentition of moustached tamarins (Saguinus mystax mystax) from Padre Isla, Peru, part 1: quantitative variation

Analyses of dental variation in geographically restricted, wild populations of primates are extremely rare; however, such data form the best source for models of likely degrees of variation within and between fossil species. Data from dental casts of a geographically restricted population of moustached tamarins (Saguinus mystax mystax) from Padre Isla, Peru, document high levels of dental variability, as measured by coefficients of variation, in a nonsexually dimorphic species, despite its isolation and small population size. Like other primates, moustached tamarins show lower variability in the dimensions of the first molars and increased variability in the dimensions of the final molars in the toothrow. Moustached tamarins from Padre Isla have a distinctive pattern of variability in the remaining teeth, including more stable tooth lengths in the anterior and posterior portions of the toothrow, and more stable tooth widths in the midregion of the toothrow. High variability in incisor width may be due to age effects of a distinctive diet and pattern of dental wear.     

新疆吐鲁番加依墓地青铜—早期铁器时代居民牙齿的磨耗

本文对新疆吐鲁番市加依墓地青铜—早期铁器时代居民的牙齿磨耗、口腔疾病和骨质隆起等特征进行了观察与研究,结果显示,加依墓地居民的牙齿磨耗较重,但前后部牙齿的磨耗程度差异不大,臼齿偏斜式磨耗现象显著,龋齿罹患率偏低。生前脱落、牙结石等口腔疾病在该人群中普遍流行,部分个体的下颌存在发育显著的骨质隆起现象。本文还通过臼齿磨耗方向指数(Wear Orientation)对加依墓地居民的偏斜式磨耗进行了量化研究,并参考相关民族学调查、考古发现以及现代医学研究成果对加依墓地居民复杂的牙齿磨耗形态和口腔疾病的成因进行了初步探讨。推测加依墓地居民的食物结构应以肉类为主,谷类亦占有一定地位;此外可能是受到恶劣生活环境及特殊谷物加工技术的影响,日常食物较为坚硬。     

Differences in Tooth Microwear of Populations of Caribou (<Emphasis Type="Italic">Rangifer tarandus</Emphasis>, Ruminantia,Mammalia) and Implications to Ecology,Migration, Glaciations and Dental Evolution

Tooth microwear was analyzed for a large sample of wild-shot barren-ground caribou (Rangifer tarandus groenlandicus) from the Kaminuriak population of eastern Canada. This sample was compared to the microwear of specimens from three Pleistocene localities in North America (Alaska) and western Europe (Caune de l’Arago in France and Salzgitter in Germany). The results show that the extant samples from eastern Canada have seasonal variation in microwear and presumably in diet. The differences in microwear between the various seasons may reflect a cyclic migration of the population within a year. The extinct population from Alaska has extremely blunt teeth (mesowear), as blunt as those of modern zebras and bison. This observation is corroborated by the lowest number of microwear pits. The findings are untypical, as most typical caribou teeth have sharper apices, and we interpret this as an indication of a local habitat that was different with animals feeding on non-typical vegetation. The combination of Rangifer from Caune de l’Arago and Salzgitter reveals a pattern in microwear variability. The Salzgitter is interglacial and shows a greater diversity of browsing (broad spectrum on average number of pits) than the glacial Caune de l’Arago. The interglacial population from Salzgitter is interesting because it shows several different types of browsing. Collectively all the Rangifer teeth show that diet of a brachydont taxon can vary across most of the dietary morphospace of ungulates as represented by tooth microwear. The three Pleistocene samples exhibit microwear that is different from the extant population in question. This observation implies that the recent diet of Rangifer has changed from the typical caribou diet in the past. This indicates dietary change within a species. This is important because it represents dietary evolution without changes in tooth morphology.     

Individual patterns of prey selection and dietary specialization in an Arctic marine carnivore

The cumulative effect of individual‐level foraging patterns may have important consequences for ecosystem functioning, population dynamics and conservation. Dietary specialization, whereby an individual exploits a subset of resources available to the rest of the population, can develop in response to environmental or intrinsic population factors. However, accurate assessment of individual diets may be difficult because analyses of recent food intake may misrepresent foraging variability within a heterogeneous environment. We used quantitative fatty acid signature analysis (QFASA) and a novel index of longitudinal dietary change to examine the individual foraging patterns of 64 polar bears Ursus maritimus successively sampled in Western and Southern Hudson Bay between 1994–2003. Estimated diets varied between and within age and sex classes, with adult male polar bears consuming significantly more bearded seal Erignathus barbatus than adult female or subadult bears, whose diets were dominated by ringed seal Pusa hispida. Among individual adult males, consumption of bearded seal accounted for 0–98% of the diet and bearded seal consumption was positively correlated with individual dietary specialization, as measured by proportional similarity (PS_i) to the rest of the population. Most individual diets were consistent from year‐to‐year and were therefore not a product of short‐term heterogeneity in prey distribution. However, a novel dietary change index indicated that adult male polar bears had the most temporally variable diets with 23% of adult males switching their diet from predominantly ringed seal to predominantly bearded seal or vice versa. We conclude that QFASA is well‐suited to analyses of individual‐level foraging because it reflects an animal's diet over the preceding weeks to months. The subpopulations of bears in this study were near the southern limit of their species range and have experienced negative individual‐ and population‐level impacts related to sea ice loss and climate warming. The tightly constrained diets of some individuals, particularly adult females and subadults, may make them especially sensitive to future climate change.     

Prey selection of subadult male northern fur seals (Callorhinus ursinus) and evidence of dietary niche overlap with adult females during the breeding season

During the breeding season northern fur seals (Callorhinus ursinus) congregate on the Pribilof Islands in large numbers creating the potential for intraspecific competition. Due to the declining trend in the Pribilof Islands population of fur seals, it is important to understand how prey resources are partitioned among the population. Fur seals exhibit a high degree of sexual dimorphism resulting in energetic differences among age and sex classes. Therefore, we hypothesized that subadult male and adult female fur seals would differ in the type and size of prey consumed. We examined the diets of subadult male (age 2–8; mean mass 28–176 kg) and adult female (age ≥ 3 yr; mean mass 13–50 kg) seals on St. Paul Island from 1992 to 2000. Prey remains found in fecal samples were compared using niche overlap indices. There was nearly complete dietary niche overlap between subadult male and adult female fur seals. Walleye pollock (Theragra chalcogramma), Pacific salmon (Oncorhynchus spp.), Pacific herring (Clupeia pallasi), and cephalopods were common prey items found in the diets of both groups. We found differences in the size of pollock consumed and that geographic location of sample collection may be important in determining diet differences. Our results indicate high levels of dietary overlap among subadult male and adult female fur seals.     

新疆吐鲁番胜金店墓地人骨的牙齿微磨耗

本文使用不同倍率的超景深电子显微镜,对新疆吐鲁番胜金店墓地中出土的13例臼齿的颊侧微磨耗形态进行了观察和研究。通过对臼齿颊侧表面凹坑和条痕形态微磨耗的测量和统计,计算出每例牙齿的微痕数量、均长、均宽、凹坑百分比和L_h/L_v比值,按照性别和年龄分组进行人群内的数据对比分析。研究结果表明,该人群中年龄较大的个体摄入更高比例的植物类食物;两性的食物结构不存在显著性差异,男性摄入植物类食物比例略高,女性的食物结构在不同的年龄阶段有所差异。将胜金店墓地人群与不同生计方式人群的L_h/L_v比值进行人群间的差异性分析,并结合胜金店墓地的随葬品特点推测,胜金店墓地人群的食物结构以肉类食物为主,其生计模式以游牧业为主,兼营种植类经济。     

Stable carbon and nitrogen isotope values of bone and teeth reflect weaning age at the Medieval Wharram Percy site,Yorkshire, UK

We report on the measurements of carbon and nitrogen stable isotopes of both bone and teeth from a single site and population (Medieval Wharram Percy), undertaken to explore variations due to weaning in a past population. There have been a number of recent studies of weaning using delta(15)N values of ribs, and we indicate a number of assumptions that must be met before the results of such studies can be correctly interpreted. We found that rib collagen delta(15)N values decrease to adult levels after age 2 years, indicating that weaning occurred at or before this age. Rib collagen delta(13)C values are also more enriched than adult delta(13)C values before age 2 years, and we argue that this is due to the so-called "carnivore" effect in delta(13)C. We measured teeth and rib delta(15)N values from the same individuals and found that for individuals up to age 11 years, tooth dentine delta(15)N is higher than adult rib delta(15)N values, indicating that the dentine was formed during breast-feeding and that there was almost no turnover of dentine since. We observed some decrease in delta(13)C and delta(15)N rib values, compared to adult rib and teeth values, for the few years after weaning that may relate to a theoretically predicted physiological nitrogen imbalance during this period of rapid growth, but this is more likely due to a childhood diet (up to age 9) which was isotopically different from later diet, possibly consisting of a greater proportion of plant foods.     

军都山古代人群牙齿磨耗及其饮食

以军都山墓地为代表的"玉皇庙文化"系中国北方青铜时代的一支具有鲜明地方特色的少数部族文化。本文对军都山墓地出土人骨牙齿标本作牙齿磨耗状况分析,试图为其饮食结构和社会经济形态的探讨提供线索。结果显示:军都山古代人群中,相同年龄组的男女两性牙齿磨耗差异不大;前部牙齿磨耗轻于后部臼齿,第一臼齿磨耗最重;臼齿磨耗样式大多呈现"正常平匀"式,臼齿磨耗角度大多较小,两者均随年龄而变化但没有显著的性别差异。经与其他样本组的对比认为军都山古代人群牙齿磨耗的特点可能与其社会经济农牧兼营的性质有关,推测动物性食物(肉食)可能在军都山古代人群主要饮食结构中占据重要比例,并包含有一定的农业经济成分。不同游牧人群牙齿磨耗程度差异较大,只有结合了磨耗形态及其他信息才有可能更切实地反映其饮食状况。     

Tool use in animals: Cognition and ecology. Edited by Crickette M. Sanz,Josep Call,and Christophe Boesch. New York,NJ: Cambridge University Press. 2013. 313 pp. ISBN 978‐1‐107–01119‐9. $110 (hardcover).

Enamel thickness has been linked to functional aspects of masticatory biomechanics and has been demonstrated to be an evolutionary plastic trait, selectively responsive to dietary changes, wear and tooth fracture. European Late Paleolithic and Mesolithic hunter‐gatherers mainly show a flat wear pattern, while oblique molar wear has been reported as characteristic of Neolithic agriculturalists. We investigate the relationships between enamel thickness distribution and molar wear pattern in two Neolithic and medieval populations. Under the assumption that dietary and/or non‐dietary constraints result in directional selective pressure leading to variations in enamel thickness, we test the hypothesis that these two populations will exhibit significant differences in wear and enamel thickness patterns. Occlusal wear patterns were scored in upper permanent second molars (UM2) of 64 Neolithic and 311 medieval subadult and adult individuals. Enamel thickness was evaluated by microtomography in subsamples of 17 Neolithic and 25 medieval individuals. Eight variables describing enamel thickness were assessed. The results show that oblique molar wear is dominant in the Neolithic sample (87%), while oblique wear affects only a minority (42%) of the medieval sample. Moreover, in the Neolithic molars, where buccolingually directed oblique wear is dominant and greatest enamel lost occurs in the distolingual quadrant, thickest enamel is found where occlusal stresses are the most important—on the distolingual cusp. These results reveal a correlation between molar wear pattern and enamel thickness that has been associated to dietary changes. In particular, relatively thicker molar enamel may have evolved as a plastic response to resist wear. Am J Phys Anthropol 155:162–172, 2014. © 2014 Wiley Periodicals, Inc.     

Wear striation direction on primate teeth: a scanning electron microscope examination.

Two experimental methods were used to produce wear striations in one direction on unworn teeth. These include: (1) sliding 22 American Indian (Juntunen site, Michigan; Late Woodland) newly erupted incisors, by hand, across a flat grass surface covered with fine loose sand; and (2) using a unidirectional motor driven mechanical wear machine to draw 56 modern human dental extractions across a flat glass surface covered with silicon carbide powder of different grit sizes. A scanning electron microscope examination of individual wear striation morphology indicates that these wear striations begin with broad pits and have extending grooves that become narrower; characteristics that indicate the motion of wear. Patterns of wear striations on the worn dentitions of American Indians (Juntunen site) and the paleocene primate Phenacolemur pagei show similar characteristics and correspond to the buccal phase of mastication when the mandible is drawn upward, forward and slightly medially into centric occlusion. The data provided by this study can be used to test competing hypotheses concerning the direction of mandibular movement during mastication and food preparation.     

Dental destruction in Broken-Hill man

The determination of the type of Broken-Hill man's diet by the study wear on occlusal surfaces may be complemented by the examination of striations left by the diet on the dental crown. Microscopic grooves of dental buccal surfaces yields new data as to what prehistoric man ate. It is suggested that Broken-Hill man allowed the development of rampant caries through his ignorance of the use of tooth picks.     

The relation of canine size to pattern and extent of attrition in baboons

For most genera of animals the association between dental morphology and diet is such that inferences concerning the diet can be made on the basis of the dentition alone. The canine is the one tooth that appears exempt from such generalisation and exhibits a wide range of variability of size and shape in all groups. In order to determine the effect of dimorphism of the canine on the dental apparatus, male and female specimens of Theropithecus and Papio baboons were examined. Occlusal relationships and dental pathology for 21 Theropithecus and 40 Papio skulls were recorded, and crown height measurements obtained for maxillary incisors, buccal and lingual molar cusps. Attrition was the most common and severe cause of abscess formation in older animals: the pattern of attrition differed in adult males and females, the latter showing more wear of the incisor and lingual molar cusps. Partial correlations for incisor, buccal and lingual molar cuspal crown height show a significant correlation between incisor and lingual cusp attrition in juveniles of both sexes and adult females (p < 0.01). Adult males show no correlation of attrition. It is proposed that the correlation of incisor and lingual molar cusp attrition is associated with anterior-posterior grinding movements, such as take place during incision, that the large canine present in the male limits such movements, the sharp blade-like canine being employed as a cutting tool. This use of the canine by reducing functional demands on other teeth, prolongs the utility of the dental apparatus, and hence the lifespan of its possessor.     

Morphological variation of introduced species: The case of American mink (Neovison vison) in Spain

We studied the morphology of American mink Neovison vison in five out of the six introduced populations in Spain. The spatial and temporal variation of body weight (BW), body length (BL), tail length, hind-foot length and ear length were analysed. Temporal trends in BW and BL in relation to years since mink introduction were also analyzed. In addition, we tested the effect of sex, age (juvenile, subadult and adult) and age–sex interaction, on each parameter. Morphological parameters differed between populations, illustrating the high variability of body size of American mink in different environments, and the phenotypic plasticity of the species. Annual variations were synchronized between populations, suggesting a large-scale effect on all of them. BW and BL showed a decreasing trend in both males and females in relation to years since introduction. This decrease may be related to mink's diet. Differences in sex and age were found, pointing to sexual dimorphism in adults, subadults and juveniles. The dimorphism in non-adult individuals suggests that subadult males may have a competitive advantage from subadult females in feeding and/or hunting on bigger prey from an early age (resource partitioning hypothesis).