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1.
The microscopic traces of use wear on teeth have been extensively studied to provide information that will assist in elucidating the dietary habits of extinct hominin species. 1 - 13 It has been amply documented that dental microwear provides information pertaining to diet for living animals, where there is a strong and consistent association between dental microwear patterns and different types of foods that are chewed. The details of occlusal surface wear patterns are capable of distinguishing among diets when the constituent food items differ in their fracture properties. 14 - 20 For example, the microwear traces left on the teeth of mammals that crush hard, brittle foods such as nuts are generally dominated by pits, whereas traces left on the teeth of mammals that shear tough items such as leaves tend to be characterized by scratches. These microwear features result from and thus record actual chewing events. As such, microwear patterns are expected to be variably ephemeral, as individual features are worn away and replaced or overprinted by others as the tooth wears down in subsequent bouts of mastication. Indeed, it has been demonstrated, both in the laboratory and the wild, that short‐term dietary variation can result in the turnover of microwear. 17 , 21 - 23 Because occlusal microwear potentially reflects an individual's diet for a short time (days, weeks, or months, depending on the nature of the foods being masticated), tooth surfaces sampled at different times will display differences that relate to temporal (for example, seasonal) differences in diet. 24  相似文献   

2.
Dental microwear analysts have demonstrated that hard diets leave numerous microscopic pits on occlusal surfaces. The relationship between occlusal pitting and gross macrowear, however, is not well known. The current study seeks to elucidate the relationship between dental microwear and macrowear by determining if microscopically pitted teeth are associated with greater expressions of macrowear. This study examined microwear and macrowear on mandibular second molars from 60 prehistoric adult Native Americans representing three dietary regimes (foraging, mixed economy, and agriculture). Initially, two dental microwear feature variables were studied: percentage of pits and mean scratch width. Standard macrowear scores ranged from 4 to 40. ANOVAs suggested that neither of the microwear variables was affected by age or sex, but age affected macrowear scores. Because of this, the sample had a balanced number of young and old adults (i.e., those below and above skeletal age 35). A Pearson's correlation showed no covariation between scratch width and the percentage of pits. Regression analysis indicated that macrowear was not a function of the percentage of pits. However, a significant positive relationship was found between dental macrowear and scratch width. A post priori test found a significant negative relationship between macrowear and the total number of scratches. It is concluded, then, that wide scratches remove more enamel and dentin than do numerous pits, although both cause dental wear. It is suggested here that the term “abrasive” be used to describe those microwear profiles that lead to heavy macrowear and have relatively wide scratches. Am J Phys Anthropol, 2010. © 2009 Wiley‐Liss, Inc.  相似文献   

3.
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.  相似文献   

4.
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。  相似文献   

5.
Conventional wisdom ties the origin and early evolution of the genus Homo to environmental changes that occurred near the end of the Pliocene. The basic idea is that changing habitats led to new diets emphasizing savanna resources, such as herd mammals or underground storage organs. Fossil teeth provide the most direct evidence available for evaluating this theory. In this paper, we present a comprehensive study of dental microwear in Plio-Pleistocene Homo from Africa. We examined all available cheek teeth from Ethiopia, Kenya, Tanzania, Malawi, and South Africa and found 18 that preserved antemortem microwear. Microwear features were measured and compared for these specimens and a baseline series of five extant primate species (Cebus apella, Gorilla gorilla, Lophocebus albigena, Pan troglodytes, and Papio ursinus) and two protohistoric human foraging groups (Aleut and Arikara) with documented differences in diet and subsistence strategies. Results confirmed that dental microwear reflects diet, such that hard-object specialists tend to have more large microwear pits, whereas tough food eaters usually have more striations and smaller microwear features. Early Homo specimens clustered with baseline groups that do not prefer fracture resistant foods. Still, Homo erectus and individuals from Swartkrans Member 1 had more small pits than Homo habilis and specimens from Sterkfontein Member 5C. These results suggest that none of the early Homo groups specialized on very hard or tough foods, but that H. erectus and Swartkrans Member 1 individuals ate, at least occasionally, more brittle or tough items than other fossil hominins studied.  相似文献   

6.
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.  相似文献   

7.
Dietary hardness and abrasiveness are inferred from human dental microwear at Ohalo II, a late Upper Palaeolithic site (22,500-23,500 cal BP) in the southern Levant. Casts of molar grinding facets from two human skeletons were examined with a scanning electron microscope. The size and frequency of microwear was measured, counted, and compared to four prehistoric human groups from successive chronological periods in the same region: pre-pottery Neolithic A, Chalcolithic (this study); Natufian, pre-pottery Neolithic B (Mahoney: Am J Phys Anthropol 130 (2006) 308-319). The Ohalo molars had a high frequency of long narrow scratches, and a few small pits, suggesting a tough abrasive diet that required more shearing rather than compressive force while chewing. These results imply that the diet of the two late Upper Palaeolithic hunter-gatherers did not focus on very hard foods. Aquatic foods with adherent contaminants, as well as grit from plant grinding tools seemed likely causal agents. The size of the pits and scratches on the Ohalo molars were most similar to microwear from the pre-pottery Neolithic A period, though they also compared well to the Chalcolithic period. These results contrasted with the larger pits and scratches from the Natufian hunter-gatherers and pre-pottery Neolithic B farmers, implying that there is no simple increase or decrease in dietary hardness and abrasiveness across the late Upper Palaeolithic to Chalcolithic development in the Southern Levant.  相似文献   

8.
Recent investigations of dental microwear have shown that such analyses may ultimately provide valuable information about the diets of fossil species. However, no background information about intraspecific variability of microwear patterns has been available until now. This study presents the results of an SEM survey of microwear patterns found on occlusal enamel of chimpanzee molars. Methods of pattern analysis are described. Selected sites on the occlusal surface included shearing, grinding, and puncture-crushing surfaces formed by both phases of the power stroke of mastication. The microwear patterns found in this sample of chimpanzees showed a high degree of regularity. However, certain parameters such as relative pit-to-striation frequencies, feature density, striation length, and pit diameter were significantly affected by facet type and molar position. Sex and age of individuals also influenced some microwear parameters, but due to the small sample size these findings are considered to be preliminary. These results show that microwear within a single species may vary because of factors that are due more to biomechanics than to diet. The study also supplies some metrical estimates of “normal” pattern variability due to functional and morphological influences. These estimates should provide a useful baseline for assessing the significance of microwear pattern differences that may be found between species of differing diets.  相似文献   

9.
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.  相似文献   

10.
In order to further evaluate the process of microwear formation on human dental enamel, microwear was experimentally produced by a chewing simulation with an Academic Center for Dentistry Amsterdam (ACTA) device. For this simulation, several cereal species were processed according to historical milling techniques, the experimental results of which were compared with those obtained from cereals processed after modern techniques, and also with natural microwear on early medieval human molars. Comparison of simulated microwear pits with natural microwear pits showed that the simulation led to traces which matched those found on the historical teeth in terms of both size and shape. Experimentally produced microwear pits were especially characteristic for the cereal species used in the simulations, and both pit morphology and enamel loss were a function of cereal phytolith content. Despite the high variability of phytolith size and shape, certain types are characteristic for certain cereals, which in turn are capable of producing cereal-specific microwear. This experimental approach is likely to further define ancient human dietary behavior, including food processing.  相似文献   

11.
Mammals of numerous lineages have evolved high‐crowned (hypsodont) teeth particularly during the last 20 million years. This major phenotypic change is one of the most widely studied evolutionary phenomena in a broad range of disciplines, though the mechanisms underlying its transformation remain unresolved. Here, we present the first Finite Element Analysis (FEA) to investigate the alternative hypothesis that there is a biomechanical link between increased hypsodonty and a more effective mastication in deer. Our FE experiments compared patterns of stress and strain within and between different fossil and living species under different loading conditions, and found that more hypsodont teeth are suited for restricting stresses to those areas where chewing loading occurs. This mechanical improvement is consequence of specific and pronounced variations in tooth geometry and morphology of the occlusal surface that are strongly related to crown growth in the vertical plane. We demonstrate that hypsodonty enables selenodont‐teeth to adopt a mechanically improved design that increases the pressure whilst shearing foods. As ruminants are physiologically limited by both the quantity of food consumed and the time spent in the mastication and digestion, hypsodonty is highly advantageous when feeding on mechanically resistant, tough and fibrous foods. Consequently, it allows grass‐eaters to spend less time chewing, thereby increasing the volume of food ingested and/or providing more time for digestion. This study provides a promising line of evidences in support of biomechanical effectiveness, in addition to or instead of increased wear resistance, as a factor in explaining the evolutionary origins of the hypsodont phenotype.  相似文献   

12.
Pitheciines (Pithecia, Chiropotes, and Cacajao) are a specialized clade of Neotropical seed predators that exhibit postcanine teeth with low and rounded cusps and highly crenulated occlusal surface enamel. Data on feeding ecology show that Pithecia consumes proportionally more leaves than other pitheciine species, and comparative studies demonstrate its greater molar relief and relative shearing potential. However, data on pitheciine food mechanics show that Pithecia masticates seeds with greater crushing resistance than those preferred by Chiropotes. This variation predicts an opposing morphology characterized by low and more rounded occlusal surfaces in Pithecia. We build on previous research using new methods for molar surface shape quantification by examining pitheciine second molar shearing crest length, occlusal relief, surface complexity, and surface curvature relative to nonseed specializing platyrrhines and within the context of the observed interspecific variation in pitheciine feeding ecology. Consistent with the previous analyses, our findings demonstrate that pitheciine molars exhibit low shearing, relief, and curvature compared with nonseed predators, independent of phylogeny. Pitheciines also exhibit highly “complex” occlusal topography that promotes the efficient breakdown of tough seed tissues. Overall, Pithecia, Chiropotes, and Cacajao share a similar topographic pattern, suggesting adaptation to foods with similar structural and/or mechanical properties. However, Cacajao differs in surface complexity, which reflects some variation in its feeding ecology. Contrary to the predictions, Pithecia and Chiropotes do not differ in any of the topographic variables examined. The range of demands imposed on the postcanine teeth of Pithecia might therefore select for an average topography, one that converges on that of Chiropotes. Am J Phys Anthropol, 2013. © 2012 Wiley Periodicals, Inc.  相似文献   

13.
Those Eocene prosimians which are possible catarrhine ancestors have four blade-like crests on each lower molar. Each crest shears in sequence across two upper molar crests. Occluding crests are concavely curved to hold the foods being sheared. Each of two medial lower molar crests bordering the principal crushing surface shear past single upper molar crests at about the same time the lateral lower molar crests contact the second rank of upper molar crests. Grinding and crushing areas are restricted to hypoconid, trigonid, and protocone surfaces. Oligocene catarrhine molars have increased crushing-grinding capacities and maintained but modify their shearing. As the crushing surface of the protocone expands and a crushing hypocone is added, the “second rank” upper molar shearing crests are functionally reduced. At the same time medial crests are increasingly emphasized so that the total shearing capacity remains virtually unchanged. Marginal shearing blades are straight edged; leading edges of occluding blades are set at different angles to the occlusal plane so that blades contact at only one point at any given time. Early Primates have separate crushing basins surrounded by shearing blades. Catarrhines tend to link expanding crushing surfaces anteroposteriorly into a continuous surface between all molars. A cladistic analysis based on both new and previously recognized characters indicates that: 1, Apidium may be more closely related to Aegyptopithecus than to Parapithecus; 2, cercopithecids are derived from a Parapithecus-related stock; 3, Oreopithecus could equally well have come from an Apidium or Aegyptopithecus stock.  相似文献   

14.
Most studies of microscopic wear on non-human primate teeth have focused on the occlusal surfaces of molars. Recent analyses of the buccal surfaces of human cheek teeth have demonstrated an association between diet and dental microwear on the these surfaces as well. In the current study, we examine microwear on both the buccal and lingual surfaces of non-human primate molars to assess the potential of these surfaces to reveal information concerning anthropoid feeding behaviors. We compare frequency of microwear occurrence in 12 extant and 11 fossil anthropoid species. Among the living primates, the occurrence of microwear on non-occlusal surfaces appears to relate to both diet and degree of terrestriality. The implications of this research for the inference of feeding behaviors and substrate use in fossil cercopithecoids are discussed. © 1996 Wiley-Liss, Inc.  相似文献   

15.
In this study we examine the labial and occlusal surfaces of incisors and canines of hominins recovered from the Sima de los Huesos (SH), middle Pleistocene site, in order to establish the possible extra-masticatory use of anterior teeth. We have compared the microwear of these fossils with microwear from the anterior teeth of Australian Aborigines, a population characterized by ethnographic evidence of the use of their teeth as a third hand. These two samples of teeth were microscopically analyzed using Scanning Electron Microscopy (SEM). Our results support the “cultural” origin of microwear observed on fossil teeth: we conclude that the SH hominins used their anterior teeth as a “third hand” for para- or extra-masticatory activities.  相似文献   

16.
Microscopic pits and scratches form on teeth during chewing, but the extent to which their formation is influenced by mandibular morphology is unknown. Digitized micrographs of the base of facet nine of the first, second, and third mandibular molar were used to record microwear features from an archaeological sample of modern humans recovered from Semna South in northern Sudan (n=38; 100 BC to AD 350). Microwear patterns of the molar row are correlated with mandibular corpus width and depth, and with mandibular length. Variations in shear and compression at the base of facet nine during chewing were inferred. It may be that some correlations between microwear and mandibular morphology are predictable, reflecting similar aspects of masticatory loading, though the full extent of the relationship remains to be resolved.  相似文献   

17.
This study investigates whether the gross morphology of mustelid and viverrid postcanine dentitions corresponds with differences in diet. For each species, the predominant foods ingested are used to form predictions of dental form and measurements of the carnassial and molar teeth determine the extent of shearing and crushing surfaces on the postcanine teeth. Principal components analysis distinguishes species according to morphological differences in the dentition and these differences are compared with predictions of dental form based on diet. Dietarily specialized species are more likely to be correspondingly specialized in the dentition and species with varied food sources are more likely to possess dental characteristics that are generalized in function. Consumers of foods with high fracture resistance, such as vertebrate tissue and hard-surfaced invertebrates, possess specialized shearing or crushing postcanine teeth. On the other hand, species that consume foods of lesser fracture resistance, such as fruit and soft invertebrates, differ greatly in dental form and are more generalized in dental function. A few species possess postcanine dentitions that do not correspond with diet; the absence of dental-dietary correlation in these species suggests that other factors, such as phylogeny, are important in determining dental form.  相似文献   

18.
The Plio-Pleistocene hominin Paranthropus boisei had enormous, flat, thickly enameled cheek teeth, a robust cranium and mandible, and inferred massive, powerful chewing muscles. This specialized morphology, which earned P. boisei the nickname "Nutcracker Man", suggests that this hominin could have consumed very mechanically challenging foods. It has been recently argued, however, that specialized hominin morphology may indicate adaptations for the consumption of occasional fallback foods rather than preferred resources. Dental microwear offers a potential means by which to test this hypothesis in that it reflects actual use rather than genetic adaptation. High microwear surface texture complexity and anisotropy in extant primates can be associated with the consumption of exceptionally hard and tough foods respectively. Here we present the first quantitative analysis of dental microwear for P. boisei. Seven specimens examined preserved unobscured antemortem molar microwear. These all show relatively low complexity and anisotropy values. This suggests that none of the individuals consumed especially hard or tough foods in the days before they died. The apparent discrepancy between microwear and functional anatomy is consistent with the idea that P. boisei presents a hominin example of Liem's Paradox, wherein a highly derived morphology need not reflect a specialized diet.  相似文献   

19.
Maxillary and mandibular molars of the American opossum, Didelphis virginiana L., were viewed in the scanning electron microscope (SEM) after acid-etching or after cutting and acid-etching. Observations were made on enamel prism patterns as they relate to functional properties of the tooth at a particular site. Molars at different stages of wear were also observed under a dissecting microscope; worn surfaces were correlated with function and enamel ultrastructure. Pounding surfaces of molar cusps wear more rapidly than near-vertical shearing surfaces or crushing basins (i.e. the trigon and talonid basin). Pounding surfaces are subjected to abrasion by food and arc not normally involved in tooth-tooth contact. Near-vertical shearing surfaces and basins used for crushing do experience tooth-tooth contact, but are surprisingly more resistant to wear. Prisms at pounding sites approach the occlusal surface at a near 90° angle and are surrounded with very thick interprismatic (IP) enamel parallel to the occlusal surface of the tooth. The pounding pattern is present at tips of cusps and at occlusal surfaces of ridges of the tooth. At near-vertical shearing surfaces, the prisms approach the outer surface obliquely and are surrounded with IP crystals which are perpendicular to the vertical surface. The angle between prismatic and IP enamel in these patterns is 60–90° in a cervical to occlusal direction. In basins of the tooth used principally for crushing and some shearing, IP enamel is perpendicular to the changing slope of the basin and the prisms are usually at a 55–65° angle to the IP enamel. When the pounding and shearing-crushing patterns meet at a ridge, a distinct seam is observed. Pounding forces occur parallel to the long axis of the prisms and perpendicular to the thick IP enamel (i.e. perpendicular to the long axis of the IP crystals) lying on either side of the prisms. Shearing and crushing forces occur at an oblique angle to the prism, and interprismatic enamel is more evenly distributed about the prism. A spiral pattern is found at the bottoms of the trigon and talonid basins, but not at the bottom of the trigonid which is a non-occluding basin. It is concluded that the differential rates of wear of the enamel surfaces are necessary in maintaining the sharp cutting edges and effective crushing basins of the tribosphenic molar, and the ultrastructural arrangements of the enamel prisms are of functional significance.  相似文献   

20.
This low magnification stereomicrowear study samples a broad range of chalicotheres (Perissodactyla, Chalicotherioidea), including basal chalicotheres and the two chalicotheriid subfamilies Schizotheriinae and Chalicotheriinae, primarily including species from North America and Europe, but also some from Asia. The schizotheriines Moropus, Tylocephalonyx, and Metaschizotherium and the chalicotheriines Anisodon and Chalicotherium are best represented. Paleodiets are interpreted via discriminant analysis, using comparison of microwear variables from fossil chalicothere teeth with those from a database of extant ungulates with known diets. The results suggest that all of the chalicotheres in the study were browsers, with no evidence of significant grass consumption. Basal chalicotheres, like basal equids, seem to have been standard fruit-dominated browsers. Stereomicrowear agrees with mesowear results by Schulz et al. (2007) and Schulz and Fahlke (2009) for Metaschizotherium bavaricum, Metaschizotherium fraasi, Anisodon grande, and Chalicotherium goldfussi in showing a highly abrasive aspect to the diet. In these species, hard food objects such as fibrous fruits, seeds, pits, and nuts may have abraded the teeth (based on high pit counts, the presence of large puncture pits, and many individuals with coarse to hypercoarse scratches). Anisodon grande and C. goldfussi, despite their relatively short, brachydont teeth, show the highest degree of abrasion within the studied sample. Moropus and Tylocephalonyx from North America show somewhat different but also abrasive microwear; in these taxa the resistant foods may have been twigs and bark (large pits common, but gouging more prevalent than puncture pits). A preliminary comparison of stereomicrowear on DP4, the deciduous upper fourth premolar, with that on molars suggests that juveniles consumed similar foods as adults but without the most abrasive elements. Some important methodological differences regarding the scoring of microwear features by different low-magnification microwear methodologies are discussed.  相似文献   

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