Dental microwear texture analysis of two families of subfossil lemurs from Madagascar

This study employs dental microwear texture analysis to reconstruct the diets of two families of subfossil lemurs from Madagascar, the archaeolemurids and megaladapids. This technique is based on three-dimensional surface measurements utilizing a white-light confocal profiler and scale-sensitive fractal analysis. Data were recorded for six texture variables previously used successfully to distinguish between living primates with known dietary differences. Statistical analyses revealed that the archaeolemurids and megaladapids have overlapping microwear texture signatures, suggesting that the two families occasionally depended on resources with similar mechanical properties. Even so, moderate variation in most attributes is evident, and results suggest potential differences in the foods consumed by the two families. The microwear pattern for the megaladapids indicates a preference for tougher foods, such as many leaves, while that of the archaeolemurids is consistent with the consumption of harder foods. The results also indicate some intraspecific differences among taxa within each family. This evidence suggests that the archaeolemurids and megaladapids, like many living primates, likely consumed a variety of food types.     

Seeds,browse, and tooth wear: a sheep perspective

While grazing as a selective factor towards hypsodont dentition on mammals has gained a lot of attention, the importance of fruits and seeds as fallback resources for many browsing ungulates has caught much less attention. Controlled‐food experiments, by reducing the dietary range, allow for a direct quantification of the effect of each type of items separately on enamel abrasion. We present the results of a dental microwear texture analysis on 40 ewes clustered into four different controlled diets: clover alone, and then three diets composed of clover together with either barley, corn, or chestnuts. Among the seed‐eating groups, only the barley one shows higher complexity than the seed‐free group. Canonical discriminant analysis is successful at correctly classifying the majority of clover‐ and seed‐fed ewes. Although this study focuses on diets which all fall within a single dietary category (browse), the groups show variations in dental microwear textures in relation with the presence and the type of seeds. More than a matter of seed size and hardness, a high amount of kernels ingested per day is found to be correlated with high complexity on enamel molar facets. This highlights the high variability of the physical properties of the foods falling under the browsing umbrella.     

Molar microwear textures and the diets of Australopithecus anamensis and Australopithecus afarensis

Many researchers have suggested that Australopithecus anamensis and Australopithecus afarensis were among the earliest hominins to have diets that included hard, brittle items. Here we examine dental microwear textures of these hominins for evidence of this. The molars of three Au. anamensis and 19 Au. afarensis specimens examined preserve unobscured antemortem microwear. Microwear textures of these individuals closely resemble those of Paranthropus boisei, having lower complexity values than Australopithecus africanus and especially Paranthropus robustus. The microwear texture complexity values for Au. anamensis and Au. afarensis are similar to those of the grass-eating Theropithecus gelada and folivorous Alouatta palliata and Trachypithecus cristatus. This implies that these Au. anamensis and Au. afarensis individuals did not have diets dominated by hard, brittle foods shortly before their deaths. On the other hand, microwear texture anisotropy values for these taxa are lower on average than those of Theropithecus, Alouatta or Trachypithecus. This suggests that the fossil taxa did not have diets dominated by tough foods either, or if they did that directions of tooth–tooth movement were less constrained than in higher cusped and sharper crested extant primate grass eaters and folivores.     

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.     

Technical note: Dental microwear textures of "Phase I" and "Phase II" facets

The power stroke of mastication has been traditionally divided into two parts, one which precedes centric occlusion, and the other which follows it-"Phase I" and "Phase II," respectively. Recent studies of primate mastication have called into question the role of Phase II in food processing, as they have found little muscle activity or accompanying bone strain following centric occlusion. That said, many researchers today look to Phase II facets to relate diet to patterns of dental microwear. This suggests the need to reevaluate microwear patterns on Phase I facets. Here we use texture analysis to compare and contrast microwear on facets representing both phases in three primate species with differing diets (Alouatta palliata, Cebus apella, and Lophocebus albigena). Results reaffirm that microwear patterns on Phase II facets better distinguish taxa with differing diets than do those on Phase I facets. Further, differences in microwear textures between facet types for a given taxon may themselves reflect diet. Some possible explanations for differences in microwear textures between facet types are proposed.     

Direct Comparisons of 2D and 3D Dental Microwear Proxies in Extant Herbivorous and Carnivorous Mammals

The analysis of dental microwear is commonly used by paleontologists and anthropologists to clarify the diets of extinct species, including herbivorous and carnivorous mammals. Currently, there are numerous methods employed to quantify dental microwear, varying in the types of microscopes used, magnifications, and the characterization of wear in both two dimensions and three dimensions. Results from dental microwear studies utilizing different methods are not directly comparable and human quantification of wear features (e.g., pits and scratches) introduces interobserver error, with higher error being produced by less experienced individuals. Dental microwear texture analysis (DMTA), which analyzes microwear features in three dimensions, alleviates some of the problems surrounding two-dimensional microwear methods by reducing observer bias. Here, we assess the accuracy and comparability within and between 2D and 3D dental microwear analyses in herbivorous and carnivorous mammals at the same magnification. Specifically, we compare observer-generated 2D microwear data from photosimulations of the identical scanned areas of DMTA in extant African bovids and carnivorans using a scanning white light confocal microscope at 100x magnification. Using this magnification, dental microwear features quantified in 2D were able to separate grazing and frugivorous bovids using scratch frequency; however, DMTA variables were better able to discriminate between disparate dietary niches in both carnivorous and herbivorous mammals. Further, results demonstrate significant interobserver differences in 2D microwear data, with the microwear index remaining the least variable between experienced observers, consistent with prior research. Overall, our results highlight the importance of reducing observer error and analyzing dental microwear in three dimensions in order to consistently interpret diets accurately.     

Dental microwear and diet of the Plio-Pleistocene hominin Paranthropus boisei

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.     

Dietary Abrasiveness Is Associated with Variability of Microwear and Dental Surface Texture in Rabbits

Dental microwear and 3D surface texture analyses are useful in reconstructing herbivore diets, with scratches usually interpreted as indicators of grass dominated diets and pits as indicators of browse. We conducted feeding experiments with four groups of rabbits (Oryctolagus cuniculus) each fed a different uniform, pelleted diet (lucerne, lucerne & oats, grass & oats, grass). The lowest silica content was measured in the lucerne and the highest in the grass diet. After 25 weeks of exposure to the diets, dental castings were made of the rabbit''s lower molars. Occlusal surfaces were then investigated using dental microwear and 3D areal surface texture analysis. In terms of traditional microwear, we found our hypothesis supported, as the grass group showed a high proportion of (long) “scratches” and the lucerne group a high proportion of “pits”. Regardless of the uniform diets, variability of microwear and surface textures was higher when silica content was low. A high variability in microwear and texture analysis thus need not represent dietary diversity, but can also be related to a uniform, low-abrasion diet. The uniformity or variability of microwear/texture analysis results thus might represent varying degrees of abrasion and attrition rather than a variety of diet items per se.     

Quantitative differences in dental microwear between primate species with different diets and a comment on the presumed diet of Sivapithecus

Studies of dental microwear have been used to relate tooth form to function in a variety of recent and extinct mammals. Probably the most important aspect of microwear analysis is the possibility of using it to deduce the diet of extinct animals. Such deductions must be based on comparative studies of modern species with known diets, but to date, only qualitative studies have been attempted and all have been based on small samples. Here we report quantitative differences in dental microwear between primate species that are known to have different diets. Occlusal facets with different functions have previously been shown to exhibit different microwear patterns. However, the differences between facets of one species are shown to be far less than those between homologous facets of different species. Study of seven species of extant primates shows that enamel microwear can be used to distinguish between those with a mainly frugivorous diet and those with a mainly folivorous one. Microwear can also distinguish hard-object feeders from soft-fruit eaters. The microwear of Miocene Sivapithecus indicus cannot be distinguished statistically from that of the chimpanzee, but it is different from that of the other species. On this evidence S. indicus was not a hard-object feeder and the adaptive significance of its thick molar enamel is at present unknown.     

The primate community of Cachoeira (Brazilian Amazonia): a model to decipher ecological partitioning among extinct species

Dental microwear analysis is conducted on a community of platyrrhine primates from South America. This analysis focuses on the primate community of Cachoeira Porteira (Para, Brazil), in which seven sympatric species occur: Alouatta seniculus, Ateles paniscus, Cebus apella, Chiropotes satanas, Pithecia Pithecia, Saguinus midas, and Saimiri sciureus. Shearing quotients are also calculated for each taxon of this primate community. Dental microwear results indicate significant differences between taxa, but are somewhat insufficient when it comes to discriminating between ecologically similar taxa. The primates of Cachoeira Porteira all incorporate a certain amount of fruit in their diet, entailing a definite amount of inter-specific competition as they must share food resources. Alouatta is the most folivorous taxon of this community, which is corroborated by dental microwear analysis. Ateles, although of a similar size to Alouatta, limits inter-specific competition by incorporating more fruit in its diet. Cebus has a very diverse omnivorous diet, which is highlighted in this study, as it compares to both fruit and leaf eating taxa. In some cases, microwear results need to be supplemented by other methods. For example, dental microwear seems insufficient to distinguish between Pithecia and Chiropotes, which eat foods with similar physical properties. However, other methods (i.e. shearing quotients and body mass) provide enough complimentary information to be able to highlight differences between the two taxa. On the other hand, dental microwear can highlight differences between primates which have similar diets, such as Saimiri and Saguinus. In this case, differences could be due to other exogenous factors.     

Diet-Related Buccal Dental Microwear Patterns in Central African Pygmy Foragers and Bantu-Speaking Farmer and Pastoralist Populations

Pygmy hunter-gatherers from Central Africa have shared a network of socioeconomic interactions with non-Pygmy Bantu speakers since agropastoral lifestyle spread across sub-Saharan Africa. Ethnographic studies have reported that their diets differ in consumption of both animal proteins and starch grains. Hunted meat and gathered plant foods, especially underground storage organs (USOs), are dietary staples for pygmies. However, scarce information exists about forager–farmer interaction and the agricultural products used by pygmies. Since the effects of dietary preferences on teeth in modern and past pygmies remain unknown, we explored dietary history through quantitative analysis of buccal microwear on cheek teeth in well-documented Baka pygmies. We then determined if microwear patterns differ among other Pygmy groups (Aka, Mbuti, and Babongo) and between Bantu-speaking farmer and pastoralist populations from past centuries. The buccal dental microwear patterns of Pygmy hunter-gatherers and non-Pygmy Bantu pastoralists show lower scratch densities, indicative of diets more intensively based on nonabrasive foodstuffs, compared with Bantu farmers, who consume larger amounts of grit from stoneground foods. The Baka pygmies showed microwear patterns similar to those of ancient Aka and Mbuti, suggesting that the mechanical properties of their preferred diets have not significantly changed through time. In contrast, Babongo pygmies showed scratch densities and lengths similar to those of the farmers, consistent with sociocultural contacts and genetic factors. Our findings support that buccal microwear patterns predict dietary habits independent of ecological conditions and reflect the abrasive properties of preferred or fallback foods such as USOs, which may have contributed to the dietary specializations of ancient human populations.     

Dental microwear and diet in Venezuelan primates.

Recent microwear analyses have demonstrated that wear patterns can be correlated with dietary differences. However, much of this work has been based on analyses of museum material where dates and locations of collection are not well known. In view of these difficulties, it would be desirable to compare microwear patterns for different genera collected from the same area at the same time. The opportunity to do this was provided by the collections of the Smithsonian Venezuelan Project (Handley, 1976), in which multiple primate genera were collected from the same humid tropical forest sites within the same month. The monkeys represent a wide range of dietary preferences, and include Saimiri, Cebus, Chiropotes, Ateles, Aotus, Pithecia, and Alouatta. As in previous microwear analyses, epoxy replicas were prepared from dental impressions, as described by Rose (1983) and Teaford and Oyen (1989). Two micrographs were taken of facet 9 on an upper second molar of each specimen. Computations and analyses were the same as described by Teaford and Robinson (1989). Results reaffirm previously documented differences in dental microwear between primates that feed on hard objects versus those that do not--with Pithecia and Alouatta at the extremes of a range of microwear patterns including more subtle differences between species with intermediate diets. The subtle microwear differences are by no means easy to document in museum samples. However, additional results suggest that 1) the width of microscopic scratches may be a poor indicator of dietary differences, 2) large and small pits may be formed differently, and 3) there are very few seasonal differences in dental microwear in the primates at these humid tropical forest sites.     

Dietary reconstruction of Spy I using dental microwear texture analysis

Spy I from the Meuse River Basin of Belgium is among the most recent Neandertals. This adult lived at the terminus of Marine Isotope Stage (MIS) 3 in cold steppe environments at the northern edge of the habitable zone for Neandertals where plants were relatively scarce. The dietary proclivities of Spy I are reconstructed using dental microwear texture analysis and compared to 33 Neandertals from western Eurasia, MIS 5 to MIS 3. Spy I has an elevated enamel surface complexity suggesting the consumption of course dietary items such as wild seeds, acorns, nuts, and underground storage organs laden with particles of grit. Unlike the young and old individuals from Hortus with low values for anisotropy, Spy I is closest to the adults from this site suggesting a common pattern of masticatory behavior typified this life cycle stage. Like many other Neandertals, Spy I probably consumed plant foods at appreciable levels, some of which were hard and brittle or poorly processed.     

Seasonal Mortality Patterns in Primates: Implications for the Interpretation of Dental Microwear

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     

In vivo and in vitro turnover in dental microwear

Given the potential usefulness of dental microwear analyses in interpretations of archaeological and paleontological material, it is surprising how little we know about changes in individual microwear features through time. The purpose of this study was to document the turnover in primate dental microwear through in vivo dental studies of monkeys raised on different diets, and through in vitro studies of the abrasive effects of monkey chow biscuits on isolated monkey teeth. As in previous studies, epoxy replicas were prepared from dental impressions and examined under a scanning electron microscope. Results indicate that, under certain conditions, the turnover in primate dental microwear can be on the order of days, hours, or even minutes. Individual microscopic wear features can be obliterated within 24 hours on the molars of laboratory monkeys, and monkey chow biscuits can easily scratch the enamel of isolated monkey teeth. Monkeys raised on a hard diet showed more rapid turnover in dental microwear than monkeys raised on a soft diet. However, paired-sample tests revealed that, for all animals, the molar shearing facets were being abraded at a significantly slower rate than molar crushing/grinding facets. In light of these results, investigators should make every effort to use large samples in interspecific comparisons of dental microwear involving species with variable diets. Another implication of these results is that changes in dental microwear might be useful indicators of changes in oral behavior over relatively short periods of time.     

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。     

Diet of upper paleolithic modern humans: Evidence from microwear texture analysis

This article presents the results of the occlusal molar microwear texture analysis of 32 adult Upper Paleolithic modern humans from a total of 21 European sites dating to marine isotope stages 3 and 2. The occlusal molar microwear textures of these specimens were analyzed with the aim of examining the effects of the climatic, as well as the cultural, changes on the diets of the Upper Paleolithic modern humans. The results of this analysis do not reveal any environmentally driven dietary shifts for the Upper Paleolithic hominins indicating that the climatic and their associated paleoecological changes did not force these humans to significantly alter their diets in order to survive. However, the microwear texture analysis does detect culturally related changes in the Upper Paleolithic humans' diets. Specifically, significant differences in diet were found between the earlier Upper Paleolithic individuals, i.e., those belonging to the Aurignacian and Gravettian contexts, and the later Magdalenian ones, such that the diet of the latter group was more varied and included more abrasive foods compared with those of the former. Am J Phys Anthropol 153:570–581, 2014. © 2014 Wiley Periodicals, Inc.     

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.     

Dental microwear and diets of African early Homo

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.     

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.