Anterior Dental Microwear Texture Analysis of the Krapina Neandertals

Some Neandertal anterior teeth show unusual and excessive gross wear, commonly explained by non-dietary anterior tooth use, or using the anterior dentition as a tool, clamp, or third hand. This alternate use is inferred from aboriginal arctic populations, who used their front teeth in this manner. Here we examine anterior dental microwear textures of the Krapina Neandertals to test this hypothesis and further analyze tooth use in these hominins. Microwear textures from 17 Krapina Dental People were collected by white-light confocal profilometry using a 100x objective lens. Four adjacent scans were generated, totaling an area of 204x276 μm, and were analyzed using Toothfrax and SFrax SSFA software packages. The Neandertals were compared to six bioarchaeological/ethnographic samples with reported variation in diet, abrasive load, and non-dietary anterior tooth use. Results indicate that Krapina anterior teeth lack extreme microwear textures expected of hominins exposed to heavy abrasives or those that regularly generated high stresses associated with intense use of the front teeth as tools. Krapina hominins have microwear attributes in common with Coast Tsimshian, Aleut, and Puye Pueblo samples. Collectively, this suggests that the Krapina Neandertals faced moderate abrasive loads and only periodically used their anterior teeth as tools for non-diet related behaviors

Dental topography and diets of platyrrhine primates

More than half a century ago, Percy Butler touted the importance of analyzing teeth to understand their function in an evolutionary context. There have been many advances in the study of dental functional morphology since that time. Here we review the various approaches to characterizing and comparing occlusal form that have been developed, especially dental topographic analysis. We also report on a new study of dental topography of platyrrhine primates (n = 341 individuals representing 16 species) with known differences in both dietary preferences and other food items eaten. Results indicate frugivores, gummivores, folivores, and seed eaters each have a unique combination of slope, relief, angularity, sharpness, and occlusal orientation patch size and count values. Likewise, among frugivores, those that supplement their diets with hard objects, insects, leaves, and seeds, also each have a distinctive suite of topographic features. We conclude that both primary and secondary diet choices select for occlusal form, and that functional morphology more reflects the types of foods and mechanical challenges they pose rather than the frequencies in which they are eaten.Peer reviewe

Implications of Diet for the Extinction of Saber-Toothed Cats and American Lions

The saber-toothed cat, Smilodon fatalis, and American lion, Panthera atrox, were among the largest terrestrial carnivores that lived during the Pleistocene, going extinct along with other megafauna ~12,000 years ago. Previous work suggests that times were difficult at La Brea (California) during the late Pleistocene, as nearly all carnivores have greater incidences of tooth breakage (used to infer greater carcass utilization) compared to today. As Dental Microwear Texture Analysis (DMTA) can differentiate between levels of bone consumption in extant carnivores, we use DMTA to clarify the dietary niches of extinct carnivorans from La Brea. Specifically, we test the hypothesis that times were tough at La Brea with carnivorous taxa utilizing more of the carcasses. Our results show no evidence of bone crushing by P. atrox, with DMTA attributes most similar to the extant cheetah, Acinonyx jubatus, which actively avoids bone. In contrast, S. fatalis has DMTA attributes most similar to the African lion Panthera leo, implying that S. fatalis did not avoid bone to the extent previously suggested by SEM microwear data. DMTA characters most indicative of bone consumption (i.e., complexity and textural fill volume) suggest that carcass utilization by the extinct carnivorans was not necessarily more complete during the Pleistocene at La Brea; thus, times may not have been tougher than the present. Additionally, minor to no significant differences in DMTA attributes from older (~30-35 Ka) to younger (~11.5 Ka) deposits offer little evidence that declining prey resources were a primary cause of extinction for these large cats

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

Dental Topography and Microwear Texture in Sapajus Apella

Dental microwear texture pattern has been associated with aspects of diet for a broad range of mammalian taxa. The basic idea is that soft, tough foods are sheared with a steeper angle of approach between opposing occlusal surfaces, whereas hard, brittle items are crushed with forces perpendicular to those surfaces; and this difference is manifested in anisotropic, striated microwear textures for tough foods, and complex, pitted ones for hard objects. Other factors may, however, influence microwear texture pattern and confound diet signals. For example, if tooth surface slope influences angle of approach between opposing teeth, then perhaps wear-related changes in tooth shape could affect microwear pattern. This study evaluates the effects of occlusal topography on microwear texture for a series of variably worn upper second molars of one primate species, Sapajus apella. Results indicate no significant covariation between any measured topographic attribute (average slope, angularity, relief) and microwear texture variable (complexity, anisotropy, textural fill volume). This suggests that, for this taxon at least, wear-related changes in tooth form do not affect microwear pattern in a consistent manner. This implies that variably worn teeth can be included in samples for comparisons aimed at distinguishing groups by diet

Conditions for Voting Equilibria in Continuous Voter Distributions

This paper extends Plott’s necessary and sufficient conditions for the existence of majority rule equilibria to the case where there is a continuous distribution of voters. Plott’s theorem extends in a natural way to this setting: It is shown that a point, x*, is a majority rule equilibrium if and only if, for every measurable cone originating at the origin, the measure of the voters whose gradients (at x*) lie in the cone is equal to the measure of the voters whose gradients lie in the negative cone

Problems with paranthropus

Carbon isotopic analysis has been challenging our ideas about hominin diet for nearly 30 years. The first study in 1994 revealed that Paranthropus robustus from South Africa consumed principally C3 foods (e.g., tree fruits and leaves) but also about 25% C4/CAM resources (e.g., tropical grasses and sedges). This result was largely consistent with morphological and dental microwear evidence suggesting P. robustus had a diet which included hard objects like nuts and seeds. Decades later, however, P. boisei from eastern Africa was shown to have eaten nearly 80% C4/CAM plants like the contemporaneous grass-eating primate Theropithecus. Moreover, dental microwear revealed no evidence of hard object consumption in P. boisei, suggesting a diet of tough foods such as grass or sedge leaf and stem. So Paranthropus presents us with two central problems: 1) Why do dietary proxies suggest different diets for the two robust australopiths despite their morphological congruity; and 2) How could P. boisei have consumed tough foods with teeth that seem unsuited to the task. Here we review these questions and more with a particular focus on new isotopic data from the Omo and insights that can be gleaned from mammals outside the haplorrhine primates. We argue that extant Primates do not capture the ecomorphological diversity of P. boisei and other extinct primates and should not narrowly circumscribe the behaviors we ascribe to extinct taxa. We also discuss possible digestive strategies for P. boisei in light of its morphology, dietary proxy data, food mechanical properties, and comparative data on mammalian digestive kinetics.info:eu-repo/semantics/publishedVersio

Dental microwear as a behavioral proxy for distinguishing between canids at the Upper Paleolithic (Gravettian) site of Predmostí, Czech Republic

Morphological and genetic evidence put dog domestication during the Paleolithic, sometime between 40,000 and 15,000 years ago, with identification of the earliest dogs debated. We predict that these earliest dogs (referred to herein as protodogs), while potentially difficult to distinguish morphologically from wolves, experienced behavioral shifts, including changes in diet. Specifically, protodogs may have consumed more bone and other less desirable scraps within human settlement areas. Here we apply Dental Microwear Texture Analysis (DMTA) to canids from the Gravettian site of P�redmostí (approx. 28,500 BP), which were previously assigned to the Paleolithic dog or Pleistocene wolf morphotypes. We test whether these groups separate out significantly by diet- related variation in microwear patterning. Results are consistent with differences in dietary breadth, with the Paleolithic dog morphotype showing evidence of greater durophagy than those assigned to the wolf morphotype. This supports the presence of two morphologically and behaviorally distinct canid types at this middle Upper Paleolithic site. Our primary goal here was to test whether these two morphotypes expressed notable differences in dietary behavior. However, in the context of a major Gravettian settlement, this may also support evidence of early stage dog domestication. Dental microwear is a behavioral signal that may appear generations before morphological changes are established in a population. It shows promise for distinguishing protodogs from wolves in the Pleistocene and domesticated dogs from wolves elsewhere in the archaeological record