Intrapopulation variation in macro tooth wear patterns—a case study from Igloolik,Canada

The pattern of human tooth wear—the way it varies between teeth in the mouth—is crucial to our understanding of important questions in archeology and paleoanthropology, such as the contrasts in diet and behavior between Neanderthals and early modern humans in Europe and Asia, or with the adoption of agriculture in the Americas. Little is known, however, about the way in which wear patterns develop with increasing age or the way in which they differ between males and females. One explanation is that few living people show the high rates of tooth wear seen worldwide throughout the preindustrial archaeological record. The study described here investigates the macroscopic pattern of tooth wear in a unique group of known age and sex dental casts from living Canadian Inuit from Igloolik. The results show that the Igloolik people possessed a pattern of extremely heavy anterior tooth wear, relative to the first molar and the other posterior teeth, which is attributed to the use of the anterior teeth in cultural practices as well as the extreme and marginal environments in which they lived. Heavy anterior tooth wear was established at an early age and maintained throughout life; statistically significant differences were found between the wear patterns of males and females and are explained in terms of sexual division of labor within the community. This study highlights the need to understand both intra‐ and interpopulation variation in tooth wear patterns when interpreting patterns in past human groups. Am J Phys Anthropol, 2012. © 2012 Wiley Periodicals, Inc.     

Evolution of middle-late Pleistocene human cranio-facial form: A 3-D approach

The classification and phylogenetic relationships of the middle Pleistocene human fossil record remains one of the most intractable problems in paleoanthropology. Several authors have noted broad resemblances between European and African fossils from this period, suggesting a single taxon ancestral to both modern humans and Neanderthals. Others point out ‘incipient’ Neanderthal features in the morphology of the European sample and have argued for their inclusion in the Neanderthal lineage exclusively, following a model of accretionary evolution of Neanderthals. We approach these questions using geometric morphometric methods which allow the intuitive visualization and quantification of features previously described qualitatively. We apply these techniques to evaluate proposed cranio-facial ‘incipient’ facial, vault, and basicranial traits in a middle-late Pleistocene European hominin sample when compared to a sample of the same time depth from Africa. Some of the features examined followed the predictions of the accretion model and relate the middle Pleistocene European material to the later Neanderthals. However, although our analysis showed a clear separation between Neanderthals and early/recent modern humans and morphological proximity between European specimens from OIS 7 to 3, it also shows that the European hominins from the first half of the middle Pleistocene still shared most of their cranio-facial architecture with their African contemporaries.     

The bony labyrinth of Neanderthals

This paper presents a comprehensive comparative analysis of the Neanderthal bony labyrinth, a structure located inside the petrous temporal bone. Fifteen Neanderthal specimens are compared with a Holocene human sample, as well as with a small number of European Middle Pleistocene hominins, and early anatomically modern and European Upper Palaeolithic humans. Compared with Holocene humans the bony labyrinth of Neanderthals can be characterized by an anterior semicircular canal arc which is smaller in absolute and relative size, is relatively narrow, and shows more torsion. The posterior semicircular canal arc is smaller in absolute and relative size as well, it is more circular in shape, and is positioned more inferiorly relative to the lateral canal plane. The lateral semicircular canal arc is absolutely and relatively larger. Finally, the Neanderthal ampullar line is more vertically inclined relative to the planar orientation of the lateral canal. The European Upper Palaeolithic and early modern humans are most similar, although not fully identical to Holocene humans in labyrinthine morphology. The European Middle Pleistocene hominins show the typical semicircular canal morphology of Neanderthals, with the exception of the arc shape and inferiorly position of the posterior canal and the strongly inclined ampullar line. The marked difference between the labyrinths of Neanderthals and modern humans can be used to assess the phylogenetic affinities of fragmentary temporal bone fossils. However, this application is limited by a degree of overlap between the morphologies. The typical shape of the Neanderthal labyrinth appears to mirror aspects of the surrounding petrous pyramid, and both may follow from the phylogenetic impact of Neanderthal brain morphology moulding the shape of the posterior cranial fossa. The functionally important arc sizes of the Neanderthal semicircular canals may reflect a pattern of head movements different from that of modern humans, possibly related to aspects of locomotor behaviour and the kinematic properties of their head and neck.     

Hominin teeth from the early Late Pleistocene site of Xujiayao,Northern China

It is generally accepted that from the late Middle to the early Late Pleistocene (～340–90 ka BP), Neanderthals were occupying Europe and Western Asia, whereas anatomically modern humans were present in the African continent. In contrast, the paucity of hominin fossil evidence from East Asia from this period impedes a complete evolutionary picture of the genus Homo, as well as assessment of the possible contribution of or interaction with Asian hominins in the evolution of Homo sapiens and Homo neanderthalensis. Here we present a comparative study of a hominin dental sample recovered from the Xujiayao site, in Northern China, attributed to the early Late Pleistocene (MIS 5 to 4). Our dental study reveals a mosaic of primitive and derived dental features for the Xujiayao hominins that can be summarized as follows: i) they are different from archaic and recent modern humans, ii) they present some features that are common but not exclusive to the Neanderthal lineage, and iii) they retain some primitive conformations classically found in East Asian Early and Middle Pleistocene hominins despite their young geological age. Thus, our study evinces the existence in China of a population of unclear taxonomic status with regard to other contemporary populations such as H. sapiens and H. neanderthalensis. The morphological and metric studies of the Xujiayao teeth expand the variability known for early Late Pleistocene hominin fossils and suggest the possibility that a primitive hominin lineage may have survived late into the Late Pleistocene in China. Am J Phys Anthropol 156:224–240, 2015. © 2014 Wiley Periodicals, Inc.     

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.     

An adolescent female Neanderthal mandible from Montgaudier Cave,Charente, France

In 1974, an incomplete human mandible was discovered in the site of Montgaudier Cave, along the Tardoire (Charente), France. The mandible was found in association with stone tools and animal bones in geological deposits referable to the very end of the Middle Pleistocene or the beginning of the Upper Pleistocene. The mandible preserves much of the anterior part of the body and three permanent teeth: left lateral incisor, canine and first molar. Estimates based on tooth eruption of modern humans, as well as occlusal wear and root development, suggest an age at death of between 12.5 and 14.5 years. Morphologically, the fossil possesses features, such as a lack of a chin and multiple mental foramina, which have been observed on immature Neanderthal mandibular specimens from Europe. Comparison with these immature European Neanderthals indicates that the jaw and teeth of the Montgaudier mandible are small for its chronological age, suggesting it was that of a female. Am J Phys Anthropol 103:507–527, 1997 © 1997 Wiley-Liss, Inc.     

山东新泰乌珠台人类牙齿的形态学特征

近些年在东亚发现的晚更新世现代人化石及其研究使得关于该地区现代人起源问题更加复杂,更多该时段人类标本的研究有助于对其有更清晰的认识。1966年在山东新泰乌珠台发现一枚古人类下颌臼齿,吴新智和宗冠福(1973)对其进行了报道,而后再无详细研究。本文将使用牙齿非测量性状的半定量化(分级)、齿冠外轮廓形状的几何形态测量、基于显微断层扫描(Micro-computed tomography 或micro-CT)的釉质厚度、釉质厚度分布规律和齿质表面三维结构复原等方法对乌珠台人类牙齿进行综合研究,进而对东亚晚更新世古人类牙齿形态特征变异有一个进一步的了解。结果显示,乌珠台人类牙齿的形态特征基本与现代人接近,但其所表现出的三角座横脊、Y型齿沟排列、原附尖在现代人中出现率较低,而更多发现在直立人或尼安德特人中。相对于东亚其他晚更新世现代人,乌珠台M3所表现出的特征组合具有特殊性,增加了东亚晚更新世现代人的牙齿形态特征多样性。未来研究可尝试测定乌珠台人类牙齿的绝对年代,以更好的将其归入到现代人演化序列中去。     

Neanderthal genomics suggests a pleistocene time frame for the first epidemiologic transition

High quality Altai Neanderthal and Denisovan genomes are revealing which regions of archaic hominin DNA have persisted in the modern human genome. A number of these regions are associated with response to infection and immunity, with a suggestion that derived Neanderthal alleles found in modern Europeans and East Asians may be associated with autoimmunity. As such Neanderthal genomes are an independent line of evidence of which infectious diseases Neanderthals were genetically adapted to. Sympathetically, human genome adaptive introgression is an independent line of evidence of which infectious diseases were important for AMH coming in to Eurasia and interacting with Neanderthals. The Neanderthals and Denisovans present interesting cases of hominin hunter‐gatherers adapted to a Eurasian rather than African infectious disease package. Independent sources of DNA‐based evidence allow a re‐evaluation of the first epidemiologic transition and how infectious disease affected Pleistocene hominins. By combining skeletal, archaeological and genetic evidence from modern humans and extinct Eurasian hominins, we question whether the first epidemiologic transition in Eurasia featured a new package of infectious diseases or a change in the impact of existing pathogens. Coupled with pathogen genomics, this approach supports the view that many infectious diseases are pre‐Neolithic, and the list continues to expand. The transfer of pathogens between hominin populations, including the expansion of pathogens from Africa, may also have played a role in the extinction of the Neanderthals and offers an important mechanism to understand hominin–hominin interactions well back beyond the current limits for aDNA extraction from fossils alone. Am J Phys Anthropol 160:379–388, 2016. © 2016 Wiley Periodicals, Inc.     

Birds of a Feather: Neanderthal Exploitation of Raptors and Corvids

The hypothesis that Neanderthals exploited birds for the use of their feathers or claws as personal ornaments in symbolic behaviour is revolutionary as it assigns unprecedented cognitive abilities to these hominins. This inference, however, is based on modest faunal samples and thus may not represent a regular or systematic behaviour. Here we address this issue by looking for evidence of such behaviour across a large temporal and geographical framework. Our analyses try to answer four main questions: 1) does a Neanderthal to raptor-corvid connection exist at a large scale, thus avoiding associations that might be regarded as local in space or time?; 2) did Middle (associated with Neanderthals) and Upper Palaeolithic (associated with modern humans) sites contain a greater range of these species than Late Pleistocene paleontological sites?; 3) is there a taphonomic association between Neanderthals and corvids-raptors at Middle Palaeolithic sites on Gibraltar, specifically Gorham''s, Vanguard and Ibex Caves? and; 4) was the extraction of wing feathers a local phenomenon exclusive to the Neanderthals at these sites or was it a geographically wider phenomenon?. We compiled a database of 1699 Pleistocene Palearctic sites based on fossil bird sites. We also compiled a taphonomical database from the Middle Palaeolithic assemblages of Gibraltar. We establish a clear, previously unknown and widespread, association between Neanderthals, raptors and corvids. We show that the association involved the direct intervention of Neanderthals on the bones of these birds, which we interpret as evidence of extraction of large flight feathers. The large number of bones, the variety of species processed and the different temporal periods when the behaviour is observed, indicate that this was a systematic, geographically and temporally broad, activity that the Neanderthals undertook. Our results, providing clear evidence that Neanderthal cognitive capacities were comparable to those of Modern Humans, constitute a major advance in the study of human evolution.     

Mandibular molar root morphology in Neanderthals and Late Pleistocene and recent Homo sapiens

Neanderthals have a distinctive suite of dental features, including large anterior crown and root dimensions and molars with enlarged pulp cavities. Yet, there is little known about variation in molar root morphology in Neanderthals and other recent and fossil members of Homo. Here, we provide the first comprehensive metric analysis of permanent mandibular molar root morphology in Middle and Late Pleistocene Homo neanderthalensis, and Late Pleistocene (Aterian) and recent Homo sapiens. We specifically address the question of whether root form can be used to distinguish between these groups and assess whether any variation in root form can be related to differences in tooth function. We apply a microtomographic imaging approach to visualise and quantify the external and internal dental morphologies of both isolated molars and molars embedded in the mandible (n = 127). Univariate and multivariate analyses reveal both similarities (root length and pulp volume) and differences (occurrence of pyramidal roots and dental tissue volume proportion) in molar root morphology among penecontemporaneous Neanderthals and Aterian H. sapiens. In contrast, the molars of recent H. sapiens are markedly smaller than both Pleistocene H. sapiens and Neanderthals, but share with the former the dentine volume reduction and a smaller root-to-crown volume compared with Neanderthals. Furthermore, we found the first molar to have the largest average root surface area in recent H. sapiens and Neanderthals, although in the latter the difference between M₁ and M₂ is small. In contrast, Aterian H. sapiens root surface areas peak at M₂. Since root surface area is linked to masticatory function, this suggests a distinct occlusal loading regime in Neanderthals compared with both recent and Pleistocene H. sapiens.     

Krapina, “Classic” Neanderthals,and the evolution of the European face

Except for the front end of the dental arch, tooth size remained at approximately the same level throughout the Middle Pleistocene. The Krapina Neanderthals at the end of the last interglacial differed from Homo erectus only in having larger front teeth. From that time on, tooth size in populations at the northern edge of the area of human occupation in the Old World has reduced approximately in proportion to the time elapsed. The “Classic” Neanderthals of western Europe, in fact, have teeth that are 15% smaller than those of the earlier Krapina Neanderthals and only 5% larger than the early Upper Palaeolithic. Reduction since the early Upper Palaeolithic has proceeded another full 20%. It is suggested that the development of heated stone cooking in the Mousterian, originally for the purpose of thawing frozen food, reduced the forces of selection that had previously maintained tooth size during the Middle Pleistocene. The operation of the Probable Mutation Effect, then produced the observed reductions.     

The Neanderthal face is not cold adapted

Many morphological features of the Pleistocene fossil hominin Homo neanderthalensis, including the reputed large size of its paranasal sinuses, have been interpreted as adaptations to extreme cold, as some Neanderthals lived in Europe during glacial periods. This interpretation of sinus evolution rests on two assumptions: that increased craniofacial pneumatization is an adaptation to lower ambient temperatures, and that Neanderthals have relatively large sinuses. Analysis of humans, other primates, and rodents, however, suggests that the first assumption is suspect; at least the maxillary sinus undergoes a significant reduction in volume in extreme cold, in both wild and laboratory conditions. The second assumption, that Neanderthal sinuses are large, extensive, or even ‘hyperpneumatized,’ has held sway since the first specimen was described and has been interpreted as the causal explanation for some of the distinctive aspects of Neanderthal facial form, but has never been evaluated with respect to scaling. To test the latter assumption, previously published measurements from two-dimensional (2D) X-rays and new three-dimensional (3D) data from computed tomography (CT) of Neanderthals and temperate-climate European Homo sapiens are regressed against cranial size to determine the relative size of their sinuses. The 2D data reveal a degree of craniofacial pneumatization in Neanderthals that is both commensurate with the size of the cranium and comparable in scale with that seen in temperate climate H. sapiens. The 3D analysis of CT data from a smaller sample supports this conclusion. These results suggest that the distinctive Neanderthal face cannot be interpreted as a direct result of increased pneumatization, nor is it likely to be an adaptation to resist cold stress; an alternative explanation is thus required.     

Nouvelle méthode d’estimation de l’âge dentaire des Néandertaliens

Several authors have already observed the dyschronic growth between Neanderthals and modern Humans permanent teeth but they never quantified it. Dental maturation is the best and mostly used way to evaluate precisely the decease age of Neanderthals. We thus present here an extensive study realised with deciduous and immature permanent Neanderthals teeth, which lead us to propose a new mode! Of dental maturation allowing to estimate their age without using the classical modern populations dental growth tables. We propose two methods, one using two mathematical formulas, the other one using a new table, which permits to directly obtain the age of a Neanderthal from his deciduous and permanent teeth degree of maturation data.     

Non-masticatory uses of anterior teeth of Sima de los Huesos individuals (Sierra de Atapuerca, Spain)

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.     

Le bassin de l’homme du Pléistocène supérieur de Liujiang, Sud de la Chine : taille du corps, forme du corps et encéphalisation

The Late Pleistocene hominin fossil assemblage from Liujiang, South China include a fairly well-preserved cranium, a right os coxa, a complete sacrum, and other postcranial elements all belonging to a single individual. This rare discovery offers us a unique and singular opportunity in understanding this Late Pleistocene hominin's body proportion and relative cranial capacity (encephalization quotient [EQ]), and also pelvic morphology. Using the available right innominate and its mirror-imaged left side, we reconstruct Liujiang hominin's pelvis. Our analysis of the pelvis indicates that the Liujiang hominin has a very gracile and modern-like pelvic morphology. Indeed, all of the pelvic dimensions are smaller than those of other Pleistocene hominins. Moreover, the pelvic characteristics typical of Middle and Late Pleistocene hominins including Neanderthals cannot be identified in the Liujiang pelvis. In contrast, both Liujiang's metric and non-metric features indicate affinities to more recent human populations including our modern Chinese collections from Guangxi of south China. Further support of this assessment comes from the EQ value of 5.754 for Liujiang which is closer to Minatogawa 2 and modern Chinese populations than to Middle and Late Pleistocene fossil hominins. Our analysis of body shape shows that Liujiang has body proportion (i.e. body height relative to body breadth) typical of warm-adapted populations. Based on these findings, we reason that the modern physical characteristics of Liujiang may allude to a more recent geological age. Alternatively, its morphological “modernity” could also point to a much higher degree of skeletal variation within Late Pleistocene hominins in East Asia.     

Modeling Human Ecodynamics and Biocultural Interactions in the Late Pleistocene of Western Eurasia

Given the complex and multidimensional nature of human evolution, we need to develop theoretical and methodological frameworks to account for and model the dynamic feedbacks between co-operational biological and cultural evolutionary systems to better understand the processes that produced modern human behavior. Equally important is the generation of explicit theory-based models that can be tested against the empirical paleoanthropological record. We present a case study that examines evidence for culturally-driven behavioral change among Late Pleistocene hominins that altered the social niche occupied by hominins in western Eurasia, with consequences for subsequent biological and cultural evolution. We draw on a large sample of 167 Pleistocene assemblages across western Eurasia and employ mathematical and computational modeling to explore the feedbacks between cultural and biological inheritance. Shifts in land-use strategies changed the opportunities for social and biological interaction among Late Pleistocene hominins in western Eurasia with a cascade of consequences for cultural and biological evolution, including the disappearance of Neanderthals from the fossil and archaeological records, and the acceleration of cultural evolution among ancestors of modern humans.     

人类牙齿齿冠和齿根分离两种技术方法对牙釉质厚度测量的影响

在基于计算机断层扫描技术（CT）和虚拟图像处理技术的灵长类牙齿测量学研究中,经常需要分离三维虚拟模型的齿冠和齿根,再进行后续测量工作,如计算机辅助的生物力学分析、釉质厚度测量等。而分离齿冠和齿根这一步骤,目前有多种方法,如,1)根据齿颈线切分齿冠,或2)人工建立基底平面切分齿冠。为了评估这两种不同的处理方式对后续的牙齿测量学上的影响,本文使用三维方法测量了82例化石和现代人类下颌后部牙齿的釉质厚度,包括南方古猿、早期人属、尼安德特人和现代人。使用配对t检验对比发现,两种方法得到的釉质厚度数值上没有显著差别,但随后进行的种间比较发现,使用基底平面切分齿冠的方法比较费时,更依赖于测量者的人工操作,并且可能弱化了物种间前臼齿绝对釉质厚度的差异,造成系统误差。其原因是对于前臼齿和前部牙齿等齿颈线形状不规则的标本,基底平面难以建立或误差较大。在未来对釉质厚度的种间差异的研究中,特别对齿颈线形状不规则的标本（如人类前部牙齿及猩猩、黑猩猩的牙齿等）,本文推荐使用齿颈线分离齿冠和齿根,测量和计算齿颈线之上的釉质厚度。釉质厚度有一定的分类学、功能形态学和系统发育学意义。本文积累了一批可供未来对比研究的原始数据,并且发现尼安德特人前臼齿的相对釉质厚度显著小于现代人,这与前人利用臼齿、犬齿所做的对比研究结果相同,支持了尼安德特人拥有较薄的相对釉质厚度这一观点。