- Biological Anthropology, Human Evolution, North African prehistory (Archaeology), Evolutionary Anthropology, Neanderthals (Palaeolithic Archaeology), Journal of Human Evolution, and 23 moreMiddle to Upper Paleolithic Transition, Mitochondrial DNA, Morphometrics, Paleogeography, Neandertals, Strontium Isotope Analysis, Laser Ablation, Human origins (Anthropology), Hominin evolution, Tooth Enamel, Microtomography, Genetics, Early Modern History, Language, Chatelperronian, Neanderthal, Enamel thickness, Denisovans, Pleistocene Archaeology Europe, Synchrotron, Neandertal dentition, Molar Tissue Volumes, and Archaeologyedit
Here we report Sr and Zn isotope ratios of teeth of medieval to early modern Breton people a population whose diet is known from historical, archeological and collagen isotope data. Most of the population, buried in the Dominican convent... more
Here we report Sr and Zn isotope ratios of teeth of medieval to early modern Breton people a population whose diet is known from historical, archeological and collagen isotope data. Most of the population, buried in the Dominican convent of Rennes, France, consists of parliamentary nobles, wealthy commoners and ecclesiastics, who had a diet rich in animal products. Our aim is to assess how the Zn isotope ratios of their teeth compare to those of other French historical populations previously studied, which were characterized by cereal-based diets, and those of modern French individuals, who daily eat animal products. We describe a clear offset (∼0.35‰) between local and non-local human individuals in Zn isotope ratios. The δ 66 Zn tooth values of local individuals overlap that of modern French people, and are lower than those of local carnivores. Non-local δ 66 Zn values are similar to those of historical individuals analyzed previously. We conclude the lower Zn isotope ratios of local humans relative to the associated fauna can be explained by the consumption of carnivorous fish and pork, in agreement with historical, zooarchaeological and collagen (C, N, S) isotope data. Zn isotopes could therefore be a tracer of fish and/or substantial meat consumption in ancient populations. The origin of Zn isotopic variability in human tissues remained unknown until Van Heghe et al. (2012) 1 , reported the strong impact of meat and fish consumption on blood Zn isotope ratios (66 Zn/ 64 Zn expressed as δ 66 Zn values), a preliminary conclusion quickly confirmed by Costas-Rodriguez et al. (2014) 2. A parallel study on African food webs did not quantify the exact relationship between diet and bone Zn isotope ratios 3 , however by focusing on a much smaller geographical area, the sensitivity of Zn isotopes to diet was demonstrated 4 : Zn isotope ratios of bones and teeth clearly differ between carnivores and herbivores, with carnivores exhibiting the lowest ratios. The dependence of Zn isotope ratios on trophic level has also been confirmed in a marine ecosystem 5. The isotopic composition of Zn in animal tissues is controlled by two dietary factors: the isotopic fractionation that occurs during intestinal absorption and the Zn isotope ratios of the food products. Dietary Zn mainly comes from animal products, notably because Zn-and preferentially its lighter isotopes-from plants tends to precipitate with the phytates in the gastro intestinal tract 6. This precipitation is likely to trigger isotopic fractionation inducing the preferential absorption of heavy Zn isotopes. Additionally, plant products usually have the most elevated δ 66 Zn values 2. As a consequence, herbivore tissues exhibit higher Zn isotope ratios compared to carnivore or omnivore tissues 3-5. Muscles are 66 Zn depleted relative to the average isotopic composition of the body and no isotope fractionation of Zn is expected during meat consumption 3. Carnivores therefore have lower δ 66 Zn values than their prey: the higher the trophic level of an animal is, the lower are the Zn isotope ratios of its body tissues 5. Zn isotope ratios of dental enamel from populations from different locations and historical periods were recently compared 7. The study highlighted a very surprising trend: the δ 66 Zn dental values of preindustrial
Objectives: Several studies have investigated potential functional signals in the trabecular structure of the primate proximal humerus but with varied success. Here, we apply for the first time a "whole-epiphyses" approach to analysing... more
Objectives: Several studies have investigated potential functional signals in the trabecular structure of the primate proximal humerus but with varied success. Here, we apply for the first time a "whole-epiphyses" approach to analysing trabecular bone in the humeral head with the aim of providing a more holistic interpretation of trabecular variation in relation to habitual locomotor or manipulative behaviors in several extant primates and Australopithecus africanus. Materials and methods: We use a "whole-epiphysis" methodology in comparison to the traditional volume of interest (VOI) approach to investigate variation in trabecular structure and joint loading in the proximal humerus of extant hominoids, Ateles and A. africanus (StW 328). Results: There are important differences in the quantification of trabecular parameters using a "whole-epiphysis" versus a VOI-based approach. Variation in trabecular structure across knuckle-walking African apes, suspensory taxa, and modern humans was generally consistent with predictions of load magnitude and inferred joint posture during habitual behaviors. Higher relative trabecular bone volume and more isotropic trabeculae in StW 328 suggest A. africanus may have still used its forelimbs for arboreal locomotion. Discussion: A whole-epiphysis approach to analysing trabecular structure of the proximal humerus can help distinguish functional signals of joint loading across extant primates and can provide novel insight into habitual behaviors of fossil hominins. K E Y W O R D S arboreal, cancellous bone, hominin, locomotion, upper limb
Mainland Southeast Asia is a key region to interpret modern human migrations; however, due to a scarcity of terrestrial proxies, environmental conditions are not well understood. This study focuses on the Tam Pà Ling cave site in... more
Mainland Southeast Asia is a key region to interpret modern human migrations; however, due to a scarcity of terrestrial proxies, environmental conditions are not well understood. This study focuses on the Tam Pà Ling cave site in northeast Laos, which contains the oldest evidence for modern humans in Indochina, dating back to MIS 4 (70 ± 8 ka). Snail remains of Camaena massiei found throughout the stratigraphic sequence contain a valuable oxygen and carbon isotope record of past local vegetation and humidity changes. Our data indicate that before the Last Glacial Maximum (LGM), northeast Laos was characterized by a humid climate and forested environments. With the onset of the LGM, a major climatic shift occurred, inducing a sharp decrease in precipitation and a significant decline in woodland habitats in favor of the expansion to more open landscapes. Only during the Holocene did forests return in northeast Laos, resembling present conditions. The first Homo sapiens arriving in Indochina therefore encountered landscapes dominated by woodlands with a minor proportion of open habitats.
Here we report Sr and Zn isotope ratios of teeth of medieval to early modern Breton people a population whose diet is known from historical, archeological and collagen isotope data. Most of the population, buried in the Dominican convent... more
Here we report Sr and Zn isotope ratios of teeth of medieval to early modern Breton people a population whose diet is known from historical, archeological and collagen isotope data. Most of the population, buried in the Dominican convent of Rennes, France, consists of parliamentary nobles, wealthy commoners and ecclesiastics, who had a diet rich in animal products. Our aim is to assess how the Zn isotope ratios of their teeth compare to those of other French historical populations previously studied, which were characterized by cereal-based diets, and those of modern French individuals, who daily eat animal products. We describe a clear offset (∼0.35‰) between local and non-local human individuals in Zn isotope ratios. The δ 66 Zn tooth values of local individuals overlap that of modern French people, and are lower than those of local carnivores. Non-local δ 66 Zn values are similar to those of historical individuals analyzed previously. We conclude the lower Zn isotope ratios of local humans relative to the associated fauna can be explained by the consumption of carnivorous fish and pork, in agreement with historical, zooarchaeological and collagen (C, N, S) isotope data. Zn isotopes could therefore be a tracer of fish and/or substantial meat consumption in ancient populations. The origin of Zn isotopic variability in human tissues remained unknown until Van Heghe et al. (2012) 1 , reported the strong impact of meat and fish consumption on blood Zn isotope ratios (66 Zn/ 64 Zn expressed as δ 66 Zn values), a preliminary conclusion quickly confirmed by Costas-Rodriguez et al. (2014) 2. A parallel study on African food webs did not quantify the exact relationship between diet and bone Zn isotope ratios 3 , however by focusing on a much smaller geographical area, the sensitivity of Zn isotopes to diet was demonstrated 4 : Zn isotope ratios of bones and teeth clearly differ between carnivores and herbivores, with carnivores exhibiting the lowest ratios. The dependence of Zn isotope ratios on trophic level has also been confirmed in a marine ecosystem 5. The isotopic composition of Zn in animal tissues is controlled by two dietary factors: the isotopic fractionation that occurs during intestinal absorption and the Zn isotope ratios of the food products. Dietary Zn mainly comes from animal products, notably because Zn-and preferentially its lighter isotopes-from plants tends to precipitate with the phytates in the gastro intestinal tract 6. This precipitation is likely to trigger isotopic fractionation inducing the preferential absorption of heavy Zn isotopes. Additionally, plant products usually have the most elevated δ 66 Zn values 2. As a consequence, herbivore tissues exhibit higher Zn isotope ratios compared to carnivore or omnivore tissues 3-5. Muscles are 66 Zn depleted relative to the average isotopic composition of the body and no isotope fractionation of Zn is expected during meat consumption 3. Carnivores therefore have lower δ 66 Zn values than their prey: the higher the trophic level of an animal is, the lower are the Zn isotope ratios of its body tissues 5. Zn isotope ratios of dental enamel from populations from different locations and historical periods were recently compared 7. The study highlighted a very surprising trend: the δ 66 Zn dental values of preindustrial
For many of archaeology's rarest and most enigmatic bone artifacts (e.g. human remains, bone ornaments, worked bone), the destruction of the 500 mg material necessary for direct accelerator mass spectrometry (AMS) dating on graphite... more
For many of archaeology's rarest and most enigmatic bone artifacts (e.g. human remains, bone ornaments, worked bone), the destruction of the 500 mg material necessary for direct accelerator mass spectrometry (AMS) dating on graphite targets would cause irreparable damage; therefore many have not been directly dated. The recently improved gas ion source of the MICADAS (MIni CArbon DAting System) offers a solution to this problem by measuring gaseous samples of 5-100 µg carbon at a level of precision not previously achieved with an AMS gas ion source. We present the results of the first comparison between "routine" graphite dates of ca. 1000 µg C (2-3 mg bone collagen) and dates from aliquots of gaseous samples of <100 µg C (<0.2 mg bone collagen), undertaken with the highest possible precision in mind. The experiment demonstrates the performance of the AixMICADAS in achieving reliable radiocarbon measurements from <0.2 mg collagen samples back to 40,000 14 C BP. The technique has great implications for resolving chronological questions for key archaeological artifacts.
Modern humans have large and globular brains that distinguish them from their extinct Homo relatives. The characteristic globularity develops during a prenatal and early postnatal period of rapid brain growth critical for neural wiring... more
Modern humans have large and globular brains that distinguish them from their extinct Homo relatives. The characteristic globularity develops during a prenatal and early postnatal period of rapid brain growth critical for neural wiring and cognitive development. However, it remains unknown when and how brain globularity evolved and how it relates to evolutionary brain size increase. On the basis of computed tomographic scans and geometric morphometric analyses, we analyzed endocranial casts of Homo sapiens fossils (N = 20) from different time periods. Our data show that, 300,000 years ago, brain size in early H. sapiens already fell within the range of present-day humans. Brain shape, however, evolved gradually within the H. sapiens lineage, reaching present-day human variation between about 100,000 and 35,000 years ago. This process started only after other key features of craniofacial morphology appeared modern and paralleled the emergence of behavioral modernity as seen from the archeological record. Our findings are consistent with important genetic changes affecting early brain development within the H. sapiens lineage since the origin of the species and before the transition to the Later Stone Age and the Upper Paleolithic that mark full behav-ioral modernity.
The detailed anatomical features that characterize fossil hominin molars figure prominently in the reconstruction of their taxonomy, phylogeny, and paleobiology. Despite the prominence of molar form in human origins research, the... more
The detailed anatomical features that characterize fossil hominin molars figure prominently in the reconstruction of their taxonomy, phylogeny, and paleobiology. Despite the prominence of molar form in human origins research, the underlying developmental mechanisms generating the diversity of tooth crown features remain poorly understood. A model of tooth morphogenesis-the patterning cascade model (PCM)-provides a developmental framework to explore how and why the varying molar morphologies arose throughout human evolution. We generated virtual maps of the inner enamel epithelium-an indelibly preserved record of enamel knot arrangement-in 17 living and fossil hominoid species to investigate whether the PCM explains the expression of all major accessory cusps. We found that most of the variation and evolutionary changes in hominoid molar morphology followed the general developmental rule shared by all mammals, outlined by the PCM. Our results have implications for the accurate interpretation of molar crown configuration in hominoid systematics.
Hand bone morphology is regularly used to link particular hominin species with behaviors relevant to cognitive/technological progress. Debates about the functional significance of differing hominin hand bone morphologies tend to rely on... more
Hand bone morphology is regularly used to link particular hominin species with behaviors relevant to cognitive/technological progress. Debates about the functional significance of differing hominin hand bone morphologies tend to rely on establishing phylogenetic relationships and/or inferring behavior from epigenetic variation arising from mechanical loading and adaptive bone modeling. Most research focuses on variation in cortical bone structure, but additional information about hand function may be provided through the analysis of internal trabecular structure. While primate hand bone trabecular structure is known to vary in ways that are consistent with expected joint loading differences during manipulation and locomotion, no study exists that has documented this variation across the numerous bones of the hand. We quantify the trabecular structure in 22 bones of the human hand (early/extant modern Homo sapiens) and compare structural variation between two groups associated with post-agricultural/industrial (post-Neolithic) and foraging/hunter-gatherer (forager) subsistence strategies. We (1) establish trabecular bone volume fraction (BV/TV), modulus (E), degree of anisotropy (DA), mean trabecular thickness (Tb.Th) and spacing (Tb.Sp); (2) visualize the average distribution of site-specific BV/ TV for each bone; and (3) examine if the variation in trabecular structure is consistent with expected joint loading differences among the regions of the hand and between the groups. Results indicate similar distributions of trabecular bone in both groups, with those of the forager sample presenting higher BV/ TV, E, and lower DA, suggesting greater and more variable loading during manipulation. We find indications of higher loading along the ulnar side of the forager sample hand, with high site-specific BV/TV distributions among the carpals that are suggestive of high loading while the wrist moves through the 'dart-thrower's' motion. These results support the use of trabecular structure to infer behavior and have direct implications for refining our understanding of human hand evolution and fossil hominin hand use.
That great ape endocranial shape development persists into adolescence indicates that the splanchnocranium succeeds brain growth in driving endocranial development. However, the extent of this splanchnocranial influence is unknown. We... more
That great ape endocranial shape development persists into adolescence indicates that the splanchnocranium succeeds brain growth in driving endocranial development. However, the extent of this splanchnocranial influence is unknown. We applied two-block partial least squares analyses of Procrustes shape variables on an ontogenetic series of great ape cra-nia to explore the covariation of the endocranium (the internal braincase) and splanchnocra-nium (face, or viscerocranium). We hypothesized that a transition between brain growth and splanchnocranial development in the establishment of final endocranial form would be manifest as a change in the pattern of shape covariation between early and adolescent ontogeny. Our results revealed a strong pattern of covariation between endocranium and splanchno-cranium, indicating that chimpanzees, gorillas, and orangutans share a common tempo and mode of morphological integration from the eruption of the deciduous dentition onwards to adulthood: a reflection of elongating endocranial shape and continuing splanchnocranial prognathism. Within this overarching pattern, we noted that species variation exists in magnitude and direction, and that the covariation between the splanchnocranium and endocra-nium is somewhat weaker in early infancy compared to successive age groups. When correcting our covariation analyses for allometry, we found that an ontogenetic signal remains, signifying that allometric variation alone is insufficient to account for all endocra-nial-splanchnocranial developmental integration. Finally, we assessed the influence of the cranial base, which acts as the interface between the face and endocranium, on the shape of the vault using thin-plate spline warping. We found that not all splanchnocranial shape changes during development are tightly integrated with endocranial shape. This suggests that while the developmental expansion of the brain is the main driver of endocranial shape during early ontogeny, endocranial development from infancy onwards is moulded by the splanchnocranium in conjunction with the neurocranium.
Objectives: Trabecular bone structure is known to be influenced by joint loading during life. However, many additional variables have the potential to contribute to trabecular bone structure of an adult individual, including age, sex,... more
Objectives: Trabecular bone structure is known to be influenced by joint loading during life. However, many additional variables have the potential to contribute to trabecular bone structure of an adult individual, including age, sex, body size, genetics, and overall activity level. There is little research into intraspecific variability in trabecular bone and ontogeny of trabecular bone structure, especially in nonhuman primates. Materials and methods: This study investigates trabecular structure in adult and immature chimpanzees from a single population using high-resolution microcomputed tomographic scans of the proximal humerus, proximal femur, and distal tibia. Trabecular bone volume fraction (BV/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N), trabecular spacing (Tb.Sp), and degree of anisotropy (DA) were quantified in specific regions of adult and immature chimpanzees , and color maps were generated to visualize the distribution of BV/TV throughout the joint in the metaphysis of immature specimens. Results: The results demonstrate that variability in adult trabecular structure cannot be explained by sex or body size. During ontogeny, there is a general increase in trabecular BV/TV and Tb.Th with age, and ratios of trabecular parameters between the fore-and hindlimb may be consistent with locomotor transitions during ontogeny. Discussion: Variation in trabecular morphology among adult individuals is not related to sex or body size, and the factors contributing to intraspecific variability, such as overall activity levels and genetic differences, require further investigation. Trabecular ontogeny in chimpanzees differs from humans in some respects, most notably the absence of a high BV/TV at birth. K E Y W O R D S cancellous bone, development, knuckle-walking, locomotion, Pan troglodytes
Aspects of trabecular bone architecture are thought to reflect regional loading of the skeleton, and thus differ between primate taxa with different locomotor and postural modes. However, there are several systemic factors that affect... more
Aspects of trabecular bone architecture are thought to reflect regional loading of the skeleton, and thus differ between primate taxa with different locomotor and postural modes. However, there are several systemic factors that affect bone structure that could contribute to, or be the primary factor determining, interspecific differences in bone structure. These systemic factors include differences in genetic regulation, sensitivity to loading, hormone levels, diet, and activity levels. Improved understanding of inter-/intraspecific variability, and variability across the skeleton of an individual, is required to interpret properly potential functional signals present within trabecular structure. Using a whole-region method of analysis, we investigated trabecular structure throughout the skeleton of humans and chimpanzees. Trabecular bone volume fraction (BV/TV), degree of anisotropy (DA) and trabecular thickness (Tb.Th) were quantified from high resolution micro-computed tomographic scans of the humeral and femoral head, third metacarpal and third metatarsal head, distal tibia, talus and first thoracic vertebra. We found that BV/TV is, in most anatomical sites, significantly higher in chimpanzees than in humans, suggesting a systemic difference in trabecular structure unrelated to local loading regime. Differences in BV/TV between the forelimb and hindlimb did not clearly reflect differences in locomotor loading in the study taxa. There were no clear systemic differences between the taxa in DA and, as such, this parameter might reflect function and relate to differences in joint loading. This systemic approach reveals both the pattern of variability across the skeleton and between taxa, and helps identify those features of trabecular structure that may relate to joint function.
The causes of Neandertal anterior tooth wear patterns, including labial rounding, labial scratches, and differential anterior-posterior wear, have been debated for decades. The most common explanation is the " stuff-and-cut " hypothesis,... more
The causes of Neandertal anterior tooth wear patterns, including labial rounding, labial scratches, and differential anterior-posterior wear, have been debated for decades. The most common explanation is the " stuff-and-cut " hypothesis, which describes Neandertals clamping down on a piece of meat and slicing a portion close to their lips. " Stuff-and-cut " has been accepted as a general aspect of Neandertal behavior without fully assessing its variability. This study analyzes anterior dental microwear textures across habitats, locations, and time intervals to discern possible variation in Neandertal anterior tooth-use behavior. Forty-five Neandertals from 24 sites were analyzed, represented by high-resolution replicas of permanent anterior teeth. The labial surface was scanned for antemortem microwear using a white-light confocal profiler. The resultant 3D-point clouds, representing 204 Â 276 mm for each specimen, were uploaded into SSFA software packages for texture characterization. Statistical analyses, including MANOVAs, ANOVAs, and pairwise comparisons, were completed on ranked microwear data. Neandertal descriptive statistics were also compared to 10 bioarchaeological samples of known or inferred dietary and behavioral regimes. The Neandertal sample varied significantly by habitat, suggesting this factor was a principal driving force for differences in Neandertal anterior tooth-use behaviors. The Neandertals from open habitats showed significantly lower anisotropy and higher textural fill volume than those inhabiting more closed, forested environments. The texture signature from the open-habitat Neandertals was most similar to that of the Ipiutak and Nunavut, who used their anterior teeth for intense clamping and grasping behaviors related to hide preparation. Those in more closed habitats were most similar to the Arikara, who did not participate in non-dietary behaviors. These Neandertal individuals had a broad range of texture values consistent with non-dietary and dietary behaviors, suggesting they varied more in anterior tooth-use behaviors and exploited a wider variety of plant and animal resources than did those from open habitats.
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The dispersal of the genus Homo out of Africa approximately 1.8 million years ago (Ma) has been understood within the context of changes in diet, behavior, and bipedal locomotor efficiency. While various morphological characteristics of... more
The dispersal of the genus Homo out of Africa approximately 1.8 million years ago (Ma) has been understood within the context of changes in diet, behavior, and bipedal locomotor efficiency. While various morphological characteristics of the knee and ankle joints are considered part of a suite of traits indicative of, and functionally related to, habitual bipedal walking, the timing and phylogenetic details of these morphological changes remain unclear. To evaluate the timing of knee and ankle joint evolution, we apply geometric morphometric methods to three-dimensional digital models of the proximal and distal tibiae of fossil hominins, Holocene Homo sapiens, and extant great apes. Two sets of landmarks and curve semilandmarks were defined on each specimen. Because some fossils were incomplete, digital reconstructions were carried out independently to estimate missing landmarks and semilandmarks. Group shape variation was evaluated through shapeeand form-space principal component analysis and fossil specimens were projected to assess variation in the morphological space computed from the extant comparative sample. We show that a derived proximal tibia (knee) similar to that seen in living H. sapiens evolved with early Homo at ~2 Ma. In contrast, derived characteristics in the distal tibia appear later, probably with the arrival of Homo erectus. These results suggest a dissociation of the morphologies of the proximal and distal tibia, perhaps indicative of divergent functional demands and, consequently, selective pressures at these joints. It appears that longer distance dispersals that delivered the Dmanisi hominins to Georgia by 1.8 Ma and H. erectus to eastesoutheast Asia by 1.6 Ma were facilitated by the evolution of a morphologically derived knee complex comparable to that of recent humans and an ankle that was morphologically primitive. This research sets the foundation for additional paleontological, developmental, and functional research to better understand the mechanisms underlying the evolution of bipedalism.
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This study explores the morphological differences between the enameledentine junction (EDJ) of maxillary and mandibular molars of Neanderthals (n ¼ 150) and recent modern humans (n ¼ 106), and between an earlier Neanderthal sample... more
This study explores the morphological differences between the enameledentine junction (EDJ) of maxillary and mandibular molars of Neanderthals (n ¼ 150) and recent modern humans (n ¼ 106), and between an earlier Neanderthal sample (consisting of Pre-Eemian and Eemian Neanderthals dating to before 115 ka) and a later Neanderthal sample (consisting of Post-Eemian Neanderthals dating to after 115 ka). The EDJ was visualised by segmenting microtomographic scans of each molar. A geometric morphometric methodology compared the positioning of the dentine horns, the shape of the marginal ridge between the dentine horns, and the shape of the cervix. We also examined the manifestation of non-metric traits at the EDJ including the crista obliqua, cusp 5, and post-paracone tubercle. Furthermore , we report on additional morphological features including centrally placed dentine horn tips and twinned dentine horns. Our results indicate that EDJ morphology can discriminate with a high degree of reliability between Neanderthals and recent modern humans at every molar position, and discriminate between the earlier and the later Neanderthal samples at every molar position, except for the M 3 in shape space. The cervix in isolation can also discriminate between Neanderthals and recent modern humans, except at the M 3 in form space, and is effective at discriminating between the earlier and the later Neanderthal samples, except at the M 2 /M 2 in form space. In addition to demonstrating the taxo-nomic valence of the EDJ, our analysis reveals unique manifestations of dental traits in Neanderthals and expanded levels of trait variation that have implications for trait definitions and scoring.
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Evolutionary studies of mammalian teeth have generally concentrated on the adaptive and functional significance of dental features, whereas the role of development on phenotypic generation and as a source of variation has received... more
Evolutionary studies of mammalian teeth have generally concentrated on the adaptive and functional significance of dental features, whereas the role of development on phenotypic generation and as a source of variation has received comparatively little attention. The present study combines an evolutionary biological framework with state-of-the-art imaging techniques to examine the developmental basis of variation of accessory cusps. Scholars have long used the position and relatedness of cusps to other crown structures as a criterion for differentiating between developmentally homologous and homoplastic features, which can be evaluated with greater accuracy at the enamel–dentine junction (EDJ). Following this approach, we collected digital models of the EDJ and outer enamel surface of more than 1000 hominoid teeth to examine whether cusp 5 of the upper molars (UM C5) and cusps 6 and 7 of the lower molars (LM C6 and LM C7) were associated each with a common developmental origin across species. Results revealed that each of these cusps can develop in a variety of ways, in association with different dental tissues (i.e. oral epithelium, enamel matrix) and dental structures (i.e. from different cusps, crests and cingula). Both within and between species variability in cusp origin was highest in UM C5, followed by LM C7, and finally LM C6. The lack of any species-specific patterns suggests that accessory cusps in hominoids are developmentally homoplastic and that they may not be useful for identifying phylogenetic homology. An important and unanticipated finding of this study was the identification of a new taxonomically informative feature at the EDJ of the upper molars, namely the post-paracone tubercle (PPT). We found that the PPT was nearly ubiquitous in H. neanderthalensis and the small sample of Middle Pleistocene African and European humans (MPAE) examined, differing significantly from the low frequencies observed in all other hominoids, including Pleistocene and recent H. sapiens. We emphasize the utility of the EDJ for human evolutionary studies and demonstrate how features that look similar at the external surface may be the product of different developmental patterns. This study also highlights the importance of incorporating both developmental and morphological data into evolutionary studies in order to gain a better understanding of the evolutionary significance of dental and skeletal features.
Research Interests:
Objectives: Internal bone structure, both cortical and trabecular bone, remodels in response to loading and may provide important information regarding behavior. The foot is well suited to analysis of internal bone structure because it... more
Objectives: Internal bone structure, both cortical and trabecular bone, remodels in response to loading and may provide important information regarding behavior. The foot is well suited to analysis of internal bone structure because it experiences the initial substrate reaction forces, due to its proximity to the substrate. Moreover, as humans and apes differ in loading of the foot, this region is relevant to questions concerning arboreal locomotion and bipedality in the hominoid fossil record. Materials and methods: We apply a whole-bone/epiphysis approach to analyze trabecular and cortical bone in the distal tibia and talus of Pan troglodytes and Homo sapiens. We quantify bone volume fraction (BV/TV), degree of anisotropy (DA), trabecular thickness (Tb.Th), bone surface to volume ratio (BS/BV), and cortical thickness and investigate the distribution of BV/TV and cortical thickness throughout the bone/epiphysis. Results: We find that Pan has a greater BV/TV, a lower BS/BV and thicker cortices than Homo in both the talus and distal tibia. The trabecular structure of the talus is more divergent than the tibia, having thicker, less uniformly aligned trabeculae in Pan compared to Homo. Differences in dorsi-flexion at the talocrural joint and in degree of mobility at the talonavicular joint are reflected in the distribution of cortical and trabecular bone.
Research Interests:
Research Interests: Chatelperronian and ZooMS
Enamel thickness figures prominently in studies of human evolution, particularly for taxonomy, phy-logeny, and paleodietary reconstruction. Attention has focused on molar teeth, through the use of advanced imaging technologies and novel... more
Enamel thickness figures prominently in studies of human evolution, particularly for taxonomy, phy-logeny, and paleodietary reconstruction. Attention has focused on molar teeth, through the use of advanced imaging technologies and novel protocols. Despite the important results achieved thus far, further work is needed to investigate all tooth classes. We apply a recent approach developed for anterior teeth to investigate the 3D enamel thickness of Neandertal and modern human (MH) canines. In terms of crown size, the values obtained for both upper and lower unworn/slightly worn canines are significantly greater in Neandertals than in Upper Paleolithic and recent MH. The 3D relative enamel thickness (RET) is significantly lower in Neandertals than in MH. Moreover, differences in 3D RET values between the two groups appear to decrease in worn canines beginning from wear stage 3, suggesting that both the pattern and the stage of wear may have important effects on the 3D RET value. Nevertheless, the 3D average enamel thickness (AET) does not differ between the two groups. In both groups, 3D AET and 3D RET indices are greater in upper canines than in lower canines, and overall the enamel is thicker on the occlusal half of the labial aspect of the crown, particularly in MH. By contrast, the few early modern humans investigated show the highest volumes of enamel while for all other components of 3D enamel, thickness this group holds an intermediate position between Nean-dertals and recent MH. Overall, our study supports the general findings that Neandertals have relatively thinner enamel than MH (as also observed in molars), indicating that unworn/slightly worn canines can be successfully used to discriminate between the two groups. Further studies, however, are needed to understand whether these differences are functionally related or are the result of pleiotropic or genetic drift effects.
Research Interests:
African and Western Asian contemporaries of Neanderthals, generally considered to be the earliest Homo sapiens, are not particularly 'modern' looking in their cranial anatomy. Here we test whether the dental morphological signal agrees... more
African and Western Asian contemporaries of Neanderthals, generally considered to be the earliest Homo sapiens, are not particularly 'modern' looking in their cranial anatomy. Here we test whether the dental morphological signal agrees with this assessment. We used a Bayesian statistical approach to classifying individuals into 'modern' and 'non-modern' groups based on dental non-metric traits. The classification was based on dental trait frequencies for two 'known' samples of 109 Upper Paleolithic H. sapiens and 129 Neanderthal individuals. A cross-validation test of these individuals correctly classified them 95% of the time. Our early H. sapiens sample included 41 individuals from Southern Africa, Northern Africa and Western Asia. We treated our early H. sapiens individuals as 'unknown' and calculated the probability that each belonged to either the Upper Paleolithic or Neanderthal sample. We hypothesized that if the earliest H. sapiens were already dentally modern, then they would be assigned to the Upper Paleolithic H. sapiens group. We also hypothesized that if there had been significant admixture in Western Asia during the initial dispersal out of Africa, these samples would have the largest proportion of individuals classified as Neanderthal. Our results indicated that the latter was not the case. The smallest proportion of misclassified individuals came from Western Asia (7%) and the highest proportion of misclassified individuals came from Northern Africa (38%). In most cases it appears to be the predominance of primitive features, rather than derived Neanderthal traits that drove the classification. We conclude (1) by the time the earliest H. sapiens dispersed from Africa they had already attained a more-or-less modern dental pattern; (2) in the past, as is the case today, Late Pleistocene Africans were not a homogeneous group, some retained primitive dental traits in higher proportions than others. Furthermore, we acknowledge that while our method is an excellent tool for discriminating between Upper Paleolithic H. sapiens and Neanderthals, it may not be appropriate for testing Neanderthal – H. sapiens admixture because all traits (primitive and derived) are weighed equally. Moreover, to best assess admixture it is likely necessary to incorporate a model for how the traits track population history and/or gene flow.
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Neandertal and modern human adults differ in skeletal features of the cranium and postcranium, and it is clear that many of the cranial differences—although not all of them—are already present at the time of birth. We know less, however,... more
Neandertal and modern human adults differ in skeletal features of the cranium and postcranium, and it is clear that many of the cranial differences—although not all of them—are already present at the time of birth. We know less, however, about the developmental origins of the postcranial differences. Here, we address this deficiency with morphometric analyses of the postcrania of the two most complete Neandertal neonates—Mezmaiskaya 1 (from Russia) and Le Moustier 2 (from France)—and a recent human sample. We find that neonatal Neandertals already appear to possess the wide body, long pubis, and robust long bones of adult Neandertals. Taken together, current evidence indicates that skeletal differences between Neandertals and modern humans are largely established by the time of birth. body proportions | climatic adaptation | Homo neanderthalensis | infracranial | ontogeny
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The Neandertal lineage developed successfully throughout western Eurasia and effectively survived the harsh and severely changing environments of the alternating glacial/intergla-cial cycles from the middle of the Pleistocene until Marine... more
The Neandertal lineage developed successfully throughout western Eurasia and effectively survived the harsh and severely changing environments of the alternating glacial/intergla-cial cycles from the middle of the Pleistocene until Marine Isotope Stage 3. Yet, towards the end of this stage, at the time of deteriorating climatic conditions that eventually led to the Last Glacial Maximum, and soon after modern humans entered western Eurasia, the Nean-dertals disappeared. Western Eurasia was by then exclusively occupied by modern humans. We use occlusal molar microwear texture analysis to examine aspects of diet in western Eurasian Paleolithic hominins in relation to fluctuations in food supplies that resulted from the oscillating climatic conditions of the Pleistocene. There is demonstrable evidence for differences in behavior that distinguish Upper Paleolithic humans from members of the Neandertal lineage. Specifically, whereas the Neandertals altered their diets in response to changing paleoecological conditions, the diets of Upper Paleolithic humans seem to have been less affected by slight changes in vegetation/climatic conditions but were linked to changes in their technological complexes. The results of this study also indicate differences in resource exploitation strategies between these two hominin groups. We argue that these differences in subsistence strategies, if they had already been established at the time of the first contact between these two hominin taxa, may have given modern humans an advantage over the Neandertals, and may have contributed to the persistence of our species despite habitat-related changes in food availabilities associated with climate fluctuations.
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The discovery of an almost complete Neanderthal skeleton in a Ch^ atelperronian context at Saint-C esaire 35 years ago changed our perspective on the beginning of the Upper Paleolithic in western Europe. Since then, the Ch^ atelperronian... more
The discovery of an almost complete Neanderthal skeleton in a Ch^ atelperronian context at Saint-C esaire 35 years ago changed our perspective on the beginning of the Upper Paleolithic in western Europe. Since then, the Ch^ atelperronian has generally been considered a " transitional " industry rather than an Upper or a Middle Paleolithic industry because of its chronological position, and the association of Neanderthal remains with blades, bone tools and personal ornaments. Several competing hypotheses have been proposed to explain the association between Neanderthals and these types of artefacts including post-depositional mixing, acculturation from anatomically modern human populations, or an independent technological evolution by local Neanderthal populations. Quinçay Cave is the only Ch^ atelperronian site where personal ornaments have been found that does not contain an overlying Upper Paleolithic layer. This means that the post-depositional mixing of later elements into the Ch^ atelperronian may not be used as an explanation for the presence of these materials. We report here on a detailed technological analysis of lithic artefacts from the three Ch^ atelperronian layers at Quinçay Cave. We compare our results with the technology of Mousterian blade industries dating to OIS (oxygen isotope stage) 5, the Mousterian of Acheulian Tradition type B, and the Proto-Aurignacian. We show that the Ch^ atelperronian is sufficiently divergent from the Middle Paleolithic to be classified as a fully Upper Paleolithic industry, with a focus on blade and bladelet production. We also show that the Quinçay Ch^ atelperronian includes retouched bladelets that resemble those found in the Proto-Aurignacian, but were produced in a different manner. We argue that a technological convergence cannot account for these behaviors, since the specific type of retouched bladelet associated with the Ch^ atelperronian was also regularly used by Proto-Aurignacian of neighboring regions. We suggest that the idea of retouched bladelets may have diffused from the northern Proto-Aurignacian to the Quinçay Ch^ atelperronian and that the transmission of the morphology of this desired end-product without the transmission of its manufacturing process may point toward a low degree of social intimacy between these groups. We conclude that the apparent paradox of the Ch^ atelperronian is the result of the complexity of interaction between Neanderthal and anatomically modern human groups in western Europe between 45,000 and 40,000 years ago.
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2 5 F e b r u a r y 2 0 1 6 | V O L 5 3 0 | N a T u r e | 4 7 7 The variation in molar tooth size in humans and our closest relatives (hominins) has strongly influenced our view of human evolution. The reduction in overall size and... more
2 5 F e b r u a r y 2 0 1 6 | V O L 5 3 0 | N a T u r e | 4 7 7 The variation in molar tooth size in humans and our closest relatives (hominins) has strongly influenced our view of human evolution. The reduction in overall size and disproportionate decrease in third molar size have been noted for over a century, and have been attributed to reduced selection for large dentitions owing to changes in diet or the acquisition of cooking 1,2. The systematic pattern of size variation along the tooth row has been described as a 'morphogenetic gradient' in mammal, and more specifically hominin, teeth since Butler 3 and Dahlberg 4. However, the underlying controls of tooth size have not been well understood, with hypotheses ranging from morphogenetic fields 3 to the clone theory 5. In this study we address the following question: are there rules that govern how hominin tooth size evolves? Here we propose that the inhibitory cascade, an activator–inhibitor mechanism that affects relative tooth size in mammals 6 , produces the default pattern of tooth sizes for all lower primary postcanine teeth (deciduous premolars and permanent molars) in hominins. This configuration is also equivalent to a morphogenetic gradient, finally pointing to a mechanism that can generate this gradient. The pattern of tooth size remains constant with absolute size in australopiths (including Ardipithecus, Australopithecus and Paranthropus). However, in species of Homo, including modern humans, there is a tight link between tooth proportions and absolute size such that a single developmental parameter can explain both the relative and absolute sizes of primary postcanine teeth. On the basis of the relationship of inhibitory cascade patterning with size, we can use the size at one tooth position to predict the sizes of the remaining four primary postcanine teeth in the row for hominins. Our study provides a development-based expectation to examine the evolution of the unique proportions of human teeth. Nearly 80 years ago, Butler 3,7 described the morphogenetic gradi ent in mammalian postcanine teeth. From anterior to posterior, the deciduous premolars and molars increase in size, and in some species the posterior molars then decrease, with only one local maximum of tooth size along the row. Butler 3 interpreted this pattern to be gener ated by a morphogenetic field, where the concentration of a diffusible morphogen determined size. The pattern appeared to apply both to deciduous premolars and to molars, which together are considered primary teeth 8. Unlike molars, deciduous premolars are replaced with a secondary dentition, called the permanent premolars. While several authors have investigated the morphogenetic gradient in hominins 4,9 , they have generally investigated permanent premolars rather than their deciduous predecessors. In 2007, a developmental mechanism controlling relative molar size in mice either by separating adjacent molars or by applying growth factors in the culture was experimentally discovered 6. In the resulting 'inhibitory cascade' model, molar activator/inhibitor ratio determines the size of subsequently developing molars. Whereas activation is prin cipally considered to be mesenchymal, previously initiated molars are the source of inhibition, thereby causing a patterning cascade from anterior to posterior molars. The model appears to explain a high pro portion of the variation in relative molar size in murines, primates and fossil mammaliaforms 6,10–15. Mice, however, lack all premolars, but the inhibitory cascade implies that a previously initiated tooth should always inhibit the subsequently developing tooth (for example, the fourth deciduous premolar, dp4, should inhibit the first molar, m1). Here, we test whether the inhibitory cascade explains the mor phogenetic gradient in the primary postcanine tooth size of homin ins and great apes. We partition the lower dentition into triplets: (1) the third and fourth deciduous premolars,
Objectives: This study investigates the effect of allometry on the shape of lower dm2 (dm 2) and lower M1 (M 1) crown outlines and examines whether the trajectory and magnitude of allometric scaling are shared between Nean-dertals and... more
Objectives: This study investigates the effect of allometry on the shape of lower dm2 (dm 2) and lower M1 (M 1) crown outlines and examines whether the trajectory and magnitude of allometric scaling are shared between Nean-dertals and Homo sapiens. Methods: Our sample included 164 specimens: 57 recent H. sapiens, 44 Upper Paleolithic H. sapiens, 17 early H. sapiens, and 46 Neandertals. Of these, 59 represent dm 2 /M 1 pairs from the same individuals. Occlusal photographs were used to obtain crown shapes of dm 2 s and M 1 s. Principal components analysis (PCA) of the matrix of shape coordinates was used to explore the pattern of morphological variation across the dm 2 and M 1 samples. Allometry was investigated by means of the Pearson product-moment correlation coefficient. Two-block partial least squares (2B-PLS) analysis was used to explore patterns of covariation between dm 2 and M 1 crown outlines of matched individual pairs. Results: The PCA confirmed significant differences between Neandertal and H. sapiens dm 2 and M 1 shapes. Allometry accounted for a small but statistically significant proportion of the total morphological variance. The magnitude of the allometric contribution to crown shape was stronger among Neandertals than among H. sapiens. However , we could not reject the null hypothesis that the two species share the same allometric trajectory. The 2B-PLS analysis of the pooled sample of paired individuals revealed a significant correlation in crown shape between dm 2 and M 1. While Procrustes distances differed significantly between dm 2 and M 1 in Neandertals, it did not among H. sapiens groups. Conclusions: Our results confirm several of the results obtained by a similar study of upper dm2/M1 (dm 2 /M 1), but there are differences as well. Neandertal dm 2 /M 1 shapes are less derived than those of the dm 2 /M 1. Such differences may support previous studies, which have suggested that different developmental and/or epigenetic factors affect the upper and lower dentitions. Am J Phys Anthropol 159:93–105, 2016. V C 2015 Wiley Periodicals, Inc.
South African hominin fossils attributed to Australopithecus africanus derive from the cave sites of Makapansgat, Sterkfontein, and Taung, from deposits dated between about 2 and 3 million years ago (Ma), while Paranthropus robustus is... more
South African hominin fossils attributed to Australopithecus africanus derive from the cave sites of Makapansgat, Sterkfontein, and Taung, from deposits dated between about 2 and 3 million years ago (Ma), while Paranthropus robustus is known from Drimolen, Kromdraai, and Swartkrans, from deposits dated between about 1 and 2 Ma. Although variation in the premolar root complex has informed taxonomic and phylogenetic hypotheses for these fossil hominin species, traditionally there has been a focus on external root form, number, and position. In this study, we use microtomography to undertake the first comprehensive study of maxillary and mandibular premolar root and canal variation in Aus-tralopithecus africanus and Paranthropus robustus (n ¼ 166 teeth) within and between the species. We also test for correlations between premolar size and root morphology as predicted under the 'size/ number continuum' (SNC) model, which correlates increasing root number with tooth size. Our results demonstrate previously undocumented variation in these two fossil hominin species and highlight taxonomic differences in the presence and frequency of particular root types, qualitative root traits, and tooth size (measured as cervix cross-sectional area). Patterns of tooth size and canal/root number are broadly consistent with the SNC model, however statistically significant support is limited. The implications for hominin taxonomy in light of the increased variation in root morphology documented in this study are discussed.
Objective: The annual turnover rate of trabecular bone by far exceeds that of cortical bone and, therefore, is very sensitive to its daily loading regime. Here we test the hypothesis that the study of the trabecular bone architecture of... more
Objective: The annual turnover rate of trabecular bone by far exceeds that of cortical bone and, therefore, is very sensitive to its daily loading regime. Here we test the hypothesis that the study of the trabecular bone architecture of the human humerus is able to differentiate between different habitual manual activities. Materials and Methods: For this purpose, we compared the trabecular architecture of the humeral head in a Neolithic population to that of a sample of contemporary Europeans using micro-computed tomography (microCT). We defined in each specimen a spherical volume of interest with a diameter of 57.5 6 2.5% of the maximal diameter of the humeral head to metrically analyze the bulk of humeral head trabecular architecture. We subsequently quantified the trabecular architectures in the VOIs, measuring seven standard 3D-morphometric parameters, and used univariate and multivariate statistical analyses for comparisons within and between populations. Results: Univariate statistical analysis showed significant differences in a combination of 3D-morphometric parameters. A principal components analysis of the 3D-morphometrics of the trabecular architectures separated the Neolithic from the contemporary samples on the basis of differences in their gross trabecular architecture, including differences in the bone volume fraction (BV/TV), the number of trabeculae per unit length (Tb N), and the distance between trabeculae (Tb Sp). Discussion: We interpret the significant differences found in the humeral trabecular bone of the Neolithic and the contemporary group as likely reflecting the distinct manual working routines. The trabecular bone configuration in the Neolithic sample shows presumably functional signatures of prehistoric subsistence techniques and activity levels. Am J Phys Anthropol 159:106–115, 2016. V C 2015 Wiley Periodicals, Inc.
The Middle Pleistocene represents a period of critical importance in human evolution, marked by encephalisation and dental reduction, and increasing diversification of temporally and spatially distributed hominin lineages in Africa, Asia... more
The Middle Pleistocene represents a period of critical importance in human evolution, marked by encephalisation and dental reduction, and increasing diversification of temporally and spatially distributed hominin lineages in Africa, Asia and Europe. New specimens, especially from areas less well represented in the fossil record, can inform the debate on morphological changes to the skeleton and teeth and the phylogenetic course of human evolution during this period. The mandible from the cave of Mala Balanica, Serbia has recently been re-dated to at least 400 ka, and its well-preserved dentition presents an excellent opportunity to characterize molar crown morphology at this time period, and reexamine claims for a lack of Neandertal affinities in the specimen. In this study we employ micro-tomography to image the internal structure of the mandibular molars (focusing on the morphology of the enamel-dentine junction, or EDJ) of the BH-1 specimen and a comparative sample (n ¼ 141) of Homo erectus sensu lato, Homo neanderthalensis, Pleistocene Homo sapiens, and recent H. sapiens. We quantitatively assess EDJ morphology using 3D geometric morphometrics and examine the expression of discrete dental traits at the dentine surface. We also compare third molar enamel thickness in BH-1 to those of H. neanderthalensis and both Pleistocene and recent H. sapiens, and document previously un-reported morphology of the BH-1 premolar and molar roots. Our results highlight the reliability of the EDJ surface for classifying hominin taxa, indicate a primitive dental morphology for BH-1 molars, and confirm a general lack of derived Neandertal features for the Balanica individual. The plesiomorphic character of BH-1 is consistent with several competing models of Middle Pleistocene hominin evolution and provides an important regional and temporal example for reconstructing morphological changes in the mandible and teeth during this time period.
Abstract In 1914, a double burial was discovered in Bonn-Oberkassel and dated to the late Upper Paleolithic period. It consisted of two nearly complete skeletons, an adult male, Oberkassel 1, and a young adult female, Oberkassel 2.... more
Abstract
In 1914, a double burial was discovered in Bonn-Oberkassel
and dated to the late Upper Paleolithic period.
It consisted of two nearly complete skeletons, an adult
male, Oberkassel 1, and a young adult female, Oberkassel
2. Interestingly, the Oberkassel male and female
skulls demonstrate striking differences in facial size and
morphology, in particular in the robust, male zygomatic
bones. Over at least the last 200 ka (thousand years) in
the evolution of Homo, studies have shown a reduction
in facial size, robusticity and presumably sexual dimorphism.
In this study we explore facial allometry in later
human evolution with a special focus on the Oberkassel
male and female faces. We present a semilandmark
geometric morphometric analysis of the Oberkassel
faces and compare them to other penecontemporaneous
Upper Paleolithic Homo sapiens specimens, as well as
more recent and early Homo sapiens (e.g., Jebel Irhoud
1, Skhul 5 and Qafzeh 9), Neanderthals and Middle Pleistocene
humans. Surface models of the Oberkassel crania
were made from computed tomographic (CT) scans,
and some minor reconstruction was performed on the
damaged areas of the facial skeletons. We digitized 671
landmarks and semilandmarks on the surface models
and analyzed the Procrustes shape and form coordinates
using multivariate statistics.
In all analyses the Oberkassel specimens fall within
the range of Upper Paleolithic and recent H. sapiens variation,
and both specimens are phenetically most similar
to recent H. sapiens from Africa. The results of our
principal component analyses indicate that while the
Oberkassel male and female facial morphology is very
similar to one another, there are clear differences in facial
size. After scaling the female face to the male size,
shape differences between the two individuals are similar
to patterns of sexual dimorphism in recent modern
humans, but more pronounced. The main differences, in
brow ridge projection and zygomatic bone size, shape
and robusticity, cannot be explained by allometry alone.
Additionally, the results presented here clearly demonstrate
that facial size is a key variable that distinguishes
early, recent and Upper Paleolithic H. sapiens from earlier
archaic humans, like the Neanderthals and Middle
Pleistocene humans.
In 1914, a double burial was discovered in Bonn-Oberkassel
and dated to the late Upper Paleolithic period.
It consisted of two nearly complete skeletons, an adult
male, Oberkassel 1, and a young adult female, Oberkassel
2. Interestingly, the Oberkassel male and female
skulls demonstrate striking differences in facial size and
morphology, in particular in the robust, male zygomatic
bones. Over at least the last 200 ka (thousand years) in
the evolution of Homo, studies have shown a reduction
in facial size, robusticity and presumably sexual dimorphism.
In this study we explore facial allometry in later
human evolution with a special focus on the Oberkassel
male and female faces. We present a semilandmark
geometric morphometric analysis of the Oberkassel
faces and compare them to other penecontemporaneous
Upper Paleolithic Homo sapiens specimens, as well as
more recent and early Homo sapiens (e.g., Jebel Irhoud
1, Skhul 5 and Qafzeh 9), Neanderthals and Middle Pleistocene
humans. Surface models of the Oberkassel crania
were made from computed tomographic (CT) scans,
and some minor reconstruction was performed on the
damaged areas of the facial skeletons. We digitized 671
landmarks and semilandmarks on the surface models
and analyzed the Procrustes shape and form coordinates
using multivariate statistics.
In all analyses the Oberkassel specimens fall within
the range of Upper Paleolithic and recent H. sapiens variation,
and both specimens are phenetically most similar
to recent H. sapiens from Africa. The results of our
principal component analyses indicate that while the
Oberkassel male and female facial morphology is very
similar to one another, there are clear differences in facial
size. After scaling the female face to the male size,
shape differences between the two individuals are similar
to patterns of sexual dimorphism in recent modern
humans, but more pronounced. The main differences, in
brow ridge projection and zygomatic bone size, shape
and robusticity, cannot be explained by allometry alone.
Additionally, the results presented here clearly demonstrate
that facial size is a key variable that distinguishes
early, recent and Upper Paleolithic H. sapiens from earlier
archaic humans, like the Neanderthals and Middle
Pleistocene humans.
Changes in diet throughout hominin evolution have been linked with important evolutionary changes. Stable carbon isotope analysis of inorganic apatite carbonate is the main isotopic method used to reconstruct fossil hominin diets; to test... more
Changes in diet throughout hominin evolution have been linked with important evolutionary changes. Stable carbon isotope analysis of inorganic apatite carbonate is the main isotopic method used to reconstruct fossil hominin diets; to test its effectiveness as a paleodietary indicator we present bone and enamel carbonate carbon isotope data from a well-studied population of modern wild western chimpanzees (Pan troglodytes verus) of known sex and age from Taï, Cote d'Ivoire. We found a significant effect of age class on bone carbonate values, with adult chimpanzees being more 13C- and 18O-depleted compared to juveniles. Further, to investigate habitat effects, we compared our data to existing apatite data on eastern chimpanzees (P. troglodytes schweinfurthii) and found that the Taï chimpanzees are significantly more depleted in enamel δ13Cap and δ18Oap compared to their eastern counterparts. Our data are the first to present a range of tissue-specific isotope data from the same group of wild western chimpanzees and, as such, add new data to the growing number of modern non-human primate comparative isotope datasets providing valuable information for the interpretation of diet throughout hominin evolution. By comparing our data to published isotope data on fossil hominins we found that our modern chimpanzee bone and enamel data support hypotheses that the trend towards increased consumption of C4 foods after 4 Ma (millions of years ago) is unique to hominins.
Objectives The premolar sub-cervical region in four non-human extant ape genera are examined to: 1) define a classification scheme for the premolar root system in order to rigorously characterize, quantify and document variation in root... more
Objectives
The premolar sub-cervical region in four non-human extant ape genera are examined to: 1) define a classification scheme for the premolar root system in order to rigorously characterize, quantify and document variation in root and canal, form, number and configuration; 2) compare this variation within and between genera; and 3) test the hypotheses that sex and size (i.e., the “size/number continuum,” Shields, 2005) of the premolar are determinants of root/canal form and/or number.
Materials and Methods
Microtomography and 3D visualization software are utilized to examine a large sample of Hylobates, Pan, Gorilla, and Pongo (n = 951 teeth). Each premolar root system is examined to ascertain the expected level of variability for each taxon. Cervical surface area (mm2) serves as a metric proxy for tooth size. A Chi-square test of independence is used to assess for variability differences between and within each taxon, and Mann–Whitney U tests are employed to assess the predicted relationship between tooth size and variation within each taxon.
Results
Our findings indicate that root and canal configurations, non-metric root traits and tooth size can distinguish between extant ape genera. Within the four ape taxa, premolar size variation is generally, but not always, correlated with canal/root number. Our results indicate that males and females within genera differ in tooth size but not in canal/root form and number.
Discussion
We report previously undocumented variation in the study taxa. Our results are discussed within the context of Miocene Apes as well as the developmental and systematic implications.
The premolar sub-cervical region in four non-human extant ape genera are examined to: 1) define a classification scheme for the premolar root system in order to rigorously characterize, quantify and document variation in root and canal, form, number and configuration; 2) compare this variation within and between genera; and 3) test the hypotheses that sex and size (i.e., the “size/number continuum,” Shields, 2005) of the premolar are determinants of root/canal form and/or number.
Materials and Methods
Microtomography and 3D visualization software are utilized to examine a large sample of Hylobates, Pan, Gorilla, and Pongo (n = 951 teeth). Each premolar root system is examined to ascertain the expected level of variability for each taxon. Cervical surface area (mm2) serves as a metric proxy for tooth size. A Chi-square test of independence is used to assess for variability differences between and within each taxon, and Mann–Whitney U tests are employed to assess the predicted relationship between tooth size and variation within each taxon.
Results
Our findings indicate that root and canal configurations, non-metric root traits and tooth size can distinguish between extant ape genera. Within the four ape taxa, premolar size variation is generally, but not always, correlated with canal/root number. Our results indicate that males and females within genera differ in tooth size but not in canal/root form and number.
Discussion
We report previously undocumented variation in the study taxa. Our results are discussed within the context of Miocene Apes as well as the developmental and systematic implications.
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We present the high-quality genome sequence of a [sim]45,000-year-old modern human male from Siberia. This individual derives from a population that lived before[mdash]or simultaneously with[mdash]the separation of the populations in... more
We present the high-quality genome sequence of a [sim]45,000-year-old modern human male from Siberia. This individual derives from a population that lived before[mdash]or simultaneously with[mdash]the separation of the populations in western and eastern Eurasia and carries a similar amount of Neanderthal ancestry as present-day Eurasians. However, the genomic segments of Neanderthal ancestry are substantially longer than those observed in present-day individuals, indicating that Neanderthal gene flow into the ancestors of this individual occurred 7,000-13,000 years before he lived. We estimate an autosomal mutation rate of 0.4 [times] 10-9 to 0.6 [times] 10-9 per site per year, a Y chromosomal mutation rate of 0.7 [times] 10-9 to 0.9 [times] 10-9 per site per year based on the additional substitutions that have occurred in present-day non-Africans compared to this genome, and a mitochondrial mutation rate of 1.8 [times] 10-8 to 3.2 [times] 10-8 per site per year based on the age of the bone.
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The first settlement of Europe by modern humans is thought to have occurred between 50,000 and 40,000 calendar years ago (cal B.P.). In Europe, modern human remains of this time period are scarce and often are not associated with... more
The first settlement of Europe by modern humans is thought to have occurred between 50,000 and 40,000 calendar years ago (cal B.P.). In Europe, modern human remains of this time period are scarce and often are not associated with archaeology or originate from old excavations with no contextual information. Hence, the behavior of the first modern humans in Europe is still unknown. Aurignacian assemblages—demonstrably made by modern humans—are commonly used as proxies for the presence of fully behaviorally and anatomically modern humans. The site of Willendorf II (Austria) is well known for its Early Upper Paleolithic horizons, which are among the oldest in Europe. However, their age and attribution to the Aurignacian remain an issue of debate. Here, we show that archaeological horizon 3 (AH 3) consists of faunal remains and Early Aurignacian lithic artifacts. By using stratigraphic, paleoenvironmental, and chronological data, AH 3 is ascribed to the onset of Greenland Interstadial 11, around 43,500 cal B.P., and thus is older than any other Aurignacian assemblage. Furthermore, the AH 3 assemblage overlaps with the latest directly radiocarbon-dated Neanderthal remains, suggesting that Neanderthal and modern human presence overlapped in Europe for some millennia, possibly at rather close geographical range. Most importantly, for the first time to our knowledge, we have a high-resolution environmental context for an Early Aurignacian site in Central Europe, demonstrating an early appearance of behaviorally modern humans in a medium-cold steppe-type environment with some boreal trees along valleys around 43,500 cal B.P.
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By comparing species-specific developmental patterns, we can approach the question of how development shapes adult morphology and contributes to the evolution of novel forms. Studies of evolutionary changes to brain development in... more
By comparing species-specific developmental
patterns, we can approach the question of how development
shapes adult morphology and contributes to the
evolution of novel forms. Studies of evolutionary changes
to brain development in primates can provide important
clues about the emergence of human cognition, but are
hindered by the lack of preserved neural tissue in the fossil
record. As a proxy, we study the shape of endocasts, virtual
imprints of the endocranial cavity, using 3D geometric
morphometrics. We have previously demonstrated that the
pattern of endocranial shape development is shared by
modern humans, chimpanzees and Neanderthals after the
first year of life until adulthood. However, whether this
represents a common hominoid mode of development is
unknown. Here, we present the first characterization and
comparison of ontogenetic endocranial shape changes in a
cross-sectional sample of modern humans, chimpanzees,
gorillas, orangutans and gibbons. Using developmental
simulations, we demonstrate that from late infancy to
adulthood ontogenetic trajectories are similar among all
hominoid species, but differ in the amount of shape change.
Furthermore, we show that during early ontogeny gorillas
undergo more pronounced shape changes along this shared
trajectory than do chimpanzees, indicative of a dissociation
of size and shape change. As shape differences between
species are apparent in even our youngest samples, our
results indicate that the ontogenetic trajectories of extant
hominoids diverged at an earlier stage of ontogeny but
subsequently converge following the eruption of the
deciduous dentition.
patterns, we can approach the question of how development
shapes adult morphology and contributes to the
evolution of novel forms. Studies of evolutionary changes
to brain development in primates can provide important
clues about the emergence of human cognition, but are
hindered by the lack of preserved neural tissue in the fossil
record. As a proxy, we study the shape of endocasts, virtual
imprints of the endocranial cavity, using 3D geometric
morphometrics. We have previously demonstrated that the
pattern of endocranial shape development is shared by
modern humans, chimpanzees and Neanderthals after the
first year of life until adulthood. However, whether this
represents a common hominoid mode of development is
unknown. Here, we present the first characterization and
comparison of ontogenetic endocranial shape changes in a
cross-sectional sample of modern humans, chimpanzees,
gorillas, orangutans and gibbons. Using developmental
simulations, we demonstrate that from late infancy to
adulthood ontogenetic trajectories are similar among all
hominoid species, but differ in the amount of shape change.
Furthermore, we show that during early ontogeny gorillas
undergo more pronounced shape changes along this shared
trajectory than do chimpanzees, indicative of a dissociation
of size and shape change. As shape differences between
species are apparent in even our youngest samples, our
results indicate that the ontogenetic trajectories of extant
hominoids diverged at an earlier stage of ontogeny but
subsequently converge following the eruption of the
deciduous dentition.
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Research Interests: Primatology and Bonobos
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The human brain is a large and complex organ, setting us apart from other primates. It allows us to exhibit highly sophisticated cognitive and behavioral abilities. Therefore, our brain’s size and morphology are defining features of our... more
The human brain is a large and complex organ, setting us apart from other primates. It allows us to exhibit highly sophisticated cognitive and behavioral abilities. Therefore, our brain’s size and morphology are defining features of our species and our fossil ancestors and relatives. Endocasts, i.e., internal casts of the bony braincase, provide evidence about brain size and morphology in fossils. Based on endocasts, we know that our ancestors’ brains increased overall in size and underwent several reorganizational changes. However, it is difficult to relate evolutionary changes of size and shape of endocasts to evolutionary changes of cognition and behavior. We argue here that an understanding of the tempo and mode of brain development can help to interpret the evolution of our brain and the associated cognitive and behavioral changes. To do so, we review structural brain development, cognitive development, and ontogenetic changes of endocranial size and shape in living individuals on the one hand, and ontogenetic patterns (size increase and shape change) in fossil hominins and their evolutionary change on the other hand. Tightly integrating our knowledge on these different levels will be the key of future work on the evolution of human brain development.
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Research Interests: Paleoanthropology, Biomechanics, Functional Morphology, Trabecular Bone, Primate Evolution, and 4 moreOrigin of Bipedality, Functional and Evolutionary Morphology of the Postcranium (Especially Hands and Feet), Primate Locomotion and Manipulative Capabilities, and Adaptation and the Comparative Method
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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... more
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.
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Humans show a unique pattern of brain growth that differentiates us from all other primates. In this study, we use virtual endocasts to provide a detailed description of shape changes during human postnatal ontogeny with geometric... more
Humans show a unique pattern of brain growth that differentiates us from all other primates. In this study, we use virtual endocasts to provide a detailed description of shape changes during human postnatal ontogeny with geometric morphometric methods. Using CT scans of 108 dried human crania ranging in age from newborns to adults and several hundred landmarks and semi-landmarks, we find that the endocranial ontogenetic trajectory is curvilinear with two bends, separating three distinct phases of shape change. We test to what extent endocranial shape change is driven by size increase and whether the curved ontogenetic trajectory can be explained by a simple model of modular development of the endocranial base and the endocranial vault. The hypothesis that endocranial shape change is driven exclusively by brain growth is not supported; we find changes in endocranial shape after adult size has been attained and that the transition from high rates to low rates of size increase does not correspond to one of the shape trajectory bends. The ontogenetic trajectory of the endocranial vault analyzed separately is nearly linear; the trajectory of the endocranial base, in contrast, is curved. The endocranial vault therefore acts as one developmental module during human postnatal ontogeny. Our data suggest that the cranial base comprises several submodules that follow their own temporally and/or spatially disjunct growth trajectories.
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Propos Recueillis par Stéphane Foucart - Le Monde, mercredi 1 octobre 2014
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Artefacts made from stones, bones and teeth are fundamental to our understanding of human subsistence strategies, behaviour and culture in the Pleistocene. Although these resources are plentiful, it is impossible to associate artefacts to... more
Artefacts made from stones, bones and teeth are fundamental to our understanding of human subsistence strategies, behaviour and culture in the Pleistocene. Although these resources are plentiful, it is impossible to associate artefacts to specific human individuals1 who can be morphologically or genetically characterized, unless they are found within burials, which are rare in this time period. Thus, our ability to discern the societal roles of Pleistocene individuals based on their biological sex or genetic ancestry is limited2–5. Here we report the development of a non-destructive method for the gradual release of DNA trapped in ancient bone and tooth artefacts. Application of the method to an Upper Palaeolithic deer tooth pendant from Denisova Cave, Russia, resulted in the recovery of ancient human and deer mitochondrial genomes, which allowed us to estimate the age of the pendant at approximately 19,000–25,000 years. Nuclear DNA analysis identifies the presumed maker or wearer o...