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Juan Luis Arsuaga - One of the best experts on this subject based on the ideXlab platform.
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the first direct esr dating of a Hominin tooth from atapuerca gran dolina td 6 spain supports the antiquity of homo antecessor
Quaternary Geochronology, 2018Co-Authors: Mathieu Duval, Juan Luis Arsuaga, Rainer Grun, J M Pares, Laura Martinfrances, Isidoro Campana, Jordi Rosell, Qingfeng Shao, Eudald Carbonell, Jose Maria Bermudez De CastroAbstract:The present study reports the results of the first direct Electron Spin Resonance (ESR) dating study of Homo antecessor, the oldest known Hominin species identified in Western Europe. The analysis of a tooth (ATD6-92) from TD6 unit of Atapuerca Gran Dolina (Spain) following a “semi non-destructive” procedure provides a final age estimate ranging from 624 to 949 ka, which covers all possible uranium uptake scenarios. Last, the additional magnetostratigraphic data collected within TD6 enables to further constrain the initial ESR chronology and to propose an age of between 772 and 949 ka for Homo antecessor, in agreement with previous dating works. Although our new results do not refine the existing chronology of TD6 unit, they nevertheless support the antiquity of H. antecessor, which pre-dates the estimated divergence age of modern and archaic human lineages based on genetic evidence. This work illustrates the challenges of dating human teeth by means of the ESR method, with the main pitfalls that are sometimes inherent to this specific application (e.g., systematic μCT-scanning of Fossil Hominin teeth; limited knowledge about the original sedimentary environment for teeth coming from old excavations; heterogeneous spatial distribution of the U-series elements in dental tissues). We identified several sources of uncertainty that may directly impact the accuracy of the age result. In particular, a slight contamination of dentine (<6%) in the enamel fragment measured by ESR was found to induce a significant age underestimation (33%) if not taken into consideration. It indeed caused not only a DE underestimation (by about 8%), but also produced a massive internal dose rate overestimation (by a factor of about 3.5). In contrast, other sources of uncertainty, such as the heterogeneity of the sedimentary environment, the variability of the water content over time, the previous μCT-scanning of the tooth or the potential preferential creation of unstable NOCORs in the ESR signal, showed here a limited impact on the final age result. Given our current understanding of the ESR method and the existing uncertainties associated with the evaluation of the DE and dose rate, this is probably as far as we can presently go in the dating study of ATD6-92 sample.
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the stratigraphy of the sima de los huesos atapuerca spain and implications for the origin of the Fossil Hominin accumulation
Quaternary International, 2017Co-Authors: Arantza Aranburu, Juan Luis Arsuaga, Nohemi SalaAbstract:Abstract The Sima de Los Huesos (SH) is one of the many archaeo-palaeontological sites in the Sierra de Atapuerca. The characteristics of this palaeoanthropological site are unusual, due to the large size of the Hominin accumulation and its location far from the karst entrances, at least today. In order to investigate the geological processes involved in the site formation and their relation to the Hominin deposit, we have performed a study of the stratigraphical sequence and depositional history of SH. Analysis and correlation of the identified layers has allowed us to redefine the depositional structure of the site based on twelve lithostratigraphic units, which can be further grouped into five allostratigraphic units delimited by erosional boundaries. The results show that there was only one stratigraphic event of Hominin accumulation. Cave bears and other carnivores occur with the Hominin Fossils in the same layer, but carnivores continued accumulating above the Hominin deposit in an overlying layer. Our findings also argue against the hypothesis that the Hominin or carnivore bones were transported to SH from a locus of primary accumulation remote from their present day location. The present study also reveals that, at the time of the Hominin and carnivore Fossil accumulations, the only possible access to the SH chamber was a deep vertical conduit, which was impossible to climb.
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middle pleistocene dental remains from qesem cave israel
American Journal of Physical Anthropology, 2011Co-Authors: Israel Hershkovitz, Patricia Smith, Rachel Sarig, Rolf Quam, Laura Rodriguez, Rebeca Garcia, Juan Luis Arsuaga, Ran Barkai, Avi GopherAbstract:This study presents a description and comparative analysis of Middle Pleistocene permanent and deciduous teeth from the site of Qesem Cave (Israel). All of the human Fossils are assigned to the Acheulo-Yabrudian Cultural Complex (AYCC) of the late Lower Paleolithic. The Middle Pleistocene age of the Qesem teeth (400–200 ka) places them chronologically earlier than the bulk of Fossil Hominin specimens previously known from southwest Asia. Three permanent mandibular teeth (C1-P4) were found in close proximity in the lower part of the stratigraphic sequence. The small metric dimensions of the crowns indicate a considerable degree of dental reduction although the roots are long and robust. In contrast, three isolated permanent maxillary teeth (I2, C1, and M3) and two isolated deciduous teeth that were found within the upper part of the sequence are much larger and show some plesiomorphous traits similar to those of the Skhul/Qafzeh specimens. Although none of the Qesem teeth shows a suite of Neanderthal characters, a few traits may suggest some affinities with members of the Neanderthal evolutionary lineage. However, the balance of the evidence suggests a closer similarity with the Skhul/Qafzeh dental material, although many of these resemblances likely represent plesiomorphous features. Am J Phys Anthropol, 2011. © 2010 Wiley-Liss, Inc.
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Hominin lower second premolar morphology: evolutionary inferences through geometric morphometric analysis.
Journal of human evolution, 2006Co-Authors: María Martinón-torres, J.m. Bermúdez De Castro, Markus Bastir, Alejandro Gómez, Susana Sarmiento, A. Muela, Juan Luis ArsuagaAbstract:Mandibular premolars are increasingly used in taxon-specific diagnostic analyses of Hominins. Among the principal difficulties in these evaluations is the absence of discrete, discernible, and comparable anatomical structures for rigorous quantitative assessment. Previous research has addressed either internal crown surface features (such as cusps and fossae) or the morphology of the crown outline. In the present paper, we integrate both types of information in the examination of morphological variation of lower P4s (n = 96) among various Fossil Hominin species with an emphasis on genus Homo. We use a set of 34 2D landmarks combining coordinate data from four classical dental landmarks on the occlusal surface and 30 sliding semilandmarks of the crown outline. Our results indicate that external shape variation is closely related to the configuration of the occlusal morphological features and influenced by dental size. The external and internal shapes of P4 are polymorphic but still useful in depicting a primitive-derived gradient. The primitive pattern seems to have been an asymmetrical contour with a mesially displaced metaconid, development of a bulging talonid, and a broad occlusal polygon. The trend toward dental reduction during the Pleistocene produced different morphological variants with a reduced occlusal polygon and decreased lingual occlusal surface in later Homo species. Homo heidelbergensis/neanderthalensis have fixed plesiomorphic traits in high percentages, whereas in modern humans a symmetrical outline with a centered metaconid and talonid reduction evolved.
Nohemi Sala - One of the best experts on this subject based on the ideXlab platform.
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the stratigraphy of the sima de los huesos atapuerca spain and implications for the origin of the Fossil Hominin accumulation
Quaternary International, 2017Co-Authors: Arantza Aranburu, Juan Luis Arsuaga, Nohemi SalaAbstract:Abstract The Sima de Los Huesos (SH) is one of the many archaeo-palaeontological sites in the Sierra de Atapuerca. The characteristics of this palaeoanthropological site are unusual, due to the large size of the Hominin accumulation and its location far from the karst entrances, at least today. In order to investigate the geological processes involved in the site formation and their relation to the Hominin deposit, we have performed a study of the stratigraphical sequence and depositional history of SH. Analysis and correlation of the identified layers has allowed us to redefine the depositional structure of the site based on twelve lithostratigraphic units, which can be further grouped into five allostratigraphic units delimited by erosional boundaries. The results show that there was only one stratigraphic event of Hominin accumulation. Cave bears and other carnivores occur with the Hominin Fossils in the same layer, but carnivores continued accumulating above the Hominin deposit in an overlying layer. Our findings also argue against the hypothesis that the Hominin or carnivore bones were transported to SH from a locus of primary accumulation remote from their present day location. The present study also reveals that, at the time of the Hominin and carnivore Fossil accumulations, the only possible access to the SH chamber was a deep vertical conduit, which was impossible to climb.
Matthew M Skinner - One of the best experts on this subject based on the ideXlab platform.
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evo devo models of tooth development and the origin of hominoid molar diversity
Science Advances, 2018Co-Authors: Alejandra Ortiz, Shara E Bailey, Jeanjacques Hublin, Gary T Schwartz, Matthew M SkinnerAbstract: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.
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premolar root and canal variation in south african plio pleistocene specimens attributed to australopithecus africanus and paranthropus robustus
Journal of Human Evolution, 2016Co-Authors: Collin Nathaniel Moore, Jeanjacques Hublin, Francis J Thackeray, Matthew M SkinnerAbstract: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 Australopithecus africanus and Paranthropus robustus (n = 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.
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microtomographic archive of Fossil Hominin specimens from kromdraai b south africa
Journal of Human Evolution, 2013Co-Authors: Matthew M Skinner, Tracy L Kivell, Stephany Potze, Jeanjacques HublinAbstract:The Ditsong National Museum of Natural History (DNMNH) and the Max Planck Institute for Evolutionary Anthropology (MPI-EVA) established a collaboration in 2010 to scan Fossil Hominin specimens housed at DNMNH using microtomography (microCT). The goal of this collaboration is to facilitate research and create a ‘virtual copy’ of the Fossils for the DNMNH records. Within the context of this ongoing collaboration, the focus of this contribution is the Fossil Hominin material from the site of Kromdraai B, South Africa. The goals are to 1) formally publish the microCT scans of the Kromdraai material and facilitate their availability to the scientific research community, 2) address uncertainties regarding specimen accession numbers, 3) highlight internal aspects of anatomy revealed through the microCT scans, and 4) clarify the Hominin status of a number of postcranial specimens. Finally, 2D images of surface models, a 3D PDF surface model, a movie of each microCT volume, and the original microCT volume of each specimen are made available via an open access online archive (http://paleo.eva.mpg.de).
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enamel dentine junction morphology of extant hominoid and Fossil Hominin lower molars
2008Co-Authors: Matthew M SkinnerAbstract:Previous research has demonstrated that species and subspecies of Pan can be distinguished on the basis of the shape of their molar crowns. Thus, there is potential for Fossil Hominin taxa to be distinguished at similar taxonomic levels, but because of occlusal attrition the surface morphology of tooth crowns is often absent in Fossil teeth. The enamel-dentine junction (EDJ) of molar teeth possesses considerable information regarding the original shape of the tooth and is preserved longer than the outer enamel surface (OES). In this study we investigate whether the shape of the EDJ of lower first and second molars can distinguish species and subspecies of Pan. Micro-computed tomography is employed to non-destructively image the EDJ and geometric morphometric analytical methods are used to compare EDJ shape among samples of Pan paniscus (N = 17), Pan t. troglodytes (N = 14), and Pan t. verus (N = 18). The classification of specimens of unknown taxonomic affiliation (N = 13) is also assessed. Results indicate that EDJ morphology successfully distinguishes among both species and subspecies of Pan and can support the designation of unknown specimens to both taxon and molar type. Morphological differences in EDJ shape among taxa are subtle and relate to the relative height and spacing of the dentine horns, the height of the dentine crown, and the shape of the crown base.
Jeanjacques Hublin - One of the best experts on this subject based on the ideXlab platform.
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rare dental trait provides morphological evidence of archaic introgression in asian Fossil record
Proceedings of the National Academy of Sciences of the United States of America, 2019Co-Authors: Jeanjacques Hublin, Shara E Bailey, Susan C AntonAbstract:The recently described Denisovan hemimandible from Xiahe, China [F. Chen et al., (2019) Nature 569, 409–412], possesses an unusual dental feature: a 3-rooted lower second molar. A survey of the clinical and bioarchaeological literature demonstrates that the 3-rooted lower molar is rare (less than 3.5% occurrence) in non-Asian Homo sapiens. In contrast, its presence in Asian-derived populations can exceed 40% in China and the New World. It has long been thought that the prevalence of 3-rooted lower molars in Asia is a relatively late acquisition occurring well after the origin and dispersal of H. sapiens. However, the presence of a 3-rooted lower second molar in this 160,000-y-old Fossil Hominin suggests greater antiquity for the trait. Importantly, it also provides morphological evidence of a strong link between archaic and recent Asian H. sapiens populations. This link provides compelling evidence that modern Asian lineages acquired the 3-rooted lower molar via introgression from Denisovans.
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evo devo models of tooth development and the origin of hominoid molar diversity
Science Advances, 2018Co-Authors: Alejandra Ortiz, Shara E Bailey, Jeanjacques Hublin, Gary T Schwartz, Matthew M SkinnerAbstract: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.
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premolar root and canal variation in south african plio pleistocene specimens attributed to australopithecus africanus and paranthropus robustus
Journal of Human Evolution, 2016Co-Authors: Collin Nathaniel Moore, Jeanjacques Hublin, Francis J Thackeray, Matthew M SkinnerAbstract: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 Australopithecus africanus and Paranthropus robustus (n = 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.
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microtomographic archive of Fossil Hominin specimens from kromdraai b south africa
Journal of Human Evolution, 2013Co-Authors: Matthew M Skinner, Tracy L Kivell, Stephany Potze, Jeanjacques HublinAbstract:The Ditsong National Museum of Natural History (DNMNH) and the Max Planck Institute for Evolutionary Anthropology (MPI-EVA) established a collaboration in 2010 to scan Fossil Hominin specimens housed at DNMNH using microtomography (microCT). The goal of this collaboration is to facilitate research and create a ‘virtual copy’ of the Fossils for the DNMNH records. Within the context of this ongoing collaboration, the focus of this contribution is the Fossil Hominin material from the site of Kromdraai B, South Africa. The goals are to 1) formally publish the microCT scans of the Kromdraai material and facilitate their availability to the scientific research community, 2) address uncertainties regarding specimen accession numbers, 3) highlight internal aspects of anatomy revealed through the microCT scans, and 4) clarify the Hominin status of a number of postcranial specimens. Finally, 2D images of surface models, a 3D PDF surface model, a movie of each microCT volume, and the original microCT volume of each specimen are made available via an open access online archive (http://paleo.eva.mpg.de).
Mark Collard - One of the best experts on this subject based on the ideXlab platform.
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3d shape analyses of extant primate and Fossil Hominin vertebrae support the ancestral shape hypothesis for intervertebral disc herniation
BMC Evolutionary Biology, 2019Co-Authors: Darlene A Weston, Kimberly A Plomp, Keith Dobney, Una Strand Viðarsdottir, Mark CollardAbstract:Recently we proposed an evolutionary explanation for a spinal pathology that afflicts many people, intervertebral disc herniation (Plomp et al. [2015] BMC Evolutionary Biology 15, 68). Using 2D data, we found that the bodies and pedicles of lower vertebrae of pathological humans were more similar in shape to those of chimpanzees than were those of healthy humans. Based on this, we hypothesized that some individuals are more prone to intervertebral disc herniation because their vertebrae exhibit ancestral traits and therefore are less well adapted for the stresses associated with bipedalism. Here, we report a study in which we tested this “Ancestral Shape Hypothesis” with 3D data from the last two thoracic and first lumbar vertebrae of pathological Homo sapiens, healthy H. sapiens, Pan troglodytes, and several extinct Hominins. We found that the pathological and healthy H. sapiens vertebrae differed significantly in shape, and that the pathological H. sapiens vertebrae were closer in shape to the P. troglodytes vertebrae than were the healthy H. sapiens vertebrae. Additionally, we found that the pathological human vertebrae were generally more similar in shape to the vertebrae of the extinct Hominins than were the healthy H. sapiens vertebrae. These results are consistent with the predictions of the Ancestral Shape Hypothesis. Several vertebral traits were associated with disc herniation, including a vertebral body that is both more circular and more ventrally wedged, relatively short pedicles and laminae, relatively long, more cranio-laterally projecting transverse processes, and relatively long, cranially-oriented spinous processes. We found that there are biomechanical and comparative anatomical reasons for suspecting that all of these traits are capable of predisposing individuals to intervertebral disc herniation. The results of the present study add weight to the hypothesis that intervertebral disc herniation in H. sapiens is connected with vertebral shape. Specifically, they suggest that individuals whose vertebrae are towards the ancestral end of the range of shape variation within H. sapiens have a greater propensity to develop the condition than other individuals. More generally, the study shows that evolutionary thinking has the potential to shed new light on human skeletal pathologies.
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bayesian analysis of a morphological supermatrix sheds light on controversial Fossil Hominin relationships
Proceedings of The Royal Society B: Biological Sciences, 2015Co-Authors: Mana Dembo, Mark Collard, Nicholas J Matzke, Arne O MooersAbstract:The phylogenetic relationships of several Hominin species remain controversial. Two methodological issues contribute to the uncertainty-use of partial, inconsistent datasets and reliance on phylogenetic methods that are ill-suited to testing competing hypotheses. Here, we report a study designed to overcome these issues. We first compiled a supermatrix of craniodental characters for all widely accepted Hominin species. We then took advantage of recently developed Bayesian methods for building trees of serially sampled tips to test among hypotheses that have been put forward in three of the most important current debates in Hominin phylogenetics--the relationship between Australopithecus sediba and Homo, the taxonomic status of the Dmanisi Hominins, and the place of the so-called hobbit Fossils from Flores, Indonesia, in the Hominin tree. Based on our results, several published hypotheses can be statistically rejected. For example, the data do not support the claim that Dmanisi Hominins and all other early Homo specimens represent a single species, nor that the hobbit Fossils are the remains of small-bodied modern humans, one of whom had Down syndrome. More broadly, our study provides a new baseline dataset for future work on Hominin phylogeny and illustrates the promise of Bayesian approaches for understanding Hominin phylogenetic relationships.
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estimating Fossil Hominin body mass from cranial variables an assessment using ct data from modern humans of known body mass
American Journal of Physical Anthropology, 2014Co-Authors: Marina Elliott, Helen K Kurki, Darlene A Weston, Mark CollardAbstract:Body mass estimates are integral to a wide range of inferences in paleoanthropology. Most techniques employ postcranial elements, but predictive equations based on cranial variables have also been developed. Three studies currently provide regression equations for estimating mass from cranial variables, but none of the equations has been tested on samples of known mass. Nor have the equations been compared to each other in terms of performance. Consequently, this study assessed the performance of existing cranial equations using computed tomography scans from a large, documented sample of modern humans of known body mass. Virtual models of the skull were reconstructed and measured using computer software, and the resulting variables were entered into three sets of published regression equations. Estimated and known body masses were then compared. For most equations, prediction errors were high and few individuals were estimated within ±20% of their known mass. Only one equation satisfied the accuracy criteria. In addition, variables that had been previously argued to be good predictors of mass in Hominins, including humans, did not estimate mass reliably. These results have important implications for paleoanthropology. In particular, they emphasize the need to develop new equations for estimating Fossil Hominin body mass from cranial variables. Am J Phys Anthropol 154:201–214, 2014. © 2014 Wiley Periodicals, Inc.