Estudio y caracterización morfológica de los patrones de crestas del trigónido y talónido en el esmalte y en la dentina de los homininos del Pleistoceno de la sierra de Atapuerca (Burgos) mediante técnicas de microtomografía computarizada. Comparativa con otros grupos humanos e inferencias evolutivas

Los dientes son una valiosa fuente de caracteres morfológicos con importancia taxonómica y filogenética. Además, su alto componente de expresión genética, los convierte en la “caja fuerte” del código genético. En esta tesis doctoral hemos caracterizado y comparado morfológicamente el patrón de crestas del talónido y del trigónido existentes en el esmalte y la dentina para la mayoría de homininos del Pleistoceno europeo. Además, para comprender la polaridad de dichos caracteres y contextualizar la evolución de las poblaciones europeas, hemos analizado también otros especímenes de diversos yacimientos de África, Asia y Oriente Medio. El total de nuestra muestra de estudio consta de 274 molares que han sido analizados mediante la técnica de la microtomografía axial computarizada (micro CT), y en la que hemos estudiado la variabilidad intra- e inter-poblacional en la expresión de las crestas del trigónido y el talónido. Asimismo, hemos analizado sus frecuencias de expresión y el grado de correlación existente entre la morfología del esmalte y de la dentina para este carácter.Teeth are an important source of morphological traits with taxonomic and phylogenetic value. In addition, their high component of genetic expression makes them the "black box" of genetic code. Through this PhD dissertation we have characterized and compared the pattern of expression of talonid and trigonid crests at the enamel and dentine for most European Pleistocene hominins. In addition, to understand the polarity of these morphological features and to contextualize the evolution of European populations, we have also analyzed other specimens from Africa, Asia and the Middle East. Our total sample consists of 274 molars that have been analyzed by means of micro-computed tomography (micro CT). We present the intra- and inter-population variability in the expression of the trigonid and talonid crests in these groups and assess the correlation between the enamel and dentine surfaces

Middle Pleistocene hominin teeth from Biache‑Saint‑Vaast, France

The study of dental morphology can be a very useful tool to understand the origin and evolution of Neanderthals in Europe during the Middle Pleistocene (MP). At present, the earliest evidence, ca. 430 ka, of a pre-Neanderthal population in Europe is the hominin sample from Atapuerca-Sima de los Huesos (SH) that present clear dental affinities with Neanderthals while other penecontemporaneous populations, such as Arago or Mala Balanica, exhibit less Neanderthal traits. We present the morphometric study of the external and internal dental structures of eleven hominin dental remains recovered from the MP, ca. 240 ka, French site of Biache-Saint-Vaast (BSV). Our analyses place the BSV hominins within the MP group, together with SH, Fontana Ranuccio, Visogliano, Steinheim or Montmaurin, that showgreater morphological affinities with Neanderthals. Moreover, we identified interpopulation variability in the expression of the enamel thickness trait, with BSV hominins sharing the unique combination of thin and thick pattern in the premolars and molars with the SH population. These results further support the coexistence of two or more populations in Europe during the MP that reflect the population and settlement of human groups suggested by the Central Area of Dispersals of Eurasia (CADE) and sink and source model

Data from: Severe enamel defects in wild Japanese macaques

<p>Plane-form enamel hypoplasia (PFEH) is a severe dental defect in which large areas of the crown are devoid of enamel. This condition is rare in humans and even rarer in wild primates. The etiology of PFEH has been linked to exposure to severe disease, malnutrition, environmental toxins, and associated with systemic conditions. In this study, we examined the prevalence of enamel hypoplasia in several populations of wild Japanese macaques (<em>Macaca fuscata</em>) with the aim of providing context for severe defects observed in macaques from Yakushima Island. We found that 10 of 21 individuals (48%) from Yakushima Island displayed uniform and significant PFEH; all 10 specimens were from two adjacent locations in the south of the island. In contrast, macaques from other islands and from mainland Japan have low prevalence of the more common types of enamel hypoplasia and none exhibit PFEH. In Yakushima macaques, every tooth type was affected to varying degrees except for first molars and primary teeth, and the mineral content of the remaining enamel in teeth with PFEH was normal (i.e., no hypo- or hyper mineralization). The aetiology of PFEH might be linked to extreme weather events or high rates of environmental fluoride causing enamel breakdown. However, given that the affected individuals underwent dental development during a period of substantial human-related habitat change, an anthropogenic related etiology seems most likely. Further research on living primate populations is needed to better understand the causes of PFEH in wild primates.</p><p>Funding provided by: University of Otago<br>Crossref Funder Registry ID: https://ror.org/01jmxt844<br>Award Number: </p><p>Funding provided by: European Resuscitation Council<br>Crossref Funder Registry ID: https://ror.org/05s6r7486<br>Award Number: 101054659</p><p>Specimens studied originate from three Japanese islands and mainland (Yakushima: 21 individuals; Honshu: 10 individuals; Koshima: 19 individuals). All specimens are curated at the Primate Research Institute (PRI) (now the Center for the Evolutionary Origins of Human Behavior), Kyoto University, Japan. All 48 individuals studied lived in the wild, with those on Koshima (Kojima) Island provisioned regularly as part of a primatological study.</p> <p>Enamel hypoplasia data was collected following Towle and Irish (2019). Teeth were held under a lamp and rotated allowing light to hit the surface at different angles. The smallest discernible macroscopic defect was recorded, with a hand lens used to rule out postmortem damage. Postmortem damage was distinguished from enamel hypoplasia by distinct characteristics, including sharp edges and contrasting coloration between the fractured enamel and the rest of the crown. These features seldom resemble common forms of enamel hypoplasia, such as pitting, linear, or plane form defects. Under a hand lens, postmortem damage also lacks evidence of wear during the individual's life. Methods for recording LEH follow Goodman and Rose (1990) and Miszkiewicz (2015). Localized hypoplasia was recorded following Skinner et al. (2016). PEH was recorded if there were multiple circular/oval enamel defects on a tooth crown (Towle and Irish, 2019). If pitting was present within a LEH band, then it was recorded as LEH not PEH, but the pitting was noted. Plane-form enamel hypoplasia was recorded following Towle et al. (2017). Data are presented by tooth count rather than individual, with the number of hypoplastic teeth displayed as a percentage of the total number of observable permanent teeth.</p> <p>The data analyzed includes the location, year of inclusion into the PRI collection and sex of each individual studied when it was available. Sex assignment was taken from the PRI database, and in the present study we did not attempt to assign sex to remaining specimens. Further details on the samples, as well as other information on tooth wear and pathologies for these populations can be found in Towle et al. (2022) and Towle and Loch (2021).</p> <p><strong>References</strong></p> <p>Towle, I., & Irish, J. D. (2019). A probable genetic origin for pitting enamel hypoplasia on the molars of <em>Paranthropus robustus</em>. <em>Journal of Human Evolution</em>, 129, 54-61.</p> <p>Goodman, A. H., & Rose, J. C. (1990). Assessment of systemic physiological perturbations from dental enamel hypoplasias and associated histological structures. <em>American Journal of Physical Anthropology</em>, 33(S11), 59‐110.</p> <p>Miszkiewicz, J. J. (2015). Linear enamel hypoplasia and age‐at‐death at medieval (11th–16th Centuries) St. Gregory's Priory and Cemetery, Canterbury, UK. <em>International Journal of Osteoarchaeology</em>, 25(1), 79-87.</p> <p>Skinner, M. F., Skinner, M. M., Pilbrow, V. C., & Hannibal, D. L. (2016). An enigmatic hypoplastic defect of the maxillary lateral incisor in recent and fossil orangutans from Sumatra (<em>Pongo abelii</em>) and Borneo (<em>Pongo pygmaeus</em>). <em>International Journal of Primatology</em>, 37(4), 548-567.</p> <p>Towle, I., Dove, E. R., Irish, J. D., & De Groote, I. (2017). Severe plane-form enamel hypoplasia in a dentition from Roman Britain. <em>Dental Anthropology</em>, 30(1).</p> <p>Towle, I., & Loch, C. (2021). Tooth chipping prevalence and patterns in extant primates. <em>American Journal of Physical Anthropology</em>, 175(1), 292-299.</p> <p>Towle, I., MacIntosh, A. J., Hirata, K., Kubo, M. O., & Loch, C. (2022). Atypical tooth wear found in fossil hominins also present in a Japanese macaque population. <em>American Journal of Biological Anthropology</em>, 178(1), 171-181. <a href="https://doi.org/10.1002/ajpa.24500">https://doi.org/10.1002/ajpa.24500</a></p&gt

Severe Enamel Defects in Wild Japanese Macaques

Plane-form enamel hypoplasia (PFEH) is a severe dental defect in which large areas of the crown are devoid of enamel. This condition is rare in humans and even rarer in wild primates. The etiology of PFEH has been linked to exposure to severe disease, malnutrition, and environmental toxins and associated with systemic conditions. In this study, we examined the prevalence of enamel hypoplasia in several populations of wild Japanese macaques (Macaca fuscata) with the aim of providing context for severe defects observed in macaques from Yakushima Island. We found that 10 of 21 individuals (48%) from Yakushima Island displayed uniform and significant PFEH; all 10 specimens were from two adjacent locations in the south of the island. In contrast, macaques from other islands and from mainland Japan have a low prevalence of the more common types of enamel hypoplasia and none exhibit PFEH. In Yakushima macaques, every tooth type was affected to varying degrees except for first molars and primary teeth, and the mineral content of the remaining enamel in teeth with PFEH was normal (i.e., no hypo- or hypermineralization). The aetiology of PFEH might be linked to extreme weather events or high rates of environmental fluoride-causing enamel breakdown. However, given that the affected individuals underwent dental development during a period of substantial human-related habitat change, an anthropogenic-related etiology seems most likely. Further research on living primate populations is needed to better understand the causes of PFEH in wild primates

Dentine morphology of Atapuerca‐Sima de los Huesos lower molars: Evolutionary implications through three‐dimensional geometric morphometric analysis

Objectives This study aims to explore the affinities of the Sima de los Huesos (SH) population in relation to Homo neanderthalensis, Arago, and early and contemporary Homo sapiens. By characterizing SH intra‐population variation, we test current models to explain the Neanderthal origins. Materials and Methods Three‐dimensional reconstructions of dentine surfaces of lower first and second molars were produced by micro‐computed tomography. Landmarks and sliding semilandmarks were subjected to generalized Procrustes analysis and principal components analysis. Results SH is often similar in shape to Neanderthals, and both groups are generally discernible from Homo sapiens. For example, the crown height of SH and Neanderthals is lower than for modern humans. Differences in the presence of a mid‐trigonid crest are also observed, with contemporary Homo sapiens usually lacking this feature. Although SH and Neanderthals show strong affinities, they can be discriminated based on certain traits. SH individuals are characterized by a lower intra‐population variability, and show a derived dental reduction in lower second molars compared to Neanderthals. SH also differs in morphological features from specimens that are often classified as Homo heidelbergensis, such as a lower crown height and less pronounced mid‐trigonid crest in the Arago fossils. Discussion Our results are compatible with the idea that multiple evolutionary lineages or populations coexisted in Europe during the Middle Pleistocene, with the SH paradigm phylogenetically closer to Homo neanderthalensis. Further research could support the possibility of SH as a separate taxon. Alternatively, SH could be a subspecies of Neanderthals, with the variability of this clade being remarkably higher than previously thought

Middle Pleistocene hominin teeth from Biache-Saint-Vaast, France

International audienceAbstract The study of dental morphology can be a very useful tool to understand the origin and evolution of Neanderthals in Europe during the Middle Pleistocene (MP). At present, the earliest evidence, ca. 430 ka, of a pre-Neanderthal population in Europe is the hominin sample from Atapuerca-Sima de los Huesos (SH) that present clear dental affinities with Neanderthals while other penecontemporaneous populations, such as Arago or Mala Balanica, exhibit less Neanderthal traits. We present the morphometric study of the external and internal dental structures of eleven hominin dental remains recovered from the MP, ca. 240 ka, French site of Biache-Saint-Vaast (BSV). Our analyses place the BSV hominins within the MP group, together with SH, Fontana Ranuccio, Visogliano, Steinheim or Montmaurin, that show greater morphological affinities with Neanderthals. Moreover, we identified interpopulation variability in the expression of the enamel thickness trait, with BSV hominins sharing the unique combination of thin and thick pattern in the premolars and molars with the SH population. These results further support the coexistence of two or more populations in Europe during the MP that reflect the population and settlement of human groups suggested by the Central Area of Dispersals of Eurasia (CADE) and sink and source model

Tooth crown tissue proportions and enamel thickness in Early Pleistocene Homo antecessor molars (Atapuerca, Spain)

International audienc