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Endostructural characterization of the H. heidelbergensis dental remains from the early Middle Pleistocene site of Tighenif, Algeria
Abstract
L’assemblage humain fossile du site pléistocène initial de Tighenif, en Algérie, compte vraisemblablement parmi les premiers représentants du morphe Homo heidelbergensis. Une précédente étude de trois molaires déciduales de cet assemblage a révélé une signature structurale interne (proportions des tissus de la couronne et topographie de l’épaisseur de l’émail) approchant le schéma humain moderne. En utilisant des techniques avancées d’imagerie virtuelle et d’analyse quantitative 3D basées sur la microtomographie, nous étendons ici de manière significative le registre actuellement disponible à 22 dents permanentes, principalement de la denture mandibulaire, et fournissons les premières descriptions détaillées de la condition structurale caractérisant cette population Nord-Africaine, autour de la limite Pléistocène inférieur-moyen. Malgré un certain degré de variation individuelle, les dents de Tighenif montrent un patron structural combinant des caractéristiques primitives, dérivées et uniques. Les molaires inférieures dévoilent au niveau de la jonction émail-dentine un ensemble de traits non métriques plus fréquemment trouvés chez les humains modernes que chez les Néandertaliens, mais aussi un mélange de caractéristiques semblables soit à celles des Néandertaliens, soit à celles des humains modernes en termes de conformation structurale et de proportions des tissus. Elles présentent aussi des cavités pulpaires volumineuses, avec une bifurcation radiculaire assez élevée et des canaux pulpaires bien séparés, s’approchant plus particulièrement de la condition rapportée pour des Atériens du Pléistocène supérieur.
... Below the external surface, the enamel-dentine junction (EDJ) of the tooth shows the dentine horns of the five main cusps and of a tuberculum intermedium and a low but uninterrupted mid-trigonid crest (Figs. 2 and 3, Supplementary Fig. 2; Methods). The latter feature is generally found in Neanderthals (80-100% depending on the molar position) [38][39][40] but is less frequent in H. erectus s.l. and H. sapiens [41][42][43][44][45][46][47] (Supplementary Fig. 5). In addition, the EDJ of TNH2-1 shows an internally-positioned metaconid reminiscent of Neanderthal molars 40 and a low crown topography similar to that of H. erectus [41][42][43][44][45][46][47] . ...
... The latter feature is generally found in Neanderthals (80-100% depending on the molar position) [38][39][40] but is less frequent in H. erectus s.l. and H. sapiens [41][42][43][44][45][46][47] (Supplementary Fig. 5). In addition, the EDJ of TNH2-1 shows an internally-positioned metaconid reminiscent of Neanderthal molars 40 and a low crown topography similar to that of H. erectus [41][42][43][44][45][46][47] . These features, as well as a slight buccal shelf present on the EDJ of TNH2-1, are all expressed on the EDJ of the Denisovan molars from Baishiya Karst Cave (Xiahe, Gansu, China) ( Supplementary Fig. 5) 15 . ...
... TNH2-1 dentine differs from the much higher and proportionally more mesiodistally compressed EDJ of Neanderthals and H. sapiens 39,40 , as well as from ARTICLE NATURE COMMUNICATIONS | https://doi.org/10.1038/s41467-022-29923-z the shorter dentine horns and more densely wrinkled occlusal basin of H. erectus s.l. [41][42][43][44][45][46][47] (Supplementary Fig. 5). ...
The Pleistocene presence of the genus Homo in continental Southeast Asia is primarily evidenced by a sparse stone tool record and rare human remains. Here we report a Middle Pleistocene hominin specimen from Laos, with the discovery of a molar from the Tam Ngu Hao 2 (Cobra Cave) limestone cave in the Annamite Mountains. The age of the fossil-bearing breccia ranges between 164-131 kyr, based on the Bayesian modelling of luminescence dating of the sedimentary matrix from which it was recovered, U-series dating of an overlying flowstone, and U-series-ESR dating of associated faunal teeth. Analyses of the internal structure of the molar in tandem with palaeoproteomic analyses of the enamel indicate that the tooth derives from a young, likely female, Homo individual. The close morphological affinities with the Xiahe specimen from China indicate that they belong to the same taxon and that Tam Ngu Hao 2 most likely represents a Denisovan.
... NG92.3, NG92 D6 ZE 57 s/d 76) (Zanolli and Mazurier, 2013;Xing et al., 2014Xing et al., , 2016Xing et al., , 2018Zanolli et al., 2014;Zanolli, 2015;Weber et al., 2016). The EDJ occlusal surface of the M-LN M 2 s is relatively smooth and different from the 'dendrite-like' EDJ described in some of Middle Pleistocene Chinese hominins (Xing et al., 2014(Xing et al., , 2015(Xing et al., , 2018Liu et al., 2017). ...
... Two-dimensional enamel thickness Table 4 summarizes the 2D measurements for the M-LN specimen and comparative sample. (Zanolli, 2015), North African Homo (NAH) from Tighenif (Zanolli and Mazurier, 2013), and RMH (Smith et al., 2006(Smith et al., , 2012. M-LN M 2 values are at the lower extreme of the variation of the TD6, HER, and MH (Fig. 7). ...
... Conversely, AET and RET values in M-LN M 2 exceed Neanderthal values (Olejniczak et al., 2008). For the percentage of dentine (a/b*100), M-LN M 2 exceeds the mean values of TD6, HER, and MH groups (although still in within the range of TD6 and MH variation) and is lower than that of Neanderthals (Olejniczak et al., 2008), approximating the value seen in the Tighenif specimen (Zanolli and Mazurier, 2013). Moreover, the percentage of dentine in M-LN M 2 falls outside the range of variation of both Javanese HER and Neanderthals (Table 4, Fig. 7). ...
Here, we present a metric and morphological study of the molar remains from the Montmaurin-La Niche mandible by means of microcomputed tomography. According to the last analysis, based on the combination of geomorphological and paleontological data, the level bearing this human mandible probably corresponds to the marine isotope stages (MIS) 7. These data place the Montmaurin-La Niche in a chronologically intermediate position between the Neanderthals and the Middle Pleistocene fossils (e.g., Sima de los Huesos, la Caune de l’Arago). A recent study has revealed that while the mandible is more closely related to the Early and Middle Pleistocene African and Eurasian populations, the morphology of the outer enamel surfaces of its molars is typical of the Neanderthal linage. The data presented here are in line with this finding because the morphology of the enamel-dentine junction of the molars is similar to that of Neanderthals, whereas the absolute and relative enamel thickness values (2D and 3D) are closer to those exhibited by some Early Pleistocene hominins. Moreover, the pulp cavity morphology and proportions are in concordance with the Neanderthal populations. Our results strengthen the hypothesis that the settlement of Europe could be the result of several migrations, at different times, originated from a common source population. Thus, the variability in the European Middle Pleistocene populations (e.g., Montmaurin, Sima de los Huesos, Arago, Mala Balanica) could indicate different migrations at different times and/or population fragmentation, without excluding the possible hybridization between residents and new settlers.
... When compared to the African Early Pleistocene H. erectus/ergaster isolated M 1 from Mulhuli-Amo [52], the SH M 1 shows a substantially higher 3D RET value. Similarly, the Middle Pleistocene specimens from the North African site of Tighenif [46] are outside the SH variability at all positions with thinner enamel. However, the generalised wear of Tighenif lower molars affect the enamel thickness estimates. ...
... The SH maxillary molars tend to display higher 3D LAET (Table 6) than the comparative sample, including Early Pleistocene H. antecessor [41], European and African Middle Pleistocene samples from Visiogliano [24] and Tighenif [46], Asian H. erectus [41], Neanderthals and modern humans [41 and original data], even though the SH results overlap with all of them. Once scaled through the 3D LRET, the differences are even more accentuated, as also illustrated by the low percentage of 3D LVcdp/LVc displayed by SH maxillary molars. ...
... Compared with the European Middle Pleistocene specimens from Visogliano [24], the SH molars show similar 3D LRET. On the contrary, the African M 1 from Tighenif [46] is outside the SH range, showing thinner enamel (Fig 7). ...
Dental enamel thickness, topography, growth and development vary among hominins. In Homo, the thickness of dental enamel in most Pleistocene hominins display variations from thick to hyper-thick, while Neanderthals exhibit proportionally thinner enamel. The origin of the thin trait remains unclear. In this context, the Middle Pleistocene human dental assemblage from Atapuerca-Sima de los Huesos (SH) provides a unique opportunity to trace the evolution of enamel thickness in European hominins. In this study, we aim to test the hypothesis if the SH molar sample approximates the Neanderthal condition for enamel thickness and/or distribution. This study includes 626 molars, both original and comparative data. We analysed the molar inner structural organization of the original collections (n = 124), belonging to SH(n = 72) and modern humans from Spanish origin (n = 52). We compared the SH estimates to those of extinct and extant populations of the genus Homo from African, Asian and European origin (estimates extracted from literature n = 502). The comparative sample included maxillary and mandibular molars belonging to H. erectus, East and North African Homo, European Middle Pleistocene Homo, Neanderthals, and fossil and extant H. sapiens. We used high-resolution images to investigate the endostructural configuration of SH molars (tissue proportions, enamel thickness and distribution). The SH molars exhibit on average thick absolute and relative enamel in 2D and 3D estimates, both in the complete crown and the lateral enamel. This primitive condition is shared with the majority of extinct and extant hominin sample, except for Neanderthals and some isolated specimens. On the contrary, the SH molar enamel distribution maps reveal a distribution pattern similar to the Neanderthal signal (with thicker enamel on the lingual cusps and more peripherally distributed), compared to H. antecessor and modern humans. Due to the phylogenetic position of the SH population, the thick condition in molars could represent the persistence of the plesiomorphic condition in this group. Still, more data is needed on other Early and Middle Pleistocene populations to fully understand the evolutionary meaning of this trait.
... However, the anterior symphyseal morphology of the Tighenif specimens as well as some Neanderthal-like features present in these specimens continue to raise some questions about their relationship with the anatomically modern humans and Neanderthal lineages (Mounier et al., 2009). Additionally, the microtomographic-based analysis of the inner structural organization of some deciduous and permanent teeth from the Algerian assemblage highlighted a complex pattern with a combination of unique, primitive, Neanderthal-like and modern human-like features (Macchiarelli et al., 2013;Zanolli and Mazurier, 2013;Zanolli et al., 2010). Thus, partly due to the robustness of the mandibles and to the rare comparative evidence available so far for human fossils sampling this chronogeographical range, the taxonomic affinities of Tighenif specimens are still unclear. ...
... Asymmetry in cortical bone topography across the mandible could also reflect handedness, as it has been suggested for the Neanderthal specimen from Regourdou (Fiorenza et al., 2019;Volpato et al., 2012). With this respect, also the Algerian fossil specimen Tighenif 1 exhibits an asymmetric occlusal wear pattern of the postcanine dentition (Arambourg and Hoffstetter, 1963;Zanolli and Mazurier, 2013). ...
... In the present study, we quantitatively assess the still unreported internal structural organization of the postcanine corpus of Tighenif 1 and Tighenif 2. Given the especially robust morphology of the two mandibles and their macrodont dentition (Arambourg, 1957;Bermúdez de Castro et al., 2007;Zanolli and Mazurier, 2013), we predict that these fossils will have an absolutely thicker cortical bone compared to extant humans. In addition, we also evaluate whether, and to what extent, buccal vs. lingual relative asymmetry in CBT distribution in the two fossils is affected by their robust morphology, i.e. if a larger size of the mandibular corpus tends to lower, or magnify, the pattern commonly measured in recent humans (Daegling and Hotzman, 2003;Demes et al., 1984). ...
The present study investigates the inner structural organization of the two mandible specimens Tighenif 1 and Tighenif 2 from the late early Pleistocene site of Tighenif, Algeria. Using (micro)tomographic scans, we built a new protocol to investigate the cortical bone topography at the post-canine level. We selected two cross-sectional slices placed between the P3/P4 and M1/M2 on the right and left sides and assessed the cortical bone thickness topography (CBT) on each slice. Our analyses demonstrate that the mandibles from Tighenif exhibit higher CBT and a different topographic distribution pattern at the molar level than in modern humans, resulting in a proportionally more robust inner structure, while a similar signal is observed between the fossil and extant specimens at the premolar level. Further studies need to be done in order to determine if this feature is related to functional constraints during mastication or paramasticatory activities; or if it is related to any independent evolutionary process.
... De nombreuses e´tudes base´es sur les caracte´ristiques dentaires ont ainsi contribue´au de´bat sur les relations phyloge´ne´tiques entre les populations europe´ennes du Ple´istoce`ne (Gomez-Robles et al., 2007, 2011Martino´n-Torres et al., 2006, 2013Lumley M.-A. de, 2015), ainsi qu'a`de´crire les modalite´s e´volutives entre le Ple´istoce`ne moyen et supe´rieur en Europe (e.g. ...
... Dean et al., 1998 ;Rightmire, 1998 ;Rosas et al., 2006 ;Hublin, 2009 ;Arsuaga et al., 2014). Il a e´te´souligne´, a`partir de l'anatomie externe des dents permanentes (Go´mez-Robles et al., 2007, 2011Martino´n-Torres et al., 2006, 2013Lumley M.-A. de, 2015) et de l'ensemble du squelette (e.g. ...
... Toutefois, notre e´tude a mis en e´vidence peu de traits morphologiques non-me´triques en commun uniquement avec les Ne´andertaliens pour les dents de´ciduales (tableau 113). Au regard des donne´es bibliographiques disponibles sur les caracte´ristiques dentaires des populations du Ple´istoce`ne en Europe (Bermu´dez de Catrso et al., 1999 ;Bermu´dez de Castro et al., 2017), en Asie (Zanolli et al., 2012) et en Afrique (Zanolli et al., 2013), la discussion porte sur la polarite´des caracte`res dentaires pre´sents au Lazaret afin de pre´ciser les affinite´s taxonomiques de cette population avec les Ne´andertaliens et les HM. ...
... The enamel thickness topographic distribution of the LLI2 FR2 specimen from Fontana Ranuccio was rendered through a 3D map generated using a chromatic scale where thickness increases from dark blue (thinner) to red (thicker) [38,49,58]. We thus compared the FR2's map to those obtained for the human LRI2 from the late Early-early Middle Pleistocene North African site of Tighenif, Algeria (NAH) [59], a Neanderthal (NEA) specimen from Krapina (KRD), Croatia (MIS 6-5e) [60] and a lateral lower incisor illustrating the most common condition represented in our comparative extant human (EH) European sample. Because of crown size differences among the four lower I2s, we scaled the investigated specimens using the cervical outline as reference. ...
... To assess the pattern of root dentine thickness repartition in FR2, we virtually unzipped the 15-85% portion of its total root length along a predefined vertical line on the labial aspect, and then unrolled it and projected its local properties into a morphometric map [38,49,61,62] generated by a custom routine developed in R v.3.4.1 [63] with the packages Momocs [64], spatstat [65] and gstat [66]. For comparative purposes, we applied the same "virtual unrolling" protocol [61] to: the LRI2 from Tighenif [59]; a sample of four Neanderthal lower lateral incisors including the specimens KRD69 and KRD71 from Krapina and both incisors from the partial skeleton Regourdou 1, from the homologous site in Dordogne (France, MIS 4) [49, 58,60]; and to four extant human LI2s. In the analysis, dentine thickness values have been standardized between 0 and 1 and each morphometric map has been set within a grid of 90 columns and 100 rows. ...
... The EDJs of both templates were superimposed to the original FR1R's shape and the height and orientation of their dentine horn apices were used to create the FR1R NEA-rec and the FR1R EH-rec chimeric models, respectively (S1 Fig). On each of the three reconstructed EDJ outlines (FR1R geom-rec, FR1R NEA-rec and FR1R EH-rec), seven landmarks were placed on the apex of the protoconid, metaconid, entoconid and hypoconid horns, and at each intermediate lowest point between two dentine horns along the dentine marginal ridge, except between the two distal horns and without considering the hypoconulid and the distal marginal ridge (S2 Fig) [59,62,73]. Finally, the three versions of the FR1R EDJ were compared by a GPA and a bgPCA analysis to: the LM1 of Tighenif 2 [59] ...
The penecontemporaneous Middle Pleistocene sites of Fontana Ranuccio (Latium) and Visogliano (Friuli-Venezia Giulia), set c. 450 km apart in central and northeastern Italy, respectively, have yielded some among the oldest human fossil remains testifying to a peopling phase of the Italian Peninsula broadly during the glacial MIS 12, a stage associated with one among the harshest climatic conditions in the Northern hemisphere during the entire Quaternary period. Together with the large samples from Atapuerca Sima de los Huesos, Spain, and Caune de l’Arago at Tautavel, France, the remains from Fontana Ranuccio and Visogliano are among the few mid-Middle Pleistocene dental assemblages from Western Europe available for investigating the presence of an early Neanderthal signature in their inner structure. We applied two- three-dimensional techniques of virtual imaging and geometric morphometrics to the high-resolution X-ray microtomography record of the dental remains from these two Italian sites and compared the results to the evidence from a selected number of Pleistocene and extant human specimens/samples from Europe and North Africa. Depending on their preservation quality and on the degree of occlusal wear, we comparatively assessed: (i) the crown enamel and radicular dentine thickness topographic variation of a uniquely represented lower incisor; (ii) the lateral crown tissue proportions of premolars and molars; (iii) the enamel-dentine junction, and (iv) the pulp cavity morphology of all available specimens. Our analyses reveal in both samples a Neanderthal-like inner structural signal, for some aspects also resembling the condition shown by the contemporary assemblage from Atapuerca SH, and clearly distinct from the recent human figures. This study provides additional evidence indicating that an overall Neanderthal morphological dental template was preconfigured in Western Europe at least 430 to 450 ka ago.
... Tooth crown tissue proportions and enamel thickness distribution are considered reliable characters for inferring taxonomic identity, phylogenetic relationships, dietary and behavioural adaptations in fossil and extant hominids [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Advances in virtual paleoanthropology evinced the existence of a temporal trend in the internal tooth structural organization within the European Neanderthal lineage [3,8,10,13,14,[17][18][19][20][21][22][23][24][25][26]. ...
... Similar results are found for the lower molars, although wider differences are seen between the H. antecessor M2s and M3s and the Neanderthals specimens [8]. Similarly, the values of the specimens from North African late Early-early Middle Pleistocene Homo specimens of Tighenif [11], as well as the Middle Pleistocene hominin mandibular molars from Mala Balanica [24] are well above the TD6 average value. Conversely, the H. antecessor mandibular molars values of b/a encompasse the modern human variability (Table 2). ...
... For both AET and RET, the H. antecessor maxillary and mandibular molars exceed or minimally overlap with the superior part of the Neanderthal range of variation [8]. Overall, the TD6 AET and RET values approximate the Javanese H. erectus condition [54] and overlap or slightly exceed most of the fossil comparative specimens/ samples [10,11,24,56,67]. The modern human range [9,10] for these two variables encompasses most of the fossil variation, including that of H. antecessor. ...
Tooth crown tissue proportions and enamel thickness distribution are considered reliable characters for inferring taxonomic identity, phylogenetic relationships, dietary and behavioural adaptations in fossil and extant hominids. While most Pleistocene hominins display variations from thick to hyper-thick enamel, Neanderthals exhibit relatively thinner. However, the chronological and geographical origin for the appearance of this typical Neanderthal condition is still unknown. The European late Early Pleistocene species Homo antecessor (Gran Dolina-TD6 site, Sierra de Atapuerca) represents an opportunity to investigate the appearance of the thin condition in the fossil record. In this study, we aim to test the hypothesis if H. antecessor molars approximates the Neanderthal condition for tissue proportions and enamel thickness. To do so, for the first time we characterised the molar inner structural organization in this Early Pleistocene hominin taxon (n = 17) and compared it to extinct and extant populations of the genus Homo from African, Asian and European origin (n = 355). The comparative sample includes maxillary and mandibular molars belonging to H. erectus, East and North African Homo, European Middle Pleistocene Homo, Neanderthals, and fossil and extant H. sapiens. We used high-resolution images to investigate the endostructural configuration of TD6 molars (tissue proportions, enamel thickness and distribution). TD6 permanent molars tend to exhibit on average thick absolute and relative enamel in 2D and 3D estimates, both in the complete crown and the lateral enamel. This condition is shared with the majority of extinct and extant hominin sample, except for Neanderthals and some isolated specimens. However, while the total crown percentage of dentine in TD6 globally resembles the low modern values, the lateral crown percentage of dentine tends to be much higher, closer to the Neanderthal signal. Similarly, the H. antecessor molar enamel distribution maps reveal a relative distribution pattern that is more similar to the Neanderthal condition (with the thickest enamel more spread at the periphery of the occlusal basin) rather than that of other fossil specimens and modern humans (with thicker cuspal enamel). Future studies on European Middle Pleistocene populations will provide more insights into the evolutionary trajectory of the typical Neanderthal dental structural organization.
... De nombreuses e´tudes base´es sur les caracte´ristiques dentaires ont ainsi contribue´au de´bat sur les relations phyloge´ne´tiques entre les populations europe´ennes du Ple´istoce`ne (Gomez-Robles et al., 2007, 2011Martino´n-Torres et al., 2006, 2013Lumley M.-A. de, 2015), ainsi qu'a`de´crire les modalite´s e´volutives entre le Ple´istoce`ne moyen et supe´rieur en Europe (e.g. ...
... Dean et al., 1998 ;Rightmire, 1998 ;Rosas et al., 2006 ;Hublin, 2009 ;Arsuaga et al., 2014). Il a e´te´souligne´, a`partir de l'anatomie externe des dents permanentes (Go´mez-Robles et al., 2007, 2011Martino´n-Torres et al., 2006, 2013Lumley M.-A. de, 2015) et de l'ensemble du squelette (e.g. ...
... Toutefois, notre e´tude a mis en e´vidence peu de traits morphologiques non-me´triques en commun uniquement avec les Ne´andertaliens pour les dents de´ciduales (tableau 113). Au regard des donne´es bibliographiques disponibles sur les caracte´ristiques dentaires des populations du Ple´istoce`ne en Europe (Bermu´dez de Catrso et al., 1999 ;Bermu´dez de Castro et al., 2017), en Asie (Zanolli et al., 2012) et en Afrique (Zanolli et al., 2013), la discussion porte sur la polarite´des caracte`res dentaires pre´sents au Lazaret afin de pre´ciser les affinite´s taxonomiques de cette population avec les Ne´andertaliens et les HM. ...
Cette étude, portant sur 18 dents du Lazaret datées de 160 ka (SIM 6), avait pour objectif de préciser la position taxonomique de cette population. L’analyse des traits non-métriques et de l’épaisseur de l’émail des dents du Lazaret au moyen de l’imagerie à haute résolution a mis en évidence une majorité de caractéristiques primitives sur les Ldm1, Ldm2, Udm2 et LC. Les dents du Lazaret combinent quelques caractères qui leur sont uniques sur les Ldm1 et les LP3 avec des traits dérivés de type néandertalien sur les Ldm1, les Ldm2, les LC et les LP3. Toutefois, l’ensemble des traits dérivés de type néandertalien n’est pas
présent sur les Ldm2, les Udm2 et les LC du Lazaret. Par conséquent, les dents du Lazaret ne peuvent pas être assignées aux Néandertaliens, mais s’intègrent dans la lignée néandertalienne.
... In both fossil and recent H. sapiens (n = 28), we did not observe the "dendrite-like" EDJ surface ( Fig. 5 and SI Fig. 10). The EDJ pattern is also more complex than that present in earlier hominins (Australopithecus and Paranthropus) and genus Homo available in the literature [38][39][40][41] . ...
... On the EDJ surface of PA69, a mesial protoconid ridge is present in the mesial aspect of the protostylid and forms a protostylid-protoconid shelf combination (Fig. 2). This structure is also present in Xichuan PA531, but less obvious on the Tighenif 2 41 and absent in MA93 from East African late Early Pleistocene 42 . From a lateral view, the width of the roots in PA69 and other Zhoukoudian M 1 s does not decrease clearly until the very apical end ( Fig. 1 and SI Fig. 8), a trait that has been described as typical of classic H. erectus from China and Java 30,43 . ...
... The EDJ surfaces of some Pongo M 2 s are indeed quite smooth and in those cases when they are more crenulated the accessory ridges are generally thinner and lower than those from Zhoukoudian, Hexian, Yiyuan, and Xichuan. None of the hominins available in the literature show this type of highly-crenulated EDJ [38][39][40][41]45 . In these specimens, the secondary grooves and ridges of both the enamel and the dentine surfaces are also reflected at the occlusal surface of the pulp cavity, being a peculiarity not recorded in any other hominin group so far (Fig. 4). ...
This study provides new original data, including the endostructure of most Zhoukoudian H. erectus teeth preserved to date, since the publication of Black in 1927 and Weidenreich in 1937. The new evidence ratifies the similarities of Zhoukoudian with other East Asian mid-Middle Pleistocene hominins such as Hexian and Yiyuan, and allows defining a dental pattern potentially characteristic of this population commonly referred to as classic H. erectus. Given the possible chronological overlaps of classic H. erectus with other archaic Homo, the characterization of this group becomes a key issue when deciphering the taxonomy and evolutionary scenario of the Middle Pleistocene hominins in East Asia. Internally, the most remarkable feature of Zhoukoudian teeth is the highly crenulated enamel-dentine junction (EDJ) and its imprint on the roof of the pulp cavity. So far, this "dendrite-like" EDJ has been found only in East Asia Middle Pleistocene hominins although a large group of samples were assessed, and it could be useful to dentally define classic H. erectus in China. The crenulated EDJ surface, together with the stout roots and the taurodontism could be a mechanism to withstand high biomechanical demand despite a general dentognathic reduction, particularly of the crowns, in these populations.
... A comparison of dental tissue proportions (acknowledging the moderate wear of the BH-1 M 1 and M 2 ) highlights the relatively small proportion of enamel and coronal dentine and relatively large proportion of root dentine volume and root pulp volume in the BH-1 (and Mauer) molars compared to Neandertals and fossil and recent H. sapiens (Fig. 4b). Following the methodology outlined by Zanolli and colleagues (Zanolli and Mazurier, 2013;Zanolli et al., 2014;Zanolli, 2015) we calculated the volume of coronal dentine and pulp as a percentage of total crown volume. Acknowledging that tooth wear is moderate on the BH-1 M 1 the value of 67.0% exceeds the H. erectus s.l. ...
... Two rooted mandibular P 3 s and P 4 s are present among australopiths and the earlier members of the genus Homo (Wood et al., 1988;Gabounia et al., 2002) and should be considered a primitive trait. Tomes' roots are present in the Early Pleistocene teeth from Sima del Elefante (Prado-Sim on et al., 2012) and from Tighenif (Zanolli and Mazurier, 2013). A particularly primitive form of Tomes' is present in Gran Dolina, in which both the P 3 and P 4 exhibit a marked lingual invagination and contain three root canals (Bermúdez de Castro et al., 1997). ...
... Most Neandertal specimens are single rooted and single canaled with the exception of a specimen from Krapina (KRP D35) which exhibits a bifurcated canal (Prado-Sim on et al., 2012) and a specimen from Valdegoba cave (VB1; Quam et al., 2001). Of the penecontemporaneous finds, marked invagination is absent in Mauer (Rosas and Bermúdez de Castro, 1998), Sima de los Huesos ; but for one mandibular fragment containing a mesiobuccal and distolingual radical) and Quesem (Hershkovitz et al., 2011), and present in Arago (Bermúdez de Castro et al., 2003) and Tighenif (Zanolli and Mazurier, 2013) where it is similar to the form inferred for BH-1. According to Bermúdez de Castro et al. (2003), this trait represents one of the characters that distinguish the Gran Dolina finds from those of Sima de los Huesos and Neandertals. ...
... A comparison of dental tissue proportions (acknowledging the moderate wear of the BH-1 M 1 and M 2 ) highlights the relatively small proportion of enamel and coronal dentine and relatively large proportion of root dentine volume and root pulp volume in the BH-1 (and Mauer) molars compared to Neandertals and fossil and recent H. sapiens (Fig. 4b). Following the methodology outlined by Zanolli and colleagues (Zanolli and Mazurier, 2013;Zanolli et al., 2014;Zanolli, 2015) we calculated the volume of coronal dentine and pulp as a percentage of total crown volume. Acknowledging that tooth wear is moderate on the BH-1 M 1 the value of 67.0% exceeds the H. erectus s.l. ...
... Two rooted mandibular P 3 s and P 4 s are present among australopiths and the earlier members of the genus Homo (Wood et al., 1988;Gabounia et al., 2002) and should be considered a primitive trait. Tomes' roots are present in the Early Pleistocene teeth from Sima del Elefante (Prado-Sim on et al., 2012) and from Tighenif (Zanolli and Mazurier, 2013). A particularly primitive form of Tomes' is present in Gran Dolina, in which both the P 3 and P 4 exhibit a marked lingual invagination and contain three root canals (Bermúdez de Castro et al., 1997). ...
... Most Neandertal specimens are single rooted and single canaled with the exception of a specimen from Krapina (KRP D35) which exhibits a bifurcated canal (Prado-Sim on et al., 2012) and a specimen from Valdegoba cave (VB1; Quam et al., 2001). Of the penecontemporaneous finds, marked invagination is absent in Mauer (Rosas and Bermúdez de Castro, 1998), Sima de los Huesos ; but for one mandibular fragment containing a mesiobuccal and distolingual radical) and Quesem (Hershkovitz et al., 2011), and present in Arago (Bermúdez de Castro et al., 2003) and Tighenif (Zanolli and Mazurier, 2013) where it is similar to the form inferred for BH-1. According to Bermúdez de Castro et al. (2003), this trait represents one of the characters that distinguish the Gran Dolina finds from those of Sima de los Huesos and Neandertals. ...
... Homo including some specimens allocated to H. heidelbergensis and H. neanderthalensis (FitzGerald, 1998;Benazzi et al., 2011;Zanolli and Mazurier, 2013 Moore et al., 2013Moore et al., , 2016 and classification Moore et al., 2013). Investigators have determined that variation between maxillary and mandibular premolar root and canal number and morphology is found in non-human primates (Moore et al., 2013), and is taxonomically distinctive in South African Plio-Pleistocene hominins (Moore et al., 2016). ...
... At 1.8 Ma Homo erectus has fewer tooth roots, especially M 3 /M3s, than earlier members of our genus, and H. erectus premolars are frequently single rooted (Anton, 2003). This trend in root number reduction continues through more recent members of genus Homo including some specimens allocated to H. heidelbergensis and H. neanderthalensis (FitzGerald, 1998;Benazzi et al., 2011;Zanolli and Mazurier, 2013). ...
This dissertation is an investigation of post-canine tooth root morphology in a global sample of modern humans. Tooth roots are variable in number, shape and orientation, and internal canal form and number do not necessarily covary with external morphology. However, this variation is poorly understood in anthropological and biological contexts. This is, in part, due to the inaccessibility of tooth roots for metric and morphological assessment. Early studies relied on x-rays, which are problematic when visualizing root structures, which are often curved or layered one on top of another. Computed tomography (CT) allows for clear visualization of tooth roots, and has revealed a previously unknown, complex combination of external and internal morphologies. Using CT scans from a global sample of humans (n = 945) a novel phenotype system is developed comprised of five elements: Root presence/absence (E1), canal root presence/absence (E2), canal location (E3), external root morphology (E4), and canal morphology and configuration (E5). Together, these five elements capture the external and internal morphology of the tooth root complex and are used to carry out four objectives: (1) to test and describe patterns of variation and divergence between root and canal number in individual teeth and between populations; (2) to develop a predictive model of tooth root morphology based on canal count and configuration; (3) to identify and define the total tooth root phenotypic set of the human sample; (4) to investigate if and how the total phenotypic set can delineate and define geographic and population structure in our sample. Novel statistical approaches are developed and used to ascertain complex patterning. Results indicate that there are clear differences between patterns of root to canal number both within and between teeth of the maxilla and mandible, and that these patterns are different between populations; that root canal number and orientation are powerful predictors of external root morphology; that the combined phenotype elements capture variation within and between populations; and that the combined phenotype elements can accurately identify and delineate population substructures. These findings are discussed in terms of evolutionary and developmental biology and biomechanics, and population structure and diversity.
... We calculated the 3D coronal pulp volume (Vcp, mm 3 ) for each tooth, since wear does not affect pulp volume. These proportions and values were compared to previously published data on Middle and Upper Paleolithic fossils and recent modern humans(Bayle et al., 2017;Kupczik and Hublin, 2010;Zanolli & Mazurier, 2013;Zanolli et al., 2019). Finally, we determined the 3D topography of the enamel thickness distribution in each tooth using the segmented enamel and dentine surfaces Avizo software (Termofisher)Bayle et al., 2011;, Zanolli, Pan, 2018. ...
Objectives
We report the discovery and description of three human teeth from the Middle Paleolithic archaeological levels of Arbreda Cave (Serinyà, Catalonia, NE Iberian Peninsula).
Materials and Methods
The teeth, two molars (one right dm 2 and one right M 2 ) from Level N (older than 120 kyr) and one P ³ from Level J (dated between 71 and 44 kyr), were morphologically described based on microCT images and compared with Neanderthal and Homo sapiens specimens.
Results
The teeth belong to a minimum of three individuals: one adult and one infant from Level N and one juvenile from Level J. The premolar from Mousterian Level J, the best preserved of the three teeth, exhibits characteristics to those from our comparative sample of Homo neanderthalensis , such as the crown measurements, EDJ traits, enamel thickness and volume of the pulp cavity.
Discussion
In contrast to the clear Neanderthal characteristics observed in the P ³ from Level J, the high degree of dental wear and poor state of preservation precludes definitive taxonomic designations of the two teeth from Level N. However, the crown dimensions and some tissue proportions are consistent with a probable assignation to Homo neanderthalensis . The teeth from Level N come from a context of long and recurrent occupations of the cave, whereas the archaeological context of the tooth from Level J is indicative of short and seasonal occupations of the cave, which may indicate a change in the lifestyle strategies of the last Neanderthals of the Iberian Peninsula.
... In most of the works in which the dimensions of dental tissues are compared between different taxa, the modern human samples employed are composed of individuals of different geographic origin (Schwartz and Dean, 2005;Olejniczak et al., 2008aOlejniczak et al., , 2008bSmith et al., 2012;Macchiarelli et al., 2013;García-Campos et al., 2020) or samples belonging to a single population (Saunders et al., 2007;Feeney et al., 2010;Zanolli and Mazurier, 2013;Zanolli et al., 2014;Martín-Francés et al., 2018). Nonetheless, it is important to note that most investigations employed European samples (e.g. ...
Numerous studies have shown that human dentition traits vary both between and within populations. However, there is still little knowledge about how dental tissue proportions differ between modern human groups. In this study, two samples of European and African individuals were compared to assess the possible differences and similarities present in the dental tissue dimensions of their permanent canines. For this purpose, the volumes and surface areas of the coronal dentine and pulp complex and the enamel cap of 127 canines were measured by microcomputed tomography. The results show the existence of interpopulation variability in the dental tissue pattern of both samples, which is mainly due to the presence of a larger enamel component in the African population, while dentine seems to play a less critical role in the differences described between both dental samples. We also observed a similar pattern of sexual dimorphism in the dental tissue proportions of European and African canines, but in this case, the intrapopulation variability was mainly due to the presence of a greater dentine component in males. Therefore, because the dimensions of dental tissues vary at both inter- and intrapopulation levels in modern human groups, our results highlight the importance of selecting comparative samples that are geographically mixed and sex-balanced for future paleoanthropological investigations on dental tissue patterns of extinct and extant species to avoid overestimating or underestimating any possible similarities or differences.
... In recent years, the development of threedimensional (3D) virtual imaging has enabled access to internal bony and tooth structures for the quantitative assessment of their endostructural organization (e.g., Bayle et al. 2010Bayle et al. , 2011Cazenave et al. 2017;Colombo et al. 2019;García-Campos et al. 2020;Genochio et al. 2019;Le Cabec et al. 2013;Puymerail 2017;Puymerail et al. 2012;Swan et al. 2020;Zanolli and Mazurier 2013;Zanolli et al. 2020). Functional adaptation is often put forward to explain differences in cortical bone and dental volumes, as well as in internal geometry of long bones and roots in hominins (Bondioli et al. 2010;Churchill 1998;Kupczik and Hublin 2010;Trinkaus and Ruff 2012). ...
Cortical bone and dentine share similarities in their embryological origin, development, and genetic background. Few analyses have combined the study of cortical bone and dentine to quantify their covariation relative to endogenous and exogenous factors. However, knowing how these tissues relate in individuals is of great importance to decipher the factors acting on their evolution, and ultimately to understand the mechanisms responsible for the different patterns of tissue proportions shown in hominins. The aims of this study are to examine age-, sex-, and ancestry-related variation in cortical bone and dentine volumes, and to preliminary assess the possible covariation between these tissues in modern humans and in five composite Neandertals. The modern analytical sample includes 12 immature individuals from France and 49 adults from France and South Africa. Three-dimensional tissue proportions were assessed from microtomographic records of radii and permanent maxillary canines. Results suggest ontogenic differences and a strong sexual dimorphism in cortical bone and dentine developments. The developmental pattern of dentine also seems to vary according to individual's ancestry. We measure a stronger covariation signal between cortical bone and dentine volumes than with any other dental tissue. A more complex covariation pattern is shown when splitting the modern sample by age, sex, and ancestry, as no signal is found in some subsamples while others show a covariation between cortical bone and either crown or radicular dentine. Finally, no difference in cortical bone volume is noticed between the modern young adults and the five young adult composite Neandertals from Marine Isotopic Stages (MIS) 5 and 3. Greater dentine Cortical bone and dentine (co)variation volumes are measured in the MIS 5 chimeric Neandertals whereas a strong interpopulation variation in dentine thickness is noticed in the MIS 3 chimeric Neandertals. Further research on the cortical bonedentine covariation will increase understanding of the impact of endogenous and exogenous factors on the development of the mineralized tissues.
... Likewise, a well-developed AF is a pattern shared with most Neanderthals (Bailey, 2002a(Bailey, , 2006aMartin on-Torres et al., 2012). In addition, the typical Neanderthal roots are single, pyramidal, with the taurodontic pulp chamber extending apically (Kupczik & Hublin, 2010;Zanolli & Mazurier, 2013). The root configuration of CA-2019-E2-2 supports the Neanderthal affinity. ...
Objectives
To present a new dental specimen that will provide additional evidence for a better understanding of early European Upper Pleistocene hominin morphological variability.
Materials and Methods
We described the morphology of this human right lower third molar at both the outer enamel surface and the enamel–dentine junction by means of micro‐computed tomography. In order to better understand hominin diversity, our morphological and metrical results were compared with those of other hominins obtained from published research. We provide a direct aspartic acid racemization dating of the molar.
Results
The direct dating (104.3 ka) situates the molar within the Marine isotopic stage 5d. The crown dimensions are comparable to those of the Sima de los Huesos sample and modern humans. The combination of a continuous middle trigonid crest and a well‐developed anterior fovea lies within the range of morphological variation reported for Neanderthal lower molars. The distal portion of the molar has a prominent protostylid.
Discussion
Crown and root morphology of this molar fits within the Neanderthal morphological pattern. However, both its dimensions and the absence of a hypoconulid tend to position this specimen away from contemporaneous Neanderthals and rather relate it more closely to some Middle Pleistocene populations.
Conclusions
A new dental specimen is added to the Iberian Peninsula fossil record from the Marine isotopic stage 5, attesting to some degree of dental variability in the early Upper Pleistocene.
... Although the morphology of lower incisors of extinct and extant Homo has been reported to be less discriminative for taxonomic purposes than that of posterior teeth (Skinner et al., 2015;Zanolli et al., 2018;Lockey et al., 2020), methodological advances have permitted the study of dental tissue proportions and provide additional avenues to assist taxonomic assessment (e.g., Smith et al., 2003Smith et al., , 2012Olejniczak et al., 2008;Macchiarelli et al., 2013;Zanolli and Mazurier, 2013;Pan et al., 2016;. For instance, previous work has shown that the anterior dental tissue proportions and dimensions for Neanderthals are distinct from other extinct hominins and extant recent modern humans (RMH; Smith et al., 2012;Le Cabec et al., 2013;Buti et al., 2017), with the SH canines exhibiting a dental tissue proportion pattern typical of Neanderthals . ...
The early Middle Pleistocene human material from Boxgrove (West Sussex, UK) consists of a partial left tibia and two lower incisors from a separate adult individual. These remains derive from deposits assigned to the MIS 13 interglacial at about 480 ka and have been referred to as Homo cf. heidelbergensis. The much larger skeletal sample from the Sima de los Huesos (Atapuerca, Spain) is dated to the succeeding MIS 12, at about 430 ka. This fossil material has previously been assigned to Homo heidelbergensis but is now placed within the Neanderthal clade. Because of the scarcity of human remains from the Middle Pleistocene and their morphological variability, this study assessed whether the Boxgrove specimens fit within the morphological variability of the homogeneous Sima de los Huesos population. Based on morphometric analyses performed against 22 lower incisors from Sima de los Huesos and published material, the data from the Boxgrove incisors place them comfortably within the range of Sima de los Huesos. Both assemblages present robust incisors distinct from the overall small recent Homo sapiens incisors, and Boxgrove also aligns closely with Homo neanderthalensis and some other European Middle Pleistocene hominins. Following morphological and cross-sectional analyses of the Boxgrove tibia compared to seven adult Sima de los Huesos specimens and a set of comparative tibiae, Boxgrove is shown to be similar to Sima de los Huesos and Neanderthals in having thick cortices and bone walls, but in contrast resembles modern humans in having a straight anterior tibial crest and a suggestion of a lateral concavity. Based on the patterns observed, there is no justification for assigning the Boxgrove and Sima de los Huesos incisors to distinct paleodemes, but the tibial data show greater contrasts and suggest that all three of these samples are unlikely to represent the same paleodeme.
... This trend in root number reduction continues through more recent members of Genus Homo including some specimens allocated to H. heidelbergensis and H. neanderthalensis (Benazzi et al., 2011;FitzGerald, 1998;Zanolli & Mazurier, 2013). Africans are primarily R1-C2, the dominant phenotypic permutation for the rest of the major geographic groups is R1-C1. ...
Descriptive morphology of tooth roots traditionally focuses on number of canals and roots. However, how or if canal and root number are related is poorly understood. While it is often assumed that canal number is concomitant with root number and morphology, in practice canal number and morphology do not always covary with external root features. To investigate the relationship between canal and root number, fully developed, adult post‐canine teeth were examined and quantified from computerized tomography scans from a global sample of 945 modern humans. We tested the hypotheses that root and canal number do not follow a 1:1 ratio, that canal to root ratios differ between teeth, and that canal to root ratios differ across major human geographical groups. Results indicate that not only is root number dependent on canal number, but that this relationship becomes more variable as canal number increases, varies between individual teeth and by major geographical group, and changes as these groups increase in geographical distance from Sub‐Saharan Africa. These results show that the ratio of canal number to root number is an important indicator of variation in dental phenotypes. Tooth root anatomy varies in canal and root number, and canal number does not always covary with root number. To investigate the relationship between canal and root number, fully developed, adult post‐canine teeth were examined and quantified from computerized tomography scans from a global sample of 945 modern humans. We tested the hypotheses that root and canal number do not follow a 1:1 ratio, that canal to root ratios differ between teeth, and that canal to root ratios differ across major human geographical groups.
... The types described here may be useful in descriptions of dental material, although it is unclear whether the types we distinguish here represent distinct traits; it is more likely that there is a continuous variation in accessory cusp placement, and that this variation is only partly captured by the categories used here. A good example illustrating this is the molar row of Tighenif 2 ( Fig. 13; see also Zanolli & Mazurier, 2013). All three molars have a LAC, but its position shifts distally along the molar row from a clear metaconid type in the M 1 , to interconulid types in the M 2 and M 3 that are situated close to the entoconid (the LACs in the M 2 and M 3 are not situated on the mesial ridge of the entoconid, which would make them an entoconid type, but they are situated close to the entoconid because the cusp is low and its mesial ridge does not extend very far mesially on the crown). ...
Studies of hominin dental morphology frequently consider accessory cusps on the lower molars, in particular those on the distal margin of the tooth (C6 or distal accessory cusp) and the lingual margin of the tooth (C7 or lingual accessory cusp). They are often utilized in studies of hominin systematics, where their presence or absence is assessed at the outer enamel surface (OES). However, studies of the enamel-dentine junction (EDJ) suggest these traits may be more variable in development, morphology and position than previously thought. Building on these studies, we outline a scoring procedure for the EDJ expression of these accessory cusps that considers the relationship between these accessory cusps and the surrounding primary cusps. We apply this scoring system to a sample of Plio-Pleistocene hominin mandibular molars of Paranthropus robustus, Paranthropus boisei, Australopithecus afarensis, Australopithecus africanus, Homo sp., Homo habilis and Homo erectus from Africa and Asia ( n = 132). We find that there are taxon-specific patterns in accessory cusp expression at the EDJ that are consistent with previous findings at the OES. For example, P. robustus M 1 s and M 2 s very often have a distal accessory cusp but no lingual accessory cusp, while H. habilis M 1 s and M 2 s show the opposite pattern. The EDJ also reveals a number of complicating factors; some apparent accessory cusps at the enamel surface are represented at the EDJ only by shouldering on the ridges associated with the main cusps, while other accessory cusps appear to have little or no EDJ expression at all. We also discuss the presence of double and triple accessory cusps, including the presence of a double lingual accessory cusp on the distal ridge of the metaconid in the type specimen of H. habilis (OH 7–M 1 ) that is not clear at the OES due to occlusal wear. Overall, our observations, as well as our understanding of the developmental underpinnings of cusp patterning, suggest that we should be cautious in our comparisons of accessory cusps for taxonomic interpretations.
... They, and others (Blumberg et al., 1971;Hamner III et al., 1964;Hillson, 1996;Kupczik & Hublin, 2010), suggest that an enlarged pulp cavity may provide an advantage to populations consuming a high-wear diet. Previous studies have examined pulp cavity morphology and volumetrics (e.g., Bayle et al., 2009;Bayle et al., 2010;Kupczik, 2003;Kupczik et al., 2019;Kupczik & Hublin, 2010;Olejniczak et al., 2008;Şenyürek, 1939;Zanolli & Mazurier, 2013). However, to date there has been no formal test comparing the pulp volume of closely related animals that consume diets that differ in abrasiveness. ...
Objectives:
One role of dental pulp is in the upkeep and maintenance of dentine. Under wear, odontoblasts in the pulp deposit tertiary dentine to ensure the sensitive internal dental tissues are not exposed and vulnerable to infection. It follows that there may be an adaptive advantage for increasing molar pulp volume in anthropoid primate taxa that are prone to high levels of wear. The relative volume of dental pulp is therefore predicted to covary with dietary abrasiveness (in the sense of including foods that cause high degrees of wear).
Materials and methods:
We examined relatively unworn lower second molars in pairs of species of extant hominoids, cebids, and pitheciids that vary in the abrasiveness of their diet (n = 36). Using micro-CT scans, we measured the percent of tooth that is pulp (PTP) as the ratio of pulp volume to that of the total volume of the tooth.
Results:
We found that in each pair of species, the taxa that consume a more abrasive diet had a significantly higher PTP than the closely related taxa that consume a softer diet.
Conclusions:
Our results point to an adaptive mechanism in the molars of taxa that consume abrasive diets and are thus subject to higher levels of wear. Our results provide additional understanding of the relationship between dental pulp and diet and may offer insight into the diet of extinct taxa such as Paranthropus boisei or into the adaptive context of the taurodont molars of Neanderthals.
... These were quickly followed by the development of synchrotron radiation microtomography (SR-µCT), a highly effective analytical tool to detail meso/microscopic features (see Tafforeau et al., 2012), including dental endostructural morphology in extinct hominids (e.g., Macchiarelli et al., 2006Macchiarelli et al., , 2007Macchiarelli et al., , 2008Mazurier et al., 2006;Tafforeau et al., 2006;Smith and Tafforeau, 2008;Tafforeau and Smith, 2008;Smith et al., 2009;Le Cabec et al., 2015). Highresolution X-µCT and SR-µCT have now become indispensable tools for the virtual exploration, extraction, cleaning, 2-3D rendering and quantitative assessment of the paleobiological information stored in fossilized remains (among the very many studies, see Rook et al., 2004;Grine, 2005, 2006;Olejniczak et al., 2008;Skinner et al., 2008Skinner et al., , 2015Skinner et al., , 2016Bayle et al., 2009Bayle et al., , 2011Macchiarelli et al., 2009Macchiarelli et al., , 2013Braga et al., 2010;Kupczik and Hublin, 2010;Benazzi et al., 2011a,b;Jaeger et al., 2011;DeSilva and Devlin, 2012;Puymerail et al., 2012a,b;Zanolli et al., 2012Zanolli et al., , 2014Zanolli et al., , 2015Zanolli et al., , 2018aBarak et al., 2013;Le Cabec et al., 2013;Zanolli and Mazurier, 2013;Spoor et al., 2015;Zanolli, 2015;Kappelman et al., 2016;Kivell, 2016;Macchiarelli and Zanolli, 2017;Martínez de Pinillos et al., 2017;Pan et al., 2017;Beaudet et al., 2018;Martín-Francés et al., 2018;Ryan et al., 2018;Beaudet, 2019;Cazenave et al., 2019a,b;Genochio et al., 2019;Grine et al., 2019;Haile-Selassie et al., 2019;Kupczik et al., 2019;Martinón-Torres et al., 2019;Pan and Zanolli, 2019). ...
The internal structure of the bones and teeth of extinct primates holds a significant amount of valuable paleobiological information for assessing taxonomy, phylogenetic relationships, functional, dietary and ecological adaptive strategies, and reconstructing overall evolutionary history. Technologies based on X-ray microfocus (X-μCT) and synchrotron radiation (SR-μCT) microtomography are increasingly used to non-invasively and non-destructively investigate the endostructural properties of fossil mineralized tissues. However, depending on the taphonomic dynamics that affected the specimens following deposition, and on the nature of diagenetic processes, X-μCT and even SR-μCT may provide only faint or no contrast between the mineralized tissues, thus complicating or inhibiting the study of structural features. Using a diverse sample of dentognathic hominid specimens from continental Asia, East Africa and Indonesia, chronologically ranging from the Late Miocene to the Early Middle Pleistocene, we present examples of the successful application of another imaging technology, neutron microtomography (n-μCT), for the extraction, 3D rendering and quantitative assessment of internal morphological detail. The specimens were scanned at the ANTARES Imaging facility (SR4a beamline) at the FRM II reactor of the Technical University of Munich, Germany, at energies ranging from 3 to 25 meV. The datasets were reconstructed with a voxel size from 20 to 27 μm, i.e., at resolutions directly comparable to the X-ray-based microtomographic records commonly used in paleobiological studies of fossil primate remains. Our analyses focused on a mandible, SNSB-BSPG 1939 X 4, representing the Late Miocene hominid Sivapithecus from the Siwaliks of Pakistan; the early Pleistocene (Gelasian) partial mandible HCRP-U18-501 from Malawi, among the earliest specimens attributed to the genus Homo; and an assemblage of hominid dentognathic specimens from the Early Middle Pleistocene deposits of the Sangiran Dome, Indonesia. While X-ray-based imaging revealed from low to moderate internal contrasts for the specimen of Sivapithecus, or from extremely poor to virtually no contrast for the Pleistocene remains from East Africa and Indonesia, the application of n-μCT produced sufficient differences in contrast to distinguish between tooth tissues on the one hand, and between cortical and trabecular bone on the other, thus enabling reliable qualitative and quantitative assessments of their characteristics.
... The EDJ has been particularly useful in geometric morphometric (GM) studies, as the sharper appearance of dental features allows for reliable placement of landmarks and semilandmarks . GM provides a powerful method of biological shape analysis, and can be useful for quantifying morphological changes in dental studies (G omez-Robles et al., 2008;Singleton et al., 2011;Carayon et al., 2019), as well as in addressing issues of hominin taxonomy Zanolli and Mazurier, 2013;Martin et al., 2017;Hublin et al., 2017;Hershkovitz et al., 2018). Typically these studies focus on mandibular and maxillary molars, although a number of studies have performed GM analysis of the EDJ of multiple tooth positions, including mandibular premolars (Braga et al., 2010;Pan et al., 2017;Zanolli et al., 2018). ...
In apes, the mandibular third premolar (P3) is adapted for a role in honing the large upper canine. The role of honing was lost early in hominin evolution, releasing the tooth from this functional constraint and allowing it to respond to subsequent changes in masticatory demands. This led to substantial morphological changes, and as such the P3 has featured prominently in systematic analyses of the hominin clade. The application of microtomography has also demonstrated that examination of the enamel-dentine junction (EDJ) increases the taxonomic value of variations in crown morphology. Here we use geometric morphometric techniques to analyze the shape of the P3 EDJ in a broad sample of fossil hominins, modern humans, and extant apes (n = 111). We test the utility of P3 EDJ shape for distinguishing among hominoids, address the affinities of a number of hominin specimens of uncertain taxonomic attribution, and characterize the changes in P3 EDJ morphology across our sample, with particular reference to features relating to canine honing and premolar ‘molarization’. We find that the morphology of the P3 EDJ is useful in taxonomic identification of individual specimens, with a classification accuracy of up to 88%. The P3 EDJ of canine-honing apes displays a tall protoconid, little metaconid development, and an asymmetrical crown shape. Plio-Pleistocene hominin taxa display derived masticatory adaptations at the EDJ, such as the molarized premolars of Australopithecus africanus and Paranthropus, which have well-developed marginal ridges, an enlarged talonid, and a large metaconid. Modern humans and Neanderthals display a tall dentine body and reduced metaconid development, a morphology shared with premolars from Mauer and the Cave of Hearths. Homo naledi displays a P3 EDJ morphology that is unique among our sample; it is quite unlike Middle Pleistocene and recent Homo samples and most closely resembles Australopithecus, Paranthropus and early Homo specimens.
... If we enlarge our sample to other contemporaneous Zhoukoudian H. erectus materials (which were lost during WWII), Weidenreich Double-rooted lower premolars are frequently reported for Early Pleistocene hominins found in Eurasian sites like Atapureca TD6 (Bermúdez de Castro & Rosas, 1999) and Sangiran (Kaifu et al., 2005), but East African early Homo has predominantly single-or Tomes' rooted lower premolars , high percentage of Tomes' root is also observed in Early Pleistocene specimens from Atapuerca TD6 and Sima del Elefante (Prado-Simón et al. 2012, b), Dmanisi and Trinil (Martinón-Torres et al., 2008). As for the Middle Pleistocene period, Tomes' root has been described for the specimens found in Tighenif (accompanied with two or three canals; Zanolli & Mazurier, 2013), mid-Middle Pleistocene specimens like H. erectus P 4 from Hexian (Liu et al., 2017) and Zhoukoudian (3/5 P 3 s and 1/2 P 4 s; Weidenreich, 1937), P 3 from Chenjiawo (this study) and a late Middle Pleistocene P 3 of Penghu 1 (Chang et al., 2015). A three-grooved P 4 root (with one circular canal) is seen in late Middle Pleistocene specimen from Changyang (this study), representing a fusion of three root branches-a rather primitive feature. ...
Objectives
The aim of this study is to explore the root and root canal morphology of Homo fossil occupying China during the Middle Pleistocene period. Human occupation and evolutionary dynamics in East Asia during the Middle Pleistocene period is one of the most intriguing issues in paleoanthropology, with the coexistence of multiple lineages and regional morphs suggesting a complex population interaction scenario. Although premolar root and canal morphology has certain phylogenetic, taxonomic, and functional implications, its morphological diversity, possible evolutionary trend and characteristics regarding Middle Pleistocene hominins inhabiting East Asia are still insufficiently understood; where these populations fits within the Homo lineage (with respect to root and pulp canal structure) needs to be explored.
Materials and methods
Using microtomography, we directly observed and assessed the nonmetric variability of root and canal forms in maxillary and mandibular premolars of Chinese Middle Pleistocene Homo (N = 19), and compared our observed variations with Eurasian Early Pleistocene specimens from the Asia continent (N = 1) and Java (N = 2), as well as with Neanderthals (N = 28) and recent modern humans (N = 67).
Results
A total number of nine types of root‐canal forms were recorded. As a whole, the Chinese Middle Pleistocene record shows an evolutionary trend toward a modern human‐like condition (a reduction of root/canal number and a simplification of root surface structure). We documented primitive signals like high percentage of Tomes' root in lower premolars. A considerable occurrence of incompletely separated root branches and bifid root and canal apices, representing evolutionary transformation from multi‐root to single‐root condition was also noticed. The results were compared with previous publications on Early and Middle Pleistocene Homo in East Africa, North Africa, and Eurasia.
Conclusion
This work provides new original data, incorporates the latest human fossil discoveries and suggests that analyzing the variation of premolar root structural organization, notably integrating together root/canal form and number, could possibly contribute to taxonomic and phylogenetic assessments. The mid‐Middle Pleistocene populations, or “classic” Homo erectus, in our study show closer affinity to Early and Middle Pleistocene hominins in Eurasia, than to East African early Homo, which supports the suggestion that at least some of the Early Pleistocene hominin groups in Eurasia contribute to the later population; on the other hand, it is still difficult to clearly trace the evolutionary fate of those late Middle Pleistocene populations (roughly assigned as archaic Homo sapiens through a craniodental perspective). More comparable materials from the Early to Middle Pleistocene period as well as precise chronological framework is needed to further explore the evolutionary trends of archaic hominins in the Asian continent before the arrival of modern humans.
... Interestingly, the M 1 of the Mauer mandible (the holotype of H. heidelbergensis) and Mala Balanica specimen lack anterior fovea and a mid-trigonid crest. According to Zanolli and Mazurier (2013), the left M 1 of Tighenif 2 shows a continuous mid-trigonid crest at the enamel and dentine. However, unlike ATD6-112, this crest corresponds to a grade 2 according to Bailey et al. (2011), since the height of the crest is relatively reduced by the sagittal groove. ...
Here we analyze the unpublished hominin dental remains recovered from the late Early Pleistocene Gran Dolina-TD6.2 level of the Sierra de Atapuerca (northern Spain), as well as provide a reassessment of the whole TD6.2 hominin dental sample. Comparative descriptions of the outer enamel surface (OES) and the enamel-dentine junction (EDJ) are provided. Overall, the data presented here support the taxonomic validity of Homo antecessor, since this species presents a unique mosaic of traits. Homo antecessor displays several primitive features for the genus Homo as well as some traits exclusively shared with Early and Middle Pleistocene Eurasian hominins. Some of these Eurasian traits were retained by the Middle Pleistocene hominins of Europe, and subsequently became the typical condition of the Neanderthal lineage. Although other skeletal parts present resemblances with Homo sapiens, TD6.2 teeth do not show any synapomorphy with modern humans. In addition, TD6.2 teeth can be well differentiated from those of Asian Homo erectus. The dental evidence is compatible with previous hypothesis about H. antecessor belonging to the basal population from which H. sapiens, Homo neanderthalensis, and Denisovans emerged. Future findings and additional research may help to elucidate the precise phylogenetic link among them.
... Therefore, comparative evidence suggests that the transition from early to middle Pleistocene gave rise to the emergence of two tendencies in the postcanine dental tissue pattern in the subsequent populations. Whereas African H. erectus/ergaster shows the intermediate-thick enamel condition (Smith et al., 2012;Zanolli, 2014) similar to that later observed in H. neanderthalensis (Olejniczak et al., 2008a), a relatively and absolutely thicker enamel is systematically found in Indonesian H. erectus and in fossil and extant modern humans (Smith et al., 2012;Zanolli and Mazurier, 2013;Zanolli, 2014;Zanolli et al., 2014. ...
Enamel and dentin patterns have awakened a considerable interest in phylogenetic studies. However, almost nothing is known about the dental tissue proportions of European Pleistocene hominins, apart from Neanderthal populations. This study aims to assess the three-dimensional dental tissue proportions of permanent canines belonging to the extensive sample of hominin teeth at Sierra de Atapuerca (Spain) through the use of microtomographic techniques. Our results show that early and middle Pleistocene populations from Atapuerca exhibit large coronal and root dentine dimensions, as well as a thinly enamelled pattern, which has been traditionally considered an autapomorphic Neanderthal trait. Therefore, these results might support an early enamel thickness decrease which is already observed 800 kyr ago in Homo antecessor and maintained in later groups such as Sima de los Huesos and Neanderthal populations during the middle Pleistocene.
... This number is purposefully much larger than that used in previous dental studies of fossil hominins ( Stringer et al., 1997;Irish, 1998;Bailey, 2000;Irish and Guatelli-Steinberg, 2003;Martin on-Torres et al., 2007Irish et al., 2013), because esti- mates of biological distance and/or ancestry are unquestionably more powerful if based on many rather than few traits (Livingstone, 1991;see also;Dembo et al., 2016;Sjøvold, 1977). Further, all 78 have been recorded and/or at least observed in Plio-Pleistocene species around the world ( Johanson et al., 1982;Wood and Abbott, 1983;Wood and Engleman, 1988;Tobias, 1991;Stringer et al., 1997;Irish, 1998;Bailey, 2002a, b;Irish and GuatelliSteinberg, 2003;Bailey and Lynch, 2005; Martin on- Torres et al., 2008Torres et al., , 2013Bailey and Hublin, 2013;Irish et al., 2013). ...
A new species of Homo, Homo naledi, was described in 2015 based on the hominin skeletal remains from the Dinaledi Chamber of the Rising Star cave system, South Africa. Subsequent craniodental comparative analyses, both phenetic and cladistic, served to support its taxonomic distinctiveness. Here we provide a new quantitative analysis, where up to 78 nonmetric crown and root traits of the permanent dentition were compared among samples of H. naledi (including remains from the recently discovered Lesedi Chamber) and eight other species from Africa: Australopithecus afarensis, Australopithecus africanus, Paranthropus boisei, Paranthropus robustus, Homo habilis, Homo erectus, Middle Pleistocene Homo sp., and Pleistocene and Holocene Homo sapiens. By using the mean measure of divergence distance statistic, phenetic affinities were calculated among samples to evaluate interspecific relatedness. The objective was to compare the results with those previously obtained, to assess further the taxonomic validity of the Rising Star hominin species. In accordance with earlier findings, H. naledi appears most similar dentally to the other African Homo samples. However, the former species is characterized by its retention and full expression of features relating to the main cusps, as well as the root numbers, with a near absence of accessory traits-including many that, based on various cladistic studies, are plesiomorphic in both extinct and extant African hominins. As such, the present findings provide additional support for the taxonomic validity of H. naledi as a distinct species of Homo.
... Shape differences were also observed between the 3D dental mor- Homo heidelbergensis, (Zanolli & Mazurier, 2013), which supports the primitive status of these Arago features. ...
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.
... Studies focusing on molar crown tissue proportions show that most fossil and extant Plio-Pleistocene hominins share absolutely and relatively thick enamel (Smith et al., 2012;Zanolli and Mazurier, 2013;Skinner et al., 2015;Zanolli, 2015;Pan et al., 2016), apart from the relatively thinly enameled Neanderthals (Macchiarelli et al., 2006(Macchiarelli et al., , 2013Olejniczak et al., 2008a) and for the condition of some isolated specimens (e.g., Zanolli et al., 2014). This does not, however, concern the still poorly explored existence of taxon/population-specific patterns in enamel thickness topographic distribution . ...
Locality 1, in the Lower Cave of the Zhoukoudian cave complex, China, is one of the most important Middle Pleistocene paleoanthropological and archaeological sites worldwide, with the remains of c. 45 Homo erectus individuals, 98 mammalian taxa, and thousands of lithic tools recovered. Most of the material collected before World War II was lost. However, besides two postcranial elements rediscovered in China in 1951, four human permanent teeth from the ‘Dragon Bone Hill,’ collected by O. Zdansky between 1921 and 1923, were at the time brought to the Paleontological Institute of Uppsala University, Sweden, where they are still stored. This small sample consists of an upper canine (PMU 25719), an upper third molar (PMU M3550), a lower third premolar crown (PMU M3549), and a lower fourth premolar (PMU M3887). Some researchers have noted the existence of morpho-dimensional differences between the Zhoukoudian and the H. erectus dental assemblage from Sangiran, Java. However, compared to its chrono-geographical distribution, the Early to Middle Pleistocene dental material currently forming the Chinese-Indonesian H. erectus hypodigm is quantitatively meager and still poorly characterized for the extent of its endostructural variation. We used micro-focus X-ray tomography techniques of virtual imaging coupled with geometric morphometrics for comparatively investigating the endostructural conformation (tissue proportions, enamel thickness distribution, enamel-dentine junction morphology, pulp cavity shape) of the four specimens stored in Uppsala, all previously reported for their outer features. The results suggest the existence of time-related differences between continental and insular Southeast Asian dental assemblages, the Middle Pleistocene Chinese teeth apparently retaining an inner signature closer to the likely primitive condition represented by the Early Pleistocene remains from Java, while the Indonesian stock evolved toward tooth structural simplification.
... Furthermore, the T648I variant in ENAM has been proposed to offer protection against caries since the reverse variant I648T, corresponding to the ancestral and today minor allele, has been associated, in combination with another ENAM polymorphism R736Q, with increased risk of carries in a French children cohort [35]. The advantageous T648I substitution nearly fixed today may have been inherited from the archaic hominins, that show rare sign of caries [54,55] and low level of defective enamel formation [37]. In addition to susceptibility to caries, mutations in the ENAM gene have been described to cause enamel defects such as hypoplasia (thinner and more irregular enamel) and hypomineralization linked to Amelogenesis imperfecta (AI) disorders [37]. ...
Environment parameters, diet and genetic factors interact to shape tooth morphostructure. In the human lineage, archaic and modern hominins show differences in dental traits, including enamel thickness, but variability also exists among living populations. Several polymorphisms, in particular in the non-collagenous extracellular matrix proteins of the tooth hard tissues, like enamelin, are involved in dental structure variation and defects and may be associated with dental disorders or susceptibility to caries. To gain insights into the relationships between tooth protein polymorphisms and dental structural morphology and defects, we searched for non-synonymous polymorphisms in tooth proteins from Neanderthal and Denisova hominins. The objective was to identify archaic-specific missense variants that may explain the dental morphostructural variability between extinct and modern humans, and to explore their putative impact on present-day dental phenotypes. Thirteen non-collagenous extracellular matrix proteins specific to hard dental tissues have been selected, searched in the publicly available sequence databases of Neanderthal and Denisova individuals and compared with modern human genome data. A total of 16 non-synonymous polymorphisms were identified in 6 proteins (ameloblastin, amelotin, cementum protein 1, dentin matrix acidic phosphoprotein 1, enamelin and matrix Gla protein). Most of them are encoded by dentin and enamel genes located on chromosome 4, previously reported to show signs of archaic introgression within Africa. Among the variants shared with modern humans, two are ancestral (common with apes) and one is the derived enamelin major variant, T648I (rs7671281), associated with a thinner enamel and specific to the Homo lineage. All the others are specific to Neanderthals and Denisova, and are found at a very low frequency in modern Africans or East and South Asians, suggesting that they may be related to particular dental traits or disease susceptibility in these populations. This modern regional distribution of archaic dental polymorphisms may reflect persistence of archaic variants in some populations and may contribute in part to the geographic dental variations described in modern humans.
... When genetic variation such as the loss of CASP12 in AMH is considered alongside the reduced expression of Neanderthal IL18 SNP found in some Europeans and Asians, combined with earlier paleopathological evidence for oral disease (Zanolli and Mazurier, 2013) and septicaemia (Gracia-Tellez et al., 2013) in Pleistocene hominin Homo heidelbergensis, there is a suggestion that selection pressure exerted by bacterial sepsis shaped the genomes of archaic and AMH, long before the assumed arrival of traditional zoonoses with the rise of agriculture in the Holocene. Likewise the introgression of genes with antiviral activity into modern human environments points toward viral infections afflicting European hominins to a degree strong enough to favor adaptive introgression (Segurel and Quintana-Murci, 2014), protecting admixed AMH against the same pathogens which afflicted the Neanderthals. ...
High quality Altai Neanderthal and Denisovan genomes are revealing which regions of archaic hominin DNA have persisted in the modern human genome. A number of these regions are associated with response to infection and immunity, with a suggestion that derived Neanderthal alleles found in modern Europeans and East Asians may be associated with autoimmunity. As such Neanderthal genomes are an independent line of evidence of which infectious diseases Neanderthals were genetically adapted to. Sympathetically, human genome adaptive introgression is an independent line of evidence of which infectious diseases were important for AMH coming in to Eurasia and interacting with Neanderthals. The Neanderthals and Denisovans present interesting cases of hominin hunter-gatherers adapted to a Eurasian rather than African infectious disease package. Independent sources of DNA-based evidence allow a re-evaluation of the first epidemiologic transition and how infectious disease affected Pleistocene hominins. By combining skeletal, archaeological and genetic evidence from modern humans and extinct Eurasian hominins we question whether the first epidemiologic transition in Eurasia featured a new package of infectious diseases, or a change in the impact of existing pathogens. Coupled with pathogen genomics, this approach supports the view that many infectious diseases are pre-Neolithic, and the list continues to expand. The transfer of pathogens between hominin populations, including the expansion of pathogens from Africa, may also have played a role in the extinction of the Neanderthals and offers an important mechanism to understand hominin-hominin interactions well back beyond the current limits for aDNA extraction from fossils alone.
... Studies focusing on molar crown tissue proportions show that most fossil and extant Plio-Pleistocene hominins share absolutely and relatively thick enamel (Smith et al., 2012;Zanolli and Mazurier, 2013;Skinner et al., 2015;Zanolli, 2015;Pan et al., 2016), apart from the relatively thinly enameled Neanderthals (Macchiarelli et al., 2006(Macchiarelli et al., , 2013Olejniczak et al., 2008a) and for the condition of some isolated specimens (e.g., Zanolli et al., 2014). This does not, however, concern the still poorly explored existence of taxon/population-specific patterns in enamel thickness topographic distribution . ...
Since the early discovery of Pithecanthropus (Homo) erectus in 1891 at Trinil, over 200 hominid dental remains were unearthed on the island of Java, Indonesia. Most of this material, predominantly consisting of permanent teeth and jaw fragments, is commonly attributed to H. erectus, even if its morphological and dimensional features vary so vastly that some of the most robust specimens have been discussed for their belonging to different taxa (Meganthropus paleojavanicus, Pithecanthropus dubius, Pongo sp.). This extensive variability likely relates to the sea level eustatic fluctuations which cyclically affected the Sunda region during the Quaternary, allowing the formation of temporary land-bridges and the possibility for intermittent faunal exchanges with the Asian mainland. In this dynamic scenario, isolation phases have periodically affected and shaped biodiversity at regional scale.
We applied advanced methods of virtual imaging for finely characterizing the inner structural morphology of dentognathic remains from the Early-Middle Pleistocene deposits of the Sangiran Dome, Indonesia, and from the site of Zhoukoudian, China. For comparative purposes, the analyses also considered dental material representing South African early Homo, North African Homo aff. erectus, Neanderthals and extant humans, as well as extant and extinct Pongo as outliers.
The results obtained for the 2-3D crown tissue proportions, the enamel thickness topographic distribution, and the comparative geometric morphometric assessment of the enamel-dentine junction point to a hominid paleobiodiversity at Java during the Early to Middle Pleistocene likely more complex than usually recognized. We also recorded some subtle inner structural differences between Indonesian and Chinese H. erectus s.s.
representatives whose extent and possible meaning remain to be assessed on larger samples and at a larger scale in order to better appreciate the complex nature of the intermittent exchanges occurred through the Pleistocene between continental and insular Southeast Asia.
... Second, the EDJ morphology serves as precursor of the outer enamel surface morphology (Guy et al., 2013;Morita et al., 2014;Skinner et al., 2009a,b), that is then affected by enamel thickness distribution, reflecting dental functions, such as occlusion and feeding. Third, as various studies have indicated, the EDJ morphology is evolutionarily conserved and useful for estimating phylogenetic relationships among fossil hominoids (Korenhof, 1960;Kraus, 1952;Macchiarelli et al., 2006Macchiarelli et al., , 2013Olejniczak et al., 2007;Skinner et al., 2008Skinner et al., , 2009aSkinner et al., ,b, 2010Smith et al., 1997Smith et al., , 2000Suwa et al., 2007;Zanolli, 2015;Zanolli and Mazurier, 2013;Zanolli et al., 2014Zanolli et al., , 2015Zanolli et al., , 2016. ...
Clarifying morphological variation among African and Eurasian hominoids during the Miocene is of particular importance for inferring the evolutionary history of humans and great apes. Among Miocene hominoids, Nakalipithecus and Ouranopithecus play an important role because of their similar dates on different continents. Here, we quantify the lower fourth deciduous premolar (dp4) inner morphology of extant and extinct hominoids using a method of morphometric mapping and examine the phylogenetic relationships between these two fossil taxa. Our data indicate that early Late Miocene apes represent a primitive state in general, whereas modern great apes and humans represent derived states. While Nakalipithecus and Ouranopithecus show similarity in dp4 morphology to a certain degree, the dp4 of Nakalipithecus retains primitive features and that of Ouranopithecus exhibits derived features. Phenotypic continuity among African ape fossils from Miocene to Plio-Pleistocene would support the African origin of African apes and humans (AAH). The results also suggest that Nakalipithecus could have belonged to a lineage from which the lineage of Ouranopithecus and the common ancestor of AAH subsequently derived.
... African Middle Pleistocene hominins from Tighenif (Zanolli & Mazurier, 2013) are described as having complex 2R Tomes' root with four canals. ...
Objectives:
This study presents the first detailed morphological description and comparison of a Middle Pleistocene hominin mandibular fragment (PA 831) and associated teeth from the Hexian site in Eastern China. We aim to investigate where the Hexian mandible fits within the genus Homo variability in the light of an increased and better characterized Asian fossils record.
Methods:
Comparative samples include Pleistocene Homo mandibles and teeth from Africa, Asia, and Europe, as well as earlier African hominins (Australopithecus and early Homo) and Holocene recent humans. Both conventional morphological description and metric analysis were used. In addition, virtual reconstructions of the enamel dentine junction (EDJ) surface, pulp cavity, and roots with micro-CT were used to the mandible and teeth.
Results:
The Hexian mandible is characterized by a plesiomorphic structural pattern for the Homo clade, with strong corpus robustness and a subparallel and low-positioned mylohyoid line that differentiates the swollen subalveolar planum from the shallow subalveolar fossa. Features that are derived compared to early Homo include a moderately curved dental arcade, a well-developed lateral prominence placed at the M2 -M3 level, and multiple mental foramina. The Hexian mandible's complex enamel surface and strong, stout root structure are primitive traits for the Homo clade. Finally, the highly crenulated "dendrite-like" EDJ found in the molars may represent a dental feature specific to the continental Asian Homo erectus, but more data is needed to confirm this.
Conclusions:
Mandibular and dental features indicate that the Hexian mandible and teeth differ from northern Chinese H. erectus and European Middle Pleistocene hominins, but show some affinities with the Early Pleistocene specimens from Africa (Homo ergaster) and Java (H. erectus), as well as the Middle-Late Pleistocene mandible from Penghu, Taiwan. Compared to contemporaneous continental Asian hominin populations, the Hexian fossils may represent the survival of a primitive hominin, with more primitive morphologies than other contemporaneous or some chronologically older Asian hominin specimens.
... In considering dental morphology, we are severely limited by the lack of good data for this period from sub-Saharan Africa, while further north the Tighennif fossils from Algeria have been considered more primitive than the antecessor material [113]. However, endostructurally, the Tighennif dentitions were considered close to the status of a Neanderthal-modern LCA by Zanolli & Mazurier [114]. ...
If we restrict the use of Homo sapiens in the fossil record to specimens which share a significant number of derived features in the skeleton with extant H. sapiens , the origin of our species would be placed in the African late middle Pleistocene, based on fossils such as Omo Kibish 1, Herto 1 and 2, and the Levantine material from Skhul and Qafzeh. However, genetic data suggest that we and our sister species Homo neanderthalensis shared a last common ancestor in the middle Pleistocene approximately 400–700 ka, which is at least 200 000 years earlier than the species origin indicated from the fossils already mentioned. Thus, it is likely that the African fossil record will document early members of the sapiens lineage showing only some of the derived features of late members of the lineage. On that basis, I argue that human fossils such as those from Jebel Irhoud, Florisbad, Eliye Springs and Omo Kibish 2 do represent early members of the species, but variation across the African later middle Pleistocene/early Middle Stone Age fossils shows that there was not a simple linear progression towards later sapiens morphology, and there was chronological overlap between different ‘archaic’ and ‘modern’ morphs. Even in the late Pleistocene within and outside Africa, we find H. sapiens specimens which are clearly outside the range of Holocene members of the species, showing the complexity of recent human evolution. The impact on species recognition of late Pleistocene gene flow between the lineages of modern humans, Neanderthals and Denisovans is also discussed, and finally, I reconsider the nature of the middle Pleistocene ancestor of these lineages, based on recent morphological and genetic data.
This article is part of the themed issue ‘Major transitions in human evolution’.
Enamel thickness and distribution provide dietary insights in hominoids. Yet, three-dimensional (3D) enamel analysis of the Late Miocene Lufengpithecus from southwest China is lacking. We digitally reconstructed 68 unworn or lightly worn Lufengpithecus (L.) lufengensis molars using micro-computed tomography (micro-CT). Comparisons with modern humans, Homo erectus, extant/fossil Pongo, Pan, and Gorilla reveal L. lufengensis has "intermediate/thick" enamel, thicker than Pongo and Gorilla, but thinner than modern humans and H. erectus. In enamel distribution, relatively thicker enamel lies on the lingual cusps of the maxillary molars. The hypoconid, hypoconulid, and entoconid exhibit relatively thicker enamel compared to the metaconid and protoconid of the mandibular molars. L. lufengensis also exhibits an uneven pattern on the lingual and buccal walls. With relatively intermediate/thick enamel and distinctive distribution pattern, L. lufengensis may be able to respond to dietary variation in seasonal habitats.
To assess the phenotypic affinities of the Sima de los Huesos (SH) mandibular incisors dental tissue proportions, and radicular dimensions, relative to Neandertals, recent modern humans (RMH), and a large comparative sample of Pleistocene hominins. Two dimensional (2D) and three dimensional (3D) data were extracted from SH (n = 22) incisors, and compared with specimens from Krapina (n = 6) and Ehringsdorf (n = 2), RMH (n = 42), as well as a comparative sample of hominins from the literature (n = 244). We calculated average enamel thickness (AET), relative enamel thickness (RET) and radicular variables (cervical area [CA] and root surface area [RSA], root linear dimensions [RL], dentine and pulp volume [RDV, RPV, TRV]). We found that SH incisor crown variables were generally undiagnostic for 2D and 3D AET and 2D RET. Trends indicated thicker 3D RET in RMH relative to SH hominins, Tighenif hominins, and Neandertals. The SH and Neandertal mandibular incisors share similar RL, RSA, and root tissue volumes when compared to other extinct members of Homo. Relative to all other extinct hominins examined here, SH incisors display a relatively narrow cervical labio‐lingual diameter. Finally, we found a weak correlations in SH and RMH between the crown and root variables. This study confirms that SH mandibular incisors' dental tissue proportions and root dimensions align more closely to Neandertals. However, the complete set of Neandertal apomorphies is not present within SH mandibular incisors. SH incisors concur with traits reported in SH canines, and contrasting patterns in the molars, revealing a dichotomy between the anterior and posterior teeth for dental tissue proportions. Transparent image of AT‐2195, displaying enamel, dentine and pulp.
The scenario of Homo sapiens origin/s within Africa has become increasingly complex, with a pan‐African perspective currently challenging the long‐established single‐origin hypothesis. In this paper, we review the lines of evidence employed in support of each model, highlighting inferential limitations and possible terminological misunderstandings. We argue that the metapopulation scenario envisaged by pan‐African proponents well describes a mosaic diversification among late Middle Pleistocene groups. However, this does not rule out a major contribution that emerged from a single population where crucial derived features—notably, a globular braincase—appeared as the result of a punctuated, cladogenetic event. Thus, we suggest that a synthesis is possible and propose a scenario that, in our view, better reconciles with consolidated expectations in evolutionary theory. These indicate cladogenesis in allopatry as an ordinary pattern for the origin of a new species, particularly during phases of marked climatic and environmental instability.
The two- and three-dimensional assessment of dental tissues has become routine in human taxonomic studies throughout the years. Nonetheless, most of our knowledge of the variability of the enamel and dentine dimensions of the human evolutionary lineage comes from the study of permanent dentition, and particularly from molars. This leads to a biased view of the variability of these features. Due to their early formation and rapid development, the deciduous teeth allow more simplified inferences regarding the processes involved in the dental tissue development of each group. Therefore, their study could be very valuable in dental palaeohistology. In this research, we have explored the dental tissue proportions of the deciduous canines belonging to some human samples of the Early and Middle Pleistocene. The purpose of this was to discuss the meaning of the similarities and differences observed in their histological pattern, as well as to evaluate the degree of covariance with that observed in the permanent dentition of these populations. Our results show that, although there are some similarities in the dental tissue proportions between the deciduous and permanent canines of the study samples, the two dental classes do not provide a similar or comparable pictures of the dental tissue pattern present in the dentition of fossil hominins. Future works on the dental tissue patterns of the anterior and posterior dentition, including deciduous teeth, of fossil samples, may help to shed light on this hypothesis.
Extensive fieldwork at Abocador de Can Mata (north-east Iberian Peninsula) has uncovered a previously unsuspected diversity of catarrhine primates in the middle Miocene (12.5–11.6 Ma) of Europe. However, the distinction of the great ape genera Pierolapithecus and Anoiapithecus from Dryopithecus (supported by craniodental differences) has been disputed by some authors. Here we revisit the diversity of great apes (dryopithecines) from the Iberian Miocene based on molar 3D endostructural morphology (relative enamel thickness, enamel distribution, and enamel–dentine junction (EDJ)). Using microtomography, we inspected an extensive sample of 49 hominoid molars representing at least five species from 12 localities. 2D and 3D relative enamel thickness values indicate that Dryopithecus and ‘Sivapithecus’ occidentalis (species inquirenda) display the thinnest and thickest enamel, respectively, while the remaining taxa (Hispanopithecus, Anoiapithecus, Pierolapithecus) show intermediate values. Upper molar enamel distribution maps exhibit a similar pattern in P. catalaunicus, A. brevirostris, D. fontani, H. laietanus and H. crusafonti whereas for the lower molars they reveal differences between H. laietanus and H. crusafonti. Lower molar enamel distribution and EDJ morphology of ‘S.’ occidentalis support the distinction of this species but do not resolve whether it is a junior synonym of Anoiapithecus brevirostris or Pierolapithecus catalaunicus. Overall our results support the distinction of middle Miocene dryopithecins from late Miocene hispanopithecins, the distinction of Pierolapithecus and Anoiapithecus from Dryopithecus among the former, and the distinct species status of H. crusafonti compared to H. laietanus among the latter. Our results highlight the potential of inner tooth morphology for hominoid alpha-taxonomy.
New finds in the palaeoanthropological and genomic records have changed our view of the origins of modern human ancestry. Here we review our current understanding of how the ancestry of modern humans around the globe can be traced into the deep past, and which ancestors it passes through during our journey back in time. We identify three key phases that are surrounded by major questions, and which will be at the frontiers of future research. The most recent phase comprises the worldwide expansion of modern humans between 40 and 60 thousand years ago (ka) and their last known contacts with archaic groups such as Neanderthals and Denisovans. The second phase is associated with a broadly construed African origin of modern human diversity between 60 and 300 ka. The oldest phase comprises the complex separation of modern human ancestors from archaic human groups from 0.3 to 1 million years ago. We argue that no specific point in time can currently be identified at which modern human ancestry was confined to a limited birthplace, and that patterns of the first appearance of anatomical or behavioural traits that are used to define Homo sapiens are consistent with a range of evolutionary histories.
Following the recent studies of East Asian mid-Middle to early Late Pleistocene hominin material, a large spectrum of morphological diversity has been recognized and the coexistence of archaic ('Homo erectus-like') and derived ('modern-like') dental morphological patterns has been highlighted. In fact, for most of these Chinese fossils, generally categorized as 'archaic Homo sapiens' or 'post-H. erectus Homo', the taxonomic attribution is a matter of contention. With the help of μCT techniques and a deformation-based 3D geometric morphometric approach, we focused on the morphological variation in the enamel-dentine junction (EDJ) of 18 upper and lower premolars from Chinese Middle Pleistocene hominins. We then compared our results with a number of fossil and modern human groups, including Early Pleistocene H. erectus from Sangiran; late Early Pleistocene hominins from Tighenif, Algeria; classic Neanderthals; and modern humans. Our results highlight an evolutionary/chronological trend of crown base reduction, elevation of EDJ topography, and EDJ surface simplification in the hominin groups studied here. Moreover, this study brings insights to the taxonomy/phylogeny of 6 late Middle Pleistocene specimens whose evolutionary placement has been debated for decades. Among these specimens, Changyang premolars show features that can be aligned with the Asian H. erectus hypodigm, whereas Panxian Dadong and Tongzi premolars are more similar to Late Pleistocene Homo. Compared with early to mid-Middle Pleistocene hominins in East Asia, late Middle Pleistocene hominins evince an enlarged morphological variation. A persistence of archaic morphotypes and possible admixture among populations during the late Middle Pleistocene are discussed.
Objectives:
The aim of this study is to understand whether the shape of three sub-regions of the mandibular corpus (the alveolar arch, corpus at M1 and posterior symphysis) are useful for making taxonomic assessments at the genus and species levels in extant hominids.
Materials and methods:
We use data taken from 3D surface scans of the mandibular corpus of seven extant hominid taxa: Gorilla gorilla gorilla, Gorilla beringei graueri, Homo sapiens, Pan paniscus, Pan troglodytes schweinfurthii, Pongo abelii, and Pongo pygmaeus pygmaeus to generate four shape variables: alveolar arch shape (AAS), corpus shape at M1 (CSM1 ), posterior symphysis shape at the midline (PSSM), and posterior symphysis shape (PSS). To ascertain how reliable each mandibular shape variable is for assessing taxonomy, we ran canonical discriminant and discriminant function analysis, reporting cross-validated results.
Results:
Using a combination of three mandibular corpus shape variables, 99% of specimens were classified correctly for genus-level analyses. A maximum of 100% of Pan specimens, 94% of Gorilla specimens and 96% of Pongo specimens were classified correctly at the species level when up to three mandibular shape variables were included in the analyses. When mandibular corpus variables were considered in isolation, posterior symphysis shape yielded the highest overall correct classification results.
Discussion:
The high taxonomic classification rates at both the genus and species level, using 3D surface data and advanced quantification techniques, show that the shape of the alveolar arch, corpus at M1 and symphysis can distinguish extant hominid taxa. These findings have implications for assessing the taxonomy of extinct hominid specimens which preserve these mandibular sub-regions.
How healthy were our ancestors? What are the costs and benefits of our interbreeding with other human species? Health is a constant battle between our genetic heritage and the adequacy of lifestyle in a given environment. We discuss how humans can preserve individual weaknesses despite the different infirmities afflicting their body and mind, resulting in increasingly longer lifespans. By probing into ancient funerary rites, tombs and relics we can envisage societal formation and discuss conflicting interests in the ownership of ancient remains.
This study investigates permanent maxillary and mandibular premolar root structural organization in East Asian Middle Pleistocene hominins. In addition to reporting and analyzing the linear and volumetric properties of the roots, we used a landmark-free approach to both qualify and quantify in 3D premolar root shape variation of Middle Pleistocene hominins in East Asia. Moreover, we focus on some mid-to late East Asian Middle Pleistocene hominin specimens whose taxonomic attribution is unclear. We find considerable cementum in this sample of hominins, similar to other fossil groups, but clearly different from modern humans which have a very small amount of cementum. Additionally, a smaller root pulp cavity is found in later Homo (Neanderthals and modern humans). Our analyses on the crown-root surface area ratio show that East Asian Middle Pleistocene Homo erectus as well as one late Middle Pleistocene Homo sp. specimen (PA 81 P4 from Changyang site) are distinguished from other fossil and extant groups by a relatively larger root surface, stout root branches and thick cementum deposits. This may represent a distinct East Asian H. erectus dental pattern. Geometric morphometric analyses on the external root surface reveal a general trend of shape simplification along the Homo lineage examined here, and distinguish Early Pleistocene Homo, Middle Pleistocene H. erectus, Neanderthals and modern human morphologies. The late Middle Pleistocene teeth from Changyang site (PA 76 P3 and PA 81 P4) are close to East Asian H. erectus and Neanderthals, while the mid-Middle Pleistocene P3 from Panxian Dadong falls within the modern human distribution. Combined with dental crown morphology and root number/form reported in previous studies, our results show that the external root shape can be considered a taxonomically relevant indicator. In general, an evolutionary tendency towards modern human morphology is observed in part of the East Asian Middle Pleistocene specimens, while a retention of primitive, H. erectus-like features is expressed in some late Middle Pleistocene specimens, supporting a multi-lineage and discontinuous scenario of human settlements in East Asia.
The mandibular third premolar (P3) exhibits substantial differences in size and shape among hominoid taxa, and displays a number of discrete traits that have proven to be useful in studies of hominin taxonomy and phylogeny. Discrete traits at the enamel-dentine junction (EDJ) can be accurately assessed on moderately worn specimens, and often appear sharper than at the outer-enamel surface (OES). Here we use microtomography to image the P3 EDJ of a broad sample of extant apes, extinct hominins and modern humans (n = 100). We present typologies for three important premolar discrete traits at the EDJ (transverse crest, marginal ridge and buccal grooves), and score trait frequencies within our sample. We find that the transverse crest is variable in extant apes, while the majority of hominins display a transverse crest which runs directly between the two major premolar cusps. Some Neanderthals display a unique form in which the transverse crest fails to reach the protoconid. We find that mesial marginal ridge discontinuity is common in Australopithecus anamensis and Australopithecus afarensis while continuous marginal ridges largely characterize Australopithecus africanus and Paranthropus. Interrupted mesial and distal marginal ridges are again seen in Homo sapiens and Neanderthals. Premolar buccal grooves, previously identified at the OES as important for hominin systematics, are again found to show a number of taxon-specific patterns at the EDJ, including a clear difference between Australopithecus and Paranthropus specimens. However, their appearance may be dependent on the morphology of other parts of the crown such as the protoconid crest, and the presence of accessory dentine horns. Finally, we discuss rare variations in the form of dentine horns that underlie premolar cusps, and their potential homology to similar morphologies in other tooth positions.
The craniomandibular morphology of Homo naledi shows variable resemblances with species across Homo, which confounds an easy assessment of its phylogenetic position. In terms of skull shape, H. naledi has its closest affinities with Homo erectus, while mandibular shape places it closer to early Homo. From a tooth crown perspective, the smaller molars of H. naledi make it distinct from early Homo and H. erectus. Here, we compare the mandibular molar root morphology of six H. naledi individuals from the Dinaledi Chamber to those of African and Eurasian Plio-Pleistocene fossil hominins (totalling 183 mandibular first, second and third molars). The analysis of five root metric variables (cervical plane area, root length, root cervix volume, root branch volume, and root surface area) derived from microCT reconstructions reveals that the molar roots of H. naledi are smaller than those of Homo habilis, Homo rudolfensis, and H. erectus, but that they resemble those of three Homo sp. specimens from Swartkrans and Koobi Fora in size and overall appearance. Moreover, though H. naledi molar roots are similar in absolute size to Pleistocene Homo sapiens, they differ from H. sapiens in having a larger root volume for a given cervical plane area and less taurodont roots; the root cervix-to-branch proportions of H. naledi are comparable to those of Australopithecus africanus and species of Paranthropus. H. naledi also shares a metameric root volume pattern (M2 > M3 > M1) with Australopithecus and Paranthropus but not with any of the other Homo species (M2 > M1 > M3). Our findings therefore concur with previous studies that found that H. naledi shares plesiomorphic features with early Homo, Australopithecus, and Paranthropus. While absolute molar root size aligns H. naledi with Homo from North and South Africa, it is distinguishable from these in terms of root volumetric proportions.
Objectives
Middle Pleistocene fossil hominins, often summarized as Homo heidelbergensis sensu lato, are difficult to interpret due to a fragmentary fossil record and ambiguous combinations of primitive and derived characters. Here, we focus on one aspect of facial shape and analyze shape variation of the dental arcades of these fossils together with other Homo individuals.
Materials and Methods
Three‐dimensional landmark data were collected on computed tomographic scans and surface scans of Middle Pleistocene fossil hominins (n = 8), Homo erectus s.l. (n = 4), Homo antecessor (n = 1), Homo neanderthalensis (n = 13), recent (n = 52) and fossil (n = 19) Homo sapiens. To increase sample size, we used multiple multivariate regression to reconstruct complementary arches for isolated mandibles, and explored size and shape differences among maxillary arcades.
Results
The shape of the dental arcade in H. erectus s.l. and H. antecessor differs markedly from both Neanderthals and H. sapiens. The latter two show subtle but consistent differences in arcade length and width. Shape variation among Middle Pleistocene fossil hominins does not exceed the amount of variation of other species, but includes individuals with more primitive and more derived morphology, all more similar to Neanderthals and H. sapiens than to H. erectus s.l.
Discussion
Although our results cannot reject the hypothesis that the Middle Pleistocene fossil hominins belong to a single species, their shape variation comprises a more primitive morph that represents a likely candidate for the shape of the last common ancestor of Neanderthals and H. sapiens, and a more derived morph resembling Neanderthals. The arcade shape difference between Neanderthals and H. sapiens might be related to different ways to withstand mechanical stress.
This study explores the morphological differences between the enamel–dentine junction (EDJ) of maxillary and mandibular molars of Neanderthals (n = 150) and recent modern humans (n = 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 M3 in shape space. The cervix in isolation can also discriminate between Neanderthals and recent modern humans, except at the M3 in form space, and is effective at discriminating between the earlier and the later Neanderthal samples, except at the M²/M2 in form space. In addition to demonstrating the taxonomic 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.
The Aterian fossil hominins represent one of the most abundant series of human remains associated with Middle Stone Age/Middle Paleolithic assemblages in Africa. Their dates have been revised and they are now mostly assigned to a period between 90 and 35 ka. Although the Aterian human fossil record is exclusively Moroccan, Aterian assemblages are found throughout a vast geographical area extending to the Western Desert of Egypt. Their makers represent populations that were located close to the main gate to Eurasia and that immediately predated the last out-of-Africa exodus. In this chapter, we present an analysis of the Aterian dental remains. The sizes of the Aterian dentitions are particularly spectacular, especially for the post-canine dentition. This massiveness is reminiscent of the Middle Paleolithic modern humans from the Near East, but also of the early Homo sapiens in North and East Africa. Morphologically, this megadontia is expressed in the development of mass-additive traits. The Aterian dentition also displays relatively thick enamel. These features help to set some of the traits observed in Neandertals in perspective and highlight their primitive or derived nature. The Aterian morphological pattern is also important to consider when interpreting the dental morphology of the first modern humans in Eurasia.
Dental enamel thickness is commonly listed among the diagnostic features for taxonomic assessment and phylogenetic reconstruction in the study of fossil homi nids, and is widely used as an indicator of dietary habits and palaeoen-vironmental conditions. However, little quantitative information is currently available on its topographic variation in deciduous crowns of fossil primates. By means of high-resolution microtomography, we investigated the inner structural morphology of the mixed lower dentition of Ouranopithecus macedoniensis, a late Miocene large-bodied ape from Macedonia, Greece. With respect to the extant African apes and Homo, O. macedoniensis shows a significant difference in occlusal enamel thickness between the relatively thin deciduous second molar and the absolutely thick-enamelled permanent first molar. © Publications Scientifiques du Muséum national d'Histoire naturelle, Paris.
Ouranopithecus macedoniensis (Mammalia, Primates, Hominoidea): reconstruction virtuelle et analyse 3D d'une denture inférieure juvénile (RPl-82 et RPl-83). L'épaisseur de l'émail dentaire est couramment incluse parmi les traits diagnostiques pour l'attribution taxinomique et la reconstruction phylogénétique dans l'étude des hominidés fossiles, et elle est aussi utilisée comme indicateur d'habitudes alimentaires et de conditions paléoenvironnementales. Cependant, peu d'informations quantitatives sont disponibles à ce jour concernant sa variation topographique dans les couronnes déciduales des primates fossiles. Grâce à la microtomographie à haute résolution, nous avons exploré la morphologie structurale interne de la denture inférieure mixte d' Ouranopithecus macedoniensis, un grand singe du Miocène supérieur de Macédoine, Grèce. Par rapport aux grands singes africains actuels et à Homo, O. macedoniensis montre une différence significative dans l'épaisseur de l'émail occlusal entre la deuxième molaire déciduale, relativement fine, et la première molaire permanente, très épaisse.
For the past 25 years NIH Image and ImageJ software have been pioneers as open tools for the
analysis of scientific images. We discuss the origins, challenges and solutions of these two programs,
and how their history can serve to advise and inform other software projects.
This paper explores the potential of high-resolution computed tomography (CT) as a morphometric tool in paleoanthropology. The accuracy of linear measurements of enamel thickness and cortical bone thickness taken from CT scans is evaluated by making comparison with measurements taken directly from physical sections. The measurements of cortical bone are taken on extant and fossil specimens with and without attached matrix, and the dental specimens studied include a sample of 12 extant human molars. Local CT numbers (representing X-ray, attenuation) are used to determine the exact position of the boundaries of a structure. Using this technique most studied dimensions, including four of human molar enamel thickness, could be obtained from CT scans with a maximum error range of ±0.1 mm. The limitations of the method are discussed with special reference to problems associated with highly mineralized fossils. © 1993 Wiley-Liss, Inc.
The species Homo heidelbergensis is central to many discussions about recent human evolution. For some workers, it was the last common ancestor for the subsequent species Homo sapiens and Homo neanderthalensis; others regard it as only a European form, giving rise to the Neanderthals. Following the impact of recent genomic studies indicating hybridization between modern humans and both Neanderthals and "Denisovans", the status of these as separate taxa is now under discussion. Accordingly, clarifying the status of Homo heidelbergensis is fundamental to the debate about modern human origins.
Linear discriminant analysis (LDA) is a multivariate classification technique frequently applied to morphometric data in various
biomedical disciplines. Canonical variate analysis (CVA), the generalization of LDA for multiple groups, is often used in
the exploratory style of an ordination technique (a low-dimensional representation of the data). In the rare case when all
groups have the same covariance matrix, maximum likelihood classification can be based on these linear functions. Both LDA
and CVA require full-rank covariance matrices, which is usually not the case in modern morphometrics. When the number of variables
is close to the number of individuals, groups appear separated in a CVA plot even if they are samples from the same population.
Hence, reliable classification and assessment of group separation require many more organisms than variables. A simple alternative
to CVA is the projection of the data onto the principal components of the group averages (between-group PCA). In contrast
to CVA, these axes are orthogonal and can be computed even when the data are not of full rank, such as for Procrustes shape
coordinates arising in samples of any size, and when covariance matrices are heterogeneous. In evolutionary quantitative genetics,
the selection gradient is identical to the coefficient vector of a linear discriminant function between the populations before
vs. after selection. When the measured variables are Procrustes shape coordinates, discriminant functions and selection gradients
are vectors in shape space and can be visualized as shape deformations. Except for applications in quantitative genetics and
in classification, however, discriminant functions typically offer no interpretation as biological factors.
KeywordsCanonical variate analysis–Linear discriminant function–Ordination–Principal component analysis–Procrustes–Selection gradient
A new multidisciplinary research program, started in 1981, provided new data on the stratigraphy, fauna, and human industries, as well as the first results on paleomagnetism and sedimentology, for the Ternifine site in Algeria, which yielded the earliest hominid remains known in North Africa. The fossils were deposited in a swamp or lake surrounded by a very open, dry environment. The lake was fed by artesian springs that raised the underlying Miocene sands. Although nothing suggests a camp or butchery site, we discovered the first undisputable bone artifact in this site, the earliest known in this part of Africa. According to paleontological data, 700,000 yr B.P. is a likely age for the Ternifine deposits, which is consistent with the paleomagnetic results.
The fossil remains from the Sima de las Palomas add to the small sample of caries lesions affecting Neandertals and reinforce the pattern of oral pathology that has been emerging for these late archaic humans. Alveolar lesions, ante mortem tooth loss, and orthodontic problems, as well as caries lesions, remain rare, in the context of high levels of occlusal and interproximal attrition, dental supereruption, and calculus accumulation. This implies a level of oral health rarely seen in more recent, sedentary human populations without routine dental care. As such, the Neandertal pattern, reinforced by the Palomas specimens, may provide a framework against which to view the abundant dentoalveolar abnormalities of recent human populations. This oral health pattern is accompanied by the abnormalities of the Palomas 59 second molar. As with a number of both Neandertal (Trinkaus, 1983; Fennell and Trinkaus, 1997) and early modern human (Formicola and Buzhilova, 2004; Trinkaus et al., 2006; Shang and Trinkaus, 2010) sets of lesions, the abnormalities are obvious, the proximate causes are sometimes apparent, but the ultimate etiologies remain obscure. Diagnosis is inhibited by incomplete fossil preservation, as with Palomas 59. Yet, these lesion patterns raise the issue of changing developmental and degenerative pathological patterns through human evolution. © 2011 International & American Associations for Dental Research.
Bringing together a variety of accomplished dental researchers, this book covers a range of topics germane to the study of human and other primate teeth. The chapters encompass work on individuals to samples, ranging from prehistoric to modern times. The focus throughout the book is the methodology required for the study of modern dental anthropology, comprising the scientific methods in use today - ranging from simple observation to advanced computer-based analyses - which can be utilized by the reader in their own dental research. Originating from the 20th anniversary meeting of the Dental Anthropology Association, this is a valuable reference source for graduate students, academic researchers and professionals in the social and life sciences, as well as clinicians.
Homo erectus: for some a single, widely dispersed, polytypic species ultimately ancestral to all later Homo, for others a regional, Asian isolate, a sidebranch of later hominin evolution. In some views, the definition of H. erectus expands to include all Early and Middle Pleistocene fossils from Africa, Europe, and Asia, whereas other views exclude the European fossils and still others include only portions of the Asian fossil record. Temporally, H. erectus may thus span from 1.8 to perhaps 0.025 Ma. In this chapter, we discuss the importance of body and brain size in the characterization of H. erectus. We also provide a historical review of the recovery of the fossil record of H. erectus because the understanding of its body size, the relationship between body and brain size, and the importance of the influence of scale on the cranial characters used in defining the taxon are all issues whose interpretation was in large part determined by the order and context in which fossil remains were recovered. We find evidence of clinal variation in stature in H. erectus, and across the taxon body size (stature) does not increase with time, whereas brain size gradually increases at a rate of about 160 cm3/Myr. Cranial characters, particularly those related to vault thickness and development of the supraorbital torus and many of those related to differentiating African from Asian H. erectus, scale with brain size in H. erectus yielding little support for a differentiation between H. erectus and H. ergaster. In contrast, H. erectus is clearly differentiated from H. sapiens in terms of the scaling relationship between brain and body size and between brain size and several cranial measurements, including foramen magnum length. On these same relationships, it is difficult to differentiate the smallest H. erectus from the largest H. habilis.
The Human Fossil Record series is the most authoritative and comprehensive documentation of the fossil evidence relevant to the study of our evolutionary past. This second volume covers the craniodental remains from Africa and Asia attributed to the genus Homo. In this monumental and groundbreaking new series, the authors use clearly defined terminology and descriptive protocols that are applied uniformly throughout. Organized alphabetically by site name with detailed morphological descriptions and original, expertly taken photographs, each entry features: Location information. History of discovery. Previous systematic assessments of the fossils. Geological, archaeological, and faunal contexts. Dating. References to the primary literature. © 2003 Jeffrey H. Schwartz and Ian Tattersall. All rights reserved.
Different views exist on the pattern of Middle Pleistocene evolution in Africa. Some favor a splitting into two or more species, for example, Homo heidelbergensis, Homo helmei, and Homo sapiens, whereas others see evidence for a continuously evolving lineage of only one chronospecies, Homo sapiens sensu lato. This latter view then considers the one chronospecies to be separated further into several subspecies, grades, steps, paleo-demes or other entities. The question is, which of these diverse perspectives is best supported by the current evidence? There is also some disagreement about the geographic pattern of the anatomical modernization process. Although there is clear evidence that northern, eastern, and southern Africa were involved, it appears difficult to assess the distinct roles of the different regions within this long-term process. Interregional migration, for example, during periods of a “green Sahara” might have led to complex patterns.
The recent application of microtomographic techniques to dental morphological studies has revealed an untapped source of biological information about extinct and extant human populations. In particular, this methodology has helped to characterize internal dental structures (enamel-dentine junction, pulp chamber, and radicular canals), maximizing the amount of information that can be extracted from a given specimen. In this study, we present a three-dimensional evaluation of the dental roots of the Sima del Elefante mandible, ATE9-1 (Atapuerca, Spain) by visual inspection, and by tomographic and microtomographic techniques. With 1.3 Myrs of age, this fossil represents the earliest hominin remains in Europe, and one of the very few human fossils for this period and region. Through this case study we aim to present a protocol for the description of the internal dental spaces, exemplify how the application of microtomographic techniques can significantly increase the amount of relevant and informative morphological features (even in the case of fragmentary/heavily worn teeth or teeth with hypercementosis), and explore some biological considerations about external and internal root morphology. There is neither a general nor straightforward correspondence between the external root morphology and the root canals. In cases where a high degree of hypercementosis is present, the external root anatomy can be highly confusing. Indeed the assessment of the internal root anatomy of ATE9-1 teeth has led us to the reclassification of the LC and the LP3 with respect to previous publications. The results of this study suggest that internal root anatomy could be used as a complementary source of biological information.
Bringing together a variety of accomplished dental researchers, this book covers a range of topics germane to the study of human and other primate teeth. The chapters encompass work on individuals to samples, ranging from prehistoric to modern times. The focus throughout the book is the methodology required for the study of modern dental anthropology, comprising the scientific methods in use today - ranging from simple observation to advanced computer-based analyses - which can be utilized by the reader in their own dental research. Originating from the 20th anniversary meeting of the Dental Anthropology Association, this is a valuable reference source for graduate students, academic researchers and professionals in the social and life sciences, as well as clinicians.
The present study of three human upper deciduous molars from the early Middle Pleistocene site of Tighenif, Algeria, constitutes the first microtomographic-based endostructural exploration of African fossil teeth likely representative of the Homo heidelbergensis morph. Comparative morphological observations and 2-3D measurements describing subtle tooth organization (crown tissue proportions) and enamel thickness topography (site-specific distribution and global patterning) indicate that their virtual extracted structural signature better fits the modern human, rather than the Neanderthal condition. Accordingly, we predict that the inner structural morphology of the deciduous molars from the Middle Pleistocene western European series better fits the primitive, and not the derived Neanderthal figures.