Clément Zanolli

Lisa Genochio
email: lisa.gh@free.fr

Jean-Francois Tournepiche

Arnaud Mazurier
email: arnaud.mazurier@univ-poitiers.fr

Roberto Macchiarelli
email: roberto.macchiarelli@univ-poitiers.fr

Clement Zanolli
email: clement.zanolli@gmail.com

The Neanderthal

Keywords: OIS 5e). Dental tissue proportions, cortical bone distribution and endostructural asymmetry La Chaise-de-Vouthon, Eemian, Neanderthal mandible, tooth endostructure, cortical bone thickness, asymmetry La Chaise-de-Vouthon, Eémien, mandibule néandertalienne, endostructure dentaire, épaisseur corticale, asymétrie

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ABSTRACTS

The 23 fossil human remains found at La Chaise-de-Vouthon Abri Bourgeois-Delaunay (Charente, Southwestern France) are all attributed to Neanderthals. The BD 1 mandible represents one of the best preserved specimens recovered in this assemblage, still bearing the entire set of 16 teeth, and attributed to an adult -likely 20-35 years old -individual. The geochronological and paleontological data indicate that the Neanderthals from Abri Bourgeois-Delaunay lived in a temperate environment between 127 and 116 ka (i.e., during the OIS 5e).

In this study, we integrate and expand the morphometric record of BD 1 by quantifying the tissue proportions of its entire permanent dentition, including radicular thickness repartition of four front teeth, and comparing its degree of endostructural asymmetry in tooth tissue organization and postcanine cortical bone topography with the patterns shown by Regourdou 1. Our results show that crown and radicular dental internal signature is typically Neanderthal, comparable with the available data for Regourdou 1, and is unambiguously distinct from the fossil and extant modern human patterns. Asymmetry in tooth tissue proportions in BD 1 and Regourdou 1 is clearly non-directional, as side dominance is nearly equally distributed between the left and the right antimeres. Similarly, both Neanderthal mandibles show no marked cortical bone asymmetry at the molar level, even if a slight right dominance is found in BD 1. Even if these results are globally consistent for the two Neanderthal mandible, extensive methodological research on the patterns of age-and sex-related endostructural variation displayed by human population samples from diverse chrono-geographic, socio-economic and biocultural contexts is still needed to more confidently evaluate the evolutionary and adaptive significance of the signals from the fossil record.

Les 23 restes humains fossiles découverts à La Chaise-de-Vouthon Abri Bourgeois-Delaunay (Charente, Sud-Ouest de la France) sont tous attribués à des Néandertaliens. La mandibule BD 1 représente un des spécimens les mieux préservés de l'assemblage, conservant encore ses 16 dents, et a été attribuée à un individu adulte -vraisemblablement âgé d'environ 20-35 ans. Les données géochronologiques et paléontologiques indiquent que les Néandertaliens de l'Abri Bourgeois-Delaunay vivaient dans un environnement tempéré il y a environ 127 à 116 ka (i.e., pendant l'OIS 5e). Dans cette étude, nous apportons des informations morphométriques complémentaires sur la structure de BD 1 en quantifiant les proportions des tissus de l'ensemble de ses dents permanentes, incluant la distribution d'épaisseur de dentine radiculaire de quatre

To André Debénath

Introduction

The Middle to Late Pleistocene site complex of La Chaise-de-Vouthon, in the department of Charente, western France, is located on the left bank of an affluent of the Charente River, the Tardoire. It is located within a Middle Jurassic (Bajocian/Bathonian) limestone platform which underwent intense erosion across the Cenozoic (Tournepiche 1998) resulting in the formation of a network of mainly NW-oriented rock shelters and karstic cavities. The galleries extend over several tens of meters and open out c. 10 m above the Tardoire River through three main cave shelters ("porches"): Duport, Bourgeois-Delaunay and Suard (Debénath 1974a[START_REF] Debénath | -The latest finds of antewürmian human remains in Charente (France)[END_REF][START_REF] Debénath | Néanderthaliens et Cro-Magnons. Les temps glaciaires dans le Bassin de la Charente[END_REF]. This prehistoric locality was discovered in 1850 by J. Fermond and, following some preliminary field work conducted since 1865 by the abbots Bourgeois and Delaunay, it was excavated starting in the '30s by P. David, especially between 1945and 1963, and then by A. Debénath, between 1967and 1983(Debénath 1974a[START_REF] Debénath A | Bibliographie des sites de La Chaise-de-Vouthon (Charente)[END_REF], 2006;[START_REF] Debénath | Préhistoire de la Charente[END_REF].

Human fossil remains at La Chaise-de-Vouthon, all attributed to Neanderthals, have been so far discovered at the Abri Suard, the Abri Bourgeois-Delaunay and, more recently, at the Tour of La Chaise cave ("grotte de la Tour"). The deposits of the Abri Suard and Abri Bourgeois-Delaunay, mostly of lacustrine origin and covered by a colluvial sequence intercalated with slump deposits and speleothems (Bertran 1999), were originally referred to a period ranging from Riss II to Riss-Würm, and from Riss III to Würm III, respectively (Debénath 1974a[START_REF] Debénath | -The latest finds of antewürmian human remains in Charente (France)[END_REF][START_REF] Debénath | Néanderthaliens et Cro-Magnons. Les temps glaciaires dans le Bassin de la Charente[END_REF][START_REF] Schvoerer | -Datation absolue par thermoluminescence des restes humains antéwürmiens de l'abri Suard à la Chaise de Vouthon (Charente)[END_REF]Schwarcz and Debénath 1979;Blackwell et al. 1983Blackwell et al. , 1990Blackwell et al. , 1992)).

According to a set of 230 Th/ 234 U speleothem dates [START_REF] Couchoud | Étude pétrographique et isotopique de spéléothèmes du Sud-Ouest de la France formés en contexte archéologique: contribution à la connaissance des paléoclimats régionaux du Stade Isotopique 5[END_REF][START_REF] Vieillevigne | -Analyse croisée des données chronologiques et des industries lithiques dans le grand sud-ouest de la France (OIS 10 à 3)[END_REF], the human remains from the Abri Suard, associated to a typically cold mammal fauna [START_REF] Griggo C | Etablissement de courbes climatiques quantifiées à partir des communautés animales pléistocènes suivi d'une application aux gisements de l'abri Suard et de la grotte du Bois Ragot (Vienne)[END_REF]; see also Bouchud and Bouchud 1953;[START_REF] David | -Considérations sur les faunes de la Chaise (commune de Vouthon, Charente). Abris Suard et Bourgeois Delaunay[END_REF], belong to the Oxygen Isotope Stage (OIS) 6 and are likely younger than 163 thousand years (ka), while the age of the human fossil assemblage from Bourgeois-Delaunay, associated to a temperate fauna (Armand 1998; see also [START_REF] David | -Considérations sur les faunes de la Chaise (commune de Vouthon, Charente). Abris Suard et Bourgeois Delaunay[END_REF], is estimated between 127 and 116 ka, i.e., to the OIS 5e [START_REF] Debénath | Néanderthaliens et Cro-Magnons. Les temps glaciaires dans le Bassin de la Charente[END_REF]. The Tour of La Chaise cave, located about 130 m W of the Suard rock shelter, was discovered in 2006 during speleological exploration. So far, it has provided a fossil human femoral shaft from a typically hyena den context whose mammal assemblage suggests a chronological attribution to the OIS 3 [START_REF] Puymerail | -A Neanderthal partial femoral diaphysis from the "grotte de la Tour", La Chaise-de-Vouthon (Charente, France): outer morphology and endostructural organization[END_REF]cf. Tournepiche 1996cf. Tournepiche , 2010)).

The human fossil record from La Chaise-de-Vouthon consists of a whole of at least 76 dental (including isolated teeth), cranial and postcranial remains representing subadult and adult individuals. Specifically, 52 specimens come from Suard, 23 from Bourgeois-Delaunay and one from the Tour of La Chaise [START_REF] David | -Découverte d'une calotte crânienne fragmentaire et de dents humaines dans un niveau moustérien de La Chaise (Charente)[END_REF]David and Piveteau 1953a, b;[START_REF] Piveteau | Remarques sur la structure de l'Homme moustérien (gisement de La Chaise, Charente)[END_REF][START_REF] Piveteau | -Les grottes de La Chaise (Charente). L'Homme de l'abri Suard[END_REF][START_REF] Debénath A | -Découverte d'une mandibule humaine à la Chaise-de-Vouthon (Charente)[END_REF]Debénath , 1974b[START_REF] Debénath | -The latest finds of antewürmian human remains in Charente (France)[END_REF][START_REF] Debénath | -Nouvelles découvertes de restes humains fossiles à La Chaise de Vouthon (Charente). Position stratigraphique des restes humains de La Chaise (abri Bourgeois-Delaunay)[END_REF][START_REF]-Etude des dents humaines isolées provenant des grottes de la Chaise-de-Vouthon (Charente)[END_REF], 1975a, b, 1976;[START_REF] Thoma A | L'occipital de la grotte Bourgeois-Delaunay (La Chaise, Charente). Etude biométrique[END_REF][START_REF] Legoux P | -Les dents de la Chaise-de-Vouthon. Etude pathologique et radiologique[END_REF][START_REF] Lacombe | Etude anatomique d'un pariétal ante-würmien provenant du gisement de La Chaise de Vouthon (Charente). Sa place parmi les fossiles humains antenéandertaliens[END_REF][START_REF] Saban R | -Les pariétaux humains de La Chaise (grotte Suard) et leur empreintes vasculaires (veines méningées moyennes)[END_REF][START_REF] Krukoff S | L'occipital de La Chaise (Suard), caractères métriques, distances de forme et de format[END_REF][START_REF]La Chaise Suard, Engis 2 et La Quina H18: développement de la morphologie occipitale externe chez l'enfant prénéandertalien et néandertalien[END_REF][START_REF]-La plus ancienne mandibule d'enfant découverte en France dans le gisement de La Chaise de Vouthon (Abri Suard) en Charente[END_REF][START_REF] Piveteau | -L'os temporal Riss-Würm (BD 7) provenant de la grotte de La Chaise (abri Bourgeois-Delaunay)[END_REF][START_REF] Coqueugniot | -L'os frontal immature de la Chaise S.15 (Abri Suard, La Chaise-de-Vouthon, Charente)[END_REF][START_REF] Condemi | Les Néandertaliens de La Chaise[END_REF][START_REF] Teilhol | Contribution à l'étude individuelle des ossements d'enfants de La Chaise-de-Vouthon (Charente, France): approche paléodémographique, paléoethnologique, aspect morphologique et étude métrique. Place phylogénique des enfants de La Chaise[END_REF][START_REF] Teilhol V | -Les os de la voûte crânienne des enfants de l'abri Suard (La Chaise, Charente, France)[END_REF][START_REF] Macchiarelli R | -How Neanderthal molar teeth grew[END_REF][START_REF] Macchiarelli R | -L'apport des nouvelles technologies à l'étude des Néandertaliens[END_REF][START_REF] Puymerail | -A Neanderthal partial femoral diaphysis from the "grotte de la Tour", La Chaise-de-Vouthon (Charente, France): outer morphology and endostructural organization[END_REF][START_REF] Puymerail | Comparative structural analysis of the Neanderthal femoral shafts BD 5 (MIS 5e) and CDV-Tour 1 (MIS 3) from La Chaisede-Vouthon[END_REF] an exhaustive list of the anthropological studies before the '90s can be found in [START_REF] Debénath A | Bibliographie des sites de La Chaise-de-Vouthon (Charente)[END_REF].

One remarkable specimen among those forming the Abri Bourgeois-Delaunay's human fossil assemblage is represented by the adult mandible BD 1, bearing the entire set of 16 teeth.

Recovered on September 12 th 1967 [START_REF] Debénath A | -Découverte d'une mandibule humaine à la Chaise-de-Vouthon (Charente)[END_REF](Debénath , 1974b)), the specimen was described in detail by [START_REF] Condemi | Les Néandertaliens de La Chaise[END_REF]. In agreement with the associated geochronological and technocultural context, the morphological and dimensional affinities (Condemi 2001: tables VII-1 and VII-2) of BD 1 indicate that it belongs to a Neanderthal individual likely 20-35 years old [START_REF] Condemi | Les Néandertaliens de La Chaise[END_REF].

Research goals

Intra-individual antimeric variation in tooth size is considered a measure of developmental instability, and fluctuating vs. directional odontometric asymmetry is used to assess the amount of relative stress a population experienced (e.g., [START_REF] Corruccini R | -Correspondence between enamel hypoplasia and odontometric bilateral asymmetry in Australian twins[END_REF][START_REF] Hoover | -Exploring the relationship between hypoplasia and odontometric asymmetry in Isola Sacra, an Imperial Roman necropolis[END_REF][START_REF] Guatelli-Steinberg D | Dental fluctuating asymmetry in the Gullah: tests of hypotheses regarding developmental stability in deciduous vs. permanent and male vs. female teeth[END_REF][START_REF] Rizk | Using geometric morphometrics to study the mechanisms that pattern primate dental variation[END_REF][START_REF] Scott | The anthropology of modern human teeth. Dental morphology and its variation in recent and fossil Homo sapiens[END_REF]. However, because of the usually advanced degree of occlusal crown wear, such external measures are barely useful in the study of fossil specimens, where an alternative approach consists in assessing antimeric variation in tooth tissue proportions and root size (e.g., Braga et al. 2010;[START_REF] Kupczik | Mandibular molar root morphology in Neanderthals and Late Pleistocene and recent Homo sapiens[END_REF][START_REF] Prado-Simón L | -Three-dimensional evaluation of root canal morphology in lower second premolars of Early and Middle Pleistocene human populations from Atapuerca (Burgos, Spain)[END_REF][START_REF] Macchiarelli R | -From outer to inner structural morphology in dental anthropology. The integration of the third dimension in the visualization and quantitative analysis of fossil remains[END_REF]. With this respect, a previous study on three-dimensional (3D) endostructural asymmetry assessed on the complete dentition of the adult Neanderthal mandible Regourdou 1 [START_REF] Maureille | -Les dents inférieures du Néandertalien Regourdou 1 (site Regourdou, commune de Montignac, Dordogne): analyses métriques et comparatives[END_REF], likely of comparable age at death of BD 1 [START_REF] Volpato | -Hand to mouth in a Neandertal: right handedness in Regourdou 1[END_REF], has revealed some discrepancies in antimeric variation between the signals provided by the outer tooth crowns and the proportions displayed by their inner tissue components [START_REF] Macchiarelli R | -From outer to inner structural morphology in dental anthropology. The integration of the third dimension in the visualization and quantitative analysis of fossil remains[END_REF]. Specifically, mostly based on a quantitative parameter often used to characterize endostructural tooth organization, i.e., the percent of crown volume that is dentine and pulp, the study has shown that antimeric variation in Regourdou 1 is fluctuating (i.e., non-directional) and globally modest [START_REF] Macchiarelli R | -From outer to inner structural morphology in dental anthropology. The integration of the third dimension in the visualization and quantitative analysis of fossil remains[END_REF].

Additionally, a recent structural analysis of the same specimen has revealed a likely functional link among degree of occlusal wear, root dentine thickness variation and site-specific variation in cortical bone distribution [START_REF] Fiorenza | -Dental macrowear and cortical bone distribution of the Neanderthal mandible from Regourdou (Dordogne, Southwestern France)[END_REF]. However, no comparative endostructural evidence from the complete permanent dentition of other Neanderthals is currently available.

In the present study, we integrate and expand the morphometric record of BD 1 [START_REF] Condemi | Les Néandertaliens de La Chaise[END_REF] by quantifying the tissue proportions of its entire permanent dentition, including radicular thickness repartition of four front teeth, and comparing its degree of endostructural asymmetry in tooth tissue organization and postcanine cortical bone topography with the patterns shown by Regourdou 1 [START_REF] Macchiarelli R | -Virtual dentitions: touching the hidden evidence[END_REF][START_REF] Macchiarelli R | -From outer to inner structural morphology in dental anthropology. The integration of the third dimension in the visualization and quantitative analysis of fossil remains[END_REF][START_REF] Fiorenza | -Dental macrowear and cortical bone distribution of the Neanderthal mandible from Regourdou (Dordogne, Southwestern France)[END_REF].

Materials

BD 1 -Because of its in situ anatomical orientation, the slightly obliquely oriented dental arcade facing downwards, BD 1 suffered some breakage and bone loss, notably at the level of the nearly completely missing left ramus and of large portions of the body and of the perialveolar bone anterior to both first molars. Parts of the missing symphyseal region and the lower margin of the mental protuberance have been reconstructed by plaster to provide support to the incisor, canine and premolar teeth of both sides, whose roots are completely exposed [START_REF] Condemi | Les Néandertaliens de La Chaise[END_REF] photos VII-1 to VII-8 and photo VIII-6; figs VII-1 to VII-5 and fig. VIII-9). As seen in anterior and posterior views, relatively large bony flakes are also missing at different points of the body, especially on the posterior aspect of the specimen. Nonetheless, following careful consolidation and restoration, BD 1 preserves a large portion of the right ramus, including most of the coronoid process, the mandibular notch and the condyle, as well as the postcanine body portion of both sides. The dentition, including the third molars, is complete and all crowns are rather well preserved with modest postdepositional damages. However, on the right side, the lower half of the root of the central incisor and the entire root of the canine are missing. Despite some locally exposed dentine patches, especially on the first molars, postcanine occlusal wear in this individual is moderate and relatively homogeneously spread between the antimeres, while occlusal enamel has been almost entirely removed on the incisors and, to a lesser extent, on the canines.

Regourdou 1 (R1) -For the purposes of the present study, we compared the BD 1's dental and bony endostructural features to those virtually extracted from the OIS 4 (71-57 ka) mandible Regourdou 1, from the eponym site at Montignac-sur-Vézére, in Dordogne (France) [START_REF] Piveteau | -Les restes humains de la grotte de Regourdou (Dordogne)[END_REF] for details and an historical review, see Maureille et al. 2015a, b). The R1 nearly intact mandible, just slightly more robust compared to BD 1 [START_REF] Condemi | Les Néandertaliens de La Chaise[END_REF]: tables VII-1 and VII-2), presents a complete set of teeth showing a degree of occlusal wear macroscopically comparable to that of the specimen from the abri Bourgeois-Delaunay [START_REF] Maureille | -Les dents inférieures du Néandertalien Regourdou 1 (site Regourdou, commune de Montignac, Dordogne): analyses métriques et comparatives[END_REF][START_REF] Macchiarelli R | -Virtual dentitions: touching the hidden evidence[END_REF][START_REF] Macchiarelli R | -From outer to inner structural morphology in dental anthropology. The integration of the third dimension in the visualization and quantitative analysis of fossil remains[END_REF][START_REF] Volpato | -Hand to mouth in a Neandertal: right handedness in Regourdou 1[END_REF][START_REF] Fiorenza | -Dental macrowear and cortical bone distribution of the Neanderthal mandible from Regourdou (Dordogne, Southwestern France)[END_REF]). However, [START_REF] Maureille | -Les dents inférieures du Néandertalien Regourdou 1 (site Regourdou, commune de Montignac, Dordogne): analyses métriques et comparatives[END_REF] observed that in R1 the teeth of the right arcade were slightly more worn than their antimeres, a characteristic recently supported for the posterior dentition by the quantitative analysis performed by [START_REF] Fiorenza | -Dental macrowear and cortical bone distribution of the Neanderthal mandible from Regourdou (Dordogne, Southwestern France)[END_REF]. This asymmetric pattern was also investigated by [START_REF] Volpato | -Hand to mouth in a Neandertal: right handedness in Regourdou 1[END_REF]. By assessing the orientation of the microwear striations over the labial surfaces of incisors and canines, they concluded that the predominance in R1 of right oblique scratches, typical of right-handed manipulations, was probably caused by the use of the anterior teeth as a vice or a third hand. In this specimen, enamel thickness asymmetry was also found on the postcanine teeth, especially between the third premolars [START_REF] Macchiarelli R | -From outer to inner structural morphology in dental anthropology. The integration of the third dimension in the visualization and quantitative analysis of fossil remains[END_REF][START_REF] Fiorenza | -Dental macrowear and cortical bone distribution of the Neanderthal mandible from Regourdou (Dordogne, Southwestern France)[END_REF].

Methods of analysis

Both mandibles BD 1 and Regourdou 1 were scanned in 2005 at the beamline ID 17 of the European Synchrotron Radiation Facility, Grenoble, France (experiment SC1587c), according to the following parameters: energy, 70 keV; projections, 1500 in half acquisition mode; integration time, 22.9 ms. The final sections were reconstructed from sinograms and saved in a 32-bit floating-point raw format at a voxel size of 45.5*45.5*45.7 µm for the scans of the teeth and with an isotropic voxel size of 350 µm for the whole mandible.

We used routinely applied standard procedures of semiautomatic threshold-based segmentation to virtually reconstruct tooth volume (for technical details, see [START_REF] Kono R | Molar enamel thickness and distribution patterns in extant great apes and humans: new insights based on a 3-dimensional whole crown perspective[END_REF][START_REF] Macchiarelli R | -How Neanderthal molar teeth grew[END_REF][START_REF] Olejniczak | -Dental tissue proportions and enamel thickness in Neandertal and modern human molars[END_REF][START_REF] Zanolli | -The late Early Pleistocene human dental remains from Uadi Aalad and Mulhuli-Amo (Buia), Eritrean Danakil: macromorphology and microstructure[END_REF]Zanolli et al. , 2018)).

A 3D virtual rendering of BD 1 in various perspectives is provided in fig. 1. [figure 1 here]

Enamel thickness distribution maps

For all teeth of both arcades, enamel occlusal distribution and thickness variation (occlusallabial for the front teeth) were comparatively rendered in BD 1 and Regourdou 1 through 3D topographic mapping (cartographies) generated using a tooth-specific chromatic scale, where thickness increases from dark blue (thinner enamel) to red (thicker enamel) and white indicates emerging underlying dentine patches (cf. [START_REF] Macchiarelli R | -Virtual dentitions: touching the hidden evidence[END_REF][START_REF] Macchiarelli R | -From outer to inner structural morphology in dental anthropology. The integration of the third dimension in the visualization and quantitative analysis of fossil remains[END_REF]Bayle et al. 2011;[START_REF] Zanolli C | Molar crown inner structural organization in Javanese Homo erectus[END_REF].

Dental tissue proportions

Twelve linear, surface, and volumetric variables describing tooth structural organization and proportions were measured or calculated for each virtually extracted tooth: volume of enamel cap (Ve, mm 3 ); total volume of dentine (Vd, mm 3 ); total volume of pulp (Vp, mm 3 ); total volume of cementum (Vcem, mm 3 ; not available for Regourdou 1); total tooth volume (Vt, mm 3 ); volume of crown dentine + pulp (Vcdp, mm 3 ); volume of the root dentine + pulp (Vrdp, mm 3 ; not available for Regourdou 1); surface area of enamel-dentine junction (SEDJ, mm²); percent of crown volume that is dentine and pulp (Vcdp/Vc, %); percent of the root volume that is cementum (Vcem/Vrdp, %; not available for Regourdou 1); 3D average enamel thickness (3D AET, mm); the scale-free 3D relative enamel thickness (3D RET).

Radicular dentine thickness distribution

To assess root dentine thickness repartition in the BD 1's front teeth (except for the roots of the right central incisor and canine, respectively incomplete and absent) and to compare this topographic pattern with that displayed by Regourdou 1, in each available specimen we virtually unzipped the 15-85% portion (15% being closer to the dental cervix) of the total root length along a predefined vertical line established at the middle of the labial aspect. By using a custom routine developed in R v.3.6 (R Development Core Team 2019) with the packages Momocs (Bonhomme et al. 2014), spatstat (Baddeley et al. 2015) and gstat [START_REF] Pebesma | Multivariable geostatistics in S: the gstat package[END_REF]), we then virtually unrolled it and projected its local properties into a morphometric map (Bondioli et al. 2010;Bayle et al. 2011;[START_REF] Macchiarelli R | -From outer to inner structural morphology in dental anthropology. The integration of the third dimension in the visualization and quantitative analysis of fossil remains[END_REF][START_REF] Zanolli | -The late Early Pleistocene human dental remains from Uadi Aalad and Mulhuli-Amo (Buia), Eritrean Danakil: macromorphology and microstructure[END_REF]Zanolli et al. , 2018)). 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 rows and 100 columns.

Cortical bone distribution

As previously noted, the BD 1's corpus presents on both sides some taphonomic breaks and local bone loss that complicate the task of reliably assessing structural variation of the cortical shell at volumetric scale. However, following the segmentation procedure recently applied to the Regourdou 1 mandible (for technical details, see [START_REF] Fiorenza | -Dental macrowear and cortical bone distribution of the Neanderthal mandible from Regourdou (Dordogne, Southwestern France)[END_REF], it was possible to confidently separate its endosteal surface from the immediately underlying cancellous bone.

We then measured left vs. right cortical bone topographic thickness distribution on two buccolingual slices taken perpendicular to the occlusal plane and virtually extracted between the first and second molars (M1/M2) and between the second and third molars (M2/M3), respectively.

The upper limit of each section was arbitrarily established immediately below the perialveolar area, where cortical bone wears thin [START_REF] Zanolli | -Structural organization and tooth development in a Homo aff. erectus juvenile mandible from the Early Pleistocene site of Garba IV at Melka Kunture, Ethiopian highlands[END_REF]. For comparison, the homologous slices were extracted on Regourdou 1. In processing the record of the two fossil specimens, minor local discontinuities along the periosteal and endosteal contours were virtually integrated by manual corrections. In the four extracted individual slices (two for each side on each mandible), cortical bone thickness topographic variation was measured by computing the distance between the periosteal and endosteal surfaces of the cortical shell where, for each point of one surface, the closest point on the other surface was computed [START_REF] Fiorenza | -Dental macrowear and cortical bone distribution of the Neanderthal mandible from Regourdou (Dordogne, Southwestern France)[END_REF].

Visualization of bone thickness variation has been rendered using the R v.3.6 package ggplot2

(Wickman 2016). To allow direct comparisons between BD 1, proportionally smaller, and

Regourdou 1, proportionally larger, we calculated the scale-free bi-dimensional (2D) Relative Cortical Thickness (2D RCT) index (see [START_REF] Cazenave | -Inner structural organization of the distal humerus in Paranthropus and Homo[END_REF]. It is given as the average cortical thickness (2D ACT) multiplied by 100 and divided by the square root of the trabecular area (TBA, in mm²) (2D RCT = 2D ACT x 100/TBA 1/2 ), where 2D ACT is the ratio between cortical area (CA, in mm²) and the endosteal contour length (in mm).

Asymmetry

For each variable measurable on both dental antimeres (84/96 of cases) and on two cortical bone virtual sections (2D RCT), percent asymmetry was calculated as: (L-R)/([L+R]*0.5), where L and R correspond to the left and right side, respectively [START_REF] Corruccini R | -Correspondence between enamel hypoplasia and odontometric bilateral asymmetry in Australian twins[END_REF].

Results

Enamel thickness distribution maps

In terms of amount and patterns of macroscopic occlusal crown wear (cf. [START_REF] Smith | -Patterns of molar wear in hunter-gatherers and agriculturalists[END_REF] and of left vs. right side distribution, BD 1 and Regourdou 1 are globally comparable (fig. 2), the only exception being represented by the peculiar wear pattern displayed by the left P3 in Regourdou 1 [START_REF] Maureille | -Les dents inférieures du Néandertalien Regourdou 1 (site Regourdou, commune de Montignac, Dordogne): analyses métriques et comparatives[END_REF][START_REF] Volpato | -Hand to mouth in a Neandertal: right handedness in Regourdou 1[END_REF]; for a recent quantitative assessment and functional interpretation, see [START_REF] Fiorenza | -Dental macrowear and cortical bone distribution of the Neanderthal mandible from Regourdou (Dordogne, Southwestern France)[END_REF]. Otherwise, together with a relatively homogeneous distribution between the antimeres of both front and postcanine teeth, the two specimens share a more marked wear on the incisors and canines, which is a typical likely functionally-related Neanderthal feature [START_REF] Volpato | -Hand to mouth in a Neandertal: right handedness in Regourdou 1[END_REF]. However, also occlusal molar topography is partially obliterated, including on the M3s. In these two Neanderthal representatives, the thickest enamel is nearly invariably found on the labial (front teeth) and buccal (postcanine dentition) aspects.

Their lateral incisors display thicker enamel than the I1s. Interestingly, BD 1's front teeth show slightly thicker enamel compared to Regourdou 1, while no difference is appreciable for the post-canine crowns, showing relatively thicker enamel at the base of the buccal cusps and thinner enamel in the occlusal basin, including in the unworn areas.

[figure 2 here]

Dental tissue proportions

Tooth tissue proportions in BD 1 are shown in tab. 1. For the tooth size-independent percent of crown that is dentine and pulp (Vcdp/Vc), its values overlap the estimates available for Regourdou 1 (cf. Macchiarelli et al. 2013: tab. 1), some very minor differences uniquely concerning the P3s, the M1s and the M3s, whose proportions are slightly lower in BD 1. In terms of enamel thickness, the P4s and M3s, i.e., the proportionally least worn postcanine crowns in BD 1 (stage 2 to 3 following [START_REF] Smith | -Patterns of molar wear in hunter-gatherers and agriculturalists[END_REF], have an average 3D RET of 15.3 and 14.6, respectively. Here again, the estimates for this scale-free parameter are comparable to those assessed in Regourdou 1, where BD 1 displays an only slightly higher value for the M3, but not the P4. As previously noted, in BD 1 the roots of the right I1 and C are respectively incomplete and missing, thus limiting tissue proportion estimates to the crown. As shown by the percent of root volume that is cementum, in BD 1 a rather thick layer of cementum covers most roots. Indeed, Vcem/Vrdp ranges from 11.6%, on the left M3, to 43.5%, on the left I1, but no direct comparison can be performed with the pattern displayed by Regourdou 1, as its cementum distribution has not been reported yet.

[table 1 here]

In BD 1, antimeric differences in tooth tissue proportions (84 cases calculated on 96) are extremely variable, as they range from nearly zero to 92% (M3 Vcem/Vrdp), the highest values systematically concerning the parameters also or uniquely integrating the radicular components. With this respect, the impact of cementum thickness variation is evident. However, when uniquely the crown is considered, absolute values of asymmetry range from 1% (M2 Vcdp) to 18.6% (M1 SEDJ), 37 out of 48 cases showing an asymmetry below 10%. The Vcdp/Vc is in absolute the least asymmetric parameter (range 0.6-4.9%). Importantly in this study, asymmetry is globally fluctuating, side dominance being nearly equally distributed between the left and the right antimeres (51% vs. 49%, respectively). This is also shown by the three variables Vcdp/Vc, 3D AET and 3D RET (fig. 3).

[figure 3 here]

Radicular dentine thickness distribution

The standardized cartographies of radicular dentine thickness distribution in four anterior teeth of BD 1 (three left and one right roots) and Regourdou 1 (one left and three right roots) are illustrated in fig. 4. The two Neanderthals exhibit a nearly identical repartition pattern, with relatively and absolutely thicker dentine found across the lingual and labial aspects, while the mesial and distal sides systematically display the thinnest dentine, notably towards the root apices. However, in all front teeth suitable for such kind of analysis, BD 1 shows more contrasted maps with relatively thicker radicular dentine spread across a larger surface than measured in Regourdou 1, even if absolutely thickest dentine is found on the right I2 of the latter specimen (c. 3.7 mm vs. c. 3.2 in BD 1). Unfortunately, intra-individual asymmetry in both specimens can be only assessed for the I2s. With this respect, the dentine of the right lateral incisor is distinctly thicker and more spread in BD 1 at all investigated sites, while only a modest site-specific left prevalence is found in Regourdou 1.

[figure 4 here]

Cortical bone distribution

Cortical bone thickness topographic variation (absolute distance values between the periosteal and the endosteal contours) assessed in BD 1 and Regourdou 1 across two homologous buccolingual slices virtually extracted at the M1/M2 and M2/M3 positions of both left and right mandibular sides is shown in fig. 5. Even if some site-specific differences are notable on both slices, especially across the inferior and buccal portions of the corpus, the two specimens show a globally similar distribution pattern, where bone thickness progressively increases from the perialveolar lingual aspect towards the inferior margin, and then progressively thins towards the perialveolar buccal margin. At nearly all sites captured by the two slices, and especially across their inferior portion, BD 1 shows absolutely thinner cortical bone compared to Regourdou 1, except at the buccal aspect of the M1/M2 right slice, where BD 1 exhibits slightly thicker cortical bone than measured in Regourdou 1.

[figure 5 here] This is also shown by the scale-free Relative Cortical Thickness index (2D RCT). For this parameter, percent asymmetry in BD 1 indicates slight right dominance at both sites (absolute values range: 9.3-12.9%), while Regourdou 1 shows no asymmetry at M1/M2 level and slight right dominance (-7.5%) at M2/M3 level (tab. 2)

[table 2 here]

Discussion and conclusions

Despite the modest preservation conditions and incompleteness of the supporting mandibular bone, the dentition of the adult Neanderthal specimen BD 1, from the Bourgeois-Delaunay shelter of the La Chaise-de-Vouthon site complex, Charente (France), is among the best preserved complete lower dentitions from the western European Eemian (OIS 5e) human fossil record [START_REF] Condemi | Les Néandertaliens de La Chaise[END_REF]). The microtomographic-based analysis of its inner structural organization performed in this study allowed a detailed comparison with the homologous features of another exceptionally-preserved Neanderthal permanent dentition: that of the c. 90 km apart OIS 4 specimen Regourdou 1 [START_REF] Maureille | -Les dents inférieures du Néandertalien Regourdou 1 (site Regourdou, commune de Montignac, Dordogne): analyses métriques et comparatives[END_REF], likely of similar age at death [START_REF] Volpato | -Hand to mouth in a Neandertal: right handedness in Regourdou 1[END_REF]) and of comparable external morphometric characteristics, including the degree of occlusal crown wear [START_REF] Fiorenza | -Dental macrowear and cortical bone distribution of the Neanderthal mandible from Regourdou (Dordogne, Southwestern France)[END_REF].

By relying upon some previous analyses of the Regourdou 1 mandible and dentition [START_REF] Maureille | -Les dents inférieures du Néandertalien Regourdou 1 (site Regourdou, commune de Montignac, Dordogne): analyses métriques et comparatives[END_REF][START_REF] Macchiarelli R | -Virtual dentitions: touching the hidden evidence[END_REF][START_REF] Macchiarelli R | -From outer to inner structural morphology in dental anthropology. The integration of the third dimension in the visualization and quantitative analysis of fossil remains[END_REF][START_REF] Volpato | -Distribution osseuse et morphologie structurale de la mandibule néandertalienne Regourdou 1[END_REF][START_REF] Volpato | -Hand to mouth in a Neandertal: right handedness in Regourdou 1[END_REF][START_REF] Fiorenza | -Dental macrowear and cortical bone distribution of the Neanderthal mandible from Regourdou (Dordogne, Southwestern France)[END_REF]), here we comparatively assessed the degree of asymmetry in BD 1 of tooth tissue proportions (entire dentition), radicular dentine thickness repartition (anterior teeth), and cortical bone topography of the molar region. Besides their acknowledged taxonomic and phylogenetic significance, such genetically-controlled features are also sensible individual indicators of environmental (including nutritional) and/or systemic physiological perturbations (growth disruption) experienced during development (e.g., [START_REF] Rizk | Using geometric morphometrics to study the mechanisms that pattern primate dental variation[END_REF], and also tend to record the variable impact of the biomechanical environment (loading regimes related to masticatory/paramasticatory activities) on the structural organization of dental and bony tissues (rev. in [START_REF] Fiorenza | -Dental macrowear and cortical bone distribution of the Neanderthal mandible from Regourdou (Dordogne, Southwestern France)[END_REF].

Preliminarily, it is anyhow relevant to note that the BD 1's crown and radicular dental endostructural signature is typically Neanderthal (cf. [START_REF] Macchiarelli R | -How Neanderthal molar teeth grew[END_REF][START_REF] Macchiarelli R | -Virtual dentitions: touching the hidden evidence[END_REF][START_REF] Macchiarelli R | -From outer to inner structural morphology in dental anthropology. The integration of the third dimension in the visualization and quantitative analysis of fossil remains[END_REF][START_REF] Olejniczak | -Dental tissue proportions and enamel thickness in Neandertal and modern human molars[END_REF][START_REF] Kupczik | Mandibular molar root morphology in Neanderthals and Late Pleistocene and recent Homo sapiens[END_REF]Bayle et al. 2011[START_REF] Zanolli | -Structural organization and tooth development in a Homo aff. erectus juvenile mandible from the Early Pleistocene site of Garba IV at Melka Kunture, Ethiopian highlands[END_REF][START_REF] Prado-Simón L | -Three-dimensional evaluation of root canal morphology in lower second premolars of Early and Middle Pleistocene human populations from Atapuerca (Burgos, Spain)[END_REF][START_REF] Le | -Anterior tooth root morphology and size in Neanderthals: taxonomic and functional implications[END_REF][START_REF] Martin | The morphology of the enamel-dentine junction in Neanderthal molars: gross morphology, non-metric traits, and temporal trends[END_REF]Zanolli et al. 2018) and is unambiguously distinct from the fossil and extant modern human patterns (cf. Le Luyer 2016).

In BD 1, asymmetry in tooth tissue proportions is clearly non-directional, as side dominance is nearly equally distributed between the left and the right antimeres. This pattern is even more accentuated than that observed in Regourdou 1, where a right dominance is found in 64% of cases [START_REF] Macchiarelli R | -From outer to inner structural morphology in dental anthropology. The integration of the third dimension in the visualization and quantitative analysis of fossil remains[END_REF]. However, this percentage decreases and approaches the BD 1's condition if the P3s are excluded from the analysis. In fact, compared to its antimere, Regourdou 1's left third premolar bears unusual semi-circular enamel wear facets likely resulting from some tooth-tool uses for daily task activities [START_REF] Fiorenza | -Dental macrowear and cortical bone distribution of the Neanderthal mandible from Regourdou (Dordogne, Southwestern France)[END_REF]. Also, compared to BD 1, the posterior dentition of Regourdou 1 is characterized by a more asymmetric wear pattern, the right side being more worn than its counterpart [START_REF] Maureille | -Les dents inférieures du Néandertalien Regourdou 1 (site Regourdou, commune de Montignac, Dordogne): analyses métriques et comparatives[END_REF][START_REF] Fiorenza | -Dental macrowear and cortical bone distribution of the Neanderthal mandible from Regourdou (Dordogne, Southwestern France)[END_REF]), a condition that likely affected the quantitative assessment of at least some among the parameters considered in our analyses.

Similarly to Regourdou 1, fluctuating endostructural asymmetry in BD 1 is globally moderate, notably for the parameters not directly affected by the variably thick coat of radicular cementum present in this specimen and, of course, for those generally poorly affected by moderate occlusal wear. With this respect, it is noteworthy that when BD 1 and Regourdou 1 are compared for the total volume of dentine (Vd) or the surface area of enamel-dentine junction (SEDJ), for example, their degree of asymmetry is comparable (cf. tab. 1 with tab. 1 in [START_REF] Macchiarelli R | -From outer to inner structural morphology in dental anthropology. The integration of the third dimension in the visualization and quantitative analysis of fossil remains[END_REF]. In some cases, asymmetry does not even exceed the measurement error reported for such kind of variables in tests run for intra-and inter-observer accuracy (e.g., [START_REF] Macchiarelli R | -Virtual dentitions: touching the hidden evidence[END_REF]. Even if currently based on the record from two individuals only, this evidence tends to support previous suggestions that, among Neanderthals, at least nutritional stresses during growth were not especially elevated compared with those affecting several present-day populations [START_REF] Hutchinson | -Stressed to the max? Physiological perturbation in the Krapina Neandertals[END_REF]. However, in both BD 1 and Regourdou 1 dental wear has also to be taken into account as additional parameter to any possible developmental noise (Benazzi et al. 2013;[START_REF] Macchiarelli R | -From outer to inner structural morphology in dental anthropology. The integration of the third dimension in the visualization and quantitative analysis of fossil remains[END_REF]. Finally, it should be pointed out that, at the best of our knowledge, no comparative quantitative data from representative extant/recent human samples is available on tooth tissue proportion antimeric variation, which currently limits our interpretations.

The significance of radicular dentine intra-and inter-individual variation is also difficult to interpret because of similar lack of comparative information from controlled reference series, as well as of the paucity of evidence from the human fossil record, limited to a handful of specimens (Bayle et al., 2011;[START_REF] Macchiarelli R | -From outer to inner structural morphology in dental anthropology. The integration of the third dimension in the visualization and quantitative analysis of fossil remains[END_REF][START_REF] Zanolli | -The late Early Pleistocene human dental remains from Uadi Aalad and Mulhuli-Amo (Buia), Eritrean Danakil: macromorphology and microstructure[END_REF]Zanolli et al., , 2018)). A recent study of the Regourdou 1 mandible has suggested a likely cause-effect functional relationship among uneven masticatory and/or non-masticatory loadings, occlusal crown macrowear, asymmetric variation in radicular dentine and postcanine cortical bone distribution [START_REF] Fiorenza | -Dental macrowear and cortical bone distribution of the Neanderthal mandible from Regourdou (Dordogne, Southwestern France)[END_REF]. However, the relative role of genetic vs. functional factors in the distribution of root dentine is not yet elucidated. Nonetheless, while few studies have investigated the long-term impact on the radicular dentine mechanoreceptors of variably frequent and intense strains and stresses [START_REF] Dean | How the microstructure of dentine can contribute to reconstructing developing dentitions and the lives of hominoids and hominins. In: Hominin biomechanics, virtual anatomy and inner structural morphology: from head to toe. A tribute to[END_REF], the capacity of bone as dynamic tissue to respond to alterations of its mechanical environment is very-well reported, notably for the mandible, where thicker cortical bone is commonly found in areas facing higher strains (e.g., [START_REF] Masumoto | -Relationships among facial type, buccolingual molar inclination, and cortical bone thickness of the mandible[END_REF][START_REF] Daegling | Functional significance of cortical bone distribution in anthropoid mandibles: an in vitro assessment of bone strain under combined loads[END_REF][START_REF] Lieberman | -Effects of food processing on masticatory strain and craniofacial growth in a retrognathic face[END_REF][START_REF] Fukase | Functional significance of bone distribution in the human mandibular symphysis[END_REF][START_REF] Fukase | Growth-related changes in prehistoric Jomon and modern Japanese mandibles with emphasis on cortical bone distribution[END_REF][START_REF] Martínez-Gomis | Relationship between chewing side preference and handedness and lateral asymmetry of peripheral factors[END_REF][START_REF] Holmes | -Dietary effects on development of the human mandibular corpus[END_REF][START_REF] Gröning | Modeling the human mandible under masticatory loads: which input variables are important?[END_REF]; but see [START_REF] Ichim | Functional significance of strain distribution in the human mandible under masticatory load: numerical predictions[END_REF].

Unfortunately, the evidence from the hominin/human fossil record is extremely limited (e.g., [START_REF] Daegling | -Compact bone distribution and biomechanics of early hominid mandibles[END_REF][START_REF] Grine | -Functional morphology, biomechanics and the retrodiction of early hominin diets. In: Hominin biomechanics, virtual anatomy and inner structural morphology: from head to toe. A tribute to[END_REF][START_REF] Zanolli | -Structural organization and tooth development in a Homo aff. erectus juvenile mandible from the Early Pleistocene site of Garba IV at Melka Kunture, Ethiopian highlands[END_REF][START_REF] Fiorenza | -Dental macrowear and cortical bone distribution of the Neanderthal mandible from Regourdou (Dordogne, Southwestern France)[END_REF], the reason of the interest here of a direct comparison between BD 1 and Regourdou 1 for evaluating if markedly uneven biomechanical demands and preferences over the molar region may have resulted into distinct cortical bone asymmetry. Limitedly to the evidence captured from two virtual sections extracted across the M1/M2 and M2/M3 boundaries, this does not seem to be the case in the two Neanderthal individuals, even if a slight right dominance is found in BD 1.

In conclusion, the results scattered from the present endostructural analysis of the OIS 5e BD 1 specimen from Bourgeois-Delaunay, which integrate and expand similar research performed on the mandible and dentition of the OIS 4 individual Regourdou 1 [START_REF] Macchiarelli R | -Virtual dentitions: touching the hidden evidence[END_REF][START_REF] Macchiarelli R | -From outer to inner structural morphology in dental anthropology. The integration of the third dimension in the visualization and quantitative analysis of fossil remains[END_REF][START_REF] Volpato | -Distribution osseuse et morphologie structurale de la mandibule néandertalienne Regourdou 1[END_REF][START_REF] Volpato | -Hand to mouth in a Neandertal: right handedness in Regourdou 1[END_REF][START_REF] Fiorenza | -Dental macrowear and cortical bone distribution of the Neanderthal mandible from Regourdou (Dordogne, Southwestern France)[END_REF], provide new original evidence on antimeric variation in Neanderthal osteodental organization. Nonetheless, extensive methodological research to be developed on the patterns of age-and sex-related endostructural variation displayed by human population samples from diverse chrono-geographic, socioeconomic and biocultural contexts is needed to more confidently evaluate the evolutionary and adaptive significance of the signals from the fossil record.

Captions to the figures

Figure 1 -

 1 Figure 1 -Photographs in superior view from the left side (A) and in lateral view showing the reconstructed portion of the inferoanterior aspect of the Neanderthal mandible BD 1 (B),

Figure 1 -

 1 Figure 1 -Photographies en vues supérieure depuis le côté gauche (A) et en vue latérale montrant la portion reconstruite de l'aspect inféro-antérieur de la mandibule néandertalienne BD 1 (B), et rendus 3D en semi-transparence basés sur le registre microtomographique du spécimen en vues antérieure (A), supérieure (B), latérales gauche (C) et droite (D) légèrement obliques. Echelle: 1 cm.

Figure 2 -

 2 Figure 2 -Enamel thickness cartographies of the entire set of virtually reconstructed teeth (I1-M3) of the Neanderthal mandibles BD 1 and Regourdou 1. Topographic variation is rendered by a tooth-specific thickness-related chromatic scale ranging from dark blue (thinner enamel) to red (thicker enamel); white areas correspond to complete enamel removal (emerging underlying dentine patches) following occlusal wear. Scale bar: 1 cm.

Figure 2 -

 2 Figure 2 -Cartographies d'épaisseur de l'émail de l'ensemble des dents virtuellement reconstruites (I1-M3) des mandibules néandertaliennes BD 1 et Regourdou 1. Les variations topographiques sont représentées par une échelle de couleur propre à chaque dent allant du bleu foncé (émail plus fin) au rouge (émail plus épais); les zones blanches correspondent à l'usure de l'émail (îlots de dentine visibles à la surface occlusale). Echelle: 1 cm.

Figure 3 -

 3 Figure 3 -Barplot of the antimeric variation (% asymm.; Corruccini et al. 2005) of three parameters representing crown enamel and dentine proportions (Vcdp/Vc, 3D AET, 3D RET) in the entire set of teeth of the Neanderthal mandible BD 1. See the text for the meaning of the variables. Negative values indicate right dominance.

Figure 3 -

 3 Figure 3 -Diagramme en bâtons des variations d'asymétrie entre antimères (% asymm.; Corruccini et al. 2005) pour les trois paramètres représentant les proportions des tissus de l'émail et de la dentine de la couronne (Vcdp/Vc, 3D AET, 3D RET) de l'ensemble des dents de la mandibule néandertalienne BD 1. Voir le texte pour la signification des variables. Les valeurs négatives indiquent une dominance du côté droit.

Figure 4 -

 4 Figure 4 -Standardized morphometric maps of the virtually unrolled root dentine (15-85% of the total root length, where 15% is closer to the dental cervix) of four anterior teeth (incisors

Figure 4 -

 4 Figure 4 -Cartographies morphométriques standardisées de la dentine radiculaire déroulée (15-85% de la longueur totale de la racine, où 15% est plus proche du cervix) de quatre dents antérieures (incisives et canines) des mandibules néandertaliennes BD 1 et Regourdou 1. Les variations topographiques de la dentine sont représentées par une échelle de couleur propre à chaque dent allant du bleu foncé (0) au rouge (1). LC: canine gauche; LI1: incisive centrale gauche; LI2: incisive latérale gauche; RI1: incisive centrale droite; RI2: incisive latérale droite; d: distal; lab: labial; ling: lingual; m: mésial.

Figure 5 -

 5 Figure 5 -Bucco-lingual slices virtually extracted between the first and second molars (M1/M2) and the second and third molars (M2/M3) from the Neanderthal mandibles BD 1 (A) and Regourdou 1 (B) and cortical bone thickness variation (in µm) measured across these sections: C, left M1/M2 section; D, right M1/M2 section; E, left M2/M3 section; F, right M2/M3 section. b: buccal side; i: inferior portion; l: lingual side.

Figure 5 -

 5 Figure 5 -Sections bucco-linguales extraites virtuellement entre les premières et secondes molaires (M1/M2) et deuxième et troisièmes molaires (M2/M3) des mandibules néandertaliennes BD 1 (A) et Regourdou 1 (B) et mesures des variations d'épaisseur de l'os cortical (en µm) au niveau de ces sections : C, section M1/M2 gauche; D, section M1/M2 droite; E, section M2/M3 gauche; F, section M2/M3 droite. b: aspect buccal; i: portion inférieure; l: aspect lingual.

Table 1 -

 1 Antimeric variation(% asymm.;[START_REF] Corruccini R | -Correspondence between enamel hypoplasia and odontometric bilateral asymmetry in Australian twins[END_REF] in tooth tissue proportions (variables from Ve to Vcem/Vrdp) and 3D enamel thickness (AET and RET) assessed in the Neanderthal mandible BD 1. See the text for the meaning of the variables. Negative values indicate right dominance; for each variable, italics and bold indicate the lowest and the highest values, respectively (cf. Macchiarelli et al. 2013: table 1). Note that, because of incomplete/missing root, some variables were not measured/calculated for the right central incisor (I1) and canine (C). Tableau 1 -Variations entre antimères (% asymm.; Corruccini et al. 2005) des proportions des tissus dentaires (variables de Ve à Vcem/Vrdp) et indices 3D d'épaisseur de l'émail (3D AET et 3D RET) estimées pour la mandibule néandertalienne BD 1. Voir le texte pour la signification des variables. Les valeurs négatives indiquent une dominance du côté droit; pour chaque variable, italique et gras indiquent respectivement les valeurs minimale et maximale (cf. Macchiarelli et al. 2013: table 1). A noter qu'en raison de racines incomplètes/manquantes, certaines variables n'ont pas pu être mesurées/calculées pour l'incisive centrale (I1) et la canine (C).

	Tooth		Ve (mm 3 )	Vd (mm 3 )	Vp (mm 3 )	Vcem (mm 3 )	Vt (mm 3 )	Vcdp (mm 3 )	Vrdp (mm 3 )	SEDJ (mm²)	Vcdp/Vc Vcem/Vrdp 3D AET (%) (%) (mm)	3D RET
	I1	left	41.98	365.23	15.89	115.29	423.10	116.21	264.91	104.13	73.46	43.52	0.40	8.26
		right	38.83	-	-	-	-	101.57	-	92.80	72.34	-	0.42	8.97
		% asymm.	7.8	-	-	-	-	13.4	-	11.5	1.5	-	-3.7	-8.2
				-	-	-
	I2	left	56.80	483.34	21.93	108.59	562.07	130.63	374.38	115.40	69.69	29.01	0.49	9.70
		right	52.92	479.63	21.91	95.95	554.47	126.05	375.43	109.05	70.43	25.56	0.49	9.68
		% asymm.	7.1	0.8	0.1	12.4	1.4	3.6	-0.3	5.7	-1.1	12.6	1.4	0.2

Table 2 -

 2 Antimeric variation(% asymm.;[START_REF] Corruccini R | -Correspondence between enamel hypoplasia and odontometric bilateral asymmetry in Australian twins[END_REF] of the scale-free bidimensional (2D) Relative Cortical Thickness (2D RCT) index[START_REF] Cazenave | -Inner structural organization of the distal humerus in Paranthropus and Homo[END_REF] comparatively assessed in bucco-lingual slices virtually extracted between the first and second molars (M1/M2) and the second and third molars (M2/M3) in the Neanderthal mandibles BD 1 and Regourdou 1. Negative values indicate right dominance.

	Tableau 2 -Variations entre antimères (% asymm.; Corruccini et al. 2005) de l'indice
	bidimensionnel (2D) et sans échelle d'épaisseur relative de l'os cortical (2D RCT) (Cazenave
	et al. 2017) estimées pour les sections bucco-linguales extraites virtuellement entre les
	premières et secondes molaires (M1/M2) et deuxième et troisièmes molaires (M2/M3) des
	mandibules néandertaliennes BD 1 et Regourdou 1. Les valeurs négatives indiquent une
	dominance du côté droit.
	Virtual slice	BD 1	Regourdou 1
	position
	M1/M2 left	10.9	15.5
	M1/M2 right	12.4	15.5
	% asymm.	-12.9	0.0
	M2/M3 left	11.3	14.2
	M2/M3 right	12.4	15.3
	% asymm.	-9.3	-7.5

Table 1 -

 1 Antimeric variation(% asymm.;[START_REF] Corruccini R | -Correspondence between enamel hypoplasia and odontometric bilateral asymmetry in Australian twins[END_REF] in tooth tissue proportions (variables from Ve to Vcem/Vrdp) and 3D enamel thickness (AET and RET) assessed in the BD 1 Neanderthal mandible. See the text for the meaning of the variables. Negative values indicate right dominance; for each variable, italics and bold indicate the lowest and the highest values, respectively (cf. Macchiarelli et al. 2013: table 1). Note that, because of incomplete/missing root, some variables were not measured/calculated for the right central incisor (I1) and canine (C).

	Tableau 1 -Variations entre antimères (% asymm.; Corruccini et al. 2005) des proportions
	des tissus dentaires (variables de Ve à Vcem/Vrdp) et indices 3D d'épaisseur de l'émail (3D
	AET et 3D RET) estimées pour la mandibule néandertalienne BD 1. Voir le texte pour la
	signification des variables. Les valeurs négatives indiquent une dominance du côté droit; pour
	chaque variable, italique et gras indiquent respectivement les valeurs minimale et maximale

(cf. Macchiarelli et al. 2013: table 1)

. A noter qu'en raison de racines incomplètes/manquantes, certaines variables n'ont pas pu être mesurées/calculées pour l'incisive centrale (I1) et la canine (C).

Table 2 -

 2 Antimeric variation (% asymm.; Corruccini et al. 2005) of the scale-free bi-

	dimensional (2D) Relative Cortical Thickness (2D RCT) index (Cazenave et al. 2017)
	comparatively assessed in bucco-lingual slices virtually extracted between the first and second
	molars (M1/M2) and the second and third molars (M2/M3) in the Neanderthal mandibles BD
	1 and Regourdou 1. Negative values indicate right dominance.
	Tableau 2 -Variations entre antimères (% asymm.; Corruccini et al. 2005) de l'indice
	bidimensionnel (2D) et sans échelle d'épaisseur relative de l'os cortical (2D RCT) (Cazenave
	et al. 2017) estimées pour les sections bucco-linguales extraites virtuellement entre les
	premières et secondes molaires (M1/M2) et deuxième et troisièmes molaires (M2/M3) des
	mandibules néandertaliennes BD 1 et Regourdou 1. Les valeurs négatives indiquent une
	dominance du côté droit.

ACKNOWLEDGMENTS

The fossil specimen BD 1 is curated at the Musée d'Angoulême, while Regourdou 1 is at the

Musée d'Art et d'Archéologie du Périgord, Périgueux. For access to Regourdou 1, we are indebted to F. Couturas, G. Marchesseau and V. Merlin-Anglade. Scanning of both mandibles BD 1 and Regourdou 1 was performed within the framework of the European "TNT Project" at the ESRF beamline ID 17 (Grenoble) thanks to the local collaboration provided by A. Bravin, C. Nemoz and P. Tafforeau. For contribution to the documentation and analysis of both fossils, we thank P. Bayle, S. Benazzi, A. Bergeret, L. Bondioli, L. Fiorenza, F. Gröning, O. Kullmer, and especially V. Volpato. For discussion, we also thank C. Dean, L.C. Fitton, B. Maureille, P. O'Higgins, P. Sémal and B. Vandermeersch. Among the authors, J.-F.T., A.M. and R.M. acknowledge the stimulating role and unique contribution provided by A. Debénath during the European "TNT Project". BIBLIOGRAPHY Bibliographic references ARMAND D. 1998 -La faune de la grotte Bourgeois-Delaunay, commune de La Chaise-de-Vouthon (Charente). Résultats préliminaires. Paleo, 10: 77-86. BADDELEY A., RUBAK E. and TURNER R. 2015 -Spatial point patterns: methodology and applications with R. Chapman and Hall/CRC Press, London, 828 p. BAYLE P., BONDIOLI L., MACCHIARELLI R., MAZURIER A., PUYMERAIL L., VOLPATO V. and ZANOLLI C. 2011 -Three-dimensional imaging and quantitative characterization of human fossil remains. Examples from the NESPOS database. In: Pleistocene databases. Acquisition, storing, sharing, Macchiarelli R., Weniger G.-C. (eds), Wissenschaftliche Schriften des Neanderthal Museums 4, Mettmann, p. 29-46. BAYLE P., LE LUYER M. and ROBSON BROWN K.A. 2017 -The dental remains: enamel thickness, and tissue proportions. In: The people of Palomas: Neandertals from the Sima de las Palomas, Cabeza Gordo, southeastern Spain, Trinkaus E., Walker M.J. (eds), Texas A&M University Press, College Station, pp. 115-137. BENAZZI S., NGUYEN H.N. KULLMER O. and HUBLIN J.-J. 2013 -Unravelling the functional biomechanics of dental features and tooth wear. PLoS One, 8: e69990. BERTRAN P. 1999 -Dynamique des dépôts de la grotte Bourgeois-Delaunay (La Chaise-de-Vouthon, Charente): apport de la micromorphologie. Paleo, 11: 9-18. BLACKWELL B.A., PORAT N., SCHWARCZ H.P. and DEBÉNATH A. 1992 -ESR dating of tooth enamel: comparison with 230 Th/ 234 U speleothem dates at La Chaise-de-Vouthon (Charente), France. Quaternary Science Reviews, 11: 231-244. BLACKWELL B.A., RUTTER N.W., and DEBÉNATH A. 1990 -Amino acid racemization analysis of mammalian bones and teeth from La Chaise-de-Vouthon (Charente), France. Geoarchaeology, 5: 121-147. BLACKWELL B.A., SCHWARCZ H.P. and DEBÉNATH A. 1983 -Absolute dating of hominids and Paleolithic artifacts of the cave of La Chaise-de-Vouthon (Charente), France. Journal of Archaeological Science, 10: 493-513. BONDIOLI L., BAYLE P., DEAN C., MAZURIER A., PUYMERAIL L., RUFF C., STOCK J.T., VOLPATO V., ZANOLLI C. and MACCHIARELLI R. 2010 -Morphometric maps of long bone shafts and dental roots for imaging topographic thickness variation. American Journal of Physical Anthropology, 142: 328-334. BONHOMME V., PICQ S., GAUCHEREL C. and CLAUDE J. 2014 -Momocs: outline analysis using R. Journal of Statistical Software, 56: 1-24. BOUCHUD P. and BOUCHUD J. 1953 -La petite faune de la grotte de La Chaise (Charente). Bulletin de la Société préhistorique de France, 50: 170-177. BRAGA J., THACKERAY J.F., SUBSOL G., KAHN J.L., MARET D., TREIL J. and BECK A. 2010 -The enamel-dentine junction in the postcanine dentition of Australopithecus africanus: intra individual metameric and antimeric variation. Journal of Anatomy, 216: 62-79.


Mihaela Danu

Erwan Messager

Jean-Michel Carozza

Laurent Carozza

Laurent Bouby

Sylvie Philibert

Patricia Anderson

Albane Burens

Cristian Micu

Phytolith evidence of cereal processing in the Danube Delta during the Chalcolithic period

Keywords:

Recent excavations at Taraschina, south-eastern Romania, have revealed an extensive Chalcolithic settlement in the heart of the Danube Delta. Based on ceramic data, Taraschina was attributed to the Gumelniţa Culture and dated to the mid 5th millennium BC by radiocarbon dating. Phytolith analysis was conducted at Taraschina in order to reconstruct some activities carried out by the Chalcolithic populations in the Danube Delta. The study was undertaken on the site sediments, as well as on additional deposits sampled around the site by coring. The results show that phytoliths characterizing cereal processing are attested in archaeological deposits, as well as in the surrounding sequence. Our study highlights an important signal of cereal processing in the heart of the Danube Delta, 6000 years ago.

Introduction

The Danube Delta biosphere reservation is a unique and original research area for the understanding of the interactions between societies and their environment, from prehistoric to present times. The Danube Delta is, due to its area (5165 km 2 ), one of the most extensive wetland areas of Europe. Far from this image of a natural protected area, the Danube Delta is inhabited by about 15 000 residents distributed in 15 communities. While multiple studies are dedicated to geographical, geomorphological and geological aspects of the Delta area [START_REF] Antipa | Wissenschaftliche und wirtschaftliche Probleme des Donaudeltas[END_REF][START_REF] Antipa | -Oceanografia, Bionomia Si Biologia Generală a Mării Negre[END_REF][START_REF] Vâlsan | Nouvelle hypothese sur le Delta du Danube[END_REF][START_REF] Brătescu | Oscilaţiile de nivel ale apelor şi bazinului Mării Negre[END_REF][START_REF] Coteţ | Evoluţia morfohidrografică a Deltei Dunării (O sinteză a studiilor existente şi o nouă interpretare)[END_REF][START_REF] Ghenea | Palaeogeography of the lower Danube valley and the Danube delta during the last 15 000 years[END_REF][START_REF] Liteanu | Transgresiunile cuaternare ale Mării Negre pe teritoriul Deltei Dunării[END_REF][START_REF] Panin | The danube delta. geomorphology and holocene evolution: a synthesis[END_REF][START_REF] Giosan | Young Danube delta documents stable Black Sea level since the middle Holocene: morphodynamic, paleogeographic, and archaeological implications[END_REF][START_REF] Romanescu | Geoarchaeology of the ancient and medieval Danube Delta: Modeling environmental and historical changes[END_REF][START_REF] Vespremeanu-Stroe | Holocene evolution of the Danube delta: an integral reconstruction and a revised chronology[END_REF], the impact of past human occupation on the Delta's environment is still poorly documented. Archaeological research [START_REF] Micu | Neo-Eneoliticul în nordul Dobrogei în lumina cercetărilor de la Isaccea şi Luncaviţa[END_REF][START_REF] Dimitriu | Geodynamic and hydro-geological constraints regarding the extension of the prospective archaeocultural area within the northern Romanian coastal zone[END_REF] has identified a limited number of sites within the Delta area, drawing an incomplete history of human occupation. This vast wetland is not easy to survey and the idea that it was not a suitable place for preand proto-historic settlement is widespread (Carozza et al., 2011a). The discovery of two Chalcolithic sites, at Taraschina [START_REF] Micu | Observations sur l'habitat neo-eneolithique dans le Delta du Danube[END_REF]Carozza et al., 2011a[START_REF] Carozza | Landscape change and archaeological settlements in the lower Danube valley and delta from early Neolithic to Chalcolithic time: a review[END_REF] and Dâmbul [START_REF] Mihail | Dâmbul lui Haralambie"un nou sit eneolitic în Delta Dunării[END_REF], provides indisputable evidence that the Delta was inhabited at least 6500 years ago. The Dâmbul site is too deeply buried and will probably never be excavated, but the Taraschina site has yielded many domestic dwellings recognized both by excavation and coring. The Chalcolithic inhabitants of Taraschina probably preferred such a strategic place to settle, favorable for both control of the region and navigation (Carozza et al., 2011b[START_REF] Carozza | Landscape change and archaeological settlements in the lower Danube valley and delta from early Neolithic to Chalcolithic time: a review[END_REF]. Which kind of activities did these Chalcolithic populations practice in this area? What was the surrounding environment of the site and how did populations manage it at that time? In such a context, it is very important to find out, which characteristics defined the landscape at that time. Among the botanical proxies, phytoliths have proved to be well-preserved in the archaeological deposits as well as in the natural deposits in the Taraschina vicinity (pollen grains were not preserved in any of analysed samples). So far, palaeo-palynological studies have been carried out on surface sea-bed samples from the north-western part of the Black Sea, in order to obtain some data on the distribution patterns of palynomorphs along transects from the Danube River delta front to the outer shelf off the delta [START_REF] Mudie | Palynology of the Danube delta and shelf -comparison of methods[END_REF]. But for Danube Delta itself, paleo-palynological data are rare because of poor pollen preservation. However, since the Bronze Age, pollen results record a mixed deciduous forest dominated by Quercus, Fagus, Carpinus, Tilia. Poaceae pollen dominates, suggesting the presence of a large reed formation [START_REF] Carozza | Landscape transformations and archaeological settlements in the upper Danube delta during early to middle Holocene: a palaeoecological insight[END_REF]. This study represents the first phytolith analysis in the Danube Delta. Although the data are preliminary, this study provides information on the subsistence activities of the Chalcolithic communities established in the Danube Delta.

Study area

The Taraschina site and its setting

The Taraschina site is located within the present day Danube Delta, close to the Mila 23 village, about 23 km upstream from the mouth of the Soulina (Fig. 1). The exceptional nature of the Taraschina site is mostly due to its position in the Danube Delta. Based on ceramic data, the Taraschina site is attributed to the Gumelniţa Culture (Chalcolithic), and was dated to the mid 5th millennium BC by radiocarbon dating. The previous oldest archaeological occupation in the alluvial context of the Danube Delta was attributed to the transition period between the Chalcolithic and the Bronze Age [START_REF] Vasiliu | Cercetări arheologice în Delta Dunării. Mormintele cu ocru de la Chilia-Veche[END_REF].

According to preliminary GPS cartography, Taraschina extends over more than 15 000 m 2 and is composed of at least two main sites (Sites 1 and 2 in Fig. 2). They are composed of several destroyed buildings, associated with many pits.

From a geomorphological perspective, this part of the delta shows that the site is probably located on the edge of an approximately 2 m slope (slope terrace or fluvial incision) that overlooks a backswamp zone (Fig. 2).

Site occupation

The chronology of site occupation deduced from analysis of the tell levels, covers a period ranging from 4800 to 4300 cal. BC (Carozza et al., 2011a(Carozza et al., , 2011b)). These habitats are mainly related to the culture of Gumelniţa. Archaeological evidence indicates that the site was gradually abandoned, around 4350-4250 cal. BC, probably due to a change of function (temporary or specialized habitat). However, the top of the sequence shows that the tell occupations continue between 4300 and 4050 cal. BC. For now, no occupation has been brought to light after 4100-4050 cal. BC.

Materials and method

Coring, core description and dating

In this study, two sequences will be presented (Fig. 2): core 12, extracted on the tell, and core 10, in the direct vicinity of the tell. Both cores were taken using a Cobra TT percussion device. The sequences were correlated by a number of distinct sediment layers. The lithology of the sequences and available radiocarbon dates are presented in Fig. 3 and Table 1.

In addition, 4 surface soil samples (RS -1 cm depth, RS2 -3 cm depth, RS3 and RS4 -15 cm depth) were also taken from the wetland Fig. 3. Stratigraphy of sequences and available radiocarbon dates.

Table 1

List of AMS 14C dates from Taraschina cores. 14C ages were calibrated using INTCAL09 [START_REF] Stuiver | Extended 14C data base and revised CALIB 3.0 14C age calibration program[END_REF]Reimer et al., 2009) surrounding the site (Fig. 2) to ensure the comparison with fossil phytolith records. Core 12. It was directly extracted from the tell of Taraschina, into the excavation zone 1. The sequence is composed of 4 m of deposits (Fig. 3). The base of the sequence, from 400 to 319 cm, corresponds to the loessic substratum. At 310 cm, a brown silty level (soil?) was observed. Another silty brown layer is recorded between 249 and 254 cm. Small charcoals from this level (256 cm) have been dated (5680 ± 30 BP, from 4590 to 4453 cal. BC). The middle part of the sequence (249-119 cm) shows alternating layers of burned and unburned materials, interpreted as buildings, with destruction and re-building phases (Carozza et al., 2011a). This pattern reflects the building dynamic of the tell. The upper part of the sequence (from 100 to 20 cm) is composed of a thick silty layer without clear subdivisions. The carbonates present in this deposit are due to recent oscillation of the groundwater table level. In this upper part of the sequence, the initial archaeological layer has been modified by present-day pedogenetic processes and all sedimentary structures of both natural and artificial origine have been removed by bioturbation (roots, fauna activity) and leaching.

Core 10. Sedimentological analysis has been focused on core 10, on which laser grain-size (Coulter Beckman 200), geochemical (XRF, AVAATECH) analyses and Magnetic Susceptibility (Bartington MS2E) have been carried out [START_REF] Carozza | Après le Déluge : évolution géomorphologique du delta du Danube après la reconnexion Mer Noire -Méditerranée et ses implications sur le peuplement énéolithique/chalcolithique[END_REF]. This core (Fig. 3) can be subdivided into four main units (see [START_REF] Carozza | Après le Déluge : évolution géomorphologique du delta du Danube après la reconnexion Mer Noire -Méditerranée et ses implications sur le peuplement énéolithique/chalcolithique[END_REF]: 1) from 300 to 259 cm (US1), fine pale brown sediments of massive structure that were interpreted as loess and palaeosoil developed on loess; from 259 to 153 cm (US2), alternated dark silt and clay were interpreted as fluviolacustrine deposits, consistent with the faunal remains (shells and fishbones); from 153 to 108 cm (US3), the deposit is a more homogeneous clay-silt organic layer; the top of the core (US4a and b) is composed of an alternation of clay-silt and sandy levels, indicating a fluvial (and more dynamic) origin.

Sampling, phytolith extraction, counting and classification

47 and 17 samples were collected from sequences 10 and 12 respectively for phytolith analysis. Sequence 10 was more sampled and analysed due to its proximity to the Taraschina settlement and its abundant data (radiocarbon dates and sediment analysis). 4 surface soil samples collected from the wetland surrounding the site were taken between 1 and 15 cm deep.

Phytoliths were extracted from sediment samples using a method adapted from techniques described by [START_REF] Lentfer | A comparison of three methods for the extraction of phytoliths from sediments[END_REF]. Carbonates were dissolved in an HCl bath and organic matter was removed with a 15% H 2 O 2 solution heated at 60 °C until reaction ceased. A 200 μm mesh sieve was then used to recover fine particles. Most of the clay particles were removed through decantation and centrifugation after shaking with 15% sodium hexametaphosphate. Densimetric separation of phytoliths (d < 2.3) from the quartz and other mineral particles was achieved using a heavy liquid solution (Sodium Polytungstate, with d = 2.35). After cleaning, the residue was suspended in Zeiss immersion oil for mounting on glass slides. The slides were observed under a "Leica DMRB ™" Microscope at 650× magnification. Each phytolith was classified according to its morphology, following several systems [START_REF] Twiss | Morphology classification of grass phytoliths[END_REF][START_REF] Mulholland | Grass opal phytolith production: a basis for archaeological interpretation in the northern plains. Archaeobotany through phytolith analysis symposium[END_REF][START_REF] Fredlund | Modern phytoliths assemblages from the north american great plains[END_REF] and the International Code for Phytolith Nomenclature [START_REF] Icpn Working Group | International code for phytolith nomenclature 1.0[END_REF].

The observed phytoliths are classified into 15 different categories. The classes of elongate (Fig. 4 a), elongate dendritic (Fig. 4 b), acicular hair cell 1 (Fig. 4 c), and bulliform (Fig. 4 d) are essentially formed in the epidermis of grasses [START_REF] Twiss | Morphology classification of grass phytoliths[END_REF][START_REF] Piperno | Phytolith Analysis: an Archaeological and Geological Perspective[END_REF][START_REF] Mulholland | Grass opal phytolith production: a basis for archaeological interpretation in the northern plains. Archaeobotany through phytolith analysis symposium[END_REF][START_REF] Fredlund | Modern phytoliths assemblages from the north american great plains[END_REF], but they can also be produced by other groups [START_REF] Piperno | Phytolith Analysis: an Archaeological and Geological Perspective[END_REF][START_REF] Strömberg | The origin and spread of grass-dominated ecosystems in the late Tertiary of North America: preliminary results concerning the evolution of hypsodonty[END_REF]. Cylindric sulcate type (Fig. 4 e) is usually assigned to herbaceous or woody dicotyledonous, but can also be produced in small amounts by conifers and ferns [START_REF] Piperno | Phytolith Analysis: an Archaeological and Geological Perspective[END_REF][START_REF] Runge | The opal phytolith inventory of soils in central Africa quantities, shapes, classification and spectra[END_REF]. Acicular hair cell 2 (Fig. 4 f) includes atypical trichome phytoliths, but has no taxonomic value because it can be produced by grasses and non-grasses. Classes rondel (Fig. 4 g), trapeziform sinuate (Fig. 4 h), bilobate (Fig. 4 i), cylindrical polylobate (Fig. 4 j) and saddle (Fig. 4 k) are produced in epidermal short cells of grasses. They can be used to identify the main Poaceae subfamilies recorded in the phytolith assemblage [START_REF] Twiss | Morphology classification of grass phytoliths[END_REF][START_REF] Fredlund | Modern phytoliths assemblages from the north american great plains[END_REF]. Rondels are frequently associated with the Pooideae subfamily [START_REF] Mulholland | Grass opal phytolith production: a basis for archaeological interpretation in the northern plains. Archaeobotany through phytolith analysis symposium[END_REF][START_REF] Piperno | The silica bodies of tropical american grasses: morphology, taxonomy, and implications for grass systematics and fossil phytolith identification[END_REF], but are also found in other Poaceae subfamilies such as the Arundinoideae [START_REF] Barboni | Phytoliths of East African grasses: an assessment of their environmental and taxonomic significance based on floristic data[END_REF]. The trapeziform sinuate morphotype can be considered as a good tracer of the Pooideae subfamily [START_REF] Barboni | Comparative study of modern phytolith assemblages from inter-tropical Africa[END_REF]. The bilobate morphotypes mainly occur in the Panicoideae and Arundinoideae subfamilies. The saddle morphotype is produced in high proportion by the Chloridoideae. Papillae type (Fig. 4 l) corresponds to silicified epidermal papillae, essentially occurring in the inflorescences of Poaceae [START_REF] Ball | An approach to identifying inflorescence phytoliths from selected species of wheat and barley[END_REF][START_REF] Berlin | Ptolemaic agriculture, ''Syrian wheat'', and Triticum aestivum[END_REF]. Globular phytoliths (Fig. 4 m) correspond to the various circular and spheroid morphotypes already recognized and considered as characteristic of the dicotyledonous group [START_REF] Bozarth | Classification of opal phytoliths formed in selected Dicotyledons native to the Great Plains[END_REF][START_REF] Alexandre | Phytoliths: indicators of grassland dynamics during the late Holocene in intertropical Africa[END_REF][START_REF] Albert | Mode of occupation of Tabun Cave, Mt Carmel, Israel during the Mousterian period: a study of the sediments and phytoliths[END_REF][START_REF] Runge | The opal phytolith inventory of soils in central Africa quantities, shapes, classification and spectra[END_REF][START_REF] Delhon | Phytolith assemblages as a promising tool for reconstructing Mediterranean Holocene vegetation[END_REF]. Blocky (Fig. 4 n) morphology is not well identified in our study. In previous work, this class has been assigned to Artemisia or to different Pinaceae genera [START_REF] Pearsall | Current Research in Phytolith Analysis: Applications in Archaeology and Paleoecology[END_REF][START_REF] Blinnikov | Reconstruction of the Late Pleistocene grassland of the Columbia basin, Washington, USA, based on phytolith records in loess[END_REF]. Silica skeletons (linked phytoliths, Fig. 4 o,p) corresponding to fragments of silicified Poaceae epidermis were also identified [START_REF] Rosen | Preliminary identification of silica skeletons from near eastern archaeological sites: an anatomical approach[END_REF]. They represent the remains of fragmented pieces of culms, leaves and inflorescences of Poaceae plants. Among this group, two classes have been separated "silica skeletons with elongate dendritic" (Fig. 4 o) coming from inflorescences and "silica skeletons with elongate" coming from culm and leaves (Fig. 4 p). Many sponge spicules (Fig. 4 q) and diatoms (Fig. 4 r) were observed, especially in the upper parts of sections. Each morphotype's relative abundance was calculated as a percentage of the sum of classified phytoliths. This sum used for percentage calculations was based on the total number of phytoliths counted per sample (more than 200 for each sample). The silica skeletons, diatoms and sponge spicules were excluded from the total phytolith sum to avoid overrepresentation of these groups. The representation of each of these groups was expressed as percentages of the sum of phytoliths plus the group sum [i.e. % of diatoms = N diatoms/(Ʃ phytoliths + N diatoms) x 100].

Results

Phytoliths are very well preserved in the archaeological sequence (core 12), as well as in the "off-site" sequence extracted around the site (core 10). Grasses (Poaceae) are the dominant taxon in all phytolith samples. Among this group, Pooideae (represented by trapeziform sinuate and a part of rondel classes) is the best recorded sub-family (Figs. 5 and6). Pooideae is the main group of Poaceae in temperate areas, but we cannot exclude that a part of the rondel could be from Arundinoideae (i.e. Phragmites). Globular morphotypes were rarely identified.

Phytoliths were not found in samples below 250 cm depth (core 12), respectively 290 cm depth (core 10).

Phytolith assemblages from core 12

In the seventeen phytolith samples from core 12 (Fig. 5), the most common short cell type phytoliths are rondel and trapeziform sinuate. Bilobate phytoliths were frequently recorded in the lower part of the sequence (up to 200 cm), demonstrating the potential occurrence of Panicoideae or Arundinoideae subfamilies.

Elongate dendritic forms, coming from inflorescences (glumes, lemma, palea) of Poaceae [START_REF] Ball | An approach to identifying inflorescence phytoliths from selected species of wheat and barley[END_REF], are well-represented throughout the entire sequence studied from the site. High proportion (up to 25%) of elongate dendritic phytoliths can be observed from 211 to 150 cm.

Another interesting feature of these assemblages is the frequent occurrence of silica skeletons (Fig. 5). These fragmented epidermal cells are rarely observed (most of time absent) in natural assemblages. This class of linked phytoliths is particularly significant (over 25%) in the middle part of the sequence (from 190 to 123 cm), displaying the same trend as for the dendritic phytoliths. All samples contain silica skeletons coming from the inflorescence (Fig. 5, those in dark blue color), which are better represented from 180 to 123 cm (i.e. up to 43 silica skeletons coming from the inflorescence, which means over 59% of silica skeletons registered at 150 cm depth sample).

Phytolith assemblages from core 10

Phytoliths are very well preserved in all samples of core 10. The assemblages recovered in core 10 are quite similar to the assemblages coming from core 12 (Fig. 6). The most common form is the rondel, and relatively high percentages of trapeziform sinuate are recorded (from 37.55% to 81.67%, except the sample from 68 cm depth where trapeziform sinuate represented 10.76%), highlighting the importance of the Pooideae group. Bilobate phytoliths are frequent in the lower part of the sequence (below 250 cm, in 77% of samples).

Elongate dendritic forms are very well-represented in the lower and middle parts of the sequence (up to 37.95%). Significant values of silica skeletons have also been recorded (i.e. over 22% at 253 cm deph). Among this group, linked phytoliths from culms and leaves are better represented (76%-100%) than those coming from inflorescences (Fig. 6).

Based on variations of the main phytolith morphotypes observed in the sequence (Fig. 6), three zones can be identified in the diagram:

•Zone 1 (Z1: 289-255 cm) is characterized by the abundance of elongate dendritic forms (10-20%) and the presence of silica skeletons (5-10%).

•Zone 2 (Z2: 254-88 cm) represents the same phytolith assemblage as zone 1, but the silica skeletons are twice as abundant (10-20%).

•Zone 3 (Z3: 87-50 cm) shows a decrease in dendritic forms and silica skeletons, with an increase in elongate and bulliform phytoliths. From a depth of 78 cm to the top, there is a huge increase in sponge spicules (from 11.37% at 78 cm depth to 43.96% at 68 cm depth) and a decline in dendritic and silica skeleton values (less than 2.5%).

Samples references

All modern soil phytolith assemblages contained large quantities of rondels (Fig. 7) (from 33.33% to 80%). Only a few dendritic forms and silica skeletons are recorded in two reference samples (RS1 and RS2) (1.53%-3.17%). Bulliforms have also been observed. What is interesting is the overwhelming presence (up to 80%) of aquatic environment markers (spicules and diatoms) in all samples (Fig. 7).

Discussion

Implications of phytolith assemblages recorded on the site

The whole site sequence (core 12) is characterized by large percentages of elongate dendritic phytoliths (up to 25.68%). While this class of phytolith is scarcely recorded in natural soil assemblages [START_REF] Novello | Grass inflorescence phytoliths of useful species and wild cereals from sub-Saharan Africa[END_REF], such as those coming from the modern reed formation (see reference samples, Fig. 7), it might be very wellrepresented in archaeological sites in which cereals have been processed [START_REF] Berlin | Ptolemaic agriculture, ''Syrian wheat'', and Triticum aestivum[END_REF][START_REF] Portillo | Husbandry practices and livestock dung at the numidian site of althiburos (El Médéina, Kef governorate, northern Tunisia): the phytolith and spherulite evidence[END_REF]. Thus, the presence of many dendritic phytoliths is taken as evidence for the presence of cereals at the Taraschina site. The abundance of silica skeletons coming from the cereal inflorescence confirms the presence of cereals in the site. Moreover, the percentages of silica skeletons coming from culms and leaves of Poaceae reflect an accumulation of threshing remains, especially in the middle part of sequence 12. This phytolith signal gives evidence for cereal processing on the site, or in the immediate vicinity.

The consumption of cereals is also attested in Taraschina by carbonized seeds and fruits. Most of these are cereal grains, especially While no farming activities had been suspected up to now in the heart of the Danube Delta for pre-and proto-historical periods, the phytolith assemblages from Taraschina tend to show that Chalcolithic populations could grow cereals in this area. Cereal importation into the Delta by the Chalcolithic populations is possible. In the hypothesis of cereal importation, cereals should have been transported already threshed and processed (grains without straw). But, the hypothesis of local cereal cultivation is strengthened by the abundance of threshing by-products (and especially the high amount of silica skeletons coming from leaves and culms in both sequences), demonstrating that entire cereal plants were brought onto the site (with straw). Moreover, the identification of sickle elements tends to show that the cereal harvesting was probably done by people living in Taraschina.

The phytolith assemblages identified in Taraschina reflects the importance of the Pooideae subfamily. This group corresponds to wild temperate grasses, as well as C 3 cereals. This taxonomical identification is in agreement with the cereals identified on the site from charred remains: Triticum dicoccum and Hordeum vulgare. Both of these species are the main cereals cultivated during the Gumelniţa Cultural period in the Romanian plain [START_REF] Cârciumaru | Étude paléobotanique pour les habitats néolithiques et énéolithiques de la Romanie[END_REF][START_REF] Cârciumaru | Paleoetnobotanica. Studii În Preistoria Si Protoistoria României (Agricultura Preistorică Si Protoistorică a României[END_REF]. The occurrence of frequent bilobate phytoliths in the lower part of the sequence is interesting because it could reflect wild grasses from the Arundinoideae or Panicoideae groups (e.g. wild Setaria or Phragmites australis), or the hypothetic presence of domesticated millet. Some seeds of broomcorn (Panicum miliaceum) and foxtail millets (Setaria italica) have already been discovered in a Gumelniţa site, called Morteni, but the author is not convinced of the origin of the material [START_REF] Cârciumaru | Étude paléobotanique pour les habitats néolithiques et énéolithiques de la Romanie[END_REF]. The beginnings of millet cultivation are still debated for Central and Eastern Europe [START_REF] Hunt | Millets across Eurasia: chronology and context of early records of the genera Panicum and Setaria from archaeological sites in the Old World[END_REF][START_REF] Motuzaite-Matuzeviciute | The early chronology of broomcorn millet (Panicum miliaceum) in Europe[END_REF]. But, broomcorn millet grains coming from old Ukrainian sites and recently 14 C dated, turned out to be significantly younger than the contexts in which they had been found [START_REF] Motuzaite-Matuzeviciute | The early chronology of broomcorn millet (Panicum miliaceum) in Europe[END_REF]. Thus, the question is not yet resolved in Eastern Europe. In Taraschina, the bilobate phytoliths may more likely come from wild Panicoideae or Arundinoideae.

Interpreting phytolith assemblages recorded around the site

Additional cores performed around the site (such as core 10) were initially intended for the palaeoenvironmental reconstructions of the Taraschina area. But, core 10 has yielded unexpected phytolith assemblages, more related to the site occupation, than to the natural environment of the site.

The phytolith assemblage from sequence 10 show significant similarities with the one coming from the archaeological deposits. In fact, many dendritic phytoliths, as well as silica skeletons (as many as 20%) have been recorded in this off-site sequence. This pattern confirms that the lower and the middle deposits of core 10 reflect a strong human impact, resulting from the cereal processing practiced by the Chalcolithic communities. Although the sequence from core 10 was taken 40 m from the site, the phytolith content of the sediments shows that the human impact still prevails. A difference between both sequences is the lower values of silica skeletons coming from inflorescences in the off-site sequence (core 10). The phytolith assemblages from this sequence could reflect threshing processes, while the assemblages from the site support in addition the hypothesis of dehusking and winnowing processes on the site.

The rich phytolith deposits coming from the vicinity of the site, characterized by the signal of cereal processing, could have different origins: 1) This signal could correspond to a cropping area, where soils could be manured with domestic waste and/or dung. The dung could be composed of by-products of processing, used as fodder for cattle [START_REF] Harvey | Investigating crop processing through phytolith analysis: the case of rice and millets[END_REF][START_REF] Lancelotti | The 'invisible' product: developing markers for identifying dung in archaeological contexts[END_REF]. 2) Another possible hypothesis could be the presence of a huge threshing floor. The big amount of silica skeletons coming from culms and leaves can support this scenario. The hypothesis of a threshing surface, associated with the use of the threshing sledge (Tribulum) has already been proposed by Skakun for Chalcolithic sites in Bulgaria [START_REF] Skakun | Agricultural implements in the neolithic and Eneolithic of Bulgaria[END_REF][START_REF] Anderson | History of harvesting and threshing techniques for cereals in the Prehistoric near east[END_REF][START_REF] Anderson | Insights from a tribological analysis of the tribulum[END_REF]. Several silica skeletons, displaying the characteristic scoring and break mark profiles of Tribulum process [START_REF] Anderson | Observations on the threshing sledge and its products in ancient and present-day Mesopotamia[END_REF][START_REF] Anderson | Premiers Tribulums, Premières Tractions Animales au Proche-Orient vers 8000-7500 BP ?[END_REF][START_REF] Anderson | Insights from a tribological analysis of the tribulum[END_REF], have been observed in the Taraschina phytolith assemblages. 3) Since light chaff can be used as temper for construction purposes, to produce for example chaff-tempered clay (or daub) or mud-bricks [START_REF] Hillman | Interpretation of archaeological plant remains: the aplication of ethnographic models from Turkey[END_REF], the corresponding phytoliths could have been released after destruction and dissolution of building materials, and mixed with the surrounding sediments [START_REF] Khedhaier | Dépiquage au tribulum au Néolithique final dans le Sud-est de la France: indices convergents de la tracéologie et de l'analyse des phytolithes. Le cas du site de Forcalquier-La Fare (Alpes-de-Haute-Provence)[END_REF]. 4) The more parsimonious hypothesis to explain the large amount of phytoliths in the surrounding deposits, is that the cereal treatment on the site and its vicinity was intense, generating a large amount of threshing remains. These remains could have been used around the site by inhabitants (i.e. fuel, building, crafts, fodder; [START_REF] Anderson | Observations on the threshing sledge and its products in ancient and present-day Mesopotamia[END_REF], or simply refused around the site.

The hypothesis that no occupation has been brought to light after 4100-4050 cal. BC is strengthened by the phytolith assemblages recorded in core 10.

The analysis of the upper parts of core 10 reveals a gradual decline of the phytoliths characterizing cereal processing. Concurrently, the aquatic environment markers such as sponge spicules and/or diatoms show a significant increase, probably caused by hydrological variation. This situation is clearly reflected in the four reference samples (Fig. 7). The large amount of bulliform phytoliths, recorded in the upper part of core 10, could have different origins: i.) bulliform phytoliths are more frequent, because when plants experience an exceptional water-stress, such as high evapo-transpiration or flooded soils, they produce more bulliform phytoliths [START_REF] Brémond | Grass water stress estimated from phytoliths in West Africa[END_REF][START_REF] Messager | Palaeoecological implications of the Lower Pleistocene phytolith record from the Dmanisi site (Georgia)[END_REF]. ii.) a part of bulliforms could have been produced by reeds (Phragmites australis), expanding at that time. So, the increase of bulliform type might indicate a variation of water level or/and probably an expansion of the reed bed in the site vicinity. This pattern appears to be simultaneous with the decrease of phytoliths characterizing cereal processing. Thus, the biogenic silica assemblages (phytoliths + sponge spicules + diatoms) indicate a significant environmental change in the Taraschina area, marked by the modification of the edaphic conditions around the site and the decline of human impact. As we can see in the reference samples, the reed formation developed nowadays in the heart of the Delta provides quite similar biogenic silica assemblages. Our results can be correlated with the sediment data, that show the development of a histosol along the last 100 cm of the sequence.

Conclusion

Phytolith assemblages have proved to be reliable markers to decipher human activities in the Danube Delta during the Chalcolithic period. Using this archaeobotanical proxy, it was possible to highlight an important signal of cereal processing on the site of Taraschina, and in its close vicinity. Massive presence of elongate dendritic phytoliths and silica skeletons provides evidence for crop processing on the site. This study, the first phytolith analysis conducted in the Danube Delta, suggests that Chalcolithic populations of Gumelniţa Culture could possibly grow cereal in the heart of the Delta, 6000 years ago. Following this, phytolith data indicate a gradual decline in phytoliths characterizing cereal processing and the simultaneous rise of aquatic environment markers. Archaeological data highlight a decrease of the anthropic signal around 4350-4250 BCE. Considering the close chronology of both events, the site of Taraschina could have been left due to rise of water and the resulting environmental change.

Fig. 1 .

 1 Fig. 1. Map showing the location of Taraschina.

Fig. 4 .

 4 Fig. 4. Pictures of phytolith morphotypes identified in Taraschina sequences: a. Elongate, b. Elongate dendritic, c. Acicular hair cell 1, d. Bulliform, e. Cylindric sulcate, f. Acicular hair cell 2, g. Rondel, h. Trapeziform sinuate, i. Bilobate, j. Cylindrical polylobate, k. Saddle, l. Papillae, m. Globular, n. Blocky, o. Silica skeletons (with elongate dendritic), p. Silica skeletons (with elongate), q. Spicules, r. Diatoms.

Fig. 5 .

 5 Fig. 5. Phytolith assemblages (%) from core 12.

Fig. 6 .

 6 Fig. 6. Phytolith assemblages (%) from core 10.

Fig. 7 .

 7 Fig. 7. Phytolith assemblages (%) from reference samples.

  .

	Lab. Code	Sample	Type	Radiocarbon Age	Age cal BC
				BP
	Beta-350 741 Core 12 (-256 cm)	charcoal 5680 ± 30 BP	4590-4453
	Poz-42867	Core 10 (-158-	charcoal 5390 ± 80 BP	4366-3997
		160 cm)
	Poz-42868	Core 10 (-190-	charcoal 5600 ± 40 BP	4504-4351
		192 cm)
	Poz-40109	Core 10	charcoal 5470 ± 40 BP	4442-4240
		(-223 cm)
	Poz-40109	Core 10 (-244-	charcoal 5610 ± 40 BP	4520-4356
		246 cm)
	Poz-40 110	Core 10	charcoal 5580 ± 40 BP	4488-4347
		(-267 cm)
	Poz-40 111	Core 10	charcoal 5660 ± 40 BP	4592-4370
		(-294 cm)

Acknowledgements

The authors would like to thank the anonymous reviewers for their helpful and constructive comments that greatly contributed to improving the final version of the paper. They would also like to thank the Editors for their generous comments and support during the review process. This research was partly founded by the project "Danube Delta Archaeology" directed by L. Carozza and supported by the "French Foreign Office" and the PN-II-CT-RO-FR-2012-1-0092 PHC Brancusi program coordinated by A. Burens and S. Ailincai. Phytolith analysis was conducted in the UMR 7264 CEPAM CNRS -Université Côte d'Azur (Nice).