[43,44]. Based on fetal behavior (e.g. thumb sucking) handedness asymmetry begins in utero [45–47] by as early as the tenth fetal week [48] and correlates with adolescent handedness in the same individuals [46]. It also is linked to further brain structural asymmetries developing before language ability [49], indicating a genetic underpinning to handedness [50,51]. Fetal behavioral evidence of asymmetry long presages later skeletal expression of right/left differences, which begins after one year and affects different dimensions of the humerus discordantly [52]. The long known connection among brain asymmetry, handed- ness and language in living populations serves as a proxy for estimating brain lateralization in the fossil record [9,17] and the likelihood of language capacity in fossils. That is, if Neandertal handedness asymmetry resembled the more ambidextrous ape frequencies, the fossils would be judged incompletely lateralized. But just to the contrary Neandertals appear to be highly lateralized like modern humans. The concordance of arm and dental evidence for handedness in Regourdou links activities directed by asymmetrical arm movements with the traces of the activities preserved on the teeth. These observations are completely concordant with earlier work showing Neandertals are lateralized like modern Homo sapiens. These observations, coupled with evidence from the archaeo- logical record [53], paleoneurology [54], audition [55,56], modern hyoid morphology and placement [57,58], Neandertal DNA with the modern FOXP2 variant [59] and complex/ritual behavior [60–68] extend evidence for language competence deep into the European past. Supporting Information Figure S1 Correlations of scratch length and angle for each tooth. Low correlation coefficients (20.03–0.07) indicate there is no relation between scratch angle and scratch length. (TIFF) Figure S2 Frequency distributions of all scratches per tooth at 106 intervals. Incisors show predominantly scratches below 90u. Both canines show the highest frequencies of scratches around 90u. (PDF) Figure S3 Box plot of the total number of scratches for each Regourdou 1 anterior tooth, using intervals in [69]. (TIFF) Data File S1 Raw data in Microsoft Xls format for dental scratch analysis on left canine. (XLS) Data File S2 Raw data in Microsoft Xls format for dental scratch analysis on right canine. (XLS) Data File S3 Raw data in Microsoft Xls format for dental scratch analysis on left first incisor. (XLS) References 1. Henri-Martin H (1923) Les hommes fossiles de la Quina. Paris: Doin. 260p. 2. Koby FE (1956) Une incisive ne´andertalienne trouvee´ en Suisse. Ver Natur Ges Basel 67: 1–15. 3. Patte E (1960) De´couverte d’un Ne´andertalien dans la Vienne. L’Anthropol 64: 512–517. 4. de Lumley MA (1973) Ante´ne´andertaliens et Ne´andertaliens du basin me´diterrane´en occidental Europe´en. E´ tude Quat 2: 1–626. 5. Lalueza C, Frayer DW (1997) Non-dietary marks in the anterior dentition of the Krapina Neanderthals. Int J Osteoarch 7: 133–149. Right-Handed Neandertals Data File S4 Raw data in Microsoft Xls format for dental scratch analysis on right first incisor. (XLS) Data File S5 Raw data in Microsoft Xls format for dental scratch analysis on left second incisor. (XLS) Data File S6 Raw data in Microsoft Xls format for dental scratch analysis on right second incisor. (XLS) Text S1 (DOC) Methods. Table S1 Degree of bilateral asymmetry (%) in Re- gourdou 1 for the cortical area (CA) and the polar second moment of area (J) measured at three cross-sectional levels (distal / lateral, around the midshaft, proximal / medial) of the diaphysis on the clavicle (35%, 50%, 65%), the humerus (35%, 44%, 65%), the radius (35%, 45%, 65%), and the ulna (35%, 50%, 65%). (DOC) Table S2 Degree of bilateral asymmetry (%) in Re- gourdou 1 for the cortical bone volume (CV) distinctly assessed for the distal (dCV, lateral for the clavicle) and the proximal (pCV, medial for the clavicle) portions of the diaphysis on the clavicle (dCV: 25–45%; pCV: 60– 80%), the humerus (dCV: 24–44%; pCV: 60–80%), the radius (dCV: 25–45%; pCV: 61–80%), and the ulna (dCV: 25–45%; pCV: 60–80%). (DOCX) Table S3 Summary straie statistics for all Regourdou 1 teeth (intervals according to [69]). (DOCX) Acknowledgments V Merlin-Anglade of the Muse´e du Pe´rigord (Pe´rigueux) granted access to Regourdou 1 for dental casting to D G-S. The Muse´e du Pe´rigord) allowed the temporary transport for microtomographic analysis of 41 skeletal elements to the European Synchrotron Radiation Facility (ESRF, Grenoble). RM and VV are indebted to F Couturas, G Marchesseau, and V Merlin-Anglade for their approval and support. The SR-mCT record was done as part of the TNT European project, scientifically led by the Stiftung Neanderthal Museum of Mettmann. For contributions to the documentation and analysis, VV and RM acknowledge A Bergeret, S Breuil, A Bravin, A Mazurier, C Nemoz, and P Tafforeau. VV and RM thank P Bayle, C Couture, C Dean, F Gro¨ning, O Kullmer, A Mazurier, P O’Higgins, L Puymerail, Rougier, CB Ruff, P Se´mal, JT Stock, E Trinkaus, B Vandermeersch and C Zanolli for discussion and scientific collaboration. Author Contributions Conceived and designed the experiments: VV RM LB DWF. Performed the experiments: VV RM IF LB. Analyzed the data: DWF VV RM LB. Contributed reagents/materials/analysis tools: DG-S VV RM LB. Wrote the paper: DWF VV RM LB DG-S. 6. Frayer DW, Lalueza-Fox C, Fiore I, Radovcˇic´ J, Bondioli L (2010) Right- handed Neandertals: Vindija and beyond. J Anthrop Sci 88: 113–127. 7. Bermu´dez de Castro JM, Bromage TG, Ferna´ndez-Jalvo Y (1988) Buccal striations on fossil human anterior teeth: evidence of handedness in the middle and early Upper Pleistocene. J Hum Evol 17: 403–412. 8. Lozano M, Bermu´dez de Castro, JM Carbonell, E Arsuaga, JL (2008) Non- masticatory uses of anterior teeth of Sima de los Huesos individuals Sierra de Atapuerca, Spain. J Hum Evol 55: 713–728. PLOS ONE | www.plosone.org 5 August 2012 | Volume 7 | Issue 8 | e43949