Right-Handed Neandertals Figure 2. Microtomographic-based 3D reconstruction of the right upper limb chain of Regourdou 1 (in anterior view) showing the average degree of bilateral asymmetry (in %) assessed for the cortical area (CA, left) and the polar second moment of area (J, right) and rendered by virtual superimpo- sition (semi-transparency, in gray) to the original outline of each element (in gold). To emphasize differences among the different elements, the amount of original asymmetry has been doubled. Scale bar is 10 cm. doi:10.1371/journal.pone.0043949.g002 ulna, the right side is between 5–13% larger than the left, leading Vandermeersch and Trinkaus [19, p. 473] to conclude … ‘‘if upper limb asymmetry can be correlated with handedness, Re´gourdou 1 was right-handed.’’ Following a preliminary biomechanical analysis of the humeri [29], synchrotron radiation microtomographic images were used to further document right/left endostructural and volumetric (cortical thickness-related) differences for the clavicle, humerus, radius and ulna. This represents the first integrated analysis concerning the entire upper limb skeletal chain (excluding bones of the hand) of a Neandertal (29]. Comparative variation across the shaft in cross-sectional geometric properties virtually assessed at Figure 3. Occlusal view of Regourdou 1 mandible. The apparent malpositioning of the teeth is due to reconstruction. Photo credit: P Se´ mal, Royal Belgian Institute of Natural Sciences, Brussels. doi:10.1371/journal.pone.0043949.g003 Figure 1. The skeleton of Regourdou 1. Photo credit: Collections Ville de Pe´rigueux, Muse´e d’Art et d’Arch e´ologie du Pe´ rigord: Inv. 85.3. doi:10.1371/journal.pone.0043949.g001 Froehle and Churchill [28], we suspect Regourdou 1 was a male but this is irrelevant to our analysis. Results: Handedness from the Skeletal Elements Vandermeersch and Trinkaus [19] were the first to document left/right asymmetry in the upper limb skeleton. They found that the right side was metrically larger and showed overall greater cross-sectional diameters than the left, which they attributed to right-handedness. For seven metrics of the humerus, radius and PLOS ONE | www.plosone.org 2 August 2012 | Volume 7 | Issue 8 | e43949