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In order to maximize sample sizes for the assessment of body size and proportions among Late Pleistocene humans, the femoral head diameter of the Regourdou 1 Neandertal was estimated from its ischial acetabular lunate surface, so as to provide a reliable measure for body mass assessment. This estimate was accomplished by fitting a sphere to the 3D surface of the acetabulum and then estimating femoral head diameter using a regression of acetabular sphere diameter to femoral head diameter based on associated recent human femora and ossa coxarum. The resultant mean and range of values for the Regourdou 1 femoral head dimension place it among the smaller of the European and southwest Asian Neandertals, although its humeral length is above average for that sample. Regourdou 1 therefore joins Kebara 2 in having moderately long arms for body core size, and it thereby emphasizes the variation in Neandertal body proportions.

Le diamètre de la tête fémorale de Regourdou 1 a été estimé à partir des dimensions de la portion ischiatique de l’acétabulum. Cette mesure permet d’estimer certaines variables corporelles et apporte ainsi de nouvelles données sur la taille et les proportions corporelles des hommes du Pléistocène supérieur. L’estimation de ce diamètre s’est faite en deux étapes. Dans un premier temps, une sphère a été virtuellement conformée sur la surface 3D de l’acétabulum ischiatique. Dans un second temps, le diamètre de la tête fémorale a été estimé à partir du diamètre de la sphère acétabulaire grâce à une formule de régression calculée sur un échantillon de référence moderne. La moyenne des résultats obtenus, comme l’étendue des valeurs, place Regourdou 1 parmi les plus petits Néandertaliens (Europe et Asie du Sud-Ouest confondus), bien que cet individu présente une longueur humérale supérieure à la moyenne de ce même échantillon. Ces caractéristiques permettent de rapprocher Regourdou 1 de Kebara 2, ces deux individus présentant des bras relativement longs par rapport à la taille du corps. Ces nouvelles données sont ainsi l’occasion d’enrichir la variation des proportions corporelles chez les Néandertaliens.

Assessments of body size among Late Pleistocene humans provide a variety of insights into their paleobiology. Body size estimates provide a baseline for scaling appendicular hypertrophy, especially for weight-supporting elements (

The Regourdou 1 partial skeleton was discovered during excavations in Level 4 of the collapsed karstic chamber at Regourdou (Montignac, Dordogne) by R. Constant and then E. Bonifay and colleagues in 1957 (

The partial skeleton consists of major portions of the mandible, the mandibular dentition, a fragmentary vertebral column, the sternum, the bilateral upper limb long bones, major portions of the hands, partial ossa coxarum, partial femora, patellae, talocrural remains, and partial pedal skeletons (

A small portion of the right femoral neck and head has been identified from among the faunal remains (

The pelvic remains (

Although the greater sciatic notch and the auricular area are preserved on both ilia, they are ambiguous as to the sex of Regourdou 1. The greater sciatic notch is largely “male” in shape, but the composite arch is “female” (cf.

To estimate the Regourdou 1 femoral head diameter, data were gathered for 91 recent human ossa coxarum and articulating femora. The sample consists of Native Americans (13 male; 14 female), EuroAmericans (16 male; 17 female) and AfroAmericans (15 each sex), from the archeological sites of Zuni and Puye Hawikkuh and the Terry, Hamann-Todd and University of Missouri collections. All are fully mature and non-pathological. Given the close developmental and functional correspondence of the femoral head and acetabulum (

The acetabular dimensions and 20 of the femoral head diameters were quantified from 3D surface scans, collected with either a Konica-Minolta Vivid 9i or a Next-Engine laser scanner, which yield comparable results (

A resin cast of the Regourdou 1 right ischium provided by B. Vandermeersch and R. Larche was scanned using a Next-Engine laser scanner to generate a 3D surface scan (

The preserved portion of the Regourdou 1 acetabulum corresponds to regions 5 to 7 of the acetabulum, as designated by

All data were ln-transformed, and a least squares (LS) regression line between femoral head and acetabular diameters was fit. LS regression is preferred over reduced major axis (RMA) for prediction purposes (

ln(FemHd) = 0.991 × ln(Acet)–0.090; SE_{est}: 0.028

in which: ln(FemHd) = natural logarithm of the femoral head diameter, and ln(Acet) = natural logarithm of the acetabular sphere diameter. The slope of the relationship does not significantly differ from 1.00. All femoral head diameter estimates were back-transformed from ln-space and corrected using the “Smearing” estimate (

Note that this acetabular sphere diameter is not the same as acetabular height, measured with calipers from the acetabular rim adjacent to the anterior inferior iliac spine to the opposite caudal rim. Acetabular height has been employed to estimate femoral head dimensions (

The acetabular sphere values for Regourdou 1 were ln-transformed, femoral head diameter estimates calculated, and the values back-transformed. 95% confidence intervals were calculated in ln-space for each estimate using the standard error of the relationship between the acetabular sphere and femoral head diameters, and back-transformed to raw data space. The best estimate of femoral head size for Regourdou 1 using the mid-point value for the acetabular estimate is 45.9 mm, with a 95% confidence interval ranging from 43.5 to 48.5 mm. Substituting the minimum and maximum estimates of acetabular sphere diameter yields estimates of 44.5 and 47.4 mm, respectively. From the 95% CIs of these two limits of the acetabular sphere 95% CI, the absolute minimum estimated femoral head diameter would be 42.1 mm and the maximum 50.0 mm. However, this total range probably overestimates the true 95% CI, since the maximum value approaches the measured sphere diameter; a more likely range is provided by the 95% CIs of the mean femoral head diameter estimate, 43.5 to 48.5 mm (

Given the relationship between femoral head diameter and body mass in recent humans (

In contrast, the Regourdou 1 maximum humeral length (310 mm), from the complete right humerus, is moderately large for a Neandertal (

The contrast between the relative dimensions of the Regourdou 1 femoral head diameter and humeral length raises questions regarding its body proportions; since femoral head diameter is a reflection of body mass and humeral length is related to appendicular length and by extension stature. Given this contrast, and the ecogeographical variation in body proportions both between recent humans and across Late Pleistocene human samples (

These two skeletal dimensions are compared using the ratio of humeral length to femoral head diameter (

The four recent human samples follow the ecogeographical pattern of average relative limb abbreviation with increasing latitude (cf.

Regourdou 1 and one Southwest Asian Neandertal (Kebara 2) have mean values well above the other Neandertals, near the middles of the arctic and cold temperate samples respectively (

The use of sphere-fitting to the partial acetabulum of Regourdou 1, as well as other partial Pleistocene human remains (

It is tempting to ascribe this contrast in this body proportion between Regourdou 1 (plus Kebara 2) and the other Neandertals to the Southwest Asian provenience of Kebara 2 and the association of Regourdou 1 with a warmer climate oscillation within the Last Glacial (

Estimation of the femoral head diameter for the Regourdou 1 Neandertal from its ischial acetabular lunate surface, using 3D sphere-fitting and regressions based on associated ossa coxarum and femora, provides a relatively modest range of values, among Neandertal females and at the lower limits of Neandertal male variation. Yet, when the Regourdou 1 humeral length is compared to its femoral head estimate, it is separate from most Neandertals, although close to the Southwest Asian Kebara 2. These assessments serve to expand the perceived variation among these late archaic humans in their body proportions.

B.M. Auerbach, D. Hunt, A. Rosas and C.B. Ruff provided comparative data, B. Vandermeersch provided the Regourdou ischial cast, and multiple individuals have permitted data collection from human remains in their care. To all, we are grateful.

(Color online.) Ventral view of the articulated Regourdou 1 ilia and sacrum with the ischial portions and the superior pubic ramus in approximate anatomical positions.

(Couleur en ligne.) Vue antérieure du bassin Regourdou 1: sacrum et iliums en connexion, associés aux fragments ischiatiques et pubiens en position anatomique.

(Color online.) Ventrolateral view of the Regourdou 1 right ischium, showing the acetabular lunate surface used for the 3D sphere-fitting.

(Couleur en ligne.) Vue antérolatérale de l’ischium droit de Regourdou 1, montrant la surface semi-lunaire utilisée pour l’estimation 3D de la sphère acétabulaire.

(Color online.) A modern human male os coxae (NMNH 1360) with the numbered sections of the acetabular portions (following

(Couleur en ligne.) Os coxal moderne masculin (NMNH 1360) présentant les différentes portions acétabulaires; ischium droit de Regourdou 1, associé à la sphère corrélée à la surface semi-lunaire. L’ischium de Regourdou correspond approximativement aux sections 5 à 7, mais le taux d’erreur considéré correspond aux sections 5–6. Les deux images proviennent de laser-scans et ne sont pas à la même échelle.

(Color online.) Femoral head diameter (left) and humeral maximum length (right) for male, female and sex indeterminate Neandertals. European Neandertals: blue diamonds; Southwest Asian Neandertals: green squares. Center line (Reg): mean estimate for Regourdou 1. Superior and inferior lines for femoral head diameter: the probable range of values for its femoral head diameter.

(Couleur en ligne.) Diamètre de la tête fémorale (à gauche) et longueur humérale maximale (à droite) pour des Néandertaliens (hommes, femmes et sexe indéterminé). Losanges bleus: Néandertaliens européens; Carrés verts: Néandertaliens du sud-ouest asiatique. Ligne centrale (Reg): estimation moyenne pour Regourdou 1. Pour le diamètre de la tête fémorale, les lignes inférieure et supérieure correspondent au domaine de variation de cette estimation.

Box plots of the ln-transformed ratio of humeral maximum length (HML) versus femoral head diameter (FHD) for Neandertals (Neand), Middle Paleolithic modern humans (MPMH), earlier Upper Paleolithic modern humans (EUP), and recent human samples (equatorial: EQ; cold temperate: CT; warm temperate: WT; arctic: ARC). The value for Kebara 2 (K2), the Neandertal high value, is indicated. The ratio from the mean femoral head diameter estimate for Regourdou 1 is provided (center line; Reg) with the ratios from the probable range of values for its femoral head diameter (superior and inferior lines) (see text for justification).

Diagrammes en boîte de la proportion entre la longueur humérale maximale (HML) et le diamètre de la tête fémorale (FHD) (valeurs ln-transformées) pour les Néandertaliens (Neand), les hommes modernes du Paléolithique moyen (MPMH) et supérieur (EUP), ainsi que des échantillons de populations actuelles issues de différentes zones climatiques (EQ: zone équatoriale; CT: zone tempérée froide; WT: zone tempérée chaude; ARC: zone arctique). La valeur pour Kébara 2 (K2) est indiquée. Dans le cas de Regourdou 1, ce rapport est calculé pour la valeur moyenne de l’estimation du diamètre fémoral (ligne centrale, Reg) ainsi que pour son domaine de variation (lignes inférieure et supérieure). Voir texte.

Femoral head diameter estimates for Regourdou 1 (Smearing correction = 1.0003).

Estimations du diamètre de la tête fémorale de Regourdou 1 (correction de Smearing = 1,0003).

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The three estimates for acetabular sphere diameter are from the mean determination value (51.9 mm) ± 3.2%, the prediction error for using regions 5 and 6 of the acetabulum (cf.

Comparative Neandertal femoral head diameters and humeral lengths. Estimates are in parentheses; such values for femoral head diameters provide the mean estimate from acetabular or condylar dimensions. Personal measurement from original remains unless otherwise indicated.

Diamètres des têtes fémorales et longueurs humérales des Néandertaliens. Les données entre parenthèses sont des estimations moyennes, celles pour les têtes fémorales sont calculées à partir des dimensions de l’acétabulum et du condyle fémoral. Sauf mention contraire, les données sont personnelles.

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Sex is attributed to Neandertal specimens only when the appendicular remains are associated with sexually diagnostic pelvic remains, principally from the region of the greater sciatic notch. Approaches using body size alone, although applicable within samples (e.g.,

The body mass estimates derive from the formulae of

Femoral head diameter estimated from lateral condyle depth [M-22 (^{2} = 0.881, _{est} = 1.6 mm (FemHdDia: femoral head diameter; LatCondAP: lateral condyle depth).

Femoral head diameter estimated from its associated acetabular height (from the rim adjacent to the anterior inferior iliac spine, using a least squares regression based on a pooled sample of recent humans: lnFemHdDia = 1.130 × lnAcetHt – 0.710, ^{2} = 0.943, _{est} = 1.3 mm (AcetHt: acetabular height).

Acetabular height (59.0 mm) from

Femoral head diameter from A. Rosas (pers. comm.).

Estimated using the mean diameter of the sphere fit to the acetabulum (