Hominin Postcranial Skeleton

In this study, a new Early Pleistocene proximal hand phalanx (ATE9-2) from the Sima del Elefante cave site (TE - Sierra de Atapuerca, Spain), ascribed to Homo sp., is presented and comparatively described in the context of the evolution of the genus Homo. The ATE9-2 specimen is especially important because of the paucity of hand bones in the human fossil record during the Early Pleistocene. The morphological and metrical analyses of the phalanx ATE9-2 indicate that there are no essential differences between it and comparator fossil specimens for the genus Homo after 1.3 Ma (millions of years ago). Similar to Sima de los Huesos and Neandertal specimens, ATE9-2 is a robust proximal hand phalanx, probably reflecting greater overall body robusticity in these populations or a higher gracility in modern humans. The age of level TE9 from Sima del Elefante and morphological and metrical studies of ATE9-2 suggest that the morphology of the proximal hand phalanges and, thus, the morphology of the hand could have remained stable over the last 1.2e1.3 Ma. Taking into account the evidence recently provided by a metacarpal from Kaitio (Kenya) from around 1.42 Ma, we argue that modern hand morphology is present in the genus Homo subsequent to Homo habilis.

Reconstructing the morphology of the Neanderthal rib cage not only provides information about the
general evolution of human body shape but also aids understanding of functional anatomy and energetics.
Despite this paleobiological importance there is still debate about the nature and extent of variations
in the size and shape of the Neandertal thorax. The El Sidr
on Neandertals can be used to
contribute to this debate, providing new costal remains ranging from fully preserved and undistorted ribs
to highly fragmented elements. Six first ribs are particularly well preserved and offer the opportunity to
analyze thorax morphology in Neandertals. The aims of this paper are to present this new material, to
compare the ontogenetic trajectories of the first ribs between Neandertals and modern humans, and,
using geometric morphometrics, to test the hypothesis of morphological integration between the first rib
and overall thorax morphology. The first ribs of the El Sidr
on adult Neandertals are smaller in centroid
size and tend to be less curved when compared with those of modern humans, but are similar to Kebara
2. Our results further show that the straightening of the first ribs is significantly correlated with a
straightening of the ribs of the upper thorax (R ¼ 0.66; p < 0.0001) in modern humans, suggesting
modularity in the upper and lower thorax units as reported in other hominins. It also supports the
hypothesis that the upper thorax of Neandertals differs in shape from modern humans with more
anteriorly projecting upper ribs during inspiration. These differences could have biomechanical consequences
and account for stronger muscle attachments in Neandertals. Different upper thorax shape
would also imply a different spatial arrangement of the shoulder girdle and articulation with the humerus
(torsion) and its connection to the upper thorax. Future research should address these inferences
in the context of Neandertal overall body morphology.

The morphology of the distal portion of the hominoid ulna is poorly studied despite its important functional role at the wrist joint. There are five qualitatively well-described fossil hominin distal ulnae belonging to Australopithecus afarensis and Australopithecus africanus, but there have been few efforts to quantify their morphology or relate it to their functional abilities. This article presents an effort to do so, using three-dimensional geometric morphometrics to analyze the shape of the distal ulna of the PlioPleistocene hominins and an extant comparative sample of great apes and humans. For the extant taxa, results show that the morphology of Pan and Pongo is distinct from that of Homo, and that these differences are likely related to climbing, clambering and below-branch suspension in the former, and the release of the limbs from locomotion and (potentially) tool manufacture in the latter. For the australopiths, results indicate that the A. afarensis sample is relatively heterogeneous. These results are driven by the morphology of A.L. 333-12, which is the largest ulna in the sample and has a unique combination of traits when compared with the other two A. afarensis specimens. Overall, the morphology of all the hominins was most consistent with the pattern displayed by extant great apes, and specifically Pan and Pongo; however, large overlap in shape in the distal ulna in the extant sample indicates that other areas of the skeleton may be more informative for functional analyses.

The femoral neck-shaft angle (NSA) varies among modern humans, both between and within population groups, and also among fossil hominins. Recent research has focused on whether differences in average NSA between groups may reflect variation in body shape at the population level due to long-term environmental adaptations — notably with regard to Bergmann’s Rule — or whether, instead, such variation is attributable to the influence of differing lifestyles and habitual activity patterns. Existing studies examining possible climatic trends in the NSA have reported ambiguous findings, but these have been hampered by measurements issues and limited population sampling. The present study addresses these problems, and it reports findings from an extensive global database comprising over 8,000 femora representing some 100 modern human groups. Analyses in relation to climatic indices show large-scale environmental patterning of variation in the NSA at the global, continental and regional levels. Average NSA values are higher in the Pacific and Africa, for example, and are lower in the Americas. Climatic trends are evident also within each of the continents and regions, consistent with predictions based on Bergmann’s Rule.

In this study, a new Early Pleistocene proximal hand phalanx (ATE9-2) from the Sima del Elefante cave site (TE - Sierra de Atapuerca, Spain), ascribed to Homo sp., is presented and comparatively described in the context of the evolution of the genus Homo. The ATE9-2 specimen is especially important because of the paucity of hand bones in the human fossil record during the Early Pleistocene. The morphological and metrical analyses of the phalanx ATE9-2 indicate that there are no essential differences between it and comparator fossil specimens for the genus Homo after 1.3 Ma (millions of years ago). Similar to Sima de los Huesos and Neandertal specimens, ATE9-2 is a robust proximal hand phalanx, probably reflecting greater overall body robusticity in these populations or a higher gracility in modern humans. The age of level TE9 from Sima del Elefante and morphological and metrical studies of ATE9-2 suggest that the morphology of the proximal hand phalanges and, thus, the morphology of...