Robusticity versus Shape: The Functional Interpretation of Neandertal Appendicular Morphology.

Abstract

The interpretation of the evolution of human manipulative and locomotor behavior from hominid fossil remains during the Pleistocene requires a clear distinction between changes in relative musculo-skeletal massiveness indicating different levels of activity (robusticity) and alterations in form implying contrasting patterns or frequencies of behavior. A review of ongoing research on Neandertal appendicular morphology with respect to the scapulo-humeral articulation, the pollical and mid-carpal carpo-metacarpal articulations, proximal femoral trabecular orientation, femoral diaphyseal cross-sectional geometry, and proximal pedal phalangeal diaphyseal proportions illustrate the nature of the problems associated with making distinctions between robusticity and shape in fossil hominid remains. Nonetheless, it is apparent that differences in shape, in addition to contrasts in robusticity, exist between the Neandertals and modern humans.

Behavioral inferences from the Skhul/Qafzeh early modern human hand remains

“…All of these features contribute to the production of power grips, those in which objects are held in the palm of the hand with the thumb serving as a brace, implying that the Neanderthal manipulatory repertoire habitually required greater power compared with late Pleistocene early modern human manipulative repertoires. This is not to say that the Neanderthals did not, or could not, use precision grips, those in which the tip of the thumb is brought into contact with the pads of the fingers, inasmuch as there are no morphological indications of limited joint movements (3,10,18,19,26,28).…”

“…More importantly, Neanderthals may have engaged in significantly altered frequencies of upper-limb behaviors relative to ethnohistorically documented hunter-gatherers, because mounting evidence from upper-limb articular morphology (including their CMC joints) indicates that the Neanderthals habitually loaded their joints not only at higher levels of joint reaction force, but also in different distributions of articular positions during peak loading (3,14,18,19,23,(28)(29)(30)(31). Within the CMC region, the Neanderthal metacarpal (MC) 1 base tends to be dorsopalmarly flat to convex, lacking the prominent palmar beak typical of most recent human MC 1 bases.…”

Postcranial remains and the origin of modern humans

“…106,107 When variation in the traits that came to characterize Neandertals exists, different Atapuerca fossils display morphologies that are either Neandertal-like or reminiscent of recent humans. 106,107 The stocky skeleton of Neandertals, with its stout long bone diaphyses, massive joints, and most of its other peculiar features, 23,113,114,116,120,149,164 thus appears to have developed from an ancestral condition that, on the whole, more closely approximated modern human morphology. 120 A few aspects of morphology distinguish the skeletons of the early modern humans from the sites of Skhul and Qafzeh in Israel from living Homo sapiens.…”

Fossil Homo femur from Berg Aukas, northern Namibia

“…The medial trabecular bundle (Koch, 1917) is broad, extending superomedially from the thick cortical bone along the inferior aspect of the neck. It forms an angle of 135" with the diaphyseal axis, as measured according to the technique employed by Heller (1989) and Trinkaus et al (1991). The arcuate bundle comprises a broad, gently curved band of trabecular lamellae that courses from the inferomedial aspect of the head to the inferolateral margin of the greater trochanter.…”