Morphology of the border cave hominid ulna and humerus

Hominid bones from Border Cave (BC) have been the subject of controversy with regard to the question of modern human origins. New dating assays suggest that while some of the BC remains are of comparatively recent age (i.e. < 20 kyr), several postcranial fragments derive from the Middle Stone Age (MSA) layers. Among the latter, a proximal ulna is comparable to one from the MSA at Klasies River Mouth, in that both have an archaic pattern of morphology in the relative heights of the coronoid and olecranon processes. This configuration appears to characterize Neandertals, and is displayed also by more ancient African ulnae. The BC humeral diaphysis has moderately thick cortical bone, but is otherwise unremarkable. The proximal ulnar morphology might suggest that the MSA inhabitants of South Africa engaged in activities similar to those of Neandertals and other postcranially archaic hominids. If the modern-looking BC-1 cranium is contemporaneous with the BC postcranial bones, this would bear testament to the mosaic nature of human evolution. Alternatively, if BC-1 proves to be of recent derivation, and the postcrania are as old as the base of the BC MSA sequence has been claimed to be (c. 195 kyr), they might have been associated with more archaic crania (perhaps similar to Florisbad). Final resolution of these questions awaits determination of the absolute ages of the BC-1 cranium and the BC postcranial bones.