The frontal sinus of the adult human cranium from Border Cave, KwaZulu-Natal, South Africa: Does it provide a contextual clue?

Human specimens from Border Cave thought to derive from its Middle Stone Age (MSA) deposits have been widely discussed in relation to Late Pleistocene evolution in southern Africa. Among the most prominent is the adult cranium BC 1. However, there are questions about the context and geochronological age of a number of these remains, including BC 1, which was recovered ex situ from a sediment dump created by miners digging for guano. The cranium has not been directly dated. Previous morphological analyses have clearly demonstrated its complete anatomical modernity, but its possible affinities to recent southern African populations have been a matter of disputation. The frontal sinus volume (FSV) of BC 1 is diminutive in relation to the values recorded for Late Pleistocene sub-Saharan fossils as well as the indigenous populations of southern Africa. While recent sub-Saharan African populations tend to possess comparatively small FSVs, the Later Stone Age (LSA) Khoe-San have notably smaller sinuses compared to the current South African isiNtu-speaking population. Among Late Quaternary fossils and more recent populations from sub-Saharan Africa, the most reasonable comparator for BC 1 appears to be the South African LSA Khoe-San. This may well have ramifications for the context and antiquity of the Border Cave 1 cranium.