Possible shell beads from the Middle Stone Age layers of Sibudu Cave,South Africa

Recent excavations at Sibudu Cave, KwaZulu-Natal, South Africa, uncovered an Iron Age horizon below which is a complex 3 m thick Middle Stone Age sequence with post-Howiesons Poort, Howiesons Poort, Still Bay and pre-Still Bay layers. Available OSL ages indicate that the Howiesons Poort occupation is older than 60 ky and the Still Bay older than 70 ky. Here we present the archaeological context and the taphonomic analysis of six Afrolittorina africana, three of which bear perforations, from the Still Bay and Howiesons Poort layers of this site. The single specimen from the latter cultural horizon comes from the lowermost layer attributed to this technocomplex. This and the depositional context of this layer suggest that this shell derives, as do the other five, from the Still Bay occupation layers. Taphonomic analysis of the archaeological specimens based on present day Afrolittorina africana biocoenoses, microscopic examination, morphometry, experimental perforation of modern shells, and a review of the natural agents that may accumulate marine shells at inland sites, indicate probable human involvement in the collection, transport, modification, and abandonment of Afrolittorina africana in Sibudu. If confirmed by future discoveries these shells would corroborate the use of personal ornaments, already attested at Blombos Cave, Western Cape Province, by Still Bay populations. The apparent absence of ornaments at Howiesons Poort sites raises the question of the mechanisms that have led to cultural modernity since it seems to contradict the scenario according to which cultural innovations recorded at Middle Stone Age sites reflect a process of continuous accretion and elaboration interpreted as the behavioural corollary of the emergence of anatomically modern humans.