Middle Stone Age shell beads from South Africa.

There are two competing models for the emergence of modern human behavior: first, a late emergence in Africa or Eurasia at 50 to 40 thousand years ago (ka), and second, a gradual transition in Africa between 250 to 50 ka (1). In both models, personal ornaments and art are unquestioned expressions of symbolism that equate with modern human behavior. The earliest undisputed African personal ornaments are 13 ostrich eggshell beads from Enkapune Ya Muto in Kenya at 40 ka (2). Evidence from Eurasia includes two perforated teeth, dated 43 ka, from Bacho Kiro in Bulgaria and 58 marine shell beads from the 41-ka layers of Üçaǧızlı, Turkey (3). Here we report on 41 perforated tick shell (Nassarius kraussianus) beads (Fig. 1) recovered from the Middle Stone Age (MSA) levels at Blombos Cave, a site located on the southern Cape shoreline of the Indian Ocean (4). Phase M1, in which 39 beads were found, was dated to 75.6 3.4 ka, by optically stimulated luminescence (OSL) signals from both single aliquots and 4800 individual quartz grains. Thermoluminescence dates for five burnt lithic samples from the same phase provide a mean age of 77 6 ka (5). Two beads that may be intrusive come from the top of the underlying, and still undated, phase M2. The MSA tick shells cannot derive from the cave walls, are too small to be leftovers from human food, and were not brought to the site accidentally by animals, because their only known predator is a gastropod (Natica tecta) that lives, like N. kraussianus, only in estuarine environments. If the tick shells had been accidentally brought to the cave site from 20-km-distant estuaries in wracks of dead Zostera capensis, a grass used for bedding by Later Stone Age (LSA) huntergatherers, all age classes would have been present, whereas Blombos Cave MSA beads include shells of adults only (fig. S1). Of the MSA tick shells, 88% are dorsally perforated near the lip (Fig. 1 and fig. S1). This type of perforation is absent in living populations and accounts for only 8.6% of naturally pierced shells in modern thanatocoenoses. Microscopic analysis of the MSA shells reveals a use-wear pattern, absent on natural shells, consisting of facets that flatten the outer lip or create a concave surface on the lip close to the anterior canal (fig. S1). A similar concave facet is seen opposite to the first one, on the parietal wall of the aperture of many of the shells. This use-wear pattern is consistent with friction from rubbing against thread, clothes, or other beads and is the principal factor that defines the MSA shells