Abstract
Approximately 74 thousand years ago (ka), the Toba caldera erupted in Sumatra. Since the magnitude of this eruption was first established, its effects on climate, environment and humans have been debated. Here we describe the discovery of microscopic glass shards characteristic of the Youngest Toba Tuff-ashfall from the Toba eruption-in two archaeological sites on the south coast of South Africa, a region in which there is evidence for early human behavioural complexity. An independently derived dating model supports a date of approximately 74 ka for the sediments containing the Youngest Toba Tuff glass shards. By defining the input of shards at both sites, which are located nine kilometres apart, we are able to establish a close temporal correlation between them. Our high-resolution excavation and sampling technique enable exact comparisons between the input of Youngest Toba Tuff glass shards and the evidence for human occupation. Humans in this region thrived through the Toba event and the ensuing full glacial conditions, perhaps as a combined result of the uniquely rich resource base of the region and fully evolved modern human adaptation.
Highlights
We describe the discovery of microscopic glass shards characteristic of the Youngest Toba Tuff—ashfall from the Toba eruption—in two archaeological sites on the south coast of South Africa, a region in which there is evidence for early human behavioural complexity
We use a date of approximately 74 ka as the time of eruption of the Youngest Toba Tuff (YTT), just before the onset of glacial marine isotope stage 4 (MIS4)[2,3]
We discovered YTT glass shards in archaeological sediments at the sites of Vleesbaai area B (VBB) and Pinnacle Point Site 5-6 (PP5-6) on the south coast of South Africa (Fig. 1 and Extended Data Fig. 1)
Summary
27.0 74.7 ± 5.8 ka Figure 3 | The shard distribution, OSL dates and artefact plots as a composite digital cutaway at VBB. a, VBB site stratigraphy and 3D plotted artefacts on a digitally rectified stratigraphic photograph. b, Shard distribution on a digitally rectified stratigraphic photograph. c, Composite. The fact that shards at VBB are a near-perfect match to YTT cryptotephra, and that OSL dates for the sediments at both sites correspond to the age of the Toba eruption, leads us to conclude that Toba is the source volcano for both sets of shards. Our results raise the question of whether the modern human population on the south coast of South Africa was the sole surviving population through a decade or more of volcanic winter, or whether populations elsewhere in Africa thrived through the YTT event and the ensuing MIS4 glacial phase This question can be tackled by applying the same suite of field and laboratory procedures[8,21,22] used here to other archaeological sites in Africa.
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