Humans thrived in South Africa through the Toba eruption about 74,000 years ago

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.

Tephra glass chemistry provides storage and discharge details of five magma reservoirs which fed the 75 ka Youngest Toba Tuff eruption, northern Sumatra

“…Marine occurrences prefixed "SO" are from the Sonne-93 cruise (Weber et al, 2003). Map excludes YTT occurrences from Lake Malawi, East Africa (Lane et al, 2013) and on the southern coast of South Africa (Smith et al, 2018). For locality information, see Supplementary Table 2 [Color figure can be viewed at wileyonlinelibrary.com] compositions, biotite compositions or spontaneous fission track density (Smith et al, 2011;Westgate et al, 2013Westgate et al, , 2014Pearce et al, 2014b;Westgate and Pearce, 2017).…”

“…Marine occurrences prefixed “SO” are from the Sonne‐93 cruise (Weber et al , ). Map excludes YTT occurrences from Lake Malawi, East Africa (Lane et al , ) and on the southern coast of South Africa (Smith et al , ). For locality information, see Supplementary Table 2 [Color figure can be viewed at wileyonlinelibrary.com]…”

Discovery of cryptotephra at Middle–Upper Paleolithic sites Arma Veirana and Riparo Bombrini, Italy: a new link for broader geographic correlations

“…Within the last two decades, tephrochronology has become more common in archaeological research due to advancements in extraction and identification methods (Blockley et al ., ) and due to its ability to work as a correlative tool as well as to more accurately date deposits (Riede and Thastrup, ; Douka et al ., ; Lowe et al ., ; Smith et al ., ). While the basic approach is similar to correlative studies that have been conducted as far back as the early 1950s (Lowe, ), the use of cryptotephra (microscopic volcanic glass shards) in archaeological research has shown great success for large‐scale correlations (Lowe et al ., ).…”

“…peat bogs, marine and lake sediments, ice cores) and can travel as far as 9000 km from the source eruption (Smith et al ., ), allowing for isochrons (precise temporal markers) to be established between archaeological and paleoenvironmental records across vast regions (Lane et al ., ; Lowe et al ., ). However, the ability to find, recognize and analyze cryptotephra involves specialized extraction methods that target the non‐visible shards (Blockley et al ., ; Lane et al ., ), making it possible to locate these microscopic shards even at very low quantities (Smith et al ., ). The extraction of shards from host sediments can be very difficult and even when shards are identified, using them as stratigraphic markers can be problematic.…”

The Role of the SO Radiative Effect in Sustaining the Volcanic Winter and Soothing the Toba Impact on Climate

“…In the literature (Yost et al, ), the maximum simulated global mean cooling anomalies range from severe 18 °C to a relatively mild 3.5 °C, which is only 5 times larger than the recent cooling observed after the 1991 Pinatubo eruption (Stenchikov et al, ). Paleodata even suggest that the climate of East Africa was not substantially affected at all (Lane et al, ; Oppenheimer, ; Smith et al, ; Yost et al, ). Thus, the assumption itself regarding extreme cooling after the Toba eruption may not be valid.…”