Subdecadal phytolith and charcoal records from Lake Malawi, East Africa imply minimal effects on human evolution from the ∼74 ka Toba supereruption.

摘要: The temporal proximity of the ∼74 ka Toba supereruption to a putative 100-50 ka human population bottleneck is basis for volcanic winter/weak Garden Eden hypothesis, which states that eruption caused 6-year-long global winter and reduced effective anatomically modern humans (AMH) fewer than 10,000 individuals. To test this we sampled two cores collected from Lake Malawi with cryptotephra previously fingerprinted supereruption. Phytolith charcoal samples were continuously at ∼3-4 mm (∼8-9 yr) intervals above below position, no stratigraphic breaks. For synchronous or proximal interval, found change in low elevation tree cover, cool climate C3 warm season C4 xerophytic mesophytic grass abundance outside normal variability. A spike locally derived grasses immediately after indicates precipitation die-off least some afromontane vegetation, but does not signal conditions. review tuff petrological melt inclusion studies suggest Tambora-like 50 100 Mt SO2 atmospheric injection. However, most models use values are one orders magnitude higher, thereby significantly overestimating amount cooling. recent genetic finds support near ∼74 ka. Based on these previous our new paleoenvironmental data, find catastrophe hypothesis conclude did 1) produce eastern Africa, 2) cause among African AMH populations, 3) bring humanity brink extinction.