Did the super-eruption of Toba cause a human population bottleneck? Reply to Gathorne-Hardy and Harcourt-Smith.

Gathorne-Hardy and Harcourt-Smith raise questions about the accuracy of estimates of the magnitude of the climatic impact of the supereruption of Toba, whether it could have caused a human population bottleneck, the form, duration and timing of the human bottleneck, and cultural capacities for behavioral responses to climatic disasters. This News and Views forum provides an opportunity to summarize the new geological, climatic and genetic evidence for the super-eruption of Toba and its consequences that supports our hypothesis (Ambrose 1998a; Ambrose and Rampino, 2000), and to address other critiques and alternative explanations (Oppenheimer, 2002; Lahr and Foley, 1998; Hawks et al., 2000).