[blam]

"The key question, though, is where and when the evolutionary bottleneck occured. Any model of geographically separated but commingling populations has to be consistent with the genetic data, which has been interpreted in terms of a very small number of humans, and a single maternal ancestor, at some time in the period 50,000 - 100,000 B.C.."

Toba fills that requirement. Many believe only 2,000-5,000 humans worldwide survived this catastrophe.

[Right Wing Professor]

I agree Toba's a plausible candidate. If the bottleneck was 75,000 years ago, that sets the date of racial divergence no earlier than that date. Furthermore, if it really was the catastrophe a lot of people believe it was, survival in China would have been far more difficult than in Africa.