[Right Wing Professor]

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..

[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.

[Physicist]

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..

But a single common ancestor (e.g., a "mitochondrial Eve") doesn't necessarily imply a genetic bottleneck. It's possible that a (mutant) woman was born with significantly superior mitochondria, which slowly over time supplanted the other mitochondria throughout a large and sustained population with an otherwise diverse gene pool, without the need for a mass die-off, or for one population pushing out another. (This could similarly work for any given chromosome.)