Adam, Eve and Population Genetics: A Reply to Dr. Richard Buggs (Part 2)

[Jonathan_Burke (Jon)]

To me, the standout feature of this post is the clear evidence that scientists have in fact previously investigated the possibility of the human population passing through an extremely small bottleneck, and their conclusion that a bottleneck of even a few individuals has been ruled out by the available evidence.

The reason why this stands out to me is that Dr Buggs has given the very strong impression that no one has ever made such an investigation before, that no scientists have ever tried to model such a small population, that no scientists have ever concluded that there is evidence ruling out such a tight bottleneck. That is the impression I have received from statements such as this.

@RichardBuggs

I agree that the genomic data presented in the existing literature are relevant, and sufficient, for an analysis to address the short sharp bottleneck hypothesis. But if the authors have not done an appropriate analysis, someone else needs to. As far as I can see this has not been done. This is what I am saying in my blog.

In contrast, Dennis has shown that several such studies have been done, and that scientists have in fact made the conclusion that a bottleneck as sharp as the one Dr Buggs is proposing has not occurred in the last 500,000 years.

• “Also suggested is that the population size has never dropped to a few individuals, even in a single generation”

• “There is no evidence for an exponential expansion out of a bottlenecked founding population, and an effective population size of approximately 10,000 has been maintained”

• “On the other hand our results also deny the hypothesis that there was a severe hourglass contraction in the number of our ancestors in the late middle and upper Pleistocene”

• “Moreover, the ancient genetic history of humans indicates no severe bottleneck during the evolution of humans in the last half million years; otherwise, much of the ancient genetic history would have been lost during a severe bottleneck”

What surprises me is that Dr Buggs has never mentioned these studies, and has in fact given the impression that such studies do not exist.

Regardless of the outcome of the discussion between Dennis and Dr Buggs, the only question I have is this (which I have posed previously to Dr Buggs).

Does your understanding of the data support the idea of an Adam and Eve who had no ancestors at all (neither human nor pre-human), as the universal progenitors of every human who has ever lived, with no humans descending from any parallel humans or pre-humans, approximately 6,000 years ago?