[GSlob]

Hmmm... the time frame might be wrong, though - it is believed that 100000 years ago is the time frame for separation of migrating groups from Sub-saharan population, and about 40000 years for the separation of [proto-] East Asians. Why would the same mutation recently and independently occur in isolated populations? Wouldn't it be easier for it to happen between 40 and 100K years before present?

[MHGinTN]

Excellent point. What bothers me most though is the PC treatment of science. I mean, what does humanity want to do, die off in a haze of political correctness? Science isn't supposed to be biased toward any particular political perspective. Besides, who knows what admitting truths and seeking solutions will bring to huamnity? So long as basic ethical strictures govern, strictures defined by the species as a whole, science can accomplish astonishing advancements for the species.

[Eagles Talon IV]

"Why would the same mutation recently and independently occur in isolated populations? Wouldn't it be easier for it to happen between 40 and 100K years before present?"

I propose that the genetic differences that may be a factor in an increase in intelligence can be easily explained by which group had earlier access to a fast food diet. I know that I can feel the old synapses cracklin' at the very thought of a couple of Big Macs and a GIANT fry or 3.

[GovernmentShrinker]

Some genes are more prone to mutation than others. An example is Fragile X syndrome, which involves a single gene on the X chromosome. It arises spontaneously fairly infrequently, usually becoming the "pre-mutation" version of the gene (which is symptomless or very faintly symptomatic, i.e. may produce a very subtle impairment in intelligence but not outside the normal range). The premutation version very often spontaneously mutates into the retardation-inducing "full mutation" when being copied from parent to offspring.

[Thombo2]

"Why would the same mutation recently and independetly occur in isolated populations?"Good point.They(mutations) wouldn't occur unless the same influence(variable)were at work in the"isolated populations"that had left sub-Sahara.Rhetorical question:Is there anything that these isolated populations could have had in common to explain the scientists theory?

[Doctor Stochastic]

How does he explain the spread of the newly mutated gene? Mostly these spread by diffusion; even considering air-travel. Are there travel patterns that go around Africa?

[Just another Joe]

Why would the same mutation recently and independently occur in isolated populations?

Could be due to the prevalence of technology.