Thanks TimJ07. One reply on a link from the second site:
http://science.slashdot.org/article.pl?sid=07/07/19/1438241As option 2 wrote:
"The populations of the various continents split apart, but there is sufficient gene flow for mutations originating in one part of the world to spread to another. By coincidence or some process I'm not familiar with, the mutations arising in Africa spread to Europe and Asia, and those arising elsewhere spread to Africa. However, Europe and Asia have less genetic exchange, even with Africa acting as an intermediary."
The writer prefers his option 3 the single origin recent out of Africa scenario but his comment regarding option 2, "By coincidence or some process I'm not familiar with" seems rather silly. After all humans have been wandering into and out of Africa continually in historic times. But the writer obviously believes modern humans are the only species capable of such movement and hybridization.
