brantoken, That's a good link. Spencer Wells has written a more detailed (but by now
slightly less current) explanation of a lot of that in a book
The Journey of Man : A Genetic Odyssey. It's quite readable, though sometimes I wished for more detail. Some people will probably want less detail.
On the Lemba:
DIJ wrote:
One should be careful to differentiate between a blood grouping and an ethnic/religious grouping.
Being Semitic or Hamitic is not the same as being one of the "lost tribes of Israel"
That is definitely true. However, as I understand the Lemba situation (and there is, of course, a strong chance that I've got it garbled

), there is a very high occurrence of a specific gene marker among Lemba men that is otherwise found only among the Jewish "Cohen" men. This certainly does not, by itself, constitute a religious affiliation, but the Lemba tradition of considering themselves Jewish does constitute at least a religious self-identification. IIRC, the genetics of the group provide very strong evidence that they did descend from at least one Jewish man, of priestly descent. IIRC, there is also some additional evidence of a connection with the Yemen area. Yemen was a area with a long Jewish connection.
I don't recall any specific evidence that places the Jewish/Yemen connection in the relevant time period of the "Babylonian Exile" which would be critical for "finding" the "Ten Lost Tribes of Israel". That evidence may be present somewhere, but so far, it has been omitted from anything I've been aware of.
Paul