From: bivalve (email@example.com)
Date: Tue Feb 04 2003 - 16:53:33 EST
>Dr. Spencer Wells traveled to all the continents to study the Y chromosomes of isolated populations. He came to the conclusion that he had found a marker in a man in Afganistan who was descended from the original person in that region. And so for several groups. I'm sure his team spent many days perhaps years doing this work. but do more studies need to be done? He seemed to be positive about his results, but are there other isolated group that could be done that would confirm or refute his findings. The program mentioned no other posibilities or theories other than his.<
Yes, there is always the possibility that an unsampled individual has a distinctive marker that was missed. Exhaustive sampling faces two difficulties. Both identification of and access to genetically distinct groups may be difficult. For example, in Afghanistan it might not have been possible to get access to every tribe. Even if every recognized tribe were sampled, it is possible that some village represents a genetically distinctive group who is culturally assimilated to another group and thus overlooked. Another difficulty is the possibility of migrations and interbreeding which could confound the geographic identification of an allele. For example, European Y chromosomes are common in some native populations. Finally, there is always a question of how to analyze the data. From my experience working with bivalve DNA, adding another sample or gene or changing the analytical technique a bit almost always gives slightly different results, though the big picture is f!
airly stable (if it is resolved in the first place). Thus, it is fairly safe to say that he has identified alleles with relatively early roots in the various regions. Depending on the sampling, there may be some confidence about identifying the extant population that has the closest genetic ties to the first settlers. However, it is not safe to say that the very first human to enter the modern boundaries of Afghanistan had the exact same allele.
Dr. David Campbell
University of Alabama
Biodiversity & Systematics
Dept. Biological Sciences
Tuscaloosa, AL 35487-0345 USA
That is Uncle Joe, taken in the masonic regalia of a Grand Exalted Periwinkle of the Mystic Order of Whelks-P.G. Wodehouse, Romance at Droitgate Spa
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