> Folks i thought this might interest some of our readers.
>
> Niamorkono.
>
>
>> The Journey of Man:
>> A Genetic Odyssey
>>
>> Spencer Wells
>>
>>      AN INTERVIEW WITH SPENCER WELLS
>>
>>      Geneticist Spencer Wells spends his life
>> traveling the globe taking blood samples from men and
>> women in order to unravel the secrets of the human
>> story: Where did humans come from? How did they spread
>> over the globe? How did different races evolve? In THE
>> JOURNEY OF MAN: A GENETIC ODYSSEY (Princeton
>> University Press), Wells answers those questions for
>> the first time using the latest discoveries of human
>> genetics. We talked to Spencer as he sat for a moment
>> between trips to Lebanon and Tunisia:
>>
>>   1. You say that there really was an Adam--a common
>> male ancestor for all humans. How did you find that
>> out?
>>
>>      We study a historical document carried in the
>> blood of everyone alive today - DNA. Tiny spelling
>> mistakes - changes in the DNA sequence - that occurred
>> in the past can give us clues about genealogical
>> relationships. If two people share a change, then they
>> are likely to share an ancestor. If we look at the
>> spelling mistakes carried by people all over the
>> world, we find that ultimately all of us share a
>> common ancestor. In the case of the male line, defined
>> by a piece of DNA known as the Y-chromosome, this
>> analysis allows us to trace back to a common male
>> ancestor for everyone alive today. In other words,
>> Adam.
>>
>>   2. Where did Adam live and what did he look like?
>>
>>      The unequivocal answer is that he lived in
>> Africa. Every piece of DNA in our bodies can be traced
>> back to an African source. The Y-chromosome traces
>> back to eastern or southern Africa, around 60,000
>> years ago. The present-day inhabitants of Ethiopia,
>> Sudan and southern Africa carry the clearest signals
>> of our earliest ancestry, signals that have been lost
>> in the rest of us. So they give us a glimpse of our
>> 60,000 year-old Adam. Adam would have been fully
>> modern, both in terms of his appearance and his brain
>> function. It is speculation, of course, but perhaps
>> the San Bushmen of the Kalahari - who in many ways are
>> a composite model of facial features from people all
>> over the world - give us a portrait of Adam and his
>> fellow early humans.
>>
>>   3. Why do you focus on men? What about Eve?
>>
>>      It turns out that the Y-chromosome gives us two
>> very important clues to the question of how we
>> populated the world. First, it shows us our most
>> recent common ancestor (Adam). This man lived in
>> Africa around 60,000 years ago. The significance of
>> this date is that it means that all modern humans were
>> living in Africa until at least that time. In other
>> words, within the past 60,000 years - only about 2,000
>> generations - our species has populated the entire
>> planet. Clearly, we are all very closely related. The
>> second clue provided by the Y-chromosome concerns the
>> routes we followed in our migrations around the
>> planet. Due to something I describe in the book as
>> 'sexual politics', the male line gives us the best
>> view of the routes followed. So, the Y - a piece of
>> DNA that really doesn't do much more than to make men
>> men - is one of the best historical documents ever
>> written. Women also have a female history written in
>> their mitochondrial DNA, showing the path to Eve
>> around 150,000 years ago. For reasons explored in the
>> book, the mitochondrial signal turns out to provide
>> less resolution for studies of population history than
>> the Y. Again, it comes down to a long history of
>> sexual politics.
>>
>>   4. How does the genetic Adam relate to the Adam of
>> the bible?
>>
>>      It's interesting that both genetics and the
>> Bible show that there is a common origin of humanity.
>> According to genetic data we come from a single male
>> ancestor. In the Bible too it is mentioned that there
>> is a single male Adam and single female, Eve. I don't
>> equate our results one-to-one with the biblical story,
>> of course, because if you count back through the
>> generations described in the Bible, Adam should have
>> existed in 4004 BC, and our Adam existed 60,000 years
>> ago. Also, our Adam and Eve weren't the only people
>> alive at the time, just the lucky ones who left
>> descendants down to the present day. But it is nice to
>> know that we arrive at the same general conclusion:
>> we're all related.
>>
>>   5. If we all came from a black man, how did men and
>> women of different colors come into being?
>>
>>      The accepted explanation for skin color
>> differences is that we first evolved in a tropical
>> region, in Africa. The tropical sun is quite strong,
>> so the skin needed the protection provided by the
>> natural sunscreen, melanin, which makes skin dark.
>> When we started moving into the Northern Hemisphere
>> 40,000 years ago, the sun was not as strong. Anyone
>> who's been to London in February can tell you that!
>> And because the sun helps us to synthesize Vitamin D,
>> which we need to grow strong bones, we had to lose
>> some of our pigmentation to allow enough sunlight
>> through.
>>
>>   6. So what do our genes tell us about the
>> biological differences between, say, Europeans and
>> Africans?
>>
>>      They are literally only skin deep. We are all
>> African cousins separated by - at most - 2,000
>> generations.
>>
>>   7. Has research on genes told us something about
>> the first people to arrive in America?
>>
>>      Yes. Our data tells us that we could not have
>> been in the Americas prior to 20,000 years ago, and
>> the most likely date of entry was around 15,000 years
>> ago. This is because the oldest Y-chromosome lineage
>> in the Americas originated in Central Asia
>> 15,000-20,000 years ago, and then migrated to the
>> northeast, across the Bering Strait. If we were still
>> in Central Asia 20,000 years ago, we couldn't have
>> been in the Americas until after that date.
>>
>>   8. How do other scientists and the public react to
>> your research?
>>
>>      In general, there is more and more agreement
>> among paleoanthropologists, archaeologists,
>> geneticists and historians about the details of our
>> past. I suppose one thing that some people still find
>> hard to accept is that we left Africa so recently, and
>> blitzed our way around the world, but it does seem to
>> have happened like that. I urge them to read the book,
>> where I discuss the archaeological, linguistic and
>> climatological clues that fill in the details of our
>> journey. It is a synthetic look at the past, not
>> simply a genetic tale.
>>
>> _________________________________________________________________
>> Annonsera gratis i 60 dagar http://gt.msn.se/EniroStartSok.asp
>>
>>
>>
>>
>> Yahoo! Groups Links
>>
>> <*> To visit your group on the web, go to:
>>    http://groups.yahoo.com/group/networkafrica/
>>
>> <*> To unsubscribe from this group, send an email to:
>>    [log in to unmask]
>>
>> <*> Your use of Yahoo! Groups is subject to:
>>    http://docs.yahoo.com/info/terms/
>>
>>
>>

¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤
To unsubscribe/subscribe or view archives of postings, go to the Gambia-L Web interface
at: http://maelstrom.stjohns.edu/archives/gambia-l.html

To Search in the Gambia-L archives, go to: http://maelstrom.stjohns.edu/CGI/wa.exe?S1=gambia-l
To contact the List Management, please send an e-mail to:
[log in to unmask]
¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤