03/19/2008
Out of Africa
In an earlier column (11/23/2005, see archives), I discussed how I had submitted my DNA to the National Geographic Society’s Genographic project. This five-year Genographic project is a project in which the goal is to collect more than a hundred thousand samples of DNA from willing individuals worldwide. One of the objectives of the project is to track down the paths of us modern humans as we spread out all over the world from our origins in Africa. In my column, I reported the results of my DNA analysis, which traced my ancestors’ travels from Africa through the Middle East and on to Europe. Last week, I revisited my Genographic Web site and found more details as to the possible reasons my ancestors followed the path that they did.
For those who don’t want to read the earlier column, a quick review of the DNA analysis. The Genographic project concentrated on the Y chromosome, the reason being that the Y chromosome is passed down unchanged from father to son. “Unchanged” is not quite true. Once in a great while, a random mutation occurs in the DNA. Typically, this mutation is not harmful and the mutation, which can simply be one “letter” in the four-letter DNA code, persists in following generations and is known as a “marker”. My DNA belongs to what is known as haplogroup I, characterized by the markers M170 or P19.
Everyone who belongs to haplogroup I has these two markers. I’m sure that many of you readers share these markers with me and belong to the same haplogroup. Today, there are many in Europe, especially in Scandinavia and in regions of the northwestern Balkan countries, where as many as half the men carry the M170 marker. Certain parts of France also have relatively large numbers of men with the marker. Tracking the DNA, the researchers have found that haplogroup I individuals earlier on had two other markers, M168 and then M89 before acquiring the M170 mutation.
Let’s look at my roots. On radio station WOR last week, there was a discussion on the comments of Geraldine Ferraro about whether Obama would be where he is if he weren’t black. A caller with biracial children maintained Obama should not be called black, but biracial. Strictly speaking, I guess we’re all African-Americans if we’re citizens of the U.S.A. My earliest “known” male ancestor was an African man who first had the marker M168. He lived between 31 and 79 thousand years ago, probably in the Rift Valley region in what today would be Ethiopia, Kenya or Tanzania. Most likely, he lived around 50 thousand years ago. At the time there were only an estimated 10 thousand of us Homo sapiens alive.
According to my Genographic report, this man’s descendants were the only ones to survive outside of Africa, making him the “Adam” of all non-African men living today! Why did his descendants move out of Africa? With all the concern about global warming today, the proposed reason for the migration out of Africa is quite relevant. Around 50 thousand years ago the Ice Age began to thaw. In Africa, the Ice Age brought drought rather than frigid temperatures. When the ice began to melt in Europe, Africa experienced warming and more moisture. The Sahara region had a brief period when grasslands sprouted and the game that our African ancestors hunted spread out into the former desert area. Our ancestors followed the animals.
It was sometime during this period that we humans suddenly became smarter and may have developed language. This made us more willing to explore and take risks, spreading out from our home base. The next big step was the acquisition about 45 thousand years ago of marker M89 by one of my male ancestors. Actually, chances are, he’s one of your male ancestors too. This M89 marker is found in 90 to 95 percent of all non-Africans today. This guy was born in either northern Africa or the Middle East. The first wave out of Africa is thought to have followed a coastal route that eventually took them to Australia.
My ancestors were in the second wave out of Africa that followed the grasslands of the Middle East and beyond. Again a climate shift, about 40 thousand years ago. The climate became colder and drier and a drought in Africa dried up the Sahara. My ancestors couldn’t go back to their origins. The new climate resulted in what my report calls a “superhighway” of semi-arid grasslands stretching from France to Korea. On these grasslands were game such as wooly mammoths, buffalo and the like, meat and hides for our ancestor hunters. In the Middle East, some M89 types stayed on in what is now Iran, others moved east to central Asia, while my ancestors turned west into Europe. In the Balkans the landscape changed from grasslands to forests and mountains.
After another 20 millennia or so, the number of us Homo sapiens had grown to hundreds of thousands. About 20 thousand years ago, a man was born with the M170 marker. The last Ice Age covered much of Europe and my first M170 ancestor was probably born in an area to which humans had to retreat to avoid the ice, possibly the Balkans. By 15 thousand years ago, the ice sheets began to retreat and my ancestors could once again spread out and populate the more northerly parts of Europe.
The M170 marker was probably passed to the paternal ancestors of my Allentown-born father in the German Rhineland area, from which the Pennsylvania “Dutch” came to this country. Unfortunately, I was not very curious about my origins when my father was alive and didn’t think to ask how much he knew of his own ancestry. Isn’t it strange that I now know more about my genealogy back tens of thousands of years than I do about my father’s back just a couple of generations? I knew my father’s father but nothing about my grandfather’s heritage. Well, not exactly nothing; I do know that his father carried the M170 marker!
Allen F. Bortrum
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