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
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
Allen F. Bortrum