Monday, December 1, 2008

Mitochondrial DNA

Mitochondrial DNA is different than the Y DNA used to trace the paternal line and different from the Nuclear DNA which makes up who we are. It traces the maternal line and technically is a parasite embedded in our DNA. But, it is more stable and is often used to identify victims of crime and to learn more about ancient bones. Men and women have mitochondrial DNA, whereas only men have the Y DNA. Again, we used my brother Jim's DNA to help us solve another family mystery.

My great-grandmother Martha Silas Watson is almost a complete unknown. She had a very difficult life plagued with mental illness and no relatives that we know of. Although I got a court order to have her records released from the mental institution, I still didn't learn very much about her family.

My sister Jane thought she might have been a Gypsy; my brother thought she might have been an American Indian. Although we knew the mitochondrial DNA would not help us with her immediate relatives, we would know if she was a Gypsy or an Indian.

I had first became interested in mitochondrial DNA when I heard about the book The Seven Daughters of Eve. Having the mitochondrial DNA would also tell us which of the Seven Daughters she came from.The map above shows the Seven Daughters and where they came from. By having our X DNA tested, we discovered we belonged to the halplogroup U5a which Bryan Sykes identifies as Ursula.

There are about 10 pages of a fictionalized account about Ursula in the book---below is a summary:

Ursula (Latin for she-bear)

Ursula lived about 45,000 years ago in what is now northern Greece. She was among the first arrivals of a new, modern human to set foot in Europe. She was slender and graceful, in marked contrast to the thickset Neanderthals with whom she and her clan shared the land for another 20,000 years. Her kind brought with them a new and more sophisticated type of stone tool with which to hunt and butcher the abundant game, animals that soon appeared on the walls of limestone caves as the first expression of human art. They spread right across Europe, west across France and north as far as the British Isles.

As the climate deteriorated 25,000 years ago, the clan began its long migration south; eventually reaching Spain and founding what became a refuge for all humans during the coldest millennia of the last Ice Age. As the climate warmed, the scattered clan led the march back to the North to reclaim the once frozen lands. They reached the British Isles and left an indelible record in the limestone caves of Cheddar Gorge. In 1998, DNA was recovered from the famous skeleton known as Cheddar Man and our analysis showed that it belonged to the clan of Ursula. In a dramatic demonstration of genetic continuity, we found that a teacher at the local school, only a few hundred yards from the cave entrance, was clearly a member of the same clan.

[Cheddar Man is below]



As you can tell above U was neither Gypsy nor American Indian. Corresponding with others whose DNA is similar to ours, we know that Martha's mother's mother's mother's. . .was probably Scotch-Irish with Viking roots.


Both The Seven Daughters of Eve and Trace Your Roots with DNA are pretty readable books. If you want a more general discussion about genetic roots, try Spencer Wells' book and video The Journey of Man: A Genetic Odessey.

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