Saturday, March 7, 2009

Ancient Baker History – by Susan Kinsella





What do you think our family history was like long ago? I mean L-O-N-G ago, way back say . . . about 150,000 years? Believe it or not, we can trace the broad strokes of our family’s history that far back through DNA research.

A few years ago, I sent a sample of cells swabbed from the cheek inside my mouth to the Genographic Project at the National Geographic Society. This project is focused on recording the DNA from the world’s indigenous populations while they still represent pure lines of descent. Its purpose is to use laboratory tests and computer analysis to trace humans’ ancient migratory history. Funding for the project comes partly by charging the rest of us $100 to reveal whatever migratory information can be read from our own DNA.

While the brush strokes are broad, it’s surprising how much can be learned from this analysis! Already, it has dramatically revamped the ancient history of Ireland and clarified much about the impacts of prehistoric climate change on human populations.

Similarities In Family DNA

Anyone who follows medical or criminology discussions about DNA has heard that no two people have the same DNA pattern (except identical twins), since everyone receives half their DNA from their mother and half from their father, so there are always new twists and turns introduced. But, while this is correct, there is also an intriguing exception to this rule, resulting in two particular small pieces of our DNA molecules that remain the same throughout related groups of people. This is what genetic anthropologists follow.

It works somewhat like this: Group A moves to a particular area, and most of them remain there for generations, creating a “pool” of people with the “Group A” DNA similarity. Then some of the people with that pattern move on after a while and settle somewhere else. At some point, someone develops a slight mutation in their DNA segment, making all their subsequent descendants into “Group AB.” Now the people at the second site can be identified as connected to the first group, but also different. When some from this second group move on to a third place, and especially if another mutation develops and a “Group ABC” pattern is passed on to their descendents, anthropologists are able to connect the dots and even determine approximate eras when these changes happened. When they combine these travel patterns with the climate changes discernible from geology and cultural changes clear from archaeology, a story starts to emerge about how, and possible reasons why, our ancestors migrated from one place to another.

Among men, a subset of the Y chromosome is passed down unchanged from father to son for thousands of years except for occasional mutations within one or more of its genes. When those mutations occur, they then become an identifying pattern passed through to subsequent generations.

Among women, a segment called “mitochondrial DNA” is passed down from a mother to all of her children, but only her daughters pass it on again. This mitochondrial DNA remains essentially unchanged for thousands of years, with only the occasional, very rare mutations becoming markers that identify different groups that ultimately broke off in one direction or another.

This means that I have the exact same mitochondrial DNA pattern as Kate Youngs Baker had, and so do her daughters and their daughters and theirs. Any of us – Julie, Dorothy, Kathryn, Cindy’s daughter, Sylva, CB or any of the other women in the family directly descended through their mothers from Kate Baker – could have done the same test that I did and get the exact same results. So what did I learn?

Out Of Africa – A Grand Journey

Genetic anthropologists say that every person now alive on the planet can trace their maternal lineage back to one woman in eastern Africa who lived about 170,000 years ago. She was not the first human woman – Homo sapiens originated some 30,000 years before that in Africa – and she was not the only woman then, but rather the one whose lineage survived over all these thousands of years. So the Baker family’s story starts with her, as well.

The descendents of this “Mitochondrial Eve” populated Africa. Following the rare mutations indicates that first the population from which we descended moved to western Africa, where people with that specific early mutation are still most numerous. But then, about 50,000 years ago, the ice sheets covering much of northern Europe began to melt, creating a brief period when the parched Sahara changed to bountiful savanna. The genetic markers show that our nomadic ancestors followed this good weather and abundant game across the former desert barrier and into North Africa. Then, probably following the Nile River valley through Egypt, they eventually migrated across the Sinai Peninsula and out of Africa.

For thousands of years, our family lived in the Middle East on the eastern side of the Mediterranean Sea, probably interacting with the Neanderthals who also lived there at that time. This includes the geographic areas we now know as Israel, Jordan, Syria, Iraq and Lebanon. Then, about 30,000 years ago, they began to move north again, this time up through Turkey, around the Black Sea, over the Caucasus Mountains, and into Georgia and Russia. From there, they turned west towards what is now Europe.

This early time in Europe resulted in great innovations in tool-making. It is also when the Neanderthals died out, probably because the Cro-Magnons, our ancestors, were better able to communicate, create weapons, and compete for scarce resources. But then, after about 10,000 years, another ice age developed, locking much of the planet’s fresh water into the polar ice caps. The cold and drought made northern Europe so difficult for survival that our early ancestors had the good sense to wait out the 5,000 or so years of the Ice Age in warmer climates such as on the beaches in Spain, Portugal, and Italy. Not that these times were entirely a Riviera holiday, however, as the populations, along with genetic diversity, drastically decreased.

Finally, about 15,000 years ago, the great glaciers began retreating. For a while, until the ice sheets melted, the oceans were considerably lower than they are now. So it is likely that our relatives walked all the way along the beaches of Spain and France and then to the northern end of the British Isles, where eventually they settled in Scotland. Whew! What travelers we are!!!

The Taylor Baker Men

So what about the women in our family who are descended from the sons in the Baker line? All families are tapestries woven from many different vibrant strands of genetic DNA that come into the family at different times and from all different directions. Women born to the men in our family carry their own mothers’ families’ mitochondrial DNA and weave it into our family.

The men in our family carry the identifying Y chromosome DNA segment from generations of their fathers’ families. This means that those directly descended from the Taylor family could do the same type of genetic testing that I did with the Genographic Project and get this information for the Taylor family. While it is likely to present a similar migration story because the genetics of our Baker family are similar to the majority of Europeans, it will also show some differences and would be great family history to have. Not to put too much pressure on Uncle Harold, George Taylor, or Bryant and Rexford Taylor’s sons . . . ahem!

And if anyone in the family has Native American ancestors through the family line of their mother or father who married into the family, it would be fascinating to trace that – probably all the way across Asia and across the ancient Alaskan land bridge before moving down and across the North American continent. My son’s father’s family has Native American ancestors in both the U.S. Southwest and in Mexico, but I haven’t yet been able to convince his grandmother to do the genetic testing.

If any of you are interested in more of this information, send me an e-mail at seek@susankinsella.com. I have a report that goes into more detail about our family’s migration than what I’ve written here, plus maps, and can point you to more information online. I have found it to be a fascinating study.


Photo 1: Our Kate Baker Family mitochondrial genome, produced from my cheek swab – this is what the identifying DNA segment maps out to look like for all the women directly descended from Kate Baker. (I know, I wouldn’t recognize it either even if I bumped into it at a family reunion, but isn’t it beautiful?)
Photo 2: The Genographic Project’s map of our family’s migration out of Africa and eventually to the British Isles

2 comments:

Pat said...

Sue,

What a lot of work you put into this story--thank you!!

Very interesting.

And, fascinating that we all have the same strand of dna carried down for thousands of years.

Diana said...

Amazing - I've been doing DNA tests on my dogs for years - never thought to DNA people!

Thanks for sharing Sue - very interesting.