The Family Tree
By Terence L. Day
Terence L. Day, genealogist and journalist, is on the Washington State University faculty. He welcomes e-mail at genealogy@moscow.com, or regular mail in care of the Tri-City Herald City newsroom, P.O. Box 2608, Tri-Cities, WA 99302-2608.
Modern science can link us to ancient history
This story was published March 30, 1997
Reading recently of a report by Oxford University scientists that two humans who lived 9,100 years apart have been positively linked by their DNA sets my mind a whirl.
In one giant step in our understanding of the history of man, molecular scientists have pushed a proven ancestral link nearly 7,900 years further back than any genealogist can chart a family tree.
Although some amateur genealogists claim to have climbed their tree all the way back to Adam and Eve in the Garden of Eden, none has ever proven such a pedigree or anything close to it and never will.
Reliable authorities believe we can prove ancestry only back to Charlemagne (768-814 A.D.), or shortly, before in Central Europe. Perhaps a bit longer in China.
But the Oxford scientists have done something no genealogist would dream of doing. They left out somewhere between 276 and 365 generations. And I don't blame them. That's between 46 and 60 charts containing six generations each.
Of course no one will have to do that work any day soon. So far, we only have two names for the chart. Adrian Targett, a 42-year-old school teacher who lives in Cheddar, England, and an ancient bloke called Cheddar Man whose bones were found in 1903 in Gough's Cave near Cheddar. And, we don't know how they are related.
Cheddar Man isn't Targett's direct ancestor, but DNA tests prove these men share a common female ances tor. We know the common ancestor is female because the DNA tests conducted by Oxford University scientists is based on DNA that is passed on only by women.
Greg Hampikian, a molecular geneticist at Clayton College and State University in Morrow, Ga., explained the biology of this story for me.
Our bodies contain two types of DNA. One is recombinant DNA, which is composed by recombining chromosome pairs, 23 from the male and 23 from the female. The other kind is mitochondrial DNA. It is produced by bacterialike mitochondria, which reproduce by cloning.
When we reproduce sexually, the male sperm sheds all of its mitochondrial DNA, transferring only recombinant DNA to the egg. Thus, all of the mitochondrial DNA in our bodies comes from women.
It would be next to impossible to link a person living now with an ancestor who died 9,100 years ago by analyzing recombinant DNA. Hampikian says analyzing recombinant DNA would do quite nicely for a few generations, but so many changes occur through recombination it becomes extraordinarily difficult to follow recombinant DNA over hundreds of generations.
Fortunately, mitochondrial DNA is much more stable. News reports indicate that Bryan Sykes, of the Oxford University Institute of Molecular Medicine believes scientists working with mitochondrial DNA may be able to find living descendants of Neantherthal Man, who lived 30,000 years ago.
One of my first reactions to reading of the Cheddar Man discovery was to wish I could dig up a few old Day bones in Wisconsin and Kentucky and run DNA tests run on them.
It certainly could help me solve my major mystery, which is the identity of four or five John Days living in Morgan County, Ky., between 1790 and 1840. I'm descended from one or more of them.
While fancifully intriguing, DNA testing would be cheating. Besides, what would genealogy be without unsolved mysteries?
For the time being, anyway, I'll stick to musty courthouse records and blurry microfilm.