News from Recent Journals of Genealogy
- DNA evidence is used in genealogy
- the Cluster Principle is explained
From APG Quarterly- on DNA Testing- The Process and the Promise
"The Science of Genetealogy"
From the March 2003 Issue...
Some months ago, there was a news story which showed the opening of graves in Halifax, Nova Scotia. They were graves of victims of the sinking of the Titanic. The task was undertaken, with special permission, by an unnamed genealogist who was attempting to prove that a living person was a direct descendant of a passenger on board the famous ship.
The results of the investigation were negative. Scientists taking the tissue samples from the graves were unable to obtain sufficient DNA-bearing material. Similar results were obtained in an attempt to identify the virus which caused the deadly flu of 1918. After several efforts, soft tissue of victims was obtained from the graves of victims buried, and frozen, in Alaska. However, researchers examining this tissue, state that the flu virus is broken and scattered throughout the tissue, and will take many years to re-compose.
But which of us has not wondered about doing the same type of investigation - obtaining DNA from a deceased ancestor, in the hope of proving forever our descent from this person?
The March 2003 issue of APG Quarterly (Vol. XVIII - Number 1), has an article written by a genealogist who is doing this type of research. I strongly suggest that you read this article... but if you can't, here are a couple of key points which I gleaned from it.
The researcher is named Megan Smolenyak. She describes her own quest to establish roots, and the unusual evidence which she was able to establish. She does not use material from deceased ancestors, only from living persons who should have, or may have, descended from a common male ancestor.
As it stands as of the date of the article, according to Ms. Smolenyak, testing can only be done with the Y-chromosome, carried only by males. This means the testing follows the surname, from father to sons, generation to generation, - but not daughters.
This means that Tom Brown of Ohio, who believes that he and Mike Brown from Manitoba, both descend from Ebenezer Brown who lived in Maine in 1749, can test whether or not they do, in fact, have a common ancestor.
If Tom's daughter Sarah is the one wanting to find this out, she must find a proven male family member - such as Tom, or her father, cousin, or brother, to take the test.
This testing is in early stages, and it is to be hoped that some aspect of the X-chromosome will likewise allow us to trace ancestry via female kin.
To get more information contact Megan at this email address:
(May 2004 update) We have heard from members that Megan also provide links to other methods of DNA research.
As of late 2004, researchers have found a way to extract DNA from the teeth of bodies. Soft tissue is no longer required. The process has been used successfully on ancient human remains in Africa. This practice promises to open many more doors into DNA analysis for genealogical purposes.
From Families, the Periodical of the Ontario Genealogical Society
vol 42, no 3, August 2003
The Theory of Pedigree Collapse
By John H. Puttenham
As implied at this web site, if one traces one's parents back for ten generations, a span of about 300 years, and you count only parents, you will find that you have 1,024 direct ancestors in ten generations.
Mr. Puttenham notes that if this is continued back to the time of the Emperor Charlemagne, one would find 281 trillion direct ancestors - many times the population of the world. "Obviously this is impossible".
"What prevents this 'retrogressive population explosion' from happening? It is the simple fact that most marriages are (historically) between cousins. Therefore we all show various ancestors, and one's own family tree has far fewer people in it than this calculation would suggest. This is where a theory called 'pedigree collapse' comes into play.
It is estimated that 80 percent of the marriages in world history have been within the second-cousin relationship. It's easy to see why. Most humans have lived in small towns, villages, tribes, and close-knit religious communities which encourage marriage within a relatively small universe of possible mates. Obviously this has been changing a lot in the last couple of hundred years, which should make our gene pool a little healthier in the long run.
The Theory of Pedigree Collapse is that every person's family tree is actually shaped something like a diamond. If you trace it back a few generations, it will eventually start to narrow and then finally converge to a few ancestors, or perhaps into a single couple (Adam and Eve?)... The further you go back, the more likely it is that an individual ancestor will occupy more than one spot on your family tree. So the actual number of ancestors at each generational level eventually begins to shrink if you go back far enough..."
Mr. Puttenham then cites several interesting studies done, and says...
"The modern human species has only been in existence for about 10,000 generations. The major races (Black, Caucasian, Asian, etc) only diverged from one another in the last 1,500 generations, at the most."
A recent show on the History Channel showed a fictionalized scenario of a courtship of a Homo Sapiens girl by a Cro Magnon man, at the time the Cro Magnons were fading. This was said to have happened 100,000 generations ago.
While we may all descend from a small number of folks in the dark moments of ancient time, we most value our genetic links to that cluster whom we call 'The Founders of the New World', as happened in the range of ten to fifteen generations ago. Like the Homo Sapiens girl who resisted the advances of the Cro Magnon man, we resist the link to other folks who lacked the values, beliefs, and principles to set out on their ships across the icy Atlantic. We cherish our links to these Founders.
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