Y-DNA of Joel Campbell (born circa 1735)

Seven known paternal descendants of Joel Campbell's father (Samuel) have submitted their DNA for genetic-genealogy testing using the Y-DNA methodology.  In addition, two results closely matching those of Samuel's descendants are also in the "Campbell Project" database at FamilyTreeDNA.  This article is a short description of what this means for genealogists of the Joel Campbell line.

Y-DNA Results for seven known relatives and two possibly related.  Click here for larger version.

Legend:  The grey row are my results.  The light blue row is a known relative, but interestingly differs in two of the 37 markers.  More about this below.  The purple column is the DYS447 marker. The result of "26" for the DYS447 marker seems to be almost unique to our recent line.  The yellow boxes highlight results of other participants which differ from mine.

Y-DNA
The Y chromosome is passed from father to son virtually unchanged.  Mutations in certain segments of the chromosome occur randomly every 300-1000 generations.  Mutations are a reshuffling of the order of building blocks of the chromosome.  There are only four building blocks which are abbreviated as A, T, C, and G.  Y-DNA research has identified chromosome segments where short sequences of the building blocks are repeated multiple times.  The Y-DNA Test counts the number of times the sequence is repeated.  These segments are called Short Tandem (adjacent) Repeats or "STR"s.

For example, the third column in the table above is the segment called DYS393 (DNA Y chromosome Segment #393).  The repeating sequence is  AGAT.  This sequence repeats 13 times in the Y chromosome of the nine persons tested.  In the general population this sequence repeats in the range of  9 to 17 times.  The mutation rate of this occurrence is about once every 1000 generations.

The likelihood of a common paternal ancestor can be calculated by testing for multiple markers.  In the above example, all nine of the participants were tested for 25 segments.  All segments are a match (except for a single segment of one participant (blue row) who is a known relative).  If the mutation rate of each segment is one in 500 generations, then the combined mutation rate of all 25 together is 25/500 or about one in 20 generations or about one in 500 years.  By testing even more markers the probability of a common ancestor can be estimated with more accuracy.

Eight of the persons above have been tested for 37 STRs, three have been tested for 65, and one has been tested for over 100 STRs.

Don't get too overwhelmed by all of the numbers, but if you are fascinated by this, you can read a lot more at the website of the International Society of Genetic Genealogy (http://www.isogg.org/) , the blog of CeCe Moore (http://www.yourgeneticgenealogist.com/), and at many other sites you can find just by following the links from these sites.

Well....what can we learn from the data?

Are we really Campbells?  Yes! The genetic data indeed shows that our Campbell heritage is genuine.  We did not adopt the name.  Just as the genetic signature has been passed down from father to son, so has the surname.  Our Y-DNA markers are too similar to other known original Campbells to be not part of that clan.

How recent is our common ancestor with the Dukes of Argyll?  The Dukes of Argyll, leaders of Clan Campbell, trace their lineage back to Cailean Mor Caimbeul, one of the earliest attested leaders of the Clan.  He died around 1300.

Our relation to that line can be determined through Y-DNA.  One benchmark we have is the Y-DNA results of a direct paternal descendant of the 4th Duke of Argyll.  FamilyTreeDNA has an algorithm that estimates the probability of a common ancestor existing between two study participants.  If I compare my 37 markers with the 37 markers of the descendant of the 4th Duke there is a genetic distance of "3."  That means that three of the STRs have a number of "repeats" that differ by one.  The FTDNA algorithm uses the mutation rate of each STR to estimate the likelihood of a common ancestor.  In this case I know that I have no common ancestor with this other person in the last 11 generations (that is going back to Archibald who is the father of Robert, grandfather of Samuel, and great grandfather of Joel).

The results show that there is almost an 80% chance that we share a common ancestor within the last 16 generations.  That takes us back to the year 1500 and the 4th Earl of Argyll.  The probability goes up to 93% within the last 20 generations.  That takes us back to about 1400 and the 1st Earl of Argyll.

It certainly appears that we are direct descendants of MacCailean Mor!

Screenshot of FamilyTreeDNA TiP Report for Most Recent Common Ancestor.  Click here for larger version.

Probabilities and random mutations   The data always reminds me that "mutations happen."  My 37 markers differ from my known relative, Tony Campbell, by two.  That is only one less than I differ from the Dukes of Argyll.  Hey, mutations may on average only happen every 500 generations, but with millions of people and hundreds of markers, they are happening all of the time.  Clues to our very recent relatives may be in the genetic data even when there is a genetic distance of two.
  

Coming up:  Finding the Descendants of the other sons of Robert (circa 1670) and Archibald (circa 1640) and In Search of the Maternal Descendants of Abigail Campbell (circa 1735).