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From the Corson Cousins newsletter, July 2005

Corson Surname DNA Project

The Corson DNA project now has 15 participants, 14 of whom have received their DNA results.  Since my report in the last issue, the project has made two significant finds: we now know the “ancestral” Y-chromosome genetic signature for Division I (New England branch) and that for Division II (Sussex Co., NJ branch).

Knowing a Division’s ancestral genetic signature makes several things possible.  With it, we can determine (1) how closely one Division is related to another and (2) whether a family with a brick-walled male-line ancestor descends from a known Division or not.  In addition, as DNA tests increase in resolution and more people are tested, knowing a Division’s ancestral genetic signature eventually can indicate where the male-line ancestors of the Division’s progenitor originated.

Determining the Y-DNA genetic signature for a given male ancestor requires testing male-line descendants of at least two different sons of the ancestor.  If the results of the two descendants match, then their common male ancestor almost certainly had the same genetic signature.  In the rest of this article, I will describe how we determined the “ancestral” genetic signatures for Divisions I and II, then explain what the results currently tell us.

Three project participants (including me) come from Division I, whose progenitor was Cornelius Cursonwhit.  Since Cornelius had only one known son we cannot determine Cornelius’ genetic signature.  Instead, we can go back only to his son, Samuel Corson, who had four sons.  Two descendants of Samuel’s son Zebulon Corson had genetic signatures that matched exactly, while a descendant of Hatevil Corson/Colson matched the other two Division I descendants on 40 of 41 markers (Fig. 1).

Two participants come from Division II, whose progenitor was Jan Corszen.  A participant with the Corsa surname, who traced his ancestry to Jan Corszen through Jan’s son Benjamin Fletcher Corsse, had the same genetic signature as a Corson participant who traced his ancestry to Jan through Jan’s son Jacobus (Fig. 2).

These ancestral genetic signatures indicate that Division I descendants belong to a broad genetic group (“haplogroup”) currently called “R1b”, while Division II descendants belong to an entirely different genetic group, currently called “I1a”.  Researchers estimate that the most recent common male-line ancestor of these two haplogroups lived about 40,000 years ago.  In other words, Cornelius Cursonwhit and Jan Corszen did not have any male-line ancestors in common for thousands of years.  Thus, Division I and Division II descendants are genealogically unrelated in the direct male line.

Their very different haplogroups, however, do not tell us whether they came from different countries or not.  Currently, the birthplaces of both men remain unknown.  Sparse documentation leans toward a Dutch origin for Cornelius Cursonwhit, while debate about a Dutch or French origin for Jan Corszen continues.  Haplogroups R1b and I1a occur throughout Europe, but with varying frequency depending upon region.  Because the haplogroups have such broad distributions, it may be more useful to look at specific marker values in the genetic signatures themselves.  For example, Division I has values of 25 and 10 for markers DYS390 and DYS391, respectively; in haplogroup R1b, this combination appears to occur more frequently in populations from northern Germany, the Netherlands, and Denmark than in populations from, for example, Ireland.  Similarly, Division II has values of 14, 22, and 13/14 for markers DYS 19, DYS 390, and DYS 385a/b, respectively; in haplogroup I1a, this combination appears to occur more frequently in Germany and Denmark than in Norway and Sweden.  Still, these statistical probabilities for just a few markers do not provide conclusive evidence.  As public DNA databases continue to add more international results, we hope to find patterns among more markers that can help us determine from what regions family progenitors may have come.  For Divisions with European origins, luckiest of all would be to find a close match with a European individual, a descendant of a Division relative who remained in Europe. 

Though we have determined these ancestral genetic signatures, we still encourage male-line descendants from Divisions I or II to join the project.  Additional participants will allow us to look for marker values that may indicate particular family lines within Divisions.  For example, male-line descendants in Division I-A (surname “Corson”) have a value of 13 at marker GATA-A10, while a descendant from Division I-B (surname “Colson”) has a value of 12 (Fig. 1).  If another Division I-B descendant has a value of 12 at GATA-A10, we will have a marker value that can tell us the difference between Division I-A and I-B descendants (though it is more useful for descendants who have the same surname).

One last finding: at the end of June, I received results from a different kind of DNA test, called an SNP (single nucleotide polymorphism) test.  It revealed that I (and the rest of Division I) belong to a subgroup of haplogroup R1b currently called “R1b1c”.  It doesn’t tell us much more about Division I right now, but current SNP research is looking into the geographic distribution and past migrations of these sub-haplogroups. 

We are still looking for additional participants from the other Divisions to help us determine their ancestral genetic signatures.  One more participant may be all we need to do so for Divisions III, IV, or VII.  For those of you unsure of which Division you may belong to, a DNA test of a male-line descendant in your family may provide the answer.  The CCFHA has one remaining $40 reimbursement of the test cost available.  You can read more about the project, see lineages of current participants, and see test results and interpretation at the project website:

http://www.geocities.com/misccorson/dna/

Please contact me if you have any questions about this project or if you, or someone you know, might be interested in participating.

(P.S. If you find any errors in the above figures, please let me know so I can correct my database.)