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For the Corson Cousins newsletter, October 2006

Corson Surname DNA Project

The pace of the project slowed during the last quarter due to my move to France in August (and preparations for it since June). Now that I'm mostly settled, I can devote more time to recruiting new participants. Because the project turns two years old in October, I'd like to focus on one of its main findings: the estimated degree of relationship among the ancestors of the families tested.

To date, the project has been able to estimate the genetic signatures of six men who, collectively, are ancestors of most CCFHA members:

Three of them are progenitors of their respective Divisions, while Samuel Corson is documented as the son of the Division I progenitor, Cornelius Cursonwhit (c.1660-c.1719), and Benjamin Corssen and Hendrick Vroom are documented as grandsons of the Division III progenitor, Cors Pieterszen (1612-1655). Given differences in the estimated genetic signatures of these six ancestors, I used an online computer program (Dean McGee's Y-DNA Utility) to estimate the number of generations to the most recent common ancestor of each pair. Because these calculations involve uncertainty about the mutation rate of genetic signatures, I calculated ranges of dates (95% confidence intervals) that most likely cover the true values. Multiplying the intervals by an average generation length of 25 years gave an estimate of the number of years to the birth of each common male-line ancestor for each pair.  Table 1 shows the likely limits on the number of years to the birth of the most recent male-line common ancestor of each pair:

Table 1. Estimated range of years to the birth of the most recent common male-line ancestor of each pair (i.e., years before the birth of each member of the pair).

Ancestor

Div. I

Div. II

Corssen

Div. III?

Vroom

Div. III?

Div. IV

Div. VII

Samuel Corson (c.1686-1764) (Div. I)

 

4950-10400

5700-11950

1225-3450

1100-3225

875-2750

Jan Corszen (c.1649-1703) (Div. II)

4950-10400

 

2850-6425

4300-9150

4625-9750

4025-8625

Benjamin Corssen (1686-1740) (Div. III?)

5700-11950

2850-6425

 

5300-11125

5300-11125

5700-11950

Hendrick Vroom (1683-1769) (Div. III?)

1225-3450

4300-9150

5300-11125

 

975-2975

875-2750

Carsten Jansen (1634-c.1697) (Div. IV)

1100-3225

4625-9750

5300-11125

975-2975

 

875-2750

Jacob Corson (c.1755-bef.1822) (Div. VII)

875-2750

4025-8625

5700-11950

875-2750

875-2750

 

(Infinite allele mutation model, mean mutation rate: 0.0024, mean generation length: 25 years, 95% c.i.)

You may first notice that the smallest number in the table is 875 years, meaning that Benjamin Corssen, Hendrick Vroom, and the progenitors of Divisions I, II, IV, and VII were not related to each other (in the direct male line) more recently than about 875 years before their births. Thus, they were not related to each other in a genealogical timeframe (i.e., since the adoption of surnames).

Also note that Benjamin Corssen and Hendrick Vroom, documented first cousins, have a greater than 5000-year period back to their most recent common male-line ancestor. Thus, at least one of the two genetic signatures does not represent Cors Pieterszen. In other words, it means that only one of the two documented Division III families tested (Corson or Vroom), if either, truly descends from Cors Pieterszen. To resolve this mystery, we will need to find more documented Division III descendants willing to participate in the project.

Network Diagrams

Diagrams represent another way to show predicted relationships among families. Twenty-two participants in the project appear to belong to a broad genetic group called "R1b", which means that they descend from a common male-line ancestor who lived thousands of years ago. To see how they may be related, I constructed a network diagram for 21 of them (one had too few markers tested in common with the others) using a computer program (Network 4.1.1.2). The program estimated degrees of relationship based on the marker values in their genetic signatures and constructed a hypothetical branching "family tree" (Fig. 1). Documented descendants from Division II and some from Division III do not appear in this diagram because they belong to a different genetic group (called "I").

This diagram shows one possible sequence of descent from the common male-line ancestor of these participants (the origin on the left-hand side). The lengths of the lines connecting participants (circles) are proportional to the relative number of mutations in their genetic signatures. The diagram shows the close relationship among the two participants from Division VII, that among the eight participants from Division I, and that among the four participants from Division IV. It also shows the close relationship between the three Vroom descendants of Hendrick Vroom (1686-1769).

The diagram also indicates that descendants of Divisions VII, I, and IV are more closely related to each other than to the other R1b participants. Outliers in this diagram include Corson participants #5, #8, #23 and the DeCoursey participant, who have genetic signatures very different from those of other R1b participants in the project. Corson participant #23 traces his descent from the Corsons of Scotland (Division Va).

New Initiatives

Now that I live in Europe, I hope to have better success recruiting European participants, particularly from Scottish Corson/Corsane and French Courson families. By chance, I now live an hour (by train) from St. Brieuc, Brittany, a "stronghold" of French Coursons since the 16th century. It will be interesting to see how their genetic signatures compare to those of Coursons living in the southern United States.

As always, if you have Internet access and would like information about the DNA Project between issues of Corson Cousins, you can visit the project website: http://www.geocities.com/misccorson/dna/