They talk about not being able to see the forest for the trees. For Q-Y2200, this is not our problem. We have found many of the Jewish Q trees in the forest, and we know that Q-Y2200 is one tree. The problem is that we cannot puzzle out the trees and their branches by looking at the leaves.
What do I mean by this?
The Y-STR Leaves
When we look at Y-STR genetic distance, we are looking at a tree's current leaves in relation to each other from above.
Based on how close the leaves are to each other, we are guessing at how likely they are to be on the same branch. It works well out on the edges of the tree.
The problem comes from the leaves near the middle of the tree.
Here, as you can imagine, there are limbs of the tree that have grown from the left across the center and into the right.
Then there are limbs on the right that have grown across the center and onto the left. Thus, you have some cases where very different branches have leaves right next to each other.
Exploring the Problem
In populations where there are surnames going back 500 years, you can use surname matching to help, and it works really well. Ashkenazi Jews do not have surnames that reach back 500 years. Thus, there is not information secondary to genetics to help. This is a problem for both Jewish genetic history and for Jewish genealogy.
The two disciplines share the problem. We need the genetic equivalent of surnames.
For genealogy, you need to know that everyone who shows as your close match is actually on the same recent branch. By recent I mean the past 150 years +/- 100 years. For Jewish genetic history, we need to know the detailed branches and dates.
Exploring the Solution
Jewish genetic history is using BIG Y results. With enough testing, BIG Y defined branches come forward to about 200 years ago (plus or minus a few generations). Those branches can be further subdivided with enough Y-STRs and traditional genealogy, and that is the work of the Jewish genealogists. Thus, we see the two interests overlap and complement each other.
How do we get there?
Well, instead of looking at the tree and leaves from the top, we start at the trunk. We follow each limb up and document each branch. Y-SNPs mark these branches. Dates can be put on the branches. This has been the talk among those working on Jewish Y-DNA, those branches and dates are lining up with recorded Jewish history.
The type of Jewish Q where we have made the most progress toward the solution is Q-Y2200. So far, 13 Q-Y2200 men in the project have BIG Y tested, one man tested at Full Genomes Corp., and 59 more have taken the Q-L245 SNP Pack test. As a result, there are now 43 defined branches of the Q-Y2200 tree.
Patterns are beginning to emerge. Most noticeable is the large percentage of Q-Y2200 men who belong to the Q-Y2754 branch. This may be due to founder who lived in Medieval times.
We do not yet have multiple men on branches recent enough to replace surnames, but it is clear that we are on the right path.