Sunday, December 14, 2014

Got BIG Y test results? Now what?

A few thousand if not several thousand men have or soon will have BIG Y test results. Of these the R1b-L21 haplogroup project has 800 all by itself. Funding the test is only the first major hurdle. Next comes the formidable task of incorporating the information into your family history.

Making sense of all the SNPs that have been discovered in the last year is overwhelming to many of us. That SNP Tsunami wave train is not a single event but a series that will be washing newly discovered SNPs ashore for the foreseeable future as more men are tested.

Hopefully you will have some SNP Superheroes in your haplogroup like the ones from whom I have benefited in L21. Without their mentoring I would still be struggling to stay afloat and would have very little understanding of the information newly liberated from my yDNA.

As I discussed in a previous post, you will find your BIG Y results in the Other Results section of your My DNA report at FTDNA. Part of that information is shown below:

Before we go further with our analysis I'd like to share with you an important caveat from Ray Banks who is the guru of the Z253 subclade of L21. My deceased father-in-law belongs to that subclade. Ray says:
"Big Y results are like slices of Swiss Cheese - full of holes and inconsistencies. It is only by putting together all of the slices that you get the full picture."
The data in the various columns in my report above are examples of Ray's slices of Swiss Cheese. As is typical of the BIG Y reports I have seen, the men in this listing share about twenty-five thousand SNPs (right column). That is interesting but so far I've not found that particularly relevant to my research. 

However, the order of the matches is relevant. You will note that they are ranked by the values in the Known SNP Difference column. Based on this column one could assume that the man listed first is my closest genealogical match. Not so. He is my second closest match in this group. My closest genealogical match is the 6th man listed. He is a known 6th cousin--once removed. Remember Ray's Swiss Cheese!

When a much more comprehensive amount of the evidence from my BIG Y results was analyzed by SNP Superhero Alex Williamson, he appears to have arrived at the correct conclusion about our relative relationships  and arranged our SNP branching in the correct sequence. Alex is the creator of The Big Tree of BIG Y results for those of us who have tested positive for R-P312 -- a parent SNP of L21. He found 5 SNPs that I shared with my known cousin after we parted company with the man listed at the top of my list above. The three of us share about twenty BIG Y novel SNPs that have not yet been found in other BIG Y results. We are hopeful that this situation will branch further when the results of three other men, thought to be somewhat distantly related, are posted in February. 

Analysis for Novices

Most of us, including Dr. D, have not begun to master the wizardry demonstrated on our behalf daily by Alex, Ray, Mike Walsh and many of their associates. However, I would like to share one trick that even novices can feel free to try at home as long as you remember the "Swiss Cheese" caveat.

Open your Big Y - Results and enter the Matching tab  

Next open the drop down menu under Shared Novel Variants. In the example below I have scrolled down the list until I came to the point where the matches start narrowing down from a few hundred to a few. The long series of numbers indicate the location on the Y chromosome where that particular SNP is located -- in this case 19201991. This just happens to be the location of the SNP that defines my subclade S1026. Note that 12 other men have tested positive for this SNP and are also members of this subclade.

Slide the scroll bar to the bottom of the list in order to find those likely to be your closest cousins. In the example above the SNPs followed by "(2)" will show two other men if the entire screen were displayed. For privacy reasons I have not shown their names or the buttons to display their email addresses. If you move the slider scroll bar completely to the bottom of the list, you may have a single individual who should be your closest match. However, remember Ray's Swiss Cheese! 
"Big Y results are like slices of Swiss Cheese - full of holes and inconsistencies. It is only by putting together all of the slices that you get the full picture."
Occasionally, you may have a SNP that is totally at random or appear to be that may match with one or a few men in some totally separate and distinct haplogroup. That is when you need to combine several slices of cheese to get the full picture. If you do look at a half dozen or more SNPs a true pattern should emerge. Happy snipping!

It think I'll go make a grilled cheese sandwich -- Swiss of course.

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