Friday, May 9, 2014

What's So Big About The BIG Y Test?

Some of you may be in a similar predicament to the one I have been in for half a century. I know who my 6th great-grandfather is on my surname line; but I don't know anything about where he came from. My ancestor, Philip Dowell showed up as an established tobacco planter in Southern Maryland in the 1690s. The rest of his life until his death in 1733 is pretty well documented. 

My first DNA test back in 2004 was supposed to help. It didn't. Well actually it did. It told me I was not related to most of the Dowells who were in Colonial Virginia. I wanted it to tell me who I was related to on the other side of the pond. On that question I have not really progressed much since 2004 or 1966 for that matter.

Over the years I have been able to make connections with many of living descendants -- including straight line male Dowell descendants of three of his four sons who lived to produce offspring. By testing our yDNA and triangulating the results we have been able to reconstruct what Philip's 111 yDNA STR marker test report would have said if he had been tested by FTDNA. However, we really are not much closer to tracing his origins prior to 1690. Over the last decade we have made contact with a few other non-Dowells who are within spitting distance of Philip's yDNA signature at 67 and 111 STR markers.

I was an easy recruit to take the BIG Y test when it was rolled out in November. My sixth cousin -- once removed, George Dowell and a more distant ySTR match, Herb McDaniel also decided to test.

yDNA Haplogroups

Many of you may know that R1b is the most common male haplogroup along the Atlantic coastline of Western Europe. One of its branches, L21, is very heavily represented in the British Isles. Many of those who have taken yDNA tests in the last decade have either been confirmed or at least projected to belong to the L21 group. 

For those of you who are not into STRs and SNPs, L21 is a SNP along the human migration path that represents permanent branching. To the best of our knowledge at the moment, the first male to have his "G" mutate to a "C" at location L21 on his yDNA did so about four millennia ago. All of his straight line male descendants have inherited this C. 

Now with the new SNP data flowing in from BIG Y and other expanded tests of SNPs along the yDNA, we are able to shrink the four millennia down somewhat. My goal is to find SNPs that have occurred in the last 3 to 5 centuries. This may help us connect our SNP paths with our STR data and with our traditional genealogical trees.

SNP Trail from R1b-L21 to S1026 and even more recently.

In the last month we have been closing that gap, but we still have a long way to go. My own most recent SNP is getting closer. Indications are that DF13 (also known by other designations shown in the box above) first appeared about 3,500 years. Now we have SNP S1026 to narrow the gap even further. After that come 5 SNPs in the center box in the chart above. They need a lot of analysis to place them in the proper sequence with each other and in the right historical era. Five of the seven of us who so far have tested positive for S1026 share those five SNPs which are just in the process of being named as I write this post. Then it looks like there are 18 additional SNPs even closer to the present that I share with Herb McDaniel. It will be interesting to see how the results of my cousin George and others help us fill in even more of our time gap. 

I am not advocating that  any of you rush and order the BIG Y or the Full Genomes Y Sequencing tests. These are still vehicles for discovery of SNP trails rather than for finding cousins. STR tests are still better for the latter. If  you want to SNP test, your dollars will be better spent if you build on what is being discovered by others. Generally your best strategy will be to find a near or even a  distant STR match who has taken one of these mega tests. First confirm the most recent SNP you appear to share by taking a single SNP test. Then consult with your haplogroup or surname project coordinators for suggestions for addition SNPs to test individually. Happy SNP chasing!

No comments:

Post a Comment