Genealogical research can only go so far as it is based on written documentation. The farther back in time one goes written records become more and more scarce. Ultimately, written records are nonexistent.
DNA research now provides a means to trace one’s ancestry back in time by determining the most recent genetic mutation in your genome. Males test their yDNA to determine the heritage of their father’s line. Tests for 12, 37, 67 or 111 genetic markers are available. The more markers tested, the more specific the results. Once results are received, however, further research is needed.
For example, I tested R1b1a2a1a1b4f or L159.2+. The R1b haplogroup arrived in Europe about 35,000 to 40,000 years ago and was the first culture in Europe to leave cave art. Today over 50% of Europeans are R1b with the highest number in the British Isles.
My test consisted of 67 markers and determined that my male line fits the L159.2+ mutation known as the Leinster Modal. This mutation is found in the ancient Irish kings of Leinster and most particular in Diarmait Mac Murchada, who was King of Leinster in the early 12th century.
The theory is that the R1b1a2a1a subclade is common to a number of British Celtic tribes migrated to southern Ireland and southwest England between 4th and 8th century. Among these are the Dumnonii that settled Cornwall and in the southern Ireland.
Recently, I expanded DNA testing to 111 markers and have moved deeper down the L159.2+ haplogroup and now am classified R-ZZ7_1.
This places my DNA in what is termed the Irish Sea Modality as I share many traits of the Irish Clan Byrne. To dig even deeper, however, I am taking the ‘Big Y Test’.
The Big Y product is a Y-chromosome direct paternal lineage test. That has been designed to explore deep ancestral links on our common paternal tree. Big Y tests thousands of known branch markers as well as millions of places where there may be new branch markers. The test is intended for those with an interest in advancing science and may also be of great interest to genealogy researchers of a specific lineage. To learn more about the methodology and science behind the Big Y test Family Tree DNA has produced a Big Y white paper published August 28, 2014 and sells the Big Y product as a Y-chromosome direct paternal lineage test.
RDNA testing is not only helpful in placing one’s family geographically in the history of human migration, it can determine a common ancestor in a range of 3 to 10 generations. For example, several Cottons who have no proven genealogical link to the Rev. John Cotton, who helped found Boston MA in the early 1630s have been linked to his line through DNA test results. (Family 11 on this link)