The Big-Y

The Big-Y DNA test is a deep test. In addition to finding men who share a paternal ancestor who lived since the era of surnames, it finds men who share a paternal ancestor who lived before the era of surnames, and in many cases a thousand + years ago. FTDNA, the company who devised the Big-Y, say this of this test:

The Big Y is a Y-chromosome direct paternal line test. We have designed it to explore deep ancestral links on our common paternal tree. This test examines thousands of known branch markers as well as millions of places where there may be new branch markers.

The Big Y test is intended for expert users with an interest in advancing science. It may also be of great interest to genealogy researchers of a specific lineage...

It is presumed that the Y-DNA of all men forms a tree at the root of which is a "Y-chromosomal Adam". The Big Y test finds a man's branch on this tree, and my uncle's branch has now been assigned a name and a location. For now there are two Livingston men on the branch known as "R-BY117365" - my uncle and an American man. 

My earliest known Livingston ancestry is in County Monaghan, the American's earliest known Livingston ancestry is in Pennsylvania. During the 17th century, Monaghan was colonised to some extent by lowland Scots, and so we can guess that the most recent common ancestor of my uncle and his match was a lowland Livingston, some of whose offspring migrated to Ireland, and some of whose offspring migrated directly or indirectly (via Ireland) to the US. A potential clue as to the identity of this person comes from the The Genealogical and Family History of Central New York which refers to a John Livingston who migrated from county Monaghan to the US in 1764, and says that he was

...a lineal descendant of Rev. John Livingston through the latter’s son James, who was also the father of Robert, “the nephew.” who came over at the invitation of his Uncle Robert, first lord of the manor of Livingston, an immense estate in Columbia county, New York.

Another potential clue is the relatively small number of Scots that entered Monaghan during the time of the Ulster Plantation: 

Just as Counties Antrim and Doon were not part of the Plantation, neither was County Monaghan. In this county most of the land remained in Irish ownership in the early 17th century.  Some Englishmen acquired large estates in the county and a number of English families settled there. However, the number of Scots in County Monaghan at this time was very small – fewer than in any other Ulster counties.

Judging by the surname and the location, it is a good bet that John Livingston and I belong to the same Livingston family, and therefore that the most recent common ancestor (MRCA) of my uncle and his Big-Y match was James Livingston (1646-1700). For what it's worth, this time frame agrees with the formula for calculating the TMRCA given in Bruce Walsh's influential 2001 paper Estimating the Time to the Most Recent Common Ancestor for the Y chromosome or Mitochondrial DNA for a Pair of Individuals. Using a mutation rate of 0.0029 we arrive at a binomial distribution that peaks 11 generations ago:

James Livingston's father, Rev. John Livingston, was the 2nd great grandson of Sir William Livingston 4th Lord Livingston of Callendar, and a presumed patrilineal descendant of the founder of the lowland Livingstons. I have tried to persuade 2 Livingston descendants of John Livingston of Monaghan to take Y-DNA tests, and have not yet succeeded.

I would be interested in a Y-DNA test result for another John Livingston (1830-1898) from County Monaghan after whom Livingston Village in Illinois is named. Upon his arrival in the US from Ireland, he worked on local farms for 50 cents a day, and eventually purchased a farm that improved over time until it encompassed 297 acres.