Mr. Tierney, I presume?

It's hard to imagine a world where surnames were not a part of everyday life. Today we rely on last names to identify ourselves and easily refer to others. But when you look at the full span of history, it was not that long ago that surnames came into use. And, interestingly enough, the Irish were probably one of the first to use them.

According to researchers Brian McEvoy and Daniel Bradley at the Smurfit Institute of Genetics at Trinity College in Dublin:

"Ireland has one of the oldest systems of patrilineal hereditary surnames in the world. While paternally inherited hereditary surnames are the norm right across Europe, early medieval Ireland was probably the first culture to adopt their usage, with some appearing in the early 10th century AD."

I've been working on my family's history since I was an adolescent, and I intend to continue for many more years. Chances are, however, that I'll probably not be able to work back in my family tree to anywhere near the 10th century. (I was thrilled a year or so ago to finally trace the Tierney family back to the time of the Great Famine in the mid-nineteenth century.)

Enter genetic genealogy. No, DNA won't give me the joy that I've received when I've found a photo of an ancestor, or discovered an ancestor's previously unknown given name on a document, but it can provide information about deeper family heritage in ways that were not possible just short years ago.

According to an article on Genetics & Genealogy by By Thomas H. Roderick, PhD of the Center for Human Genetics:

"By adding DNA analysis to our armamentarium of genealogical tools, we...are adding a new approach that can verify or deny established genealogical lines, provide through similar DNA findings hypotheses for where and when lines may be related and thus new areas in location and time to use the standard genealogical tools, provide understandings of relationships prior to the historical record and to provide insights into our Y-line [patrilineal] and M line [matrilineal] ethnic heritage."

The Y-line that Roderick mentioned is the family tree of the father of the father of the father...and so on. This is also referred to as patrilineal DNA. It turns out that each male has a Y chromosome identical to that of his father, and his father's father, and his father's father's father, back through all ancestral generations on what is called the "Y line".

A simple cheek swab test can provide information about your patrilineal family tree many generations back, particularly with regard to where the family originated. It can also provide you with connections to other descendants of the same family line that are living today - distant cousins who share the same heritage. This information can be shared with others through a Y-DNA surname project.

Because of the nature of patrilineal genetics, you must be male to test Y-line DNA. (The other type of frequently used DNA test is matrilineal or mitochondrial DNA, otherwise known as mtDNA. For more information see the Ireland Heritage mtDNA project.)

Take a look at the frequently asked questions section (under the For Newbies tab on the left sidebar) on the International Society of Genetic Genealogy website for more information about how DNA testing works and what information it can provide.

If your name is Mr. Tierney, and you are interested in learning more about your family's genetic heritage, you may be interested in the Tierney Surname Y-DNA Project. For more information, go to the Tierney Clans Society website or access the project directly at Family Tree DNA .

Similar projects are available for other Irish surnames (not to mention surnames of other backgrounds). You can find more information on some Irish surname projects at Irish Heritage DNA Project and the Ireland Heritage Y-DNA Project Family Tree DNA, although the list is by no means exhaustive. (Tierney and Kennedy, for example, surnames for which I know that there are projects available, are not listed on Irish Heritage.)

It's exciting to be researching family history now that technology is aiding us in so many amazing ways, including the area of genetics. Genealogy has never been as easy or as rewarding.

This post was created as part of the Carnival of Genealogy on genetics. See The Genetic Genealogist for more entries and information about genetic genealogy.