DNA 

 

Our February 2012 meeting was Linking the Past with the Present through DNA presented by scientist Darvin Martin of Lancaster County. The presentation answered some key questions that many genealogists have concerning DNA testing.

We began with a biology lesson on What is DNA? DNA, Deoxyribonucleic acid, is a series of chemical markers inherited from our parents that makes each of us unique. DNA is a generally a combination from each parent, with two exceptions: Y-Chromosomal DNA which is inherited by male children from their father and mitochondrial DNA which all children inherit from their mother. DNA provides the chemical information that is transformed into traits that are passed from generation to generation.

Why is it useful for family history? Our genetic code holds the story of our heritage that has been passed down through the generations. Comparing DNA between individuals can tell you whether or not the individuals are closely related, the approximate distance to a common paternal or material ancestor, and whether people with a specific surname are related through that surname.

The most common DNA test is the Y-DNA test that looks at the male inherited Y-chromosome DNA. As the Y-chromosome is passed on from a father to his sons, it is only found in males. Y-DNA testing can then be used to trace clearly a direct paternal line. While Y-DNA short tandem repeat (STR) testing tells about the most recent generations (1 to 45) of a male’s paternal heritage, single nucleotide polymorphisms (SNPs) tell of the line’s deeper history and trace back to ancient times.

A mitochondrial DNA (mtDNA) test looks at your female-inherited mitochondrial DNA. Maternal DNA testing offers you the opportunity to at least partially overcome that barrier of inadequate historic records by testing your mtDNA to learn about your maternal heritage in both recent and ancient times.

How does one take a DNA test and interpret the results? A DNA test is painless and only requires a small amount of saliva and a few skin cells from the inside of the cheek. Probably the most important decision is how many markers to test. Testing at 67-markers is preferred as the standard 37-marker test only provides basic information. An advanced 111-marker test is used in rare cases to solve genealogical puzzles that are unsolvable by testing at fewer markers. However, information on deeper origins (historical and anthropological) may be better answered with a Y-DNA Deepclade test. There are on-line resources available to  help you interpret your results … www.familytreedna.com, www.ysearch.org, and the Lancaster Mennonite Historical Society’s online forum at http://lmhs.org to name a few.

MRCA = Most Recent Common AncestorWhat does one’s DNA reveal about one’s ancient lineages?

The human genome project began in 1990 and sought to decode the entire genetic sequence of humanity. The project was completed in 2003, and concluded that humans have around 3.3 billion base pairs that are 99.9% the same. The differences can be traced back through time to link every human to a common origin in East Africa. These common African ancestors eventually populated the entire globe. Paternally all people descend through one of twenty haplogroups. Your haplogroup can be determined by a DNA test. Regardless of whether your ancestry is African, Asian or European, you fall into one of these haplogroups. Europe’s most common Y-DNA haplogroup is R1b. Ironically, Swiss families appear quite diverse, and fall within at least six of the twenty haplogroups … E, G, I, J, L, and R. [If you are interested, I found a discussion of the origins of the various haplogroups on-line at ww.kerchner.com/haplogroups-ydna.htm]

Using DNA we can confirm which ancestors were the original Germanic tribes, which were Roman, and which lived in Switzerland long before any of these. Information gathered from DNA, combined with political and social history, begins to reveal the migration patterns of our ancestors. Darvin Martin authored an article in the July 2010 issue of Pennsylvania Mennonite Heritage that extends genealogy and family history research to a whole new level that of one’s deep ancestry … “Imagine uncovering which of your ancestors have Greco-Roman, central Asian or Mid-Eastern ancestry. Imagine discovering that one’s ancestry shares a DNA signature with the ancient Hebrews or ancient Egyptians. Imagine finding a common ancestor among the indigenous tribes of India, the Chaldeans of the Tigris and Euphrates, or the ancient peoples of East Africa. Today family historians, through the interpretation of genealogically-based DNA testing, can not only speculate origins prior to written records but prove family connections back thousands of years.” The Lancaster Mennonite Historical Society offers DNA tests to trace your “Deep Ancestry” and has set up a forum for the discussion of DNA research as it relates to Mennonite family history at http://lmhs.org.

DNA testing can be expensive, however, almost every genealogist has spent money and a great deal of time and effort attempting to learn even the smallest bit of information about an individual in their family tree. DNA is another way to add to that information. 

 

written by  Cynthia Hartman