Different Language: The language of DNA

Better late than never, right?

Initially, ฉันต้องการเขียนเกี่ยวกับภาษาแม่ของฉัน ภาษาไทย. I mean, you can’t get more different than between two completely different cultures that had little contact in ancient history and about zero common root words. Not to mention the script! But, I really don’t know much more than I have already written about.

So, let’s go back to DNA. Now that is a different language. It’s tough when you have to stop reading how-to articles on deciphering your DNA results after every sentence to look up the big words or the tricky little words you thought you understood but are being used in a completely different context than you’re comfortable with.  

Before I go further, though… Uncle M and Aunt C, if/when you read this, I have a letter with more boring details than this blog. It is in draft still and almost ready to send to grandma – don’t leak anything to her! I just had to stop because work got in my way. Grrr.

Ok…now that we have that behind us. Onward.

I recently had my Grandmother’s mtDNA tested. We’ll call her GB for simplicity.

I thought I was ready for mtDNA. I felt I had been getting pretty good with autosomal and Y-DNA deciphering, and I was anxious to break through my current ultimate Grandmother’s brick wall – Marion B. Tucker, wife of George W. DeJean. Our (that is, my father’s, Aunt’s, Uncle’s, and GB – not mine) mtDNA line goes:

My dad
His mother (GB) – Generation 1
Mary Gage – Generation 2
Luella DeJean – Generation 3
Marion B. Tucker – Generation 4

I could do an autosomal for GB, but that would give me too many results in other branches of the family that would take time to sort through to find relations to the Tucker family. And if Uncle M and dad’s autosomal results are any indication of what to expect – it’s pretty much a bunch of Alecks. That branch seems to like genealogy and DNA testing. So mtDNA would focus the results on relations to Marion B. Tucker.

I was disappointed (and very confused) with how genetic distancing worked for mtDNA. All you DNA newbies out there…pay attention to the fine print; mtDNA mutates much slower than Y-DNA, so your match pool will be much larger. Y-DNA tests’ genetic distance interpretations are on a sliding scale of confidence vs. distance in time up to 15 generations researching the same surname and the sliding scale can help you weed out the furthest relations. But with mtDNA, there is no sliding scale. It’s just a base level of confidence. Read more about genetic distances here. GB had a full sequence mtDNA done that loosely narrows my search range down to 22 generations for matches at a genetic distance of 4 or less. At 22 generations of different surnames – that’s a lot of research!! So Y’s 15 vs. mt’s 22, not a large difference, but it’s often difficult to trace the first five maternal lines, let alone up to 22!  I can only get to the 4th maternal generation with any confidence.

The different charts at FTDNA depicting the interpretation of genetic distances between Y-DNA verses mtDNA. Note, GB was tested for mtFullSequence.

There are two meanings for Genetic Distance:
1. Genetic Distance is the number of differences, or mutations, between two sets of results. A genetic distance of zero means there are no differences in the results being compared against one another, i.e., an exact match. This is the meaning when comparing Y-chromosome DNA or mitochondrial DNA.
2. For autosomal DNA comparisons, genetic distance may refer to the size of a DNA segment. The genetic distance is then the length of the segment in centiMorgans (cM).

FamilyTreeDNA

centimorgan is a unit used to measure genetic linkage. One centimorgan equals a one percent chance that a marker on a chromosome will become separated from a second marker on the same chromosome due to crossing over in a single generation.

Genome.gov

I focused on matches with a genetic distance of 0. Keep reminding yourself, a genetic distance of 0 does not mean you are cousins. It just means there are 0 genetic mutations between your DNA sample and your match’s sample. Make this your DNA mantra.

GB had 23 matches at the 0 genetic distance level. Which apparently is high even for mtDNA. Nice – but what do these 23 matches tell us? Well, not much at face value. Of the 23 who published their maternal research, many could not go back any further than me in generations, and none of them had surnames that rang any bells for me. It’s important to note that surname matching is what you would do for Y-DNA or (to some degree) autosomal matches…but now I have to rethink, relearn, and recalibrate my thought process.

Because women change their names each time they got married, and the mtDNA line deals with a different surname for each generation, we have to start with commonalities in time and place instead of the surname. Since Marion is my brick wall, we start at Marion’s birth date and location. 

  1. According to my great-aunt, she was born 15 or 16 June 1844 in New York, possibly Fulton County, to unknown parents. I do not have my great-aunt’s notes, and she has sadly passed away, so I can’t confirm the accuracy of this information. Census supports her birth occurring in 1844/1845 and in New York.  
  2. I then must estimate her mother’s birth year at around 1820 (assuming she was still in her 20’s when Marion was born), possibly in New York, but I’ll look at any place in the north eastern United States. This is my target time and place for women who married men named Tucker.
  3. I do not know her mother’s maiden name, and I assume Marion’s maiden name is Tucker because her children record that name in their marriage records. But she was at least 22 when she married George W. DeJean in Wisconsin, so it is possible she was married at least once before.  
  4. New first step: look at the direct maternal ancestors for the 23 matches at the genetic distance of 0, and narrow the focus down to generation born in (or near) New York around 1820. Even if they are not Marion’s mother, these women would be her mother’s generational peers.

So far – none of the trees have women who married a man named Tucker, nor do they have sisters or daughters who married a man named Tucker. But I am only partway through the list. There is one woman of note who was filtered into the time/place criteria. She was born as Sarah Herrenton or Harrington. I have subsequently stumbled across an Ancestry.com tree of a person named Harrington who has several Tucker’s, to include Marion and even has parents assigned, but does not appear to be related to Sarah or her daughters. Unfortunately, their sole source is the Ancestry tree of another person, who cites various “OneWorldTree” records. These are basically database index of old genealogy done by long gone genealogists. No way to reproduce their research until I can travel to the locals were events are supposed to have happened or to the Family History Library in Utah.

Step 2: Repeat the process with the batch of genetic distance of 1 matches. There are 12 matches at the 1 level; 8 of them provide trees.

Step 3: Repeat the process with the batch of genetic distance of 2 matches…etc.

It’s gonna be a long winter.

What else did GBs mtDNA tell us? Well, like Y-DNA, GB’s mtDNA was assigned to a haplogroup. Haplogroups are distinctly different between mtDNA and Y-DNA. They identify DNA’s human migration pattern (deep, deep history) to two completely different people – obviously. My father, Uncle, and male cousins belong to Y-DNA haplogroup R and trace back to genetic Adam – not biblical Adam, but as close as science can prove. Their mtDNA (via GB) belongs to haplogroup J and traces back to genetic Eve – ditto on the caveat. It just means all humans are related to one ultimate common male and female ancestor. Oh, by the way, genetic Adam was not the husband or mate of genetic Eve. Something about the confidence of distance in genetic tracing between the two. You’ll have to do your own research to turn that one over in your head. I would muck up the explanation.

Haplogroups are DNA sequence polymorphism variations that have occurred over more than 150 000 years and correlate with the geographic origins of populations traced through the paternal or maternal lineages.

ScienceDirect.com

So, mtDNA haplogroup J descend from haplogroup N, which left Africa some 60,000 years ago and migrated into the region we identify today as Europe. GB belongs specifically to J2a1a1a2; each number and letter correspond to a significant mutation in the haplogroup gene pool (I think). Something I don’t understand is, J only occurs in 12% of modern Europeans. More accurately, 12% of the test pool at FTDNA (representative numbers, not total numbers). Haplogroup H is the most common mtDNA group in Europe at 41%. So, now I need to learn the statistical language. SMH.

The Rhoades’ Y-DNA haplogroup is R1 (subclade), which is the most common Y-DNA haplogroup in Europe.

Here’s something interesting. GB and King Richard III (1452-1485), the one they found under a parking lot in 2012, are cousins. LOL, not really close cousins, of course. They share a common ancestress sometime long before King Richard was born. So far back that he is in the J1 subclade.

A subclade is a subgrouping in the haplogroups of the human genetic trees. This may be either the Y-chromosome tree or the mitochondrial tree. Subclades are more specific to a location or population group than the major branches (haplogroups).

FamilyTreeDNA

My final tidbit of interesting but practically useless information (unless you like this sort of thing, guess which camp I am in?) Of the matches to GBs mtDNA, most self-identified as having German (Central Europe), British Isles, and Scandinavian origins. I keep hearing my Uncle asking me where the Scandinavian numbers came from in his autosomal results. Well, quite a few ultimate maternal surnames associated with GBs matches end in “…dotter”, i.e., Jonsdotter/Johansdotter, Andersdotter, Hansdotter, etc., and their line is still in Scandinavia today. I can rule them out in my initial search, though. They clearly are far out of my “time and place” phase, and half are at the 3rd genetic distance, so they’re probably closer to the 22nd generation common ancestress.

All this mtDNA research prompted me to listen to a 20-hour lecture from The Great Courses called “The Other Side of History” by Robert Garland (hint hint, it currently comes free with a subscription to Audible). This is pretty much for history geeks, not your average hobby genealogist. I found it to be essential, though, to understand historical timelines and their relation to some haplogroup movements. Thank goodness I am a history geek, and thank goodness I had a 16 hour round trip commute last week. Great lecture!

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s