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DNA Testing - A Tool For the Macrogenealogist by Chris Krawczyk

Introduction

People often ask about DNA testing and its usefulness in genealogical research. Some people are skeptical and argue it is of little value. Others claim that it is tremendously beneficial and provides a world of information. So, which group is correct? Like most things in life, the answer to that question depends entirely on your perspective.

Microgenealogy vs. Macrogenealogy

Whether or not DNA testing will be helpful to you depends on what your goals are. More specifically it depends on whether you are asking questions that are micro or macrogenealogical in nature.

Specific details are the world of the microgenealogist. For example: When was your great great grandfather born? What city was he born in? What was his name? - we all live in this world of documentation, photocopies, microfilms, birth certificates, vital statistics and citation. If you're reading this article there is a good chance that you are already a fairly seasoned microgenealogist.

But what about the larger picture? What about your family history on an epic scale spanning tens of thousands of years? That is the world of the macrogenealogist. Macrogenealogy forgoes all of the minute detail and instead focuses on learning about trends, probabilities, and movements of groups of ancestors across time and geography.

We know that all of our ancestors came from Africa, but when did your ancestors migrate from Africa to Europe or another continent? Where did they settle? Then what happened? What ethnic group or culture were they a part of? What happened to those people?

The benefit of Macrogenealogy is that it deals with timescales unheard of to the microgenealogist: thousands, tens of thousands, and even hundreds of thousands of years come into play. Periods of time where no records existed. Periods of time where no language existed.

We believe that there is a curious macrogenealogist in all of us. We are all interested in where we come from: Both from generation to generation AND from millennium to millennium. On that epic scale there is no better way to get this information than DNA testing. This article will give you a basic understanding of what DNA is and the main DNA tests that are available today.

What is DNA

Let's start with some basic science. Inside every cell in your body you will find what's called the nucleus. For every human being, inside the nucleus of everyone of those cells you will find 23 pairs of chromosomes. Each chromosome is wrapped around its counter part, in what is referred to as the double helix, (shown graphically below), kind of like two sides of a zipper linked together and spiraling around each other.

Now, picture twenty three pairs of those chromosomes floating in the nucleus. That's what is referred to as the human genome. A road map of everything that we are.

Now, Those chromosomes are made of really long strands of a chemical called DNA. DNA stands for deoxyribonucleic acid. A long word but really quite simple.

DNA is made up of sequences of four chemicals: adenine, thymine, guanine, and cytosine. Geneticists refer to them simply as A,T,G, and C. Those same four chemicals arrange in countless arrays and combinations millions and billions of times containing the information that is us. To give you an idea of how much DNA you have, if you were to lay all of the chromosomes in your body end to end they would stretch further than the moon.

It is the order of these chemicals, over and over again, billions and trillions of times that determines everything about your physical body. In essence they are templates, blue prints that allow your cells to make the proteins they need to become things like hair, kidney, and liver cells. In short they make you.

Here's the cool part. Every cell in your body contains an entire map of everything that you are. Chemical switches, part of something called your epigenome, regulate which genetic code is actually executed in a given cell. For example they say "hey you're a liver cell, you need to act like this" or "hey you're a spleen cell, you need to act like that." Spleen cells would contain all of the code needed to make liver cells. That code would just be dormant.

You inherit half of your DNA from each parent, basically randomly selected from each parents set of chromosomes. That is why brothers and sisters will look alike but have many differences. It stands to reason that if you're related to someone your DNA will be somewhat similar to theirs. It also stands to reason that the more related you are to someone the more similar their DNA will be to yours. That is the premise behind DNA testing: comparing that DNA, or parts of that DNA, to see how similar it is.

Issues With Genetic Similarity and Time

The first thing you need to know is that Nucleic DNA (DNA found in the Nucleus) has a tendency to mutate or change over time. Genes jump around, get shuffled, or dropped from the chromosomes from time to time, different proteins can result and cause cells to do different things. This could be a change of eye color, a larger brain, or a heart that forms outside of the body - or the change could be something not noticeable at all. Who knows. Mutations are largely random and have random effects.

Most scientists will tell you that these mutations over millions of years are why we're not hanging out in the jungle with the monkeys any more. If a mutation is successful, we pass it on when we breed. If it's really successful we thrive. If it's not successful - or detrimental (like a heart outside of the body for example) then we die and don't pass it on. This process is called natural selection. In terms of this article we need to know one thing: Nucleic DNA likes to mutate making its use for Macrogenealogical research over hundreds of thousands of years less than ideal.

In smaller timescales the vast majority of our DNA is identical from human to human. Most of it is related to the basic design and mechanics of who we are. In fact, the vast majority of our DNA is identical to many mammal species. A 2005 study showed that in fact our DNA was 96% similar to chimpanzees (note #1).

So let's consider the very small sections of DNA that vary from human to human. Things like eye color, skin color, etc... While there are still millions of lines of code about such things they represent a very small percentage of our genome.

Let's discuss the code that makes us different. Every time conception occurs those cards are shuffled, half of the chromosomes essentially coming from each parent. Therefore, logically you are 50% similar to your parents, your parents are 50% similar to their parents.... meaning you are 25% similar to your grandparents. Now, extend this logic back twelve generations or roughly 360 years: after twelve generations that similarity would drop to only 0.024%; quite diluted indeed.

Additionally, if you go up your family tree and back in time you very quickly gain family members. Two parents. Four grandparents. Eight great grandparents. By the time you get to the twelfth generation.... get this... 4096 great great great great great great great great great great great grandparents. You have millions and millions of cousins. That would make for a heck of a big barbeque... and that's only 360 years of history. Imagine what happens if you go back a few thousand years. The numbers grow exponentially.

The Most Recent Common Ancestor

As you can see there is a point that occurs where we're all related to each other. This is referred to as the Most Recent Common Ancestor of MRCA. The concept can be used to compare two individuals, it can be used to compare all of humanity, or it can be used to compare species.

The Most Recent Common Ancestor does not mean the point of origin. Rather, it is a measure of how long ago an individual lived who is included vertically up the family tree of all of the subjects.... in other words how long ago a common grandparent occurred.

According to some research the Most Recent Common Ancestor for all humans alive today likely lived between 5,000 and 15,000 years ago. The MRCA for people of European lineage occurred.... get this.... as recently as the year 1,000 A.D. (note #2) According to the study of chimpanzees mentioned above the Most Recent Common Ancestor between us and all living chimpanzees likely occurred around six million years ago.

As you can now see, given the problems of mutation, exponential family size, and time, scientists needed to find better ways to use DNA testing as a macrogenealogical tools. They found two such processes: Mitochondrial DNA testing and Y Line testing.

Mitochondrial DNA

The mitochondria is a part of the cell that essentially acts kind of like a power plant. It has it's own DNA - referred to as mitochondrial DNA (or mtDNA). mtDNA is not found in the nucleus, it is found in the normal cytoplasm of the cell.

You inherit this DNA from your mother only, she inherited it from her mother, and so on. Males do not pass mtDNA on to their children. Due to this, mtDNA does not suffer from the dilution issues from above. Also, mtDNA has a very low tendency to mutate. Your mtDNA should be virtually exactly the same as your mothers. mtDNA will slowly change over thousands and tens of thousands of years. This makes it a very useful tool.

If two people have an exact match in their mtDNA the odds are very high that they share a common maternal ancestor. The problem is we can't tell whether that was two or twelve generations ago. So while it's a brilliant tool to tell you if you're related to someone, it is not very good at telling you "how related" you are. It can however give you a probability range within a handful of generations and identify the MRCA with some success.

For this reason mtDNA is really useful in telling us where our ancestors came from over thousands, tens of thousands, and even millions of years. When you have an mtDNA test you are assigned to a broader group called a haplogroup. Knowing your haplogroup can tell you more about your distant family origins or ethnic background, tracing your origins back to a time where humans couldn't even read or write. Tracing the path of your ancestors as they migrated out of Africa a long long time ago.

The image above shows you one such chart, showing various haplogroups migrating out of Africa and going back 130 to 170 thousand years. Where did your ancestors come from? You'd be amazed how many people are surprised with the results.

Y Line Tests

One of the first things we learned about chromosomes and DNA was how to differentiate human males from human females. Females have the classic XX chromosomes. Males have a single X with a shorter Y chromosome.... or XY.

Males always inherit their Y chromosome from their father. Females, by their nature, do not have Y chromosomes. For this reason, despite being nucleic in nature, tests on the Y chromosome are very useful as no shuffling occurs across generations.

Y Line tests look at specific markers on the Y chromosome. These tiny markers create a distinct pattern, also known as a haplotype. If two males have similar markers then there is a good chance they are related however, as with mtDNA testing, it is difficult to evaluate the extent of the relationship. This type of testing is most commonly used by male individuals to determine if they share a common ancestor and is also popular in establishing the relationship between family groups of the same name.

Y-Line testing is very useful in confirming common ancestry along paternal lines. It can tell you with as much as 99.9% certainty whether you're related to someone with a given timeframe.

What's also really interesting is that if you test your mtDNA, which is maternal, and your Y Line DNA, which is paternal, you will likely find two totally different lines. However, for very long term Macrogenealogical purposes mtDNA is by far the preferred method as there is a much lower incidence of mutation in the non-nucleic DNA.

Ethnic Tests

Tests on Nucleic DNA non-sex chromosomes or Autosomal Tests are often used to establish ethnic ancestry. Some companies have the ability to break the results out into as many as fifty ethnic groups. Essentially these tests can tell you what percentage you are genetically of a particular ethnic group. Such tests can also sometimes be done using mtDNA or Y Line testing as well.

How DNA testing works for you

Like all research you do it is vitally important that you start off by setting goals. Write down exactly what it is that you want to know. For example: Do you want to know if your Smith Family in Nebraska is related to the Smith Family in Oregon? Do you want to know if you are related to someone with the same last name you just met? Do you want to know if you have Native American ancestry and how much? Or, Do you want to know simply how your ancestors migrated across the globe? The questions determine the testing.

If you are testing family or individual relationships you can use either mtDNA or Y-Line testing. You would need to contact the people you need to test and arrange for their involvement. Normally testing is as simple as a cheek swab to get a few cells. Some companies are even using gum these days, you chew it and put it in a vial and mail it in.

The one thing you always need to remember is the maternal nature of mtDNA testing and the paternal nature of Y-Line testing. Depending on what you want to test, your own sample may not be of use and you may have to recruit aunts, uncles, nieces, nephews, cousins etc.... who are along the maternal or paternal line you want to look at and get them to volunteer.

If you're looking for answers on long term migration, mtDNA is definitely the way to go. Y-Line testing is also valuable but is subject to slightly more mutation over time. It is interesting to compare the different results you may find however.

If you're looking for answers on percentage ethnicity or inclusion in a group there are a variety of products from mtDNA, Y-Line tests, or autosomal tests to help you.

No matter what you are testing, our advice is to do your research and ask lots of questions before you contract the company. Different companies offer different services. Make sure you see samples of the reporting you will get. Make sure that you can understand what those reports mean before you buy anything. Some companies are excellent at making things easy to understand, others not so much.

While it used to be that the cost of DNA testing was prohibitive, that's not true anymore. You can purchase home based tests relatively easily and affordably. Regardless of what you are testing the process is generally the same. It usually consists of a cheek swab or chewing gum to collect a few cells, you mail the kit to the lab, a few months later you have your results.

In Conclusion

Most of us could be referred to as Microgenealogists. We are focused on building our family trees. Finding out when our great great grandfathers third sons daughter was born. Getting the facts, recording them, finding documents, etc... This is a noble pursuit but DNA Testing will also likely be of little help to us in those areas. DNA testing will not tell you specifics about your ancestors.

That being said, DNA testing is of great help to the curious Macrogenealogist that exists in all of us. We could learn for example that our ancestors left Africa 150,000 years ago, migrated through Europe over the next "X" thousand years and settled in "insert country here", eventually migrating to "insert place here" with the last ice age. Who knows what you'll find out when you start to compare haplogroups.

DNA testing can help you to learn where your ancestors lived before written words were recorded for the first time. While you won't ever find any birth certificates that old, the knowledge is still pretty neat and provides a really great introduction to any family history book or website. That's a heck of a preface for a book when you think about it. A map showing the "family" moving out of Africa over one hundred millennia ago.

DNA testing can also help you to prove or disprove your research. If you think your family came from a place a thousand years ago, you may be able to prove it. DNA testing can provide clues into your ethnic origins as well.

DNA testing can also confirm if two people, or families, are related (i.e. descend from a common ancestor), but it struggles to tell you exactly how many generations ago that occurred. It can give you very high probabilities within a certain time range. It can also tell you with certainty that two individuals or families are not related within a given time range.

So, in conclusion, DNA testing can be a useful tool to the modern genealogist. If you're looking at things from a macrogenealogical level it can provide you with a world of information. As long as you understand how it works and what it can and can't tell you it can be a very helpful tool. We hope this article helps you with that understanding and wish you luck in all of your research, whether Macro or Microgenealogical in nature.

Footnotes

#1 Source: National Geographic News
http://news.nationalgeographic.com/news/2005/08/0831_050831_chimp_genes.html
#2 Source: Wikipedia http://en.wikipedia.org/wiki/Most_recent_common_ancestor

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