-A curious adult from Missouri
January 19, 2007
The reason you're having trouble finding out much is that U1a is a very specific subgroup. Which means there aren't that many of you around. The same goes for U8.
The letters and numbers refer to specific kinds of mitochondrial DNA (mtDNA). U1a people share very similar mtDNA. And U1a DNA is different than U8 DNA.
That means people with U1 DNA have different ancestors than people with U8 DNA. But all people in the U group share ancestors in their recent past.
Each mtDNA group (like U, R, T, or A) is commonly found in a different region of the world. U is the most common mtDNA found in Europe, for example.
Men and women of the U1a group live in all sorts of places. They live in Tuscany in Northern Italy and the Altai region of Northern Russia and Mongolia. In fact, your ancestors were both nomadic Mongolians and Italian mountaineers.
Your husband's group, U8, has different European ancestors. They probably settled in Northern Europe. Loads of U8 people live in parts of Scandinavia where they speak Finnish.
So that explains what the letters and numbers refer to and where your ancestors may come from. But where did these numbers and letters come from? And what is mtDNA and why did scientists choose to look at that? And how did U DNA end up in Europe?
First, let's talk about mtDNA. Most of our DNA is found in the nucleus of the cells. A very small bit is found in our mitochondria.
Nuclear and mtDNA have a number of important differences. The key one that makes mtDNA so ideal for tracing our ancestry is that mtDNA passes from mother to child virtually unchanged.
When an egg or sperm gets made, the DNA in the nucleus gets shuffled around. But the mtDNA does not. This makes it easy to trace.
But mtDNA is not perfect. Because it passes only from mother to child, you can only trace one line on your mom's side of the family. Of course since mtDNA doesn't shuffle, you can trace that line back thousands and thousands of years.
You can only trace one maternal line with mtDNA. And one paternal line with Y DNA.
Notice I said that mtDNA passes unshuffled. This does not mean that it never changes. If it didn't there wouldn't be any difference between your U1a and your husband's U8!
So where do the changes come from? From mutations.
DNA changes all the time for lots of different reasons. Most of the time our bodies can fix the mistakes but occasionally one will get through.
Sometimes these changes are harmful and can cause diseases like cancer
. More rarely the changes are helpful. But most of the time DNA mutations don't have any effect.
Now as I said, DNA changes are mostly caught and fixed before they can have any effect. But this is less true for mtDNA. The machinery in our mitochondria is not very good at fixing mtDNA. Which means changes can build up pretty quickly.
Changes in egg mtDNA (called germline DNA) happen every 5 or 6 generations, on average. Children from this egg will have different mtDNA from their mother.
And every child descending from that egg will also have the changed mtDNA. Of course, only the females will pass the change on. This all means that there is a good chance that your mtDNA is different from that of even your great-great grandmother.
Each time there is a change in mtDNA, it results in a different mtDNA type. One change isn't enough to cause scientists to reclassify someone though. You need a bunch of changes to get lumped into a new haplotype.
So all your female ancestors along one line come from mtDNA group U. After many years, there were enough DNA changes that some ancestors were switched to group U1. Many generations later some got changed to U1a. And that is just your family.
Each person's family does the same thing in a new mtDNA group. You can imagine how many groups there must be!
This mtDNA change is the reason you are having a hard time finding specific information about your group: Your group is very specific, and does not contain very many people.
The important thing to remember is that both U1a and U8 are small branches on much larger trees. You can follow information from the small U1a branch back a little way. Then you can learn more about your branch from the U1 group. Finally, you can learn even more from the U group.
If you search hard enough, you might find the very first woman! Somewhere, we all have to be related through an original mtDNA. Scientists think mtDNA shows all humans coming from Africa. That is really the trunk of the tree!
Because it is so useful and easy to get, scientists have piles of data on mtDNA from people all over the world. What do they do with it? They group them together, and look for patterns.
As I said, there are lots of Europeans with group U. That made scientists think this group started out in Europe.
They don't think this anymore. Now they think that the U group started out in the Near East around 55,000 years ago. This bold and adventurous group then set out and headed across the Caucasus Mountains to the north.
They crossed over to Southern Russia and eventually to the grassy highlands along the Black Sea. Over time this group spread out across Eurasia. They are now spread all over Europe and the Eastern Mediterranean.
So there you have it. Our DNA changes over time and we can trace back our ancestry. And your mtDNA is nearly unique -- only a very few people share your exact same mtDNA.