DNA Series: Update on Vance Groups 1 and 2, Part 3

This article, the last in our three-part series on DNA research into Vance Groups 1 and 2, focuses on what is known so far about Vance Group 2.  For more about Y-DNA testing in general and Vance DNA Group 1 please read our first and second articles in this series.

Group 2 of the Vance DNA project is made up of descendants of at least 16 known immigrants to the United States and Canada between the early 1700s and mid 1800s.  Several of those immigrants have been traced to Ireland and most of the others were recorded as Irish so efforts to find the original family have centered on Ireland, but no related lines have yet been discovered outside of North America.  All known family lines carry the surname Vance except for one line of descendants who have the last name Whalen, stemming from a Patrick Whealen from the south of Ireland in the early 1800s.

The descendants of Group 2 most notably include all descendants of Matthew Vance of Pittsylvania and the well-known figures Abner Vance of Abingdon, VA and his grandson Jim Vance of Hatfield-McCoy feud fame.

From initial DNA testing we know that Group 2 split fairly early on (say around 1300-1500AD and probably in Ireland) into two Groups usually called Groups 2a and 2b.  For an overview of what was uncovered from initial testing please read Adam Bradford's excellent summary of Group 2 as a whole.   More recently there has been a surge of advanced Y-DNA testing in Group 2 including three "Big Y" tests and targeted SNP ("single nucleotide polymorphism") testing aimed at discovering the SNP blocks and branching that define Groups 2a and 2b.

Group 2 (marked by red circle) shown with all known L513 descendant lines (click to enlarge)
Credit:  Mike Walsh, L513 Yahoo! Group

As noted in our first article in this series, what we now know is that the Group 2 male line split off from the rest of L513 about 3500 years ago and is defined by a VERY long string of about 31 SNP mutations, meaning no other branches have yet been found so only one family line may have survived in one continuous straight line for about the next 2800 years after it broke from L513.  Group 2 is the last few of that 3500-year-old ancient line (among those who have DNA tested so far, at least).

Group 2's long 2800-year descendant line marked by many SNPs (click to enlarge)
Credit:  Alex Williamson, http://www.ytree.net

In more recent times the family tree branches. Group 2 overall's defining SNP is Z23507 and within Group 2, Group 2a is Z23506+ (positive) and Group 2b is Z23506- (negative) (Note:  there probably is a different SNP that Group 2b is positive for, but we will need someone in Group 2b to take a Big Y or Full Genomes test to find that).

So now the narrative picks up some 2800 years after L513 as follows:  some time around 1300-1500AD a man with the last name of Vance (or something close) and carrying the SNP Z23507 was born.  His descendants then split into two lines which became Group 2a and 2b.  Was this man already living in Ireland?  It appears that both his Group 2a and 2b descendants all come from Ireland, so it's very likely he lived there as well.

In any case on the Group 2b side, descendants started arriving in North America from Ireland by the early 1700s.

On the Group 2a side, one man around 1500-1650AD developed the Z23506 mutation.  In this timeframe one Vance line split off and became my Vance line, who emigrated from northern Ireland to the US in 1804.  On the other line a man in Ireland around 1600-1700AD developed the Z23516 mutation.  That man's descendants split IN IRELAND into two lines - one which eventually became Patrick Whealen born around 1816 who then emigrated to Ontario, and the other which led to Matthew Vance of Pittsylvania born around 1720 who shows up in the US and had several descendant lines there.   Given the timeframes involved, it is unlikely that Matthew Vance was the actual man who developed the Z23516 mutation but it IS likely that the two were within a few generations of each other.

The other Group 2a and 2b descendant lines probably fall out as shown on this family tree picture.  But note that until these other descendant lines (the ones shown with lighter descendant lines) are confirmed through SNP testing, this family tree is only representative, not certain.

Group 2a/2b Family Tree with branch-defining SNPs and likely timeframes marked in Green

So where did the Group 2 male line spend the years between 1500 BC and 1300AD?  When did it arrive in Ireland and with what tribe or group?  Did it also come from Scotland, like Group 1 appears to be?  Unfortunately those questions will have to wait until we discover other descendant lines that split off between L513 and Z23507 and hopefully bring their own clues to add new chapters to this evolving story.

DNA Series: Update on Vance Groups 1 and 2, Part 2

Hey, so it’s been awhile.  Life and work intruded.  But our genealogy hasn’t changed, and our knowledge especially of our ancient genealogy based on our DNA continues to evolve.  

This article is a continuation of our look at Vance DNA Groups 1 and 2 within what’s called the L513 SNP.   To see more about that SNP and these two groups in general, see our first article on Y-DNA testing.  Here I’ll talk about what we know about Group 1, which is important partly because it includes the lineal heir of the Scottish Lairds of Barnbarroch, and so has been tied to the traditional descent of the Vance surname.  If you need a refresher on that Vance history, read our explanation of A Short History of the Vance Surname.

The coming of “affordable” (meaning less than about $600) exploratory Y-DNA testing in recent years has generated an explosion of Y-DNA testing by people hoping to find out more about their male-line genealogy. Under L21 alone there are more than 14,000 men currently recorded in the DNA project database.   That’s a lot, but it only scratches the surface of the total population of L21 men among the 3.5+ billion men in the world.   The more people test their DNA, the more our knowledge of the origins and spread of our ancient genealogy increases.  

I say “ancient” because what Y-DNA testing has told us so far is mainly about our male-line genealogy back before surnames were first adopted about 1000 years ago.   We are only just starting to see clues to where these male lines have been living from about 1000AD forward.  

So what of Group 1 specifically?  In Y-DNA terms, the Group 1 members of the Vance/Vans/etc surname project are part of what has been known until now as the L193 subgroup of L513.  The L193 subgroup is known as a “superfamily” of various Scottish family names with a strong association with southwest Scotland near Ayrshire and Galloway (although as I said in the first article, its origins are still under fierce debate).  The current structure for this sub-tree of L513 looks like this:

What does this mean?  So adding a few (approximate) timelines to the tree, the story unfolds like this:

Some time about 500 AD (give or take a few hundred years) a man was born with the L193 SNP mutation.  His descendants appear to be of uniformly Scottish origin, so perhaps (more about this later) he was born in Scotland.   At some point however before or around 1000AD, one of his descendants was born with the A3 SNP mutation.  HIS descendants then split into two lines – one became the Vans/Vance line which includes today’s Vans of Barnbarroch families, and the others split into two lines themselves, one of which gained family names of Clendaniel, Glendinning, McVittie (and others), and the other which became family lines of Kennedy, Little, Taylor, and Beatty.  

Working backwards, we know that some of the Vances in Group 1 can trace their ancestry back to the 1700s, so clearly the A3 SNP line was part of the Vans surname for several hundred years.  And in fact, the split into Vance Group 1a and 1b is also very old (probably back to the 1300-1400s), so we can be pretty sure that A3 was the DNA of the male line of the Vans family of Barnbarroch back to around the time that Barnbarroch was founded.  Other scenarios are possible in theory, but they’re just too much of a stretch.  

 One conclusion (that we already pretty much knew) is that any male Vances whose DNA testing show they are part of Group 1 are directly related to the Vans family of Barnbarroch.  We don’t know yet how Group 1b broke off from the Barnbarroch line, but they are all related to a man who was either a Vans of Dirleton or of Barnbarroch and who broke off of the main Barnbarroch line very early on.  

But the Vans line of Barnbarroch was supposed to be founded by the Vans of Dirleton, who themselves were a Norman family who reached Scotland sometime around 1100-1200.  If the L193 and A3 lines look like they are of old Scottish origin, does this mean that the ancestry of the Vans of Barnbarroch is NOT Norman?  

Possibly, but not necessarily.  Of course, it IS possible that the Vans of Dirleton or Barnbarroch adopted a son from an ancient Scottish line who brought the A3 SNP into the family DNA.  That was not uncommon in medieval times and might not have been recorded.  But movement between the British Isles and the European continent was VERY common for thousands of years before and during this time.  L513 descendants, for instance (but not yet L193 descendants) have been found in Scandinavia, Germany, Belgium, and other parts of Europe besides England, Scotland, and Ireland.  It is not inconceivable that a L193 descendant might have emigrated to Scandinavia or Europe and his line some few hundred years later came back to Scotland among the Norman settlers.  An interesting event if it occurred, but certainly within possibility.  

What would help?  Well it would certainly help to locate and test a known male descendant of the Vans of Dirleton.  That would tell us whether the Barnbarroch and Dirleton lines were in fact related.  And certainly testing a known male descendant of the de Vaux of Normandy would be a coup also.  

Without having those to tell us how the Vans/Vance lines evolved, our best chance at learning more about these lines is just for more men to continue to have their Y-DNA tested and having more L193 descendants identified.   For instance, finding European descendants of the A3 SNP would help us understand more about the spread of this subgroup that includes the Vances of Group 1. 

DNA Series: Update on Vance Groups 1 and 2, Part 1

This is the first in a three-part series on recent DNA analysis of Vance Groups 1 and 2.  While this series will be interesting primarily for Vances who descend from those Groups, I hope it will also show the current state of genetic genealogy and what you can learn by having a male in your family take a Y-DNA test.   This update owes a lot to Adam Bradford's original analyses of these Groups which can be found on the Vance Y-DNA Project's website, and it is a tribute to his original work that the current analysis agrees with and simply builds on it.  

The charts shown here are developed and maintained by the volunteer administrators of the R1b-L21 and R1b-L513 projects and I am including them here for information.  Please respect their hard work, do not use these for commercial purposes, and give them credit for these charts.


I'll confess to being a genetic genealogy junkie.  It's not likely that paper records will get me any farther than the 1700s in Ireland on my Vance line, so I've latched onto DNA testing as the most likely way to get more information about my Vance history.  And while our ancestors unfortunately didn't write their names in our DNA, they did leave us many clues that we're only just beginning to understand.

My own DNA is in Group 2 of the Vance/Vans/Wentz Y-DNA Project so that's the DNA research that I follow most closely.  But Group 1 and Group 2 are related within the last 4000 years (give or take) so I'm close to Group 1 as well.   So this series is an update on the DNA research into both Groups 1 and 2.  In this first article, we'll review the current state of the overall DNA analysis that includes Groups 1 and 2.  I'll concentrate on each of those Groups in the rest of the series.

When I talk about DNA and genetic genealogy here I'm focusing ONLY on Y-DNA testing, which is especially relevant to the Vance surname because only men have and pass on a Y chromosome so a Y-DNA test traces back through your direct male line (your father's father's father's father etc) which includes the first male in that genetic ancestry who adopted a surname.  Other very important DNA tests (mitochondrial and autosomal tests) can help you trace your other ancestral lines but I won't be covering those here.

When I first took a DNA test nearly 10 years ago it gave you more anthropology than genealogy.  I found out I descended from Cro-Magnon men who came into Western Europe some 30,000 years ago; which left me a gap of a few years from there to my Irish Vance ancestor in the 1750s.   In the years since then genetic genealogy has been working forwards from those Cro-Magnons to help fill that gap.

2014 was a banner year for genetic genealogy with major advances both in affordable tests and in the expansion of the family trees of our ancient ancestors.  So let's close the gap a bit and jump from the Cro-Magnons to Vance Groups 1 and 2, pausing first on a man living about 4000 years ago on the European continent in a Bell Beaker culture whose descendants make up what is now known as group (haplogroup) R1b-L21.  Most of his descendants became associated with Celtic cultures and while they originally populated Western Europe and the British Isles in great numbers, the group is now most concentrated in the British Isles and Brittany and Normandy in France.  There is a map showing the current distributions of R1b-L21 here.

Roberta Estes, a noted blogger in the genetic genealogy community, showed the advances in 2014 in group R1b-L21 on her blog in this post which is a great progress summary for the year for anyone interested.  But repeating her point about the progress in L21 last year, this is the descendant tree for R1b-L21 at the start of 2014:

R1b-L21 Descendant Tree as of January 2014 (credit:  R1b-L21 Y-DNA Project)

And here it is in January 2015.  This tree now connects over 13,000 men living today to their common ancestor about 4000 years ago.  Note the sub-tree in the pink box which is known as R1b-L513, where Vance Groups 1 and 2 sit.

R1b-L21 Descendant Tree as of January 2015 (credit:  R1b-L21 Y-DNA Project)

Narrowing things down further, we get into territory that is under intense study and debate.  Around 4000 years ago (so about 2000 BC), the common ancestor of the L513 sub-group arose.  It seems most likely that this man was a Celt living on the European continent, although some argue he already lived in the British Isles.   In any case his descendants are now predominantly of Scottish and Irish origins, as shown in this map of the most distant known ancestral origins of the L513 group.

Locations of most distant known ancestors for members of R1b-L513 (credit:  Family Tree DNA)

And this is the family tree of that man from 4000 years ago down to present day covering about 1800 of his male descendants.  This is the same sub-tree as in the pink box above, just expanded to show more detail and surnames.

R1b-L513 Descendant Tree as of January 2015 (credit:  R1b-L513 Y-DNA Project)

You'll need to click on that picture to read it, so let's zoom in on the left hand side and see where Vance Groups 1 and 2 sit.    We'll add a few markers and a very rough timeline:

Excerpt from R1b-L513 Descendant Tree as of January 2015 (credit:  R1b-L513 Y-DNA Project)

What does this mean?  Every subgroup has a label (which for those who follow genetic genealogy refers to a SNP that everyone in that group is positive for).

Vance Group 2, which is now defined by SNP Z23519,  broke off of L513 pretty early on, like about 3500 years ago.  To date, that group's descendants have ONLY been found with origins in Ireland and apart from one man of the surname Whalen, are exclusively of the surname Vance.   So far we know that this Vance line was in Ireland by around 1600 at least.  But while there are some clues, we don't yet know for sure where it was before that, or when it arrived in the British Isles.

Vance Group 1, on the other hand, is part of a much larger group of current descendants which includes a whole variety of surnames, some of which you can see on this last chart.  About 1000 years ago under the SNP A3 the Vans/Vance line split off from the rest and so far all the men on that branch carry a variant of the same surname.   This whole line, and in fact most of its parent L193, shows a very strong connection with Scotland and particularly with southwest Scotland near Ayrshire and Galloway, but its origins are still under fierce debate.  Some say it is of Pictish origin, and others think it could have arrived in Britain as late as the Norman Conquest.

That's the older story so far, and how the members of Vance Groups 1 and 2 relate to the rest of their wider groups.  I know for most Irish Vances, we want to know "so what does that all mean to the origins of these Vances and where our ancestors lived and who they were?".  We don't have a complete answer to those questions yet but we have more clues.  We'll explore the evolving story of Group 1 in the next article, and Group 2 after that.

A word of caution about Vance DNA

I'd like to throw some caution out there about what DNA tells us about the Irish Vances.  Over the past few months I've seen several comments on Facebook, public forums and via email from well-meaning researchers who are unwittingly cutting off potential avenues of research because of assumptions about what DNA results mean.

Here's how it starts.  As you can read in the Vance Surname DNA Project, (also summarized here under DNA Project Resources), the Vances of Irish descent belong to at least 5 different DNA Groups (I'm thinking of Groups 1, 2, 3, 6, and 8, but there may be others).   Two other things we know about the Irish Vances are:

1. The best-known origin of the Irish Vances is from the Rev. John Vans of Kilmacrenan, who apparently came from the Vans of Barnbarroch line in Scotland, and according to the best available records they descend from the de Vaux of Scotland and England.  
2. And the current Laird of Barnbarroch has been DNA-tested and matches Vance Group 1.

Those are the "simple facts".  So therefore based on DNA results, the Vances in Group 1 descend from the Rev. John Vans and the Vans of Barnbarroch and from the de Vaux.  And the Vances in the other Groups don't.  That's the only possible conclusion, right?

Wrong.  It certainly is one perfectly logical conclusion.  It's just not the only conclusion.

Why not?

First of all, let's eliminate the Rev. John Vans from this DNA discussion.  We have no family lines that reliably connect back to him, so we don't know what DNA Group he belonged to.  We don't even have a hint about who his parents were.  We do know he was Scottish and he went to Ireland, and that he sealed his will with a coat of arms that looked a lot like the Vans of Barnbarroch arms.  So certainly he could be the ancestor of the Vances in Group 1.  But we don't have any actual evidence of that, so it's really just conjecture.  He could also be from any or none of the other DNA Groups.

We do know the Vans of Barnbarroch share a more recent ancestor with the Vances of Group 1 than the Vances of any other DNA Group.  So at least we can say that a man from the same family as the Vans of Barnbarroch went to Ireland, maybe in the early 1600s, and all the Vances in Group 1 descend from him.   Although maybe it was more than one man who went to Ireland.   And maybe it was later than the 1600s, or some in the 1600s and some later.   Ok, there are still many possibilities for how Group 1 got started, but they did come from the same family as the Vans of Barnbarroch.  That much we do know.

But we don't know anything about the earlier DNA of the Vans of Barnbarroch before that or about the DNA of the de Vaux.  In genetic genealogy terms, Group 1 is called R1b-L193, which is concentrated in Scotland especially in lowland Scotland near the border with England and includes many other surnames like Little, Clendennin, and McClain.  The best analysis so far says that one man in early medieval times probably started the whole line.  Unless it was one of the de Vaux, that would eliminate any DNA link between the de Vaux and the Vans.  But we don't really know anything for sure.   Maybe there were different de Vaux family lines, too.  The possibilities are still endless.

Why am I bringing all this up?  Several Vance researchers in the other Irish Vance DNA Groups besides Group 1 have made statements recently like "we don't descend from the Rev. John Vans", or "we don't descend from the de Vaux".  My point isn't that those statements are true or false, only that we still don't really know.  You can still make a case for any Irish Vance DNA Group, including Group 1, to be descended from them.  Or maybe none of them are.  Just don't eliminate possibilities for yourself or others.

One person even went so far as to say that they didn't join the Vance Family Association because their DNA test said they "weren't part of those Vances" - i.e. the Vans of Barnbarroch line.  So let me be clear about that too.  The Vance Family Association is for ALL Vances and their descendants, regardless of origin.  It says so right on their website.   Yes, when the VFA started in 1984, the Rev. John Vans etc origin was the only one anyone knew about.   But for decades now it has included everyone whether of Irish, German, or any other Vance descent.   There is a lot of information in the VFA on many lines.

People using DNA for genealogy are fond of saying "DNA doesn't lie" but the truth is that after so many centuries what it's saying is pretty garbled and you can interpret it in many ways.  I'm not saying that any interpretation is better than any other.  Just remember that without traditional research to back it up, there are always multiple interpretations.

Back to DNA: Is it Worth It?

The past few weeks have been pretty hard on genetic genealogy (DNA testing).  First, a professor of evolutionary genetics came out strongly against genetic genealogy, calling it "genetic astrology".  Next one of the testing companies was accused of making exaggerated claims at a genetics conference.  And then a widely-publicized "consumer report" was issued slamming DNA testing and the companies and their claims.  

Debate still rages around the Internet about the value of these warnings, but most of the cooler heads seem to agree that the extreme positions are unwarranted; that DNA testing for genealogy can be very useful but people should have realistic expectations - and yes, some testing companies have made exaggerated claims.  So I thought I would post my own experience of what people should expect that DNA testing can and can't do for them.  

What it CAN do:

1.  The best value – by far – of any DNA test is that it can match your DNA to others who may already know more about your common ancestors.   An autosomal test could find a second cousin who knows who your biological parent was.  A Y-DNA test could connect you to someone with a documented 400-year old family tree.  This is mostly luck and depends on others testing and available historical data, not just DNA.  But you might never know you were connected to those people and that research if you didn’t take the test.  I include here the connections you can make to the projects that collect and analyze what is known about people with related types of DNA to help them as a group learn more about their origins - for instance, the Vance/Vans/Wentz Y-DNA Project is a great example of group knowledge you can connect to.  

2.  A Y-DNA (and to some extent a mtDNA) test can estimate for any two tested people how long ago their common ancestor lived (but still with a fairly wide margin of error, so it can’t tell you who that common ancestor was).   

3.  Any DNA test can identify general geographical areas where people with your DNA are believed to have lived.  But there are limitations.  Y-DNA and mtDNA tests identify your haplogroups which reveal the migrations of your ancestors thousands of years ago (many years before your family tree).  Autosomal testing identifies general areas for your more recent ancestors – areas as wide as “British Isles”, or “Eastern European”; nothing more specific, and it won’t say which ancestors or when or for how long they lived there. 

4.  A DNA test can tell you what countries today have the highest number of tested people that most closely match your DNA.  That could be useful as a general indicator of what part of the world your ancestors came from.  Or it could just be a coincidence if someone from a branch way back in your family tree moved there and had a particularly large number of descendants.   

5.  A DNA test can put you in a group that will continue to grow as more people are tested, and whose story will continue to grow with each test.  It may take months or years, but our knowledge of our ancestry will continue to evolve as the information and knowledge grows.

What it CAN’T do, unless you luck into a match with someone who has that information already:

1.  By itself a DNA test can’t name your ancestors, and it won’t add people to your family tree.

2.  Although some testing companies like 23andMe can give you medical information based on your DNA, the test can’t tell you which of your ancestors had those medical conditions.   Or where you inherited your red hair, blue eyes, or webbed toes from.

3.  It can’t tell you that your ancestors were Vikings, Celts, Romans, Normans, what tribe of Indians they were from, or how you personally connect to any other historical group of people.  Actually the experts can theorize that close matches to your DNA existed, say, among the Vikings, either through modern analysis or because they tested old bones.  But people intermixed so much throughout history that all those groups were made up of many kinds of DNA, and that’s still no evidence that YOU personally descended from one group and not another.  Any identification with a historical group is based on a general theory, not from anything they discovered in your DNA. 

4.  It can’t tell you that you’re descended from royalty or any historical figure, although groups who already believe they do try very hard to claim it’s proven when the DNA shows they all really ARE a close match to each other.   It’s still the historical research that proves the lineage, not the DNA.   You don’t have proof through DNA unless you dig the ancestors up.    Even if you match a known descendant of Prince Eduardo the Magnificent, your ancestor might have been his third cousin Fergus the Drooler. 

5.  And finally, a DNA test only tests part of your family tree, because even an autosomal test only gathers data from pieces of your total DNA and anyway you have many more ancestors than sections of DNA so many of your ancestors aren't reflected in your DNA at all.  So be prepared that the test may show a different ancestry than the one you thought you had.  You may still be right.

So... is it worth testing?  Only you can answer that.  But I still thought it was and I learned many interesting things from my tests and connected with many people who share my interests and research.  Just be sure you know what you're getting into before you test.

Holiday Season DNA Sales!

I'm not one to push any particular company or commercial venture, but sitting here in mid-December it would be remiss of me not to mention to a group of people interested in genealogy that if you were ever considering getting your DNA tested, or were looking for an unusual gift for anyone else, now's the time.  At least two of the major DNA testing companies - Family Tree DNA and 23andMe, have significant sales going on.  The third major DNA tester - Ancestry.com, has offers out as well; I just couldn't tell if they were having a sale when I checked.

If you want to know what it's all about, just type "genetic genealogy" or "genealogy DNA testing" into your favorite search engine; there really are a ton of helpful sites out there now to explain it all.  But to start you off, here's my amateur's explanation:

There are three main types of DNA being tested:  one is autosomal DNA, which covers all the DNA you got from all your ancestors but can only give you general percentages of how many of your ancestors were from what ethnic backgrounds... interesting if you think you have certain ethnic heritages, but it won't help you with who specifically your ancestors were.  Then there is mitochondrial DNA, a very specific piece of DNA both men and women get from their mothers, which gives you very general information on your mother's mother's mother's mother's mother's mother's... you get the idea.  Interesting but again it won't lock in specific ancestors.  Finally, there is y-DNA - the Y chromosome that men inherit from their fathers, and women don't have.  Since traditionally family surnames were passed down through males in Western society, this is the DNA most often studied for genealogy; but it only tells you about your direct male ancestry (your father's father's father's father's father's father's... yeah I know, you get the idea).

There are two types of y-DNA testing: most test anywhere from 12 to 111 "STRs", which are a combination of markers on the Y-chromosome.  Think of it as if every father told their sons the same story, and usually the sons remembered the story exactly, but very rarely one son got a word wrong here or there and passed it on that way to his own sons.  With billions of fathers and sons over many generations, the stories remembered by each male living today would be very different.  STR testing pulls your version of the story out of your DNA, and by comparing it to others you can tell whose stories are closest to yours and therefore who is closest to you (through male ancestry, at least) on the great family tree that connects us all.

The other type of y-DNA testing is SNP testing, which finds specific mutations in your DNA that tie you back to older groups of humans.  Mapping SNP migrations is an on-going activity that one day may show us the exact path our male ancestors took across the globe, but for now can usually only barely reach about 1000 years ago when surnames first started.   Many of the debates though are VERY interesting... this is a science being born as we speak. 

How does this all help our search for ancestors?  Well, apart from the general "gee whiz" factor of knowing something about your most distant ancestors, DNA testing can only give you hints unless someone else closely related to you has more historical research you can connect to.  Just as an example, I have tested my STR markers and found that my Vance ancestors are connected to a number of other Vance immigrant lines to the United States.  The group is called "Group 2" by the Vance/Vans/Wentz Y-DNA surname project.  My Vance line is known to have come from northern Ireland, and a couple of the other descendants have traced their lines to Ireland also, so we know we're all connected to Vances that lived there around 1600-1700, and that we are more closely related to each other than we are to other Vances.  Beyond that, we don't yet know how our family trees connect.  But at least we all know we're working on the same puzzle.

So bear in mind that DNA testing won't (yet) tell you exactly who your ancestors were, or break through that brick wall to find where in the "old country" your Vance or Wentz ancestor was born, etc.   And you should also know some people have found adoptions in their family histories through DNA testing, so you need to be prepared for a possible surprise (I should note NONE of this does anything close to paternity testing). 

But the other advantage of DNA testing is that as the science evolves, you will continue to find out more and more about your own ancestry; both facts that can be verified through traditional genealogy, and facts that you could never hope to trace far enough back to learn.  It can be a fascinating parallel study to your historical record research.  If you were ever considering joining in, or getting additional tests done, this may be the cheapest time in awhile to do it - but act fast!