Mitochondrial DNA Mutation Rates and Common Ancestors

One of the most common questions I receive about mitochondrial DNA is what matches with 1 or 2 differences, meaning mutations, mean relative to how long ago the two people are related.

And the answer, is, of course, “it depends.”  Don’t you just hate that.

First, it depends on whether you are referring to just the mutations in the HVR1 or HVR1+HVR2 regions, or the entire full sequence.  Clearly, the full sequence test provides the most refinement, because it tests the entire mitochondria, all 16569 locations, and compares them with others who take the full sequence test.

Family Tree DNA has this to say.

    • Matching on HVR1 means that you have a 50% chance of sharing a common maternal ancestor within the last fifty-two generations. That is about 1,300 years.
    • Matching on HVR1 and HVR2 means that you have a 50% chance of sharing a common maternal ancestor within the last twenty-eight generations. That is about 700 years.
    • Matching exactly on the Mitochondrial DNA Full Sequence test brings your matches into more recent times. It means that you have a 50% chance of sharing a common maternal ancestor within the last 5 generations. That is about 125 years.

Because of the constantly changing surnames of the females as they marry, it’s very difficult to track the mitochondrial line back very many generations.

Recently, a paper was published, titled “Identification of the remains of King Richard III” by Turi King et al, that focused on identifying the skeletal remains found in 2012 in Leicester as those of King Richard III.  Interestingly enough, one of the ways that they confirmed the identity of the remains is through mitochondrial DNA matching.

In order to do this, the researchers had to find at least one individual who descended directly from a matrilineal line in common with Richard.  The mitochondrial DNA is passed from the mother to all of her offspring, but only females pass it on.  Richard’s sister, Anne of York, had two descendants who fit the bill, and both of them were willing to DNA test.

The results compared the full mitochondrial sequence, and it was determined that in one case, Richard and the participant were an exact match, and in the second case, only one mutation difference.

This is really quite interesting because we can see a real life example of mutations that do, and don’t occur.  In this case, the timeframe involved was over 500, almost 600, years since the births of Richard and Anne from their common ancestor, their mother, Cecily Neville.

King Richard mtDNA Chart

As this chart of descent from the supplementary materials from the paper shows, there were 18 generations in the case of Michael and 20 generations in the case of Wendy.  We know that there was no mutation in this line from Anne of York through Catherine Manners, because Catherine would have passed any mutation she carried to both of her children, so the one single mutation in one of the descendants’ results happened someplace between Catherine and the present day testers.

So while you may have a common ancestor with someone you match exactly at the full sequence level in the last few generations, you may also share an ancestor a long way back on your common tree – much further back than most of us will ever be able to reach genealogically – unless, of course, you’re lucky enough to be descended from King Richard III’s mother.

16 thoughts on “Mitochondrial DNA Mutation Rates and Common Ancestors

  1. I have a zero mutation match on the full sequence MtDNA, but he doesn’t show up as a match at all on Family Finder. Is this possibly an example of a much earlier common ancestor than the MtDNA would suggest?

  2. Roberta,

    Very interesting. i am one of the co-admins for the H1 Project and what I usually tell the members there is to reference Behar, et al’s Copernicus to see the estimated years per mutation for their Haplogroup.

    In my case, I am basal H1c and we have Gokhem2 as a base with which to work as she too is basal H1c. She is also 4500~ years old. Behar tells us that we are 1100 years per mutation, so all of my exact matches could and so share a MRCA within that time frame.

    I have 19 exact matches, but their geography ranges from Lithuania/Poland (primarily) to the 1700’s colonies. We also have an Italian and a French in our group. Knowing what I know about basal H1c, I understand your point about estimation flexibility. It does not seem likely that all of us would share a MRCA within 5 gens, but within 11000 years seems feasible.

    Thank you for your post!
    Rosario

  3. I have tested myself and my half brother through FTDNA. Tested Mitochondrial DNA Full Sequence. Our Haplogroup is H1be. My brother comes up as a match with 1 difference. I have had my half sister tested and my children and they all come up as a zero match, he is the only one to come up with this difference.

  4. Both Gary (my full sequence MtDNA match) and I took the family finder tests. We are haplogroup J1c4c. From what I can find on mutation rates, J seems to have a much lower rate. Rosario, do you have a link for this Bejar study?

  5. Roberta, Can it be established where the Y break was? Where the new Y-line began? Was it Richard III’s father, or his father, etc. And then, Who was the person with the new Y? One article I read said it was a unique Y, wouldn’t that make it easier to pinpoint the male? Perhaps it was a royal cousin, or the cook?

  6. Roberta, I have twelve matches of zero at Full FMS, seven of whom have done Family Finder. It stands to reason that with a 50% chance of a common ancestor within five generations, most of these should show up with nice FF results, especially since our Jewish endogamy tilts the field in favor of better matches.

    In fact, two of the seven do not match me at all. two are “fifth-remote,” two are “fourth-remote” and “one is third-fifth cousin.”

    When I put the five matches into my chromosome browser, there is only one place where there is any overlap at all within that group of five – a segment of less than 6 cM between one of the fourth-remotes and one of the fifth-remotes.

    I am limited in what I can do without DNA as my g-gm died in 1896 in Russia (probably in her late thirties) and we have no idea what her birth surname is. But a 50% chance of a common ancestor within five generations should produce better results. Maybe my 50% are in the five who didn’t do a Family Finder.

    • Hi Israel, You’re luckier than most because most people have no common matches between mtDNA and FF. It must be the endogamy. Do you have any common geography with any of them? That’s the next most telling question. X segments can sometimes help a bit too, although they are the least reliable I think.

      • I disagree with you Roberat, as I know enough about my family from resources and researching that I have found matches based on Family Tree dna and I haven’t done the full sequence test yet. I intend to purchase the full sequence test before the sale is over. I have had luck figuring out some of my matches. Especially when I have 5 people who have the same family tree that match me. I may not know who the common ancestor is, and I hope that the full sequence test will give me a lot more hints and details. I’ve watch the video clips several times that youall have for educational purposes, and I think it is so confusing, but I guess I’ll give it a try.

        Would love to see more of the ancestry charts such as the one you provided. Oddly enough, I saw Yelverton which as I recall I also saw on a Tabb relative. Would love to see more of that.

        I too would love to have the dna tested of these royals….Lord Hunsdon Cary is suppose to be of my lineage, I would like to know for use as well as if he is really the son of King Henry VIII.

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