Announcement

Collapse
No announcement yet.

Evaluating a Big Y match

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Evaluating a Big Y match

    I did a search on this topic but they ended up being subclade specific. Is there a quick way , that is a general way, to evaluate a Big Y match ? For example the highest novel variant matches I have are 54. However it is shown this novel variant match happened a few thousand years old. How many novel variants would a person share if the match was 500 years ago?
    Could someone summarize a quick and dirty evaluation method.?
    I am particularly interested in more recent times (last 600 hundred years). What would their novel variant sharing look like? What should I look for?

  • #2
    Not what you had asked for

    A quick check. Do you have any known SNPs that you two differ on? If yes, do they have MRCA time estimate on YFull?

    Comment


    • #3
      Originally posted by Brunetmj View Post
      Could someone summarize a quick and dirty evaluation method.?
      I am particularly interested in more recent times (last 600 hundred years). What would their novel variant sharing look like? What should I look for?
      1) Go to your Big Y Matches page.
      2) Under the column title "Shared Novel Variants", click on the dropdown box (which initially says "Show All").
      3) In the resulting dropdown list, scroll down to the bottom.
      4) Look for entries with "(1)". These should be the SNPs that you share with exactly one other person. But beware, some or all of these may be in unreliable segments of the Y chromosome (and hence are not valid grounds for a match). In particular, locations beginning with 222, 223, or 224 are usually unreliable.
      5) Look for entries with "(2)", "(3)", etc. These should be SNPs that you share with just a few other men.

      Unfortunately, this is all very error-prone for anyone but experts. That's why I routinely suggest ordering a professional analysis from YFull.

      Comment


      • #4
        In several of the 54 to 52 novel variant matches it does not list a difference in the differences column. So your suggestion is a good one, but for me not quick. Well maybe just answer this question, how much novel variant exists is say someone who shared a common ancestor but in the last 500 years? I guess to narrow down my question is there a relationship between the novel variants shared and the closeness in time to the person who shares them ? What is the average novel variants shared by family members?

        Comment


        • #5
          Thank you lgmayka. I am on Yfull and all my results are in the hands of experts. I have seen the section which you describe and have used it. I suppose to find someone from more modern times I would have to have a list of recent snp's and just watch for those.

          Comment


          • #6
            Originally posted by Brunetmj View Post
            I suppose to find someone from more modern times I would have to have a list of recent snp's and just watch for those.
            It is easier and more reliable, though a little more expensive, simply to contact your nearest Big Y matches and offer to submit their BAM files to YFull (at your own expense, if necessary). YFull will then estimate TMRCAs for you.

            Comment


            • #7
              Thank You for your suggestions

              Comment


              • #8
                Originally posted by Brunetmj View Post
                I did a search on this topic but they ended up being subclade specific. Is there a quick way , that is a general way, to evaluate a Big Y match ? For example the highest novel variant matches I have are 54. However it is shown this novel variant match happened a few thousand years old. How many novel variants would a person share if the match was 500 years ago?
                Could someone summarize a quick and dirty evaluation method.?
                I am particularly interested in more recent times (last 600 hundred years). What would their novel variant sharing look like? What should I look for?
                I did some calculations for a grand-nephew/grand-uncle pair in R-M269. That was quite tedious, so I wish FTDNA displayed such information by default.

                They are listed as sharing 78 novel variants.

                Excluding those that do not have Confidence High or are not reliable (locations 222xxxxx, 223xxxxx, or 224xxxxx), they share 20 novel variants that nobody else among their matches has.

                After excluding locations 222xxxxx, 223xxxxx, or 224xxxxx, the interesting part is that
                • one of them has 8 novel SNPs not shared with the other, 5 of these are such that none of his Big Y matches has them, 3 are shared with another, another four and another nine of his matches;

                • the second one has 3 novel SNPs not shared with the other, 2 of these are such that none of his Big Y matches has them, 1 is shared with another five of his matches.

                W. (Mr.)

                P.S.
                I doubt that these two individuals differ by 7 genealogically significant SNPs, thus quite possibly those 7 SNPs (they do not share) occur with many individuals all across the tree. FTDNA has that information and should be labelling novel SNPs accordingly.

                Comment


                • #9
                  dna
                  Thanks
                  That's the kind of information I was looking for. That is , a sense of what two related people might share in the way novel variants. I wasn't clear about the 78 novel variants , do they share that with other? Or with you. If with each other how many do they share with you?

                  Comment


                  • #10
                    Originally posted by Brunetmj View Post
                    dna
                    Thanks
                    That's the kind of information I was looking for. That is , a sense of what two related people might share in the way novel variants. I wasn't clear about the 78 novel variants , do they share that with other? Or with you. If with each other how many do they share with you?
                    I am running a small surname project, we did not originally intend to test family members that closely related (both in paper trail and Family Finder and Y-DNA), it turned out that way - a very long story.

                    78 novel variants are shared between these two individuals, while with the other matches they share at most 55-57 novel variants.

                    It might be of interest to you that none of their twenty Big Y matches is shown by FTDNA as a match in their Y chromosome STR tests (from 12, through 25, 37, 67 to 111 markers). I went through 1000+ entries in Advanced Matching for 12 markers to make sure about that.

                    However, in Y-DNA12 results one of the matches differs by 1 in DYS393, and another by 1 in DYS385.

                    W. (Mr.)

                    Comment


                    • #11
                      Originally posted by dna View Post
                      I am running a small surname project, we did not originally intend to test family members that closely related (both in paper trail and Family Finder and Y-DNA), it turned out that way - a very long story.

                      78 novel variants are shared between these two individuals, while with the other matches they share at most 55-57 novel variants.

                      It might be of interest to you that none of their twenty Big Y matches is shown by FTDNA as a match in their Y chromosome STR tests (from 12, through 25, 37, 67 to 111 markers). I went through 1000+ entries in Advanced Matching for 12 markers to make sure about that.

                      However, in Y-DNA12 results one of the matches differs by 1 in DYS393, and another by 1 in DYS385.

                      W. (Mr.)
                      So 78x90 is around 7000 years for a TMRCA.

                      Comment


                      • #12
                        What counts is unshared novel variants. A lot of the 78 are shared with everyone else in your haplogroup. To be clear, novel doesn't mean unique, it just means new, as in just discovered.

                        I can see a benefit in testing people with closely related patrilines. Here is my thinking. Many of the early immigrants to America were born between 1580 & 1650. Assuming 135 years per novel variant, consider the years 1580, 1715, 1850, 1985. Such an immigrant may have descendants who have incurred as many as 3 novel variants since immigrating. If someone born in 1985 had no unshared novel variants with a match, we would know that the MRCA for the two was likely born after 1850. If he had one unshared novel variant, we would know that the MRCA was likely born after 1715. Two unshared novel variants: MRCA likely born after 1580. These tiny subclades would be a more sound way of determining distance to the MRCA than y-str data.

                        Timothy Peterman

                        Comment


                        • #13
                          Originally posted by 1798 View Post
                          So 78x90 is around 7000 years for a TMRCA.
                          No, please refer to my earlier post this is a grand uncle/grand nephew pair. That means only four (4) births are separating them.


                          Originally posted by T E Peterman View Post
                          What counts is unshared novel variants. A lot of the 78 are shared with everyone else in your haplogroup. To be clear, novel doesn't mean unique, it just means new, as in just discovered.

                          I can see a benefit in testing people with closely related patrilines. Here is my thinking. Many of the early immigrants to America were born between 1580 & 1650. Assuming 135 years per novel variant, consider the years 1580, 1715, 1850, 1985. Such an immigrant may have descendants who have incurred as many as 3 novel variants since immigrating. If someone born in 1985 had no unshared novel variants with a match, we would know that the MRCA for the two was likely born after 1850. If he had one unshared novel variant, we would know that the MRCA was likely born after 1715. Two unshared novel variants: MRCA likely born after 1580. These tiny subclades would be a more sound way of determining distance to the MRCA than y-str data.

                          Timothy Peterman
                          This is a grand uncle/grand nephew pair (father of the first man is great grandfather of the second man). One has two (2) unshared novel variants, the other has five (5) unshared novel variants. In my opinion, it is unlikely that there are 7 genealogically relevant SNPs that separate them. FTDNA possibly can verify in their entire database, whether these are SNPs that occur at many locations in the haplotree. Maybe these private SNPs, but we are not investing into more Big Y tests in that particular family branch.

                          W. (Mr.)

                          Comment


                          • #14
                            Very interesting. I think 7 may be a bit too many as well.

                            Would be nice to get some real data on this. If the 135 years, or 5 generation rule is correct, as I see it: there is a 25% chance that a novel variant occurred between my father (1918) & I, there is a 50% chance that a novel variant occurred between my grandfather (1892) & I, there is a 75% chance a novel variant occurred between my great-grandfather (1862) & I, there is a 100% chance a novel variant occurred between my great-great grandfather (1829) & I.

                            To continue, there is a 100% chance one novel variant occurred between my great-great-great grandfather (1788) & I, and a 25% chance two novel variants occurred between my great-great-great grandfather & I.

                            There is a 100% chance one novel variant occurred between my g-g-g-g grandfather (1755) & I, and a 50% chance two novel variants occurred between my g-g-g-g grandfather & I.

                            Am I calculating this correctly?

                            I think there is a 100% chance that one novel variant would occur between two men as you described: the MRCA is the father of one & the great-grandfather of the other.

                            But the whole logic of 135 years per novel variant may be flawed. In some lines, several hundred years could pass before there is a novel variant. In other lines, several novel variants might be incurred with each generation. 135 is likely just an average.

                            But, unlike with y-str data where the counts fluctuate, once a man incurs a novel variant, all of his patrilineal descendants would share that novel variant; the chances of a reverse mutation are rather small.

                            Timothy Peterman

                            Comment


                            • #15
                              What counts is unshared novel variants. A lot of the 78 are shared with everyone else in your haplogroup. To be clear, novel doesn't mean unique, it just means new, as in just discovered.
                              For me that's an important statement . I was under the impression that novel variant meant unique to my family line. Instead it means as described in your statement . This means to evaluate a recent match a person needs to be in my unique subclade. I am alone in a sub branch of my subclade. So a person would have to posses these same snp's to be in a recent family line with the possibility of having some I do not have.

                              Comment

                              Working...
                              X