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  • Timeline Question

    Hi!

    I just received my mtDNA results and are curious about someting.
    I belong to haplogroup T2, and I have the understanding that my mutations happened about 40.000, 60.000, 80.000 (and so on) years ago.

    First: I do not want to start a bible/creation vs. science debate here, I already found that thread...

    But, I'm just really curious about some science facts:
    1. What is it in the research of the DNA (mt/Y) mutations that tells the scientists that this mutation must have happend about 40.000 years ago? Not 10.000 or 100.000 years ago. And that the previous mutation was 60.000 years ago?
    2. Why is it, from a scientist's point of view (and when looking upon the DNA evidence), impossible that all this mutations happened during the "biblical" 6.000 years (or about 4.000 years--since Noah's flood...)?

    I'm not a scientist myself, so I might need the "dumbed down" version, but try me

    Thank you
    Last edited by hydra; 25 March 2008, 09:41 AM. Reason: spelling

  • #2
    hydra:

    the "age" of mutations are estimates. That is, scientists have estimated that on average there is one mutation in HVR1 every 20,000 years. So 3 mutations mean an average of 60,000 years. But of course this is just an average. By chance, a couple of mutations can happen within a few thousand years, or equally by chance we could have no mutations for 50,000 years.

    By looking at the entire mtdna (rather than just at HVR1), one can perhaps get a more precise estimate, because the entire mtdna contains many more mutations. But still, these are just estimates.

    Now, as for which mutation happens when, this can be sometimes established by constructing a genealogical tree, so to speak. Mutations higher up in the tree must have happened earlier. Eg., suppose that there is a mutation that only your family has; then this must have happened recently. Instead, a mutation that all T people have must have happened earlier in the past.

    cacio

    Comment


    • #3
      Timeline basis is still arguable.

      This question made me Google furiously after finding out that the MtDNA age-estimates are based on a *judgemental reconciling* of known fossil age specimens, without MtDNA recovered,(dated on geological find levels and sometimes radio-isotope ageing); with observed mutation rates, and geographical separation distance, in very recent human MtDNA specimens.

      There is indeed a (reasonable) "leap of faith" involved in making that correlation, which merits continuing review.

      Cheddar Man and Paviland man are among the oldest human MtDNA sources reported, and there has been some fragmental Neanderthal material.

      The "creation scientists" some with astute rationale, quote wide variations of directly observable rapid mutation rates that have been reported, leaving doubts about the validity of very slow estimates. They point to the direct correlation gap between the fossil record (which some explain as a "deception by God") and the estimated MtDNA clock.

      My take was that the "Daughters of Eve" clock is a reconstruction based on the geographical separation of modern differences, and the allocation of a reasonable time estimate to estimated distance travelled by the migrant ancestors. Not to be rejected, but not rated as accurate, at least within a few deca-millennia.
      As for good old Genesis, often quoted in support of Bishop Ussher's short leap of faith, it lacks validated time units or benchmarks to compare with or argue against, leaving us to do what we can.

      Comment


      • #4
        still more confusion

        I just peeked at Mitosearch before I logged onto this forum. And it strikes me as amazing that there are over a dozen haplogroup "H" with my exact HVR1 "mutations', but only one other haplogroup "U5" with an exact match. I have only two mutations in HvR1. The two mutations are 16270T & 16519C. And that's what those others have. So evolution has played a game here. I mean, 16270T is supposed to designate "U5." So all those with "H" are unauthorized posessors of 16270T. It's a good thing I had an FGS done to clarify my own situation, mtDNA-wise.

        U5b2 & R1a1

        Comment


        • #5
          Originally posted by PDHOTLEN
          I just peeked at Mitosearch before I logged onto this forum. And it strikes me as amazing that there are over a dozen haplogroup "H" with my exact HVR1 "mutations', but only one other haplogroup "U5" with an exact match. I have only two mutations in HvR1. The two mutations are 16270T & 16519C. And that's what those others have. So evolution has played a game here. I mean, 16270T is supposed to designate "U5." So all those with "H" are unauthorized posessors of 16270T. It's a good thing I had an FGS done to clarify my own situation, mtDNA-wise.

          U5b2 & R1a1
          I'm confused as to whether or not you are confused but there should be no confusion so just to clarify in case others are similarly confused. The 16270T mutation is one of the markers for U5 (the sole one if HVS-I is used alone) but it is not exclusive to U5. The same mutation has happened in other haplogroups. According to the Genographic Project publication by Behar et al (2007), it is not uncommon in Hgs L, H and K as well as U and it also occurs occasionally in I, V and J. This is purely random. It does not indicate any relationship between U5 and these groups.

          Using full sequence, the coding region markers for U5 are 3197C, 9477A, 13617C.

          In addition, there is a whole group of U5s (including me) that do not have 16270T. It has back mutated. My HVS-I signature is 16192T, 16311C but I am also U5.

          In summary, therefore, 16270T is the HVS-I marker for U5 but its presence does not necessarily prove that a person belongs to U5, nor does its absence mean that a person is not U5. There is nothing mysterious - just random mutations.

          Comment


          • #6
            hummmmmmmmm so gosh we could only match L,H,K,U,B,I,V,J and they don't even have to have 270 because they back mutated so lets add the rest of the alphabet
            and my 519 is just like can be in a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y and z.
            and we will not even go into the 73's to 309's in region II. all of them can all in be in the
            ABCDEFGHIJKLMNOPQRSTUVWXYZ too.

            so I could actually be matching any one of these... because we do not know if the groups tested in any study , were all tested the same... and exactly how they decided those tested were or were not a u5 or h or V or Bcdefghijk...... because anyone may have or not have "back mutated" in any region and any number.
            I can se this is like alot of science...

            Comment


            • #7
              Cookery?

              What do the last few posts have to do with the Timescale question?

              Alas, let me not demean the expensive lab-time and painstaking biochemistry involved in separating and labelling of bands and strands of desoxyribosenucleic acid and the protein formations they ordain!
              But some of our conversations here, staged in a sort of virtual semantic reality, resemble being served a rare and complex French cuisine, and claiming, by taste alone, to identify all the processes, ingredients and spices involved.
              We deserve a prize for stubborn conceptual imagination at least!

              Comment


              • #8
                my results agree

                I just checked my FGS results (U5b2), and I have the same 3197T, 9477A, 13617C & 16270T.

                Since so many people in other haplogroups have 16270T, then why doesn't Family Tree DNA specify the haplogroup in the mtDNA Matches section of our personal site? Any or most of the low level matches are probably not U5, if the Mitosearch lists are any indication.

                U5b2 & R1a1

                Comment


                • #9
                  Originally posted by PDHOTLEN
                  I just checked my FGS results (U5b2), and I have the same 3197T, 9477A, 13617C & 16270T.

                  Since so many people in other haplogroups have 16270T, then why doesn't Family Tree DNA specify the haplogroup in the mtDNA Matches section of our personal site? Any or most of the low level matches are probably not U5, if the Mitosearch lists are any indication.

                  U5b2 & R1a1
                  The mtDNA matches on your personal FTDNA pages should only list people who have been tested for U-specific mutations, as FTDNA do a series of SNPs as part of even basic HVS-I analyses (I'm not sure how long this has been the case). Unless you get full sequence, the tested SNPs only define the highest level of U (not U5). If you are U with 16270T, then there is a very, very high probability that you are U5. But you shouldn't have H people mixed in on your personal pages as far as I know.

                  On the other hand, if you search for just 16270T in Mitsoearch, you will drag up everything.

                  Comment


                  • #10
                    Originally posted by derinos
                    What do the last few posts have to do with the Timescale question?

                    Alas, let me not demean the expensive lab-time and painstaking biochemistry involved in separating and labelling of bands and strands of desoxyribosenucleic acid and the protein formations they ordain!
                    But some of our conversations here, staged in a sort of virtual semantic reality, resemble being served a rare and complex French cuisine, and claiming, by taste alone, to identify all the processes, ingredients and spices involved.
                    We deserve a prize for stubborn conceptual imagination at least!
                    Absolutely nothing and apologies for hijacking the thread.

                    Comment


                    • #11
                      Mickm- no apology necessary- your post does show how increasingly complex is the basic information available, to match the distant regional samples, from which the Timeline is being (approximately still) deduced!

                      Comment


                      • #12
                        re Mitosearch

                        On Mitosearch, I searched for my two mutations in HVR1. I only have 16270 & 16519 in HVR1. It's almost CRS. In the part of the Mitosearch list that shows exact matches, there are lots, but only one of those is a U5. All the others are haplogroup H.

                        I look under GMNSC, and not mine, since I get better results that way. Maybe it's due to the settings I selected.

                        U5b2 & R1a1

                        Comment

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