Hi Brad and Sheila, You mentioned 67 markers, and I had an unexpected experience with that. I initially tested at 37 markers, but had only 3 matches there. Yet for the sake of science I upgraded to 67 markers, but to be quite honest about it I also assumed that at 67 markers I would get wiped out, with perhaps no matches at all. But no! To my astonishment, at 67 markers I have not just 3 matches but 54 matches (how did that happen?) although none of them are particularly close, 2 at a GD of 5, 12 at a GD of 6 and all of the rest of them at a GD of 7. Then, following such astonishment, curiosity got the best of me and so I upgraded from 67 to 111 markers. The results of that test are now due in a few days, 26 Nov. And I have no idea of what to expect of that. Maybe this time I will get wiped out, or maybe not? Doug FTDNA 196477 On Fri, Nov 22, 2013 at 7:55 PM, Susan Hedeen < [email protected]> wrote: > Reverse also known as back mutations are seemingly a reality; we > generally do not know when an observed mutational difference is a back > mutation...and a back mutation can appear as either an up or down repeat > value. In some large lineages we may suspect where a back mutation is > evident. > > Some observations on the molecular level have suggested that the alleles > have a preferred repeat sweet spot; hence the repeats may extend up or > down but are inclined to return to the sweet spot. > > The statisticians and model builders have made allowances for back > mutations in their analytical models. Most calculating TMRCA will use > analytical models which have built into the model a means to correct for > back mutations. Susan > > On 11/22/2013 5:30 PM, Malcolm McClure wrote: > > However, I am bothered about the influence of reverse mutations on > > ancestral projections and comparisons. We need widespread sampling of > > several related generations to establish the importance of this > > possible effect, but those data are unlikely to become available for > > many years, if not generations. > > > > > ------------------------------- > To unsubscribe from the list, please send an email to > [email protected] with the word 'unsubscribe' without the > quotes in the subject and the body of the message >