Re: TMRCA aging of Z16357 haplogroups
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Thanks for your feedback and thoughts Joel! A few comments are below. It may be interesting for you to share your findings on the R1b-L513 Facebook page to see what some of the other experts think there also.?
Yes, I'll share soon. It sounds like some things may change in the near future as we get some additional test results in. ?
Tiger Walsh has stated on, I believe, the L513 Facebook page that older SNPs can be in the range of 65 to 75 years per SNP.
Yes, this aggregating?effect for SNP counts based?on multiple testers increasing?reliability of reads is known,?but is a bit tricky to account for. We're already well in or even faster than that 65 to 75 range with both old and new SNPs - and across both Y700 and Y500 testers. My hope is to eventually apply factoring for "years per SNP" based on age of the SNP and whether it's a 700 or 500 test to account for much of this. I'd also like to calculate confidence intervals on the various age estimates. James Irvine has an excellent, recently-published journal article that covers these TMRCA topics in depth -?
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Or we just are producing more than the average SNPs. Which is good for branching and dating.
Everything seems to suggest that our branches have notably higher SNP counts than most. This is very useful for us for near-term age estimates and branch generation, but it does make aging more tricky when our SNP counts don't align with the predicted "formed" dates for our old haplogroups - it's difficult to know whether we're actually making more SNPs or whether Z16357 is just much older than predicted. ? However, their actual individual Private Variants are 5 and 2. I am told that is because some of their individual Private Variants are not from trusted areas of tested YDNA.
Yes, this is essentially the opposite problem of the effect discussed above.?Alex's Big Tree looks more closely at these private variants. 4 years ago I did the same with raw results for most of the folks then in our group, but with a lot more people now and the transition since then to hg38 for raw data, I'm not sure if I want to take on this rather complex kit-by-kit analysis again. Doing so would require everyone to provide me their?updated raw BigY data (or administering an FTDNA project in which everyone is a member). For now, I'm prone to use FTDNAs conservative estimates for private variants. With the opposite effect for older haplogroups, perhaps this is a bit of a wash overall?
Supposedly FTDNA is going to provide their own age estimates one of these years. We'll see. ? Your date of 900 for the formation of A11132 is interesting also as it implies that there should be other non-Hartleys in this group that we have not found yet.
It should also imply that there would be others more closely related to me - yet, alas, I'm still stuck rather isolated at the ~1000 year old A11138. These types of long branches that were seemingly isolated for many generations are really the story of much of Z16357 - it's what makes us fairly unique and what makes me so interested in solving some of these puzzles.
Cheers,
Jared
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Jared Smith