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ADW_1981
06-05-2015, 12:14 AM
Would anyone be able to provide links to any paper(s) on the N-S/Z220 R1b cluster?
I recall there was at least one within the last couple years.
Thanks in advance

razyn
06-05-2015, 05:10 AM
Interesting, if true. I've been working on Z220 (and its numerous "equivalent" SNPs -- currently numbering eight on the YFull version of the haplotree, some having more than one name because anybody can name the same SNP differently) for about four years, and Ken Nordtvedt was for several years before that. But I've never seen anything as formal as an actual paper about the SNP, or the N/S cluster. The following link shows the current crop of YFull equivalents:

http://www.yfull.com/tree/R1b1a2a1a2a1a/

I don't know of any particularly good reason to prefer one over another, they seem to go together, so far. I'm disinclined to believe that loci such as this with a group of parallel mutations represent seven sequential mutations below Z220, that all happen to survive together because nobody with any of the other six alternates has spawned an independent line of descendants. I rather suspect all eight (and perhaps more, that we have yet to find) happened at the same time -- to the same individual -- whose descendants will carry all eight, unless/until one of those Y chromosome positions gets a back-mutation, in some specific descent line.

And that, in turn, is the main reason I think SNP counting is a faith-based method of estimating the age of a contemporary subclade, as distinguished from science. It isn't exactly wrong; the law of large numbers probably smooths out the difference between the theory and reality to some extent. And guys like Mark Jost retain quite a broad error range, either in STR- or SNP-based estimates. Whether the SNP-counting exercise and the search for a mutation rate "constant" is sufficiently accurate to be worth the effort remains to be seen. I know some of the guys doing it are smart people, but that doesn't make me trust the basic assumption that the observed mutations are sequential. Looks to me as if that is sometimes the case, but pretty often not.

R.Rocca
06-05-2015, 11:37 AM
Interesting, if true. I've been working on Z220 (and its numerous "equivalent" SNPs -- currently numbering eight on the YFull version of the haplotree, some having more than one name because anybody can name the same SNP differently) for about four years, and Ken Nordtvedt was for several years before that. But I've never seen anything as formal as an actual paper about the SNP, or the N/S cluster. The following link shows the current crop of YFull equivalents:

http://www.yfull.com/tree/R1b1a2a1a2a1a/

I don't know of any particularly good reason to prefer one over another, they seem to go together, so far. I'm disinclined to believe that loci such as this with a group of parallel mutations represent seven sequential mutations below Z220, that all happen to survive together because nobody with any of the other six alternates has spawned an independent line of descendants. I rather suspect all eight (and perhaps more, that we have yet to find) happened at the same time -- to the same individual -- whose descendants will carry all eight, unless/until one of those Y chromosome positions gets a back-mutation, in some specific descent line.

And that, in turn, is the main reason I think SNP counting is a faith-based method of estimating the age of a contemporary subclade, as distinguished from science. It isn't exactly wrong; the law of large numbers probably smooths out the difference between the theory and reality to some extent. And guys like Mark Jost retain quite a broad error range, either in STR- or SNP-based estimates. Whether the SNP-counting exercise and the search for a mutation rate "constant" is sufficiently accurate to be worth the effort remains to be seen. I know some of the guys doing it are smart people, but that doesn't make me trust the basic assumption that the observed mutations are sequential. Looks to me as if that is sometimes the case, but pretty often not.

I can see two or three tops mutating at the same time, in the same individual as perhaps some fluke, especially if a couple of them are in a less stable part of the Y-chromosome (e.g. those that start with 22), but eight at one time seems an impossibility. When I see ancient DNA results that include haplogroup C or dark skin alleles in pre-historic Europe, it is not difficult to imagine that the great majority of lineages did not survive.

razyn
06-05-2015, 12:52 PM
I can see two or three tops mutating at the same time, in the same individual as perhaps some fluke, especially if a couple of them are in a less stable part of the Y-chromosome (e.g. those that start with 22), but eight at one time seems an impossibility. When I see ancient DNA results that include haplogroup C or dark skin alleles in pre-historic Europe, it is not difficult to imagine that the great majority of lineages did not survive.

Is there any known reason for that (seeming impossibility), apart from the a priori assumption that any mutation is a rare and random occurrence?

Another school of thought assumes that mutations may be caused, notably (but perhaps not exclusively) by the background radiation level. And that, in turn, is mostly extraterrestrial (prior to the 20th century human manipulation of it). I'm not talking about little green men with their phasers set on Mutate; just known phenomena such as solar flares, supernovae within the Milky Way galaxy, and maybe a couple less well understood.

This is OT with respect to the putative article about Z220; but that does happen to be one of the SNPs with multiple equivalents. I used to think it necessary for each person who finds one to test for all of them, to see how they relate hierarchically. I'm much less inclined that way, in this specific case (and several others under DF27).

Actual branching points are important, and dating them (even very approximately) should be useful for interdisciplinary work: phylogeography as a specialty in genetic anthropology, helping to date the dig by the DNA of the remains, or whatever. On the other hand, if eight different named SNPs mark the same branching point, they are like road signs saying it's 2462 kilometers to Moscow in eight languages. Pick one you can read, and head on down that road. And don't multiply its generational distance (is it 170 years, this week?) by eight, vis-a-vis some higher or lower branching point that isn't so prolific.

R.Rocca
06-05-2015, 06:00 PM
It is not an assumption, but rather a mental interpretation based on the FGC/Big-Y etc. data I've seen.