I agree with Maciamo, The arrival of a gene in a given region is NOT the date of birth of that gene. Given the high % of the R1-b subclasses in today's population of Europe, I would think that they were present in more than one individuals by 2500BC. ...
I just wanted to clear up a couple of things on the estimations that Nordtvedt's methodology produces. The most important this is that you should go to his web site and read through his charts documenting his formulas.
http://knordtvedt.home.bresnan.net/
The following quotes are from a string emails between Ken and myself. They were person to person but I don't think he'd mind me quoting him on this because they are just clarifications of his published method. Do go to his web site for to understand everything in context.
1. The modals are
NOT the basis fo the
interclade TMRCAs.
Ken Nordtvedt said:
The modal for each clade is only for auxiliary purposes. It plays no role whatsoever in estimating the interclade node ages or the clade coalescence ages. It’s use is only for two purposes; to evaluate some sigmas and to estimate (intra)clade tmrcas which I do not consider as good as the interclade node estimates.
I inserted the "(intra)" because that is what I interpret his intent to be.
2. The interclade TMRCA estimate
IS for the specific "node" man that is the
Most Recent Common Ancestor both of the two clades (P312 & U106 in this case.) It is NOT a coalescence age. It is estimating that one father-son event.
Ken Nordtvedt said:
the interclade node age estimate is for a specific event in history. Age of the father of the two sons, each of whose descendant line leads to one clade or the other.
3. His output includes
coalescence ages but they are clearly labeled as so. I interpret these ages are
more akin to times of signficant expansion.
Ken Nordtvedt said:
Coalescence Age for a clade is a different thing. It does not estimate time of a specific event. It is an abstract age and in words is the average tmrca of all the pairs you can form from the clade haplotype sample collection in use.
4. Don't focus too much on the
single most probable age. That undoubtedly is NOT the precise date of the MRCA.
It is the range that counts.
In the case example for this thread, what "U106 & P312 Nested Age___4.5 __ (5.2-3.8)" provides the
range of 5.2K to 3.8K years ago. That is the one sigma range so basically Ken's methodology is saying there is a
68% chance that actual MCRA date will fall in that range. That's all it is saying. 4.5K is just the most likely part of the whole range. Most people take a range like this and use the high end, but the truth is the odds are as good it could be younger as well as older.
I know some don't want to believe young ages like these, but this just what the numbers show (and we do have a lot of numbers [long ht's] now.) The real argument is over the mutation rates. I don't see why we wouldn't use the germ-line rates that we use in genealogical calculations since Ken throws out the multi-copy STRs anyway... but this is whole area is debatable.