Hi Paul I think I've worked out where you are going wrong. Let's suppose two people B and C have a nearest common ancestor A. A must have had two or more sons. Let's say B is a descendant of one of the sons and C is the descendant of a different son. Time passes. Let's say after G generations, 10 mutations have occurred in each line. If all 10 mutations are different, B and G will have a GD of 20 (ignoring reverse mutations). The time estimate back to the common ancestor is not 20 x 167 = 3340 years, but 10 x 167 = 1670 years. And if we then use the 134 years implied by Chandler's estimated mutation rates instead of 167, we get 10 x 134 =1340 years. You may find it useful to go to http://dna-project.clan-donald-usa.org/tmrca.htm Here it is explained that "Note that the number of transmission events is essentially twice the number of generations back to the MRCA". So 20 x 167 (or 20 x 134) is approximately equal to 2G, not to G. Hope this helps. Sandy -----Original Message----- From: dna-r1b1c7-bounces@rootsweb.com [mailto:dna-r1b1c7-bounces@rootsweb.com] On Behalf Of pabloburns@comcast.net Sent: 29 October 2011 18:19 To: dna-r1b1c7@rootsweb.com Subject: [R-M222] Age of M222 Sandy (or anyone), Since I left university 55 years ago, the math portion of my brain mas atrophied from lack of use to where I now have trouble calculating the tip for restaurant service. Consequently, I was relieved when some kind soul posted that the average for 67-marker mutations is 167 years. I am sure that the real gurus were horrified, but I see on other forums that some continue to use this mutation figure in comparisons. That might be fairly close for my Sligo cousin and me. We are at a GD of 4, which would place the MRCA at 668 ybp. But, using another example, my cousin is at a GD of 20 from from our suspected Scot (20413). At 167 years per mutation the time to their MRCA would be 3340ybp. If both are M222, then either M222 was around well back in the BC period, or they mutated separately. Am I figuring this all wrong, or is using the 167 years per mutation approach completely out of the question? Paul R1b1c7 Research and Links: http://clanmaclochlainn.com/R1b1c7/ ------------------------------- To unsubscribe from the list, please send an email to DNA-R1B1C7-request@rootsweb.com with the word 'unsubscribe' without the quotes in the subject and the body of the message