Dear Mike,   Yes, I'm happy to explain what I think you are asking about haplogroups.  I hope that I am correct in thinking that you are asking when in the past there was a common ancestor to which all the Boyds can link?  If this is NOT what you want, please re-phrase the question and ask again.   Using the link below my signature, you will arrive at the public Y-results chart for the Boyd DNA Project.  You will notice that the list is organised into several different groups.  These are the haplogroups.  The Boyds have, so far, members in haplogroups A, E, I, J and R, haplogroup A being the oldest haplogroup and haplogroup R being the most recent to develop.  Within those groups are finer distinctions, for example, there is R1a and R1b.  Within THOSE groups are even further distinctions.  These distinctive groups are called "sub-clades."   Using the tree as metaphor, think of the trunk as haplogroup A.  Then think of the other haplogroups as branches from that trunk.  To give you some sense of time over which these various groups developed, it is believed that the R branch of the haplogroup tree appeared about 27,000 years ago.  The two big branches of R to have been identified are R1 and R2.  All of the haplogroup R Boyds can be found on the R1 branch, which is itself estimated to have arisen about 18,500 years ago.   Every time a further refinement of any haplogroup is identified, a new letter or number is added to its description.  This can be cumberson, so a sort of shorthand has developed.  Here is an example.    R1b1b2, a further branching of the R1 branch, is estimated to have arisen approximately 4,000 to 8,000 years ago in southwest Asia, spreading into Europe from there.   Most European R1b1b2 belong to haplogroups R1b1b2a1a1 or R1b1b2a1a2.  You can see how cumbersome this nomenclature is becoming.  So R1b1b2a1a1 is called U106 (the U signifies the lab where it was identified).  The most recent refinement of U106 is U198.  So now we are no longer imagining branches of the tree so much as we are imagining twigs.   I'm not meaning to confuse you and, if I am, I apologize.  But it is important that you get the sense of the passage of time that separates one haplogroup from another and what that means to genealogy research.  Haplogroup A existed about 60,000 years ago and haplogroup R developed about 27,000 years ago.  So you can see that, for the purpose of genealogy research, there is never going to be a common ancestor for haplogroup A Boyds and haplogroup R Boyds.   They simply are NOT related.  The same can be said about all the haplogroups.  They are NOT related within any meaningful time.   Now we can talk about who CAN be said to be related and I'll use U198 as an example.  The U198 group is a relatively rare sub-clade of R, yet it is quite numerous in the Boyd DNA Project.  These Boyds are definitely related.  The question is, how closely are they related?  I am a member of this group so I'll use myself as an example.    FTDNA calculates the chances of relatedness for every "match."   Their calculations for the chances of my being related to my closest match are:   Generations               Percentage  2                               16.55%  4                               46.30%  8                               85.51% 10                              93.33% Generations Percentage 2 16.55% 4 46.30% 6 70.63% 8 85.51% 10 93.33% 12 97.08% 14 98.77% 16 99.50% 18 99.80% 20 99.92% 22 99.97% 24 99.99% 26 100.00% Generations Percentage 2 16.55% 4 46.30% 6 70.63% 8 85.51% 10 93.33% 12 97.08% 14 98.77% 16 99.50% 18 99.80% 20 99.92% 22 99.97% 24 99.99% 26 100.00%   So each member of the project can tell approximately how many generations they need to go back in their genealogical research to discover their MRCA (most recent common ancestor) with any of their matches.   I am grateful for the opportunity your question provided to explain this once again.  I know it's a difficult subject and hope I've explained it clearly.   Kind regards, Jeri Ann Boyd Administrator Boyd DNA Project     Generations Percentage 2 16.55% 4 46.30% 6 70.63% 8 85.51% 10 93.33% 12 97.08% 14 98.77% 16 99.50% 18 99.80% 20 99.92% 22 99.97% 24 99.99% 26 100.00%   http://www.familytreedna.com/public/boyddnanet/default.aspx?section=yresults --- On Sat, 1/29/11, Mike Boyd <mikejboyd@bigpond.com> wrote: From: Mike Boyd <mikejboyd@bigpond.com> Subject: Boyd DNA - R-U198 Haploid group To: BOYD-L@rootsweb.com, "Jeri Ann Boyd" <boyddna@sbcglobal.net> Date: Saturday, January 29, 2011, 9:05 AM David Boyd of Maryland wrote to me a few days ago and advised that that his DNA test had come back as R-U198 Haploid group. While Lauren and I did discuss a wide range of topics, I do not think that we touched on the Boyd DNA "groups" and how they may be linked to the "paper" Boyd family trees. So Jeri Ann (or others) tell us what are the Boyd DNA groups and how many generations these go back to make a common link? Thank you Mike Boyd Historical Committee, HBS