Interpreting Results

We all share common ancestors - the question is how recently.  Is it “recent”, since the advent of surnames, long ago or very long ago?  Here is an explanation from Terry that may help interpret your results.

• I think in these time frames
  • Within several hundred years - a shared recent common ancestor or “RCA” 
  • Since the advent of surnames (c1100).  I call this common ancestor since the advent of surnames a “CAS”
  • In the range of 1000s of years.  This is defined by men sharing the same "Haplogroup" (which can go to 10-20,000 years ago)
  • In the range of 10s of 1000s of years.  This is shown by men who do not share a Haplogroup
• Matches are evaluated in terms of markers which have the same result. 
  • Based on a large database, a Haplogroup assignment can be made for most results - based on an assessment of the first 12 markers. 
    • Sometimes, a SNP (pronounced "snip" test is required to identify the Haplogroup.
    • Haplogroup assignments at FTDNA are color coded
      • Green - SNP tested
      • Red - estimated by FTDNA, based on matches (or near matches) to other results which were SNP tested
      • Black - other estimates of the Haplogroup
    • For those interested in exploring this a little further, Whit Athey has developed a tool to estimate your haplogroup.  Click Here .
  • If a sufficient quantity of markers match, then we can confirm a RCA or CAS
  • Once we have at least two matches at 25 markers or more, we (World Families Network) declare a "Lineage" - which is a group of men descending from a Common Ancestor
    • As we get more results, we can often define the exact result of the Common Ancestor at every marker.  We call this the "Ancestral Haplotype"
    • As we get more results, the paper trails give us insight into when and where this Common Ancestor may have lived.
  • Within a Lineage, the non-matching markers may give us more information
    • Typically, the mismatches will be only one count - except on the markers which mutate the fastest (464 and CDY)
    • We call the mismatches "Mutations"
    • If the mutation has no match - it is simply a mutation (for now)
    • If the mutation is matched by another result, we likely have an indication of a branch recent common ancestor (BRCA) who also descends from the RCA, but lived more recently and is shared by the two men with the matching mutation
    •  
    • Statistical analysis is disappointingly vague, as the mutations are pretty random, but we can still make some useful generalities - as long as we don't try to become too precise in our interpretation.  I think of these statistical results as a "fuzzy" answer.
      • One approach to this analysis is "Time to Most Recent Common Ancestor" or tMRCA" which can be reported at the 50% probability (this can very misleading)
      • Family Tree DNA's FTDNATiP calculator makes a similar calculation and reports the probabilities for each 4 generations (which they call 100 years.  Because this approach gives a range of answers, it is a more appropriate form of answer - but is not "satisfying" in simplicity) 12 markers

• A 12/12 match of the men of the same surname usually indicates a RCA - or possibly an earlier CAS (or both)
• Many 12/12 matches of men with differing surnames will fall apart at 25 markers - as the 12/12 resolution isn't regularly sufficient to discern relationships across differing surnames
• A few 12/12 matches of men of the same surname also  "fall apart" at 25 markers, but most maintain a “Match” (see the Russell example below)
• A number of 11/12 matches and most 10/12 matches fall apart at 25 markers - indicating no RCA or CAS
• I prefer not to have to assess relationships based on 12 marker results and won't "call" a Lineage until at least two men "match" at 25 markers

On 25 markers:

• Matches of 23/25, 24/25 & 25/25 indicate a RCA and CAS.  In shorthand - a match of 23/25 or better is even called a "Match"
• Matches of 22/25 or even 21/25 may indicate a CAS - but probably not a RCA.   This situation requires more markers to have clear insight
• Matches lower than 21/25 typically indicate that there is no CAS
• When in doubt about the interpretation at 25 markers, upgrades to 37 markers provide additional clarity

On 37 markers

• Matches of 33/37 and better indicate a RCA and CAS.  These are the ones typically called a "Match"
• Matches of 29/37 and higher indicate a moderate to higher probability of CAS, increasing in probability as the match gets tighter
• Some families mutate faster than others, providing additional insight as the number of results in a Lineage increases

On matches at markers with mutations, we can begin identifying the BRCAs.  This is when yDNA testing begins to directly correlate with paper trails.

• Matches indicating BRCA are a close match to the Ancestral Haplotype, but share a mutation that is different.

• It is possible for more than one BRCA to show on a result (see the Barton example below)

• It is in the context of the BRCA that a 37 marker test for someone whose paper trail already puts them in the Lineage can potentially benefit themselves and others of the Lineage, as they begin to help in defining the branch structure.

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Here is a sample from the Russell family, which shows men who were 12/12 (or 10/12 and 11/12)

1. R-2, R-23 and R-25 are all 12/12 to each other and to the Lineage I Haplotype

2. R-3 is 11/12 to the others and to the Lineage I Haplotype

3. It appears that all 4 men share a RCA.

Then, all men upgrade

All men have upgraded to 25 or 37 markers:

1. The blue group - at 25 markers

   1. Each man is 25/25 to each other and to the Lineage I Haplotype

2. The orange group

   1. Are 11/12 to each other, and 24/25 to each other. 

   2. They share a RCA.

   3. They should be separated from the blue group and become their own Lineage II (and this was done in the project)

3. The two groups appeared to share a RCA at 12 markers - but it wasn't true - as we see at 25 markers.

   1. The orange men were 11/12 and 12/12 to the blue Ancestral Haplotype, but are 18/25 and 19/25

   2. The orange group and the blue group do not share a RCA after all.

4. At 37 markers

   1. R-2 is 37/37 to the Lineage I Haplotype (I have additional info not shown)

   2. R-23 is 36/37 to the Lineage I Haplotype

   3. The orange R-3 goes to 25/37 to the blue Ancestral Haplotype, further confirming their different ancestry.

5. Conclusion: The 12 marker results were useful for the blue group separately and for the orange group separately, but when they were combined, the indication was very deceptive

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Here is a sample from the Barton family - showing a number of issues, with a focus on the RCA and BRCA: