As well as detailing our Y-DNA, it would be useful to outline in simple terms how the different versions of a Y-chromosome are described. The analogy used is that of a branching tree where each bough, branch, sub-branch or twig represents a new version mutating away from an established one. The first human male (called Adam) represents the tree trunk. There are twenty boughs emanating from this trunk and they are labeled A to T in chronological order of discovery. Our bough is I and it has two downstream branches labeled I1 and I2 [letter followed by digit]. Such branches are called haplogroups by genetic genealogists. Our haplogroup is I1. Ancestry.com named this ethnic lineage I1 after "The Stonemasons" while BritainsDNA just called it "Teutonic". Currently, most genetic genealogists prefer to say that our heritage is of ‘Germanic’ origin. Our branch I1 further splits into three smaller but substantial sub-branches (I1a, I1b & I1c) and a few twigs. Ours is the first sub-branch (or subclade) I1a.
Tests for deep ancestry focus on genetic markers called Single Nucleotide Polymorphisms (SNPs) as they highlight genes where a mutation (and hence a branching point in the tree) has occurred in the past. Mutations happen only rarely so these modified chromosomes can be traced back many generations to one's ancient ancestors. Each bough, branch, sub-branch or twig on the tree can be defined by the SNP that uniquely identifies it. For example, I is defined by the SNP known as M170, I1 is defined by M253 and I1a by DF29; so I is synonymous with I-M170, I1 with I-M253 and I1a with I-DF29. [The SNP's initial letter(s) indicate the researcher or research group that first identified it and the number is simply allocated in chronological order of discovery.] Therefore, any part of the tree may be described by its pathway from the trunk or by its bough and unique marker; for example, by I1a (meaning I then 1 then a) or by I-DF29.
Tests for recent ancestry instead focus on how many Short Tandem Repeats (STRs) occur at each given SNP marker within a set of such markers. The number of such STRs at a SNP marker site varies much more frequently than genes mutate. Close male relatives are unlikely to display any differences in number while distant cousins will differ. The greater the generational distance between cousins, the more differences should be expected. It is through such knowledge that close and distant family members can be identified. Gerald Mendenhall and I both undertook an Ancestry Y-46 test. This meant that the number of STRs at 46 SNP marker sites were determined for each of us. We only had a different number of STRs at two of the 46 SNP sites so, as fourteenth cousins, this outcome was not unexpected. Gerald's immediate family member showed no differences at all, again as anticipated.
Both our familial Ancestry.com tests predicted that our haplogroup was I1. I had also previously taken a BritainsDNA deep Y-DNA test that confirmed our haplogroup as being I1. It further established that our Y-chromosome is a very rare sub-type of I1a / I-DF29. It was classified as I1a* where the asterisk signified that it did not belong to any of the ten then-known downstream branches (I1a1 through to I1a10). According to the FamilyTreeDNA dataset at that time, all three men with this classification had the surname Mendenhall.
More recently, I and three distant cousins have taken a comprehensive FamilyTreeDNA BigY test and all four of us are reconfirmed as positive for the I-DF29 marker. Given the much increased number of SNPs tested, we also tested positive for the I-BY183623 one and its downstream I-BY182841 branch. Currently, according to FamilyTreeDNA, we are the only men belonging to this new subclade of I-DF29. At present, these two new SNPs differentiate genuine male Mendenhalls (or Mildenhalls) from all other men but it remains to be seen whether this holds true as more tests are accumulated. For my three US cousins, a further SNP - I-BY183042 - has also been identified. So, again currently, this marker differentiates between the two main branches of the family tree. A positive result is associated with US Mendenhalls and a negative one with English Mendenhalls. Hence, the mutation that gave rise to the I-BY183042 marker must have occurred between about 1460 when Thomas Myldenale was born and 1630 when Thomas Mildenhall was born; see paternal pedigrees below.
I and one of my US cousins recently submitted our Y-DNA to YFull for analysis. The new subclade of I-DF29 that is specific to our Mendenhall family is known as I-FTB21048 by YFull. It is the same subclade as the Family Tree one they call I-BY183623. These two names both refer to the eleventh and newest subclade (I1a11) of I-DF29. YFull estimate that it was formed about 4500 years ago and that the time to our most recent common ancestor is roughly 500 years ago. As he was born about 1460, our genealogical researches have been confirmed by our genetic testing. Our forefathers are who we believe them to be.
All three of my US cousins share Thomas Mildenhall (born 1630) are their most recent common ancestor. However, one is descended from his son Benjamin Mendenhall and the other two from his son John Mendenhall. Their surnames evolved following emigration from England to America. For the two descendants of John Mendenhall, the I-BY182987 marker has just been positively identified. For the descendant of Benjamin, this marker is negative. So, to date at least, this marker differentiates between these two founding members of the American family.
For further information, visit the FamilyTree Haplotree I-DF29 and the FamilyTree Haplotree I-BY183042 web pages. Both these web pages are regularly reviewed and updated as new information is continually acquired; so expect frequent changes to them. Also, see Eupedia Haplogroup I1 and Wikipedia Haplogroup I1 for further background information relating to our Germanic heritage.
Sources:
Paternal Pedigree of all American Mendenhalls:
Paternal Pedigree of all English Mendenhalls:
Descendants .......... Surname List .......... Name Index .......... Our Journey to Mildenhall .......... Our Y-DNA