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Haplotree changes

Something that may seem very weird happened last week to your DNA results if you’re a male and you’ve tested for YDNA with Family Tree DNA.

For example, my cousin Johnny went to bed as an I1 and woke up as an I-M253. My cousin Michael went to bed as a J2 and woke up as a J-M172. My uncle David went to bed as an R1b1a2 and woke up as an R-M269. My brother? Bedtime E1b1b1a1b. Morning E-V13.

What the…?

Not to worry. Nothing has changed with your DNA results.

YDNA haplotree from Family Tree DNA

What’s changed is, first and foremost, what science today knows about your DNA results. And because that’s changed, what had to change is how scientists talk about your DNA results.

All of these designations — I1 or I-M253, R1b1a2 or R-M269, J2 or J-M172.– are ways of saying exactly what your YDNA haplogroup is. YDNA, remember, is the type that shows “a man’s patrilineal or direct father’s-line ancestry” because the Y chromosome, which only men have, “passes down (essentially) unchanged from father to son.”1

And a haplogroup, remember, is “a genetic population group of people who share a common ancestor on the direct paternal or maternal line. Haplogroups are assigned letters of the alphabet, and refinements consist of additional number and letter combinations.”2 Put more simply, YDNA haplogroups are “the major branches on the human paternal family tree.”3

All of the top-level YDNA haplogroups — and there are, today, 20 of them designated by letters A-T — are arranged and displayed in what’s called the YDNA haplotree. That’s a kind of phylogenetic tree — a graphical representation in chart form or “a branching diagram or ‘tree’ showing … evolutionary relationships.”4 Looking just at the top-level YDNA haplogroups, it looks like this chart you see above and to the left here. (You can click on the image to see it bigger.)

The problem is, more haplogroups are being discovered. Once upon a time, in the far distant past of genetic genealogy — 2006, that is — there were only 18 recognized top-level YDNA haplogroups. Haplogroup S and T didn’t join the official haplotree until 2008.5

And a much bigger problem is, there are a lot more levels to haplogroups than just those top levels. And those levels are being refined and subdivided at an explosive rate as DNA testing becomes more common and data more available. Case in point, the R haplogroup, described as “perhaps the most prominent Y-DNA lineage on Earth today. It is the pre-eminent Y haplogroup in Europe, the U.S. and India.”6

You’ll have to click on the image to the right to really see this, but just a few years ago, back in 2006, the haplotree breakdowns within YDNA haplogroup R were fairly limited — no more than a handful, really. That’s the information on the left side in this image. By 2013, the R haplotree had been expanded to what you see on the right. It’s among the most complex in existence — and it’s getting bigger and more complex every day.

That’s because we’re coming to understand more and more that every one of the particular genetic components looked at in YDNA testing — each single-nucleotide polymorphism (SNP, pronounced snip)7 — is a significant marker to place each man into exactly his right place on the YDNA haplotree, the same way that the arrangement of those SNPs in patterns called short tandem repeats (STR)8 provides the markers that help place each man into his right family tree. (Note: paragraph edited 29 Jan 2013 for accuracy.)

And as the significance of each subgroup is recognized, the haplotree has to be expanded to include that group — a task initially undertaken by the scientific group called the Y Chromosome Consortium9 and refined for use by genetic genealogists by the International Society of Genetic Genealogy.10

Every one of those changes and refinements can change the name of a person’s haplogroup. Somebody who was R1b1a in 2006 could easily be R1b1a2a1a1a3b2b1a1a1a here in 2013.

Now, that’s a mouthful, isn’t it?

And it could get worse! By next year, Mr. R1b1a2a1a1a3b2b1a1a1a could well be Mr. R1b1a2a1a1a3b2b1a1a1a1a1a1a and so on into the future.

Now I don’t know about you… but I’m not at all confident of my ability to remember that a cousin was R1b1a2a1a1a3b2b1a1a1a. I can’t even remember that my brother is E1b1b1a1b. But I have no trouble at all remembering that he’s E-V13.

But is E1b1b1a1b the same thing as E-V13? Yep. You see, the reason my brother is classified as E1b1b1a1b is because the very last SNP that we know is in his YDNA — the so-called “terminal SNP” or “the one furthest down the tree that defines” his specific place in the haplotree11 — is V13 and we know that because I had his DNA specifically tested for that.12

What we have here is longhand versus shorthand. As explained on the YDNA results page of every man who’s tested his YDNA with Family Tree DNA:

Long time customers of Family Tree DNA have seen the YCC-tree of Homo Sapiens evolve over the past several years as new SNPs have been discovered. Sometimes these new SNPs cause a substantial change in the “longhand” explanation of your terminal Haplogroup. Because of this confusion, we introduced a shorthand version a few years ago that lists the branch of the tree and your terminal SNP, i.e. J-L147, in lieu of J1c3d. Therefore, in the very near term, Family Tree DNA will discontinue showing the current “longhand” on the tree and we will focus all of our discussions around your terminal defining SNP.

This changes no science – it just provides an easier and less confusing way for us all to communicate.

So hi! My paternal haplogroup (courtesy of my brother’s test) is E-V13. What’s yours?


 
SOURCES

  1. ISOGG Wiki (http://www.isogg.org/wiki), “Y chromosome DNA tests,” rev. 21 Jan 2013. Note that I added the parenthetical “(essentially)” because YDNA can change slightly through mutation even between a father and a son.
  2. ISOGG Wiki (http://www.isogg.org/wiki), “Haplogroup,” rev. 21 Jan 2013.
  3. What is a Y-chromosome DNA (Y-DNA) haplogroup?,” FAQs, Family Tree DNA (http://www.familytreedna.com/faq/ : accessed 26 Jan 2013).
  4. Wikipedia (http://www.wikipedia.com), “Phylogenetic tree,” rev. 12 Jan 2013.
  5. Y-DNA Haplogroup Tree 2008,” International Society of Genetic Genealogy (http://www.isogg.org/ : accessed 26 Jan 2013).
  6. Learn about Y-DNA Haplogroup R,” Learning Center, Genebase.com (http://www.genebase.com : accessed 26 Jan 2013).
  7. ISOGG Wiki (http://www.isogg.org/wiki), “Single-nucleotide polymorphism,” rev. 17 Jan 2013.
  8. ISOGG Wiki (http://www.isogg.org/wiki), “Short tandem repeat,” rev. 22 Jan 2013.
  9. ISOGG Wiki (http://www.isogg.org/wiki), “Y Chromosome Consortium,” rev. 13 Jan 2013.
  10. See generally “Y-DNA Haplogroup Tree 2013,” ISOGG (http://www.isogg.org/ : accessed 26 Jan 2013), and the earlier trees linked on that page.
  11. Roberta Estes, “To SNP or not to SNP??,” DNAeXplained – Genetic Genealogy, posted 10 Aug 2012 (http://dna-explained.com : accessed 26 Jan 2013).
  12. See generally Judy G. Russell, “Happy Father’s DNA Day!,” The Legal Genealogist, posted 17 Jun 2012 (http://www.legalgenealogist.com/blog : accessed 26 Jan 2013).
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