I-M170 and the Babylonian confusion of Y-Haplogroup names


The child needs a name!
A clear one! An unmistakable one!
A Y-Haplogroup is a group of men, all descended from one man, a “forefather “, in a purely paternal line. We want to give this forefather a name and there are two different ways of doing this, both of which have their pitfalls and can lead to great confusion. The aim of this article is to show the possibilities for naming and the confusion potential.
My multiple “forefather” is I-M170. All my ancestors tested so far (via cousins) are his descendants (L38 and L621). Therefore I take this Y-Haplogroup as an example.

Y-Haplogroup I-M170

I-M170 is the oldest major haplogroup in Europe and most likely the only one that originated here, apart from sub-branches of other haplogroups.

Fig. 1: Pedigree of IJ-P214 (YFull.com)

The “father” of I-M170 is the haplogroup IJ-P124. The ancestors of I-M170 and J-M304 split about 43,000 years ago. The common ancestor of haplogroup I-M170 lived about 27,500 years ago. This is also where the first known split of the two main groups took place.
I1-M253 and I2-M438.

Fig. 2: Y-Heatmap of I-M170: I1 and I2. (Phylogeographer)

The highest distribution of I1-M253 is in northern Europe, especially in the Scandinavian countries. The common ancestor of this haplogroup lived about 4600 years ago, according to YFull’s age estimate. The long “bottleneck” of over 20,000 years and over 300 SNPs is remarkable.

In I2-M438, on the other hand, there were several branches in the last 27,000 years. Depending on the respective subclade, there are completely different distributions across Europe. Fig. 2 shows the distribution of I1 and I2. I2 has not been subdivided again here. Anyone is welcome to look at the distributions for the individual subclades for themselves at Phylogeographer.

Fig. 3: Pedigree of I-M170

Figure 3 shows the pedigree of I-M170. The times for the TMRCA were taken from the age estimation of YFull.com. The number of tester of each haplogroup was taken from the public Y-tree of FamilyTreeDNA and shown proportionally as the base (height) of the triangles. A list of the SNPs used can be found in Table 2. Only branches formed by NGS tests of living testers are shown. Extinct branches from ancient DNA, such as the “Twins of Krems” (I-L758*) or Cheddar Man (S2524*) have been deliberately omitted to avoid additional confusion.

I-M170 prediction for FTDNA and Y-haplogroup projects

If you do a Y-STR test on FTDNA, you will get the values for the ordered STR and a predicted Y-haplogroup, which is very conservative. Typical predictions are I-M253, I-M223, I-P37 and in some cases only I-M170. You can get a more accurate determination yourself by entering the STR values into the Predictor at Nevgen.org.
If you only get I-M170 as prediction, it is because you either belong to a rare subgroup of I-M253, I-M223, I-P37 or to the rarer haplogroups I-L38, I-L417 and L596. In any case, I recommend joining the appropriate Y-haplogroup project. There, volunteer administrators can take a closer look at the STR values and make more precise predictions.

Main Projects at FTDNA:
All I-M170: I M170+ YDNA Haplogroup
M253: I1 yDNA Haplogroup
P37: I2a Y-Haplogroup
M223: I-M223 Y-DNA Haplogroup
L38: Haplogroup I-L38
L596 und L417: I2b I-L415, I2a2 (was I2c) I- L596

Naming the Y-haplogroup, ISOGG Long Form

Probably the best known form for naming Y-haplogroups is the “long form” maintained by ISOGG (International Society of Genetic Genealogy) in their “Y-DNA Haplogroup Tree“. This consists of starting with a capital letter and then alternating between numbers and lower case letters. Until a few years ago, this was the most common name for Y-haplogroups. The advantage of this designation was that it was quite “figurative”. Even today, some still like to use the 2010 version. In the meantime, ten years have passed and the Y-tree has grown considerably due to the drop in prices for NGS tests. Table 1 shows an overview of the versions of the ISOGG trees of the last 14 years. One can see impressively how the long form designations have changed over the years.

version / SNP
Pre 2006I1aI1bI1c
Tab. 1: Comparison of ISOGG trees from 2006 to 2020 (First column, links to ISOGG.org. First row, links to YFull.com)

  • I2a is no longer only P37, but almost all I-M170 except M253 and L417.
  • I2b is no longer M436, but L417.
  • I2a1b is no longer M423 but M436, the previous I2b.
  • I2a1b2 is no longer L621, but Y10705, “father” of L38.
  • I2a2, still L423 in 2010, was M436 for 7 years and is now L596.

This is just a small excerpt from the “long form” name confusion. Without specifying which version was used, this naming is not unique. If you use it, you should always specify the year for the version. In this way, it is possible to determine in retrospect which Y-haplogroup it is, even if changes have been made to the tree in the meantime.

Naming the Y-haplogroup after a SNP

Another form of naming for Y-haplogroups is naming after a SNP. This is not “figurative” but unambiguous if only SNPs are used that do not occur in other haplogroups. However, there is some confusion here.
A SNP can have multiple names and the haplogroups in the trees can have different names.

Naming the SNPs:

If new variants are added to the tree, they are named by the person who “discovered” them. Depending on the “discoverer”, different prefixes are used. The most common ones at the moment are:

  • A = YSEQ.net
  • BY = Big Y-500 from FTDNA
  • FGC = Full Genomes Corp. (FGC)
  • FT = Big Y-700 from FTDNA
  • Y = YFull.com

A complete list of prefixes is available at ISOGG.org.

It can happen that SNPs are “discovered” and named by several at the same time, so that one and the same SNP has several names. These are often written together with a slash (e.g. M436/P214/PF3856/S33).

Naming the Y-haplogroups, after a SNP of a block

Y-haplogroups are defined by several SNPs. Until the mutation order of the SNPs is determined, they are referred to as phyloequivalent SNPs, i.e. they are equivalent in that block. In the case of M253, there are even another 309 SNPs (Table 2) that would be eligible for the designation of I1. However, the haplogroup is uniformly named I-M253 in all Y-trees.

Long Form

+ SNPs

Tab. 2: SNPs in the ISOGG, YFull and FTDNA trees.

In the Y-trees (ISOGG, FTDNA and YFull), there are no consistent rules for labeling the haplogroup, so that different SNPs can be used for the same haplogroup. This is the case with Y3120 (see Table 2). There are eight other SNPs in the block. Of these, three different SNPs are used at ISOGG, FTDNA and YFull to name this subgroup.
At ISOGG S9952/YP189, at YFull Y3120 and at FTDNA S20602.
The second name of SNP Y3120 is FGC12083. The second name of SNP S20602 is YP196.
That is a total of six SNPs for I2a1a2b1a1a (2020).

Fig. 4: SNP block for Y haplogroup Y3120 (YFull.com)


A unique and unmistakable name for the common ancestor of a Y-haplogroup can only be obtained with the “long form” if everyone is aware of which version of the ISOGG tree they are dealing with. Also, the strings can get very long when naming young branches. In my case, this would be I2a1b2a2b2b1 (2020). This is not very long compared to other haplogroups, but for me it is not pictorial, nor can I or will I remember it.
I prefer to use the SNP. I-Y130323, subgroup of I-L38.
If someone has no idea what this means, all they have to do is press the SNP search at YFull and they will have this within a few seconds.

Fig. 5: Y130323, subclade of the Y haplogroup I-L38 (YFull.com)

3 thoughts on “I-M170 and the Babylonian confusion of Y-Haplogroup names”

  1. I took a DNA test with National Geographic Society about 20 years ago and result was haplogroup I (M-170). My dad’s family is from a small town on Elbe River near Meissen.

    The additional results of test contained a string of numbers that I don’t understand since it doesn’t match any of descriptions of descendants of original I (M170) person. Who do you recommend I get a new test from to determine which sub category of I M170 I belong to?

    1. Hi Will,
      I-M170 is very basic.
      If you can afford, I would do a NGS test. (See my other blog post) The easiest to use is the BigY700 from familytreedna.com . This would give you the deepest clade possible and includes Y-STR markers for Y-DNA matching, also. This test is quite expensive. Starting with an Y-STR panel like Y37 or Y111 is also possible, but this gives you just a predicted subclade and in rare cases, a deep prediction is not possible, but only a basic one.
      Therefore BigY700 directly, or first Y111 and later upgrade to BigY700. At the week of 25th of April it will be DNA day and there should be some sales with reduced prices.
      Kind Regards

  2. I utilized a FT YDNA Test with the Oliver YDNA Project and have found myself an I-M170. Family came from Virginia early 1700. We used YDNA information to connect two lines where paper trail has been lost (common in Virginia, damned yankees..). Have found Surname research to be fairly limited in going back further than Tidewater Virginia 1720. YDNA is much more interesting and promising.

    Are you familiar with “Traced” by Dr. Nathaniel Jeanson? I think his research with a Biblical, Historical time frame is much more realistic in this study of genetics

    I need to study your work herein. Look forward to more, Bravo, well done, Cousin.

    SMO-NW WA State, USA

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