A Hartley Z17911 STR Tree

In my previous blogs on Hartley YDNA, I mentioned that my terminal SNP is Z17911. That is a part of the L513 Branch of the larger L21 Branch of R1b. Here is what the L513 Branch looks like. This Tree represents those who have taken the Big Y Test in the colored area above.


My Hartley Z17911 is difficult to see but it is slightly to the left of the middle and to the left of an orange area. The checkerboard pattern shows the part of England that my Hartleys are from. As far as I know I am the only Hartley that has had SNPs tested positive for Z17911, or for L513, for that matter.

STRs and Z17911

However, quite a few Hartleys have tested their YDNA. They have tested STRs. As a result, it is possible to do a comparison to others taking this test. STRs are not SNPs which are a more definitive designation of where you are on the Y Tree. However, they can suggest what SNP you should belong to. I belong to an L513 and the Administrator Mike is actively looking for others that might be in L513. As a result, Mike has put out lists of people that appear to be L513 based on their STR patterns. I have mentioned in past Blogs that some of those people are Hartleys.

Here is a recent list:


The first on the list above is me. Then follows three other Hartleys. Administrator Mike has grouped these other 3 Hartleys next to me. Based on their STRs, he has grouped them as Z17911. This is even though these 3 have not tested for Z17911, L513, or probably not even for L21 which is way up on the Y Tree. The row with the orange, green and yellow above the results has what is called STR Rates. These are the rates at which each individual STR mutates. Some are very slow and some mutate relatively quickly. The selected mode above is likely the mode of L513. This will come in handy later on in this Blog in a few ways.

Z17911 and Signature STRs

It turns out that STRs form themselves into groups. That means that for groups of people that are related by YDNA have combinations of STRs that are almost always unique to that group. Here I will make an assumption that the other 3 Hartleys are indeed Z17911, even though they haven’t tested their SNPs.

In the results section to the right of the Hartley names are the values for each STR marker. The colored values are the ones that vary from the L513 Mode. These values, especially the ones that are in the darker colors will result in a signature for these Z17811 Hartleys. The darker colors indicate more of a variance or distance from the mode. Another way to put it, is that the L513 mode is the older value and the Z17811 Hartley numbers are the newer values for the STRs that have mutated away from the L513 mode.

Up or Down?

These Z17811 STRs may mutate up or down. The blue shaded numbers are going down and the reds are going up. Why is this important? It is important as I’d like to build a tree from these 4 Hartleys. I will need to know who is descending from whom. Or at least, which of the 4 branches of Hartleys may be the oldest.

Here is an example:


These are some of the results of our 4 presumed positive Z17911 Hartleys. It is  difficult to create a mode of these results as the mode is the value which occurs the most. If there are 2 of each value, which value do you use? This happens the #449 Marker results. I am 31 at the top, but there are two 31’s and two 32’s. I have the L513 mode at the top of the image. The value for Marker #449 is 29. That means I have the older 31 value and the other 2 Hartleys have newer 32 values. They are moving away from 29.

Defining Hartley Z17911 STRs

Next, I looked at all the STRs where the 4 Hartley had different results. The other results are interesting but in comparing Hartley to Hartley they don’t matter if they are the same. Well, they might matter if there was a STR that mutated up and back down again, but the chance of that happening should be relatively rare.


Here I have compacted 67 STR results to 12. This is a good time to point out the STR rates. The rate for 447 is about 0.09. The rate for CDYb is 35. That means that CDYb will change over 350 times as fast as 447. Another point is that Hartley #4 seems to be a special case. He was categorized as a non-L513 person which was thought by the L513 Administrator Mike to be a mistake. I don’t know if that was ever resolved. I do note that some of his STRs are a bit different than the other 3 Hartleys, but not totally different. I also note that he has tested positive for R-L21, so perhaps this has been resolved.

But Wait, There’s More

I had forgotten, there is one more Hartley in the group. He doesn’t have a Hartley last name but believes that he is descended from the Hartley Line. Great news. I will call him Hartley #5.


Previously, I had missed Marker 481. Also when I copied things, my numbers didn’t get colors, but that’s alright. Now I have 13 markers and 5 Hartleys.

References for Trees

I’m aware of 3 references for creating STR trees.

  • Robert Laurence Baber – He has written quite a few articles on STR trees. I have not read them all yet. I downloaded a 5 part study he wrote but I don’t totally understand his method yet – though I understand some of the principles. He uses an upstream STR mode as I tried to do above.
  • Robb Hand Drawn Tree example – He compares a hand drawn tree to the Fluxus software. Although he likes the hand drawn version better, he learns some from using difficult to use the Fluxus software
  • Gleeson STR Tree – Maurice Gleeson gives a method and example of how to build a STR tree

More on Modes

I seem to be getting hung up on Modes:


Here I have the L513 Mode and various modes from downstream SNPs. The 458 mode went quickly from 17 for L513 to 19 for S5668 and then appeared to stay there for quite a while.As a result, I chose 19 for the mode. Had I just looked at the older L513 Mode, I may have come to a different conclusion as to which way this STR was mutating.

Then the very fast CDYb seemed to move up in a regular way through the ages. Of course, in reality, it could have gone up and down over that period of time, but we wouldn’t know it if it did. I picked the lower 39 value for the CDYb STR at the Hartley mode level. To the right, I have the GD or generational distance from the Hartley Mode. This says that these Hartleys should be related at about the same level – around 4 or 5 GDs or STR mutations.

A 5 Hartley Likely Z17911 STR Tree

Here is the tree I came up with. It is along the line of and in the form of the Gleeson STR Tree example mentioned above:


  • The Hartley common ancestor’s signature STR values are listed at the top. The mutations from that are shown down the branches to the individual Hartleys.
  • I also added some dates assuming that on average, a STR will mutate every 170 years given a test of 67 STRs. The lower horizontal lines above happen at the 2 or 3 STR mutation rate (which is the same as the GD). The top horizontal line happens at a GD of 4 or 5. The Hartley #5 horizontal line is up higher as the 358b mutation is a double one from 16 to 18.
  • In the above scenario, Hartley #5 is by himself. Another scenario would have Hartley #4 and Hartley #5 together as they share a mutation at 389b. Instead, I chose the above tree due to Hartley #1, 4, 3, and 2 each sharing 2 STRs.

This image shows some of my rationale for the tree:


I chose the double combo of 25-32 that Hartley #2 and #3 shared. I also chose the double combo of 17-40 (in yellow) that Hartley #1 and #4 shared. Other possible single combos that I didn’t choose to group were the two step 16>18 mutation for Hartley #4 and 5, the 11 mutation for Hartley #1 and 5 and the 16 mutation for Hartley #1 and 3. The principle used is to try to get the tree as simple as possible. This is what Gleeson calls the parsimony principle. My assumption is that my groupings achieve that goal.

How Do the Hartleys Compare to the Z17911 Mode?

In comparing Hartleys to the Z17911 Mode,  I go from the age of surnames to before the age of surnames. There are 4 that have tested positive for Z17911. They are Hartley (me), Goff, Thomas and Merrick. In that group, the level of GD’s and the variance in surnames indicate a pre-surname common ancestor.

So the GD’s will be further back also.


Here I am assuming no back mutations. Under the previous tree I assumed that Hartley #5 had a back mutation at CDYb. Due to the volatility of this marker, it is sometimes ignored in these analyses. Notice that now the range of GDs is from 3 to 8. Again, I group Hartley #1 and #4 together and Hartley #2 and #3 together.


Hartley #4 has the GD of 8. This is due to 2 double mutations. That pushes back his connection to Z17911 to around the year 600. This seems to be pushing back to a possible age of Z17911. Z17911 positive Thomas has submitted his Big Y results to YFull, so I am hoping to get a date from YFull for Z17911. It will be interesting to see what they come up with. The structure of the tree is the same as the previous Hartley Tree. I just adjusted the relative heights of the horizontal arms.

Summary and Conclusion

  • STRs from 5 Hartleys who have tested their YDNA seem to indicate a relatively close relationship – at least in YDNA terms
  • I have had my SNPs tested and the administrator of the R1b-L513 project has grouped the other STR-testing Hartleys in the same Z17911 group as me based on similar STR patterns. That is quite a way down the SNP tree.
  • If any of these Hartley were to test for for the L513 SNP or further down for Z17911, it could confirm what the STRs seem to be saying. Then I wouldn’t be the lone SNP tested Z17911 Hartley
  • SNPs create a solid reliable marker for relationships. It is best to have the SNP relationship established through testing before doing this type of STR analysis. However, even without SNP testing, STR trees can be informative
  • Back mutations and the different mutation rates leading to unpredictable STR mutations are the 2 major variables that make STR testing less accurate than SNP testing
  • The weakness of the SNP testing is that many have not done it. The other issue is SNP testing may only take you up to a certain date. After that date, STR analysis is  more useful
  • STR testing is best used in conjunction with SNP testing
  • Making a STR tree takes some practice and knowledge of STRs and mutations.
  • This YDNA research and resulting connections could shed light on the history of this branch of the Hartley family over the past 400-1400 years or so.


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