I’ve writen this article for people who are interested in their (or their male relative’s) y DNA and are thinking about how much time, effort and money they invest in it.
I’ve split this article into two parts, the “Whats” and the “Whys”, but there is inevitably some overlap between the two.
The Human y DNA haplotree starts with “y DNA Adam” at the base. At some point one of his males descendants had a mutation, a SNP, in his y DNA.
As a result there were some of “y DNA Adam’s” descendants who had this mutation and some who didn’t.
To plot these mutations genetic genealogists can use two methods. These are parts of the y DNA that form short repeated patterns (typically repeating somewhere between 8 and 32 times).
Rather like an office photocopier they sometimes make mistakes and produce one too many, or one to few copies.
Examining the areas of the Y chromosome that show best variance in these repeating patterns means you can identify other males that are likely to share a common paternal ancestor with recent history.
These tests can be taken through familytree and used to evaluate 12, 37, 67 or 111 STR markers.I’m using my results from my Living DNA test to show when I-Z138 sits within Haplogroup I.The same structure can been seen at the y Full and ISOGG websites.The other obvious thing to state is that as a haplogroup result becomes more refined the dates of origin of the mutation become closer to the present time.How close it will come depends on both how deeply you test and how many people with there are with similar results to you.The structure of the y DNA Haplogroup tree and the likely locations of the each haplogroup mutation’s origin are very nicely shown in the results you get from Living DNA, the Genographic Project or Family Tree DNA.