THE PHYLOGENIC TREE

Read first the description of the MCRA.

So, now that we know who Y-chromosome Adam is and that we think he lived about 150,000 – 200,000 years ago, can we draw a link to him from our J-M172 (J2) ancestor? Well, of course the answer is yes or I would not have asked the question. But first a little bit more about how they do this.

The Y-DNA test that I have thus far had done was an STR37 test. This tests the repeating pairs on 37 different markers or areas on the Y-DNA. This test is really only good for more recent genealogy (last 15 generations or so) but FTDNA can from these results determine what haplogroup you come from with 100% certainty. So that is why we know we are in haplogroup M172. But to really define the genealogy tree in a more expensive test, they look at 12 – 16 million individual base pairs on the DNA strand for mutations. A mutation will be where an individual base pair changes its chemical makeup (remember that it only has four choices of chemicals so if it changes it must change to one of the other three). These mutations are called SNPs (single nucleotide polymorphism).

Someone at Cambridge came up with a standard that they map your DNA against and then list the mutations or the differences (SNPs). The National Geographic study did this with thousands of people all over the world and began building the haplogroup tree. The tree is becoming quite refined but they continue to add to it as new DNA data comes in. Sometimes they just add to the bottom and sometimes they have to insert a branch they did not previously know existed.

So our starting point on the tree is haplogroup M172.  M172 is actually just the first mutation that was discovered for this haplogroup. There are many more mutations that are unique to this line of people such as L228, F4272, F4283, F3343, PF4597, PF4886, CTS886, PF4925, PF4935. The name of the mutation just depicts the lab where the SNP was discovered by the letter(s) and a sequential number of the SNP that lab has discovered. As long as there are no further mutations this haplogroup can go on for many generations and have lots of descendants before a mutation happens that will create a new branch. Now you may ask how this would happen. All those mutations I listed probably did not happen to the same poor guy all at once. But then it is possible that other lines (i.e. the brothers of the additional mutations) have died out since then, or they have not yet been discovered which is why they have to go back and insert branches all the time.

There can also be a branch that has a mutation and the rest of the clad continues on with the original set. It is not until another mutation happens that they create a “sibling” branch. These siblings could have lived hundreds of years apart in real life though. If no sibling appears then there is no branch and the mutation gets added to the original list.

I will build our tree from M172 back to Y-Adam because it is interesting reading. M172’s haplogroup parent is M304(J), and his sibling is M267(J1). With help from the Wiki page and a few edits…