Why Test 67 Markers?

People who wish to test their Ydna often ask which test its best. First you have to determine what your goal is and then find the test that best meets it.

As genealogists, we want our test to further our research; therefore, it is imperative that the test be helpful within a genealogical time frame. The following numbers of markers that are tested give results which are and are not within genealogical time. Although the following are the tests provided by Family Tree DNA, any testing company using about that number of markers will produce a similar result. However, note that at this time, no other company tests 67 markers on the Y chromosome, except Family Tree DNA.

Thus chart indicates the time frame for a match within a set of markers.

DNA TMRCA (Time to the Most Recent Common Ancestor) and Probability to the Most Recent Common Ancestor (MRCA)

12 marker Ydna test tells you only about your most ancient ancestry....over 600 yrs ago and before surnames. The Genographic Project uses only the 12 marker for males as they are only interested in tracking the migration pattern of our most ancient ancestors. Their project is an anthropological study; not a genealogical one, but in time their data will help us.

25 marker match gives you a 95% probability of having a common ancestor within the last 600 yrs.

37 marker match gives you a 95% probability of having a common ancestor within the last 300 yrs.

67 marker match gives you a 95% probability of having a common ancestor within the last 150-200 yrs.


This means that the 37 marker and the 67 marker are the genealogists’ best choices as they fall withing a genealogical time frame. Prior to 600 years ago some cultures did not establish surnames. Actually, the Irish were probably the oldest culture and they began around 1000 years ago. However, the Welsh, the Jews and many others hae only had surnames for the last few hundred hears..

Although one can order the lesser number of markers (37) and upgrade at any time to a 67 marker test, the cost is a bit more than the difference between the two. There are also good reasons to update to a 67 marker and, in cases, reasons not to bother, at least until it is necessary.

So why upgrade to a 67 marker?

The following information will help the tester determine if a 67 marker is important to your goals.

It is important to know that a Ydna 67 marker test can:

* further refine the estimate of how closely related two individuals are.

* help groups of related testers find mutations which identify sub-branches in the family.


The following scenarios are good reasons to upgrade to a 67 marker:

If you are a member of a group of closely related testers with a good 37 marker match, but there is no paper trial to connect the croup, it may be wise to upgrade as:

* More mutations can result, giving you the opportunity to further subdivide the large group and look for more recent common ancestors.
(See Talley Project at www.familytreedna.com/puiblic/Talley-Tally)

If you are a member of a group with many mutations (more than the usually number…i.e., more than 3 with a 37 marker) and you think you are closely related with the paper trail.

* The marker increase may not increase the mutations.

* The marker mutations may increase, pushing the common ancestor too far away from the group.

* The marker mutations may help bridge the mutations within the group. Often this happens when you find a family who has many mutations and the paper trail supports a good connection. Some families do mutate more often than others. Finding more testers for the family may bridge the gap between those who have greater genetic differences. A 67 marker may also show the testers re closely related as the markers from 38-67 have few to no mutations. The more markers tested the greater number of genetic differences can be accepted for still being a close relationship.

www.familytreedna.com/public/Talley-Tally
http://www.boltancestry.com/boltdnamystery.htm

Probability for Most Recent Common Ancestor
(MRCA)

The following times back to the MRCA when ALL the markers match are based in the latest results of the mutation rate study conducted by the University of Arizona.

For example, with 37/37 match there is a 50% probability that the MRCA was no longer than 2 generations, and a 90% probability that the MRCA was within the last 5 generations.

Compare these with 25 and 12 -- with 25 markers, there is a 50% probability that the MRCA was within the last 3 generations, while with 12 markers, there is a 50% probability that the MRCA was within the last 7 generations.

For a chart showing the Probability for Most Recent Common Ancestor (MRCA), see: http://www.familytreedna.com/faq2.html

SO, in conclusion, if your test results fits within one of the above scenarios, it may be advantageous to upgrade to a 67 marker.

In time, there may be an increase in available markers to test so upgrading to a 67 marker may be only a step to the future and not the end.

©aulcino@hevanet.com, 1 Nov 2008