Sile,
I found a better TMRCA calculator than MacDonald's, it's by Tim Janzen and can be accessed from
http://www.isogg.org/wiki/Y-DNA_tools under TMRCA Calculators. His Excel program allows for hundreds of haplotypes to be put in at once and puts out several TMRCAs in generations and years based on different methods and using different STRs.
I put into it my STRs, your's (your are Pretotto, correct?), Knox from N Ireland, Knox from US, and Mason as we are the only CTS8862 whose STRs are available. Knox from US and Mason are predicted CTS8862 due to their close relation to Knox from N Ireland who is confirmed CTS8862. Looking at the TMRCAs that removed the fast STRs and included the best methods and corrections, I discovered that our most recent common ancestor was about 64 generations ago or 1,900 years. Since I used my father as a reference point, that puts our MRCA in the 1st century to 2nd century CE. This may not be the actual appearance of our SNP but it is still significant because for our paternal lines to be traced in "recent" times to the British Isles, Italy, and Spain yet still be related at some point almost 2,000 years ago is very interesting. I looked at our individual relations, aka inputting only 2 haplotypes at a time, and saw that I was closest in relation to Knox from N Ireland, with a MRCA living 595 years ago, putting that man living around the late 14th century. What does this all mean? I have yet to figure it out, but there must have been some demographic event or historical population that could have caused a far flung distribution of descendants in a short amount of time. I looked into the Jewish diaspora from Judaea after the destruction of the Second Temple and it correlates with the time period of our last common ancestor. These Jews, who either fled to other parts of the Roman Empire or were sold into slavery in Rome likely distributed themselves far and wide. It cannot be said how quickly they could have converted into Christianity to assimilate and avoid the cycle of persecution they suffered throughout time or if they did so at all. For my MRCA with Knox, there could be a link to the Sephardi Jews that fled Spain only a century later in the late 15th century, some of which did migrate to the British Isles... but that occurred during the 17th and 18th centuries, possibly contradicting these theories since Knox's earliest ancestor was born 1759 in Strabane.
Janzen did state that the 37 and 67 STR calculations in his Excel program did sometimes underestimate the TMRCA, for which I can see is a possibility here. I also went along and tried evaluating the TMRCA for other T-L131 sub-clades, including L446 itself. Here is what I got:
L446: 5,000 years ago (not including Saudi and Kuwaiti STRs, might be older once I include them)
-CTS11984: 3,800 years ago
--CTS8862: 1,900 years ago
--PS11: 900 years ago
P322: 3,400 years ago
*All of these results were done using 37 STRs.
