Tim Janzen’s spreadsheet (downloadable at http://www.timjanzen.com/dna.html)
allows one to calculate the estimated time to an MRCA using a variety of different methodologies and mutation rates.
This website posts the results for Janzen spreadsheets calculating time to MRCA for different groups of R1a1a Ashkenazi Levites. Those results show that the men who have tested to 111 markers share an MRCA who is considerably closer in time than the MRCA of the men who have tested only to 67 markers. Because the time to MRCA for both groups of men is calculated by reference to 67-marker results, this discrepancy necessarily reflects a sampling error, apparently arising from the likelihood that men with close matches at 67 markers are more likely to upgrade their results to 111 markers. As more men with varying results have tested, this discrepancy has decreased, but it is still significant.
The Janzen spreadsheet calculations posted on the website rely upon results calculated using Ken Nordtvedt’s method and Chandler’s mutation rates; that method and those mutation rates seem to yield results that are consistent with the known genealogical and historical record.
One may also run Janzen spreadsheets for subclusters of R1a1a Ashkenazi Levites (e.g., men sharing certain marker values). Those results will show the time to an MRCA for these subgroups, providing insight into, inter alia, the times at which their shared marker values mutated and the likely order of mutations among the subcluster.
Y-DNA Analysis >