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Using the Y-Utility Spreadsheets

Posted on the website are spreadsheets, generated using the Y-Utility developed by Dean McGee (available at http://www.mymcgee.com/tools/yutility111.html) as modified by Mark Yost to accept 111 markers (available at http://tinyurl.com/McGee111ModBurgarella2010Rates), that include three types of information for the R1a1a Ashkenazi Levites who have tested to 37 markers and whose results I have located.[1]

The first page of the first spreadsheet, named “Deviations from Mode,” provides marker values, color-coded to show deviations from the R1a1a Ashkenazi Levite mode and number of steps from the mode (but not to indicate the direction of deviation from the mode).

The second through fourth pages of the first spreadsheet, named “Genetic Distance @ 111,” “Genetic Distance at 67,” and “Genetic Distance at 37,” are large tables that allow you to determine, at 111 markers, 67 markers, and 37 markers, respectively, the number of genetic steps by which each R1a1a Ashkenazi Levite on the list differs from (1) the R1a1a Ashkenazi Levite mode and (2) each other R1a1a Ashkenazi Levite on the list.
[2]

The first through third pages of the second spreadsheet, named “MRCA – gens (50%) (@111),” “MRCA – gens (50%) (@67),” and “MRCA – gens (50%) (@37),” provide estimates of the number of generations to an MRCA for each R1a1a Ashkenazi Levite on the list, calculated by reference to 111 markers, 67 markers, and 37 markers, respectively, to (1) the R1a1a Ashkenazi Levite mode and (2) each other R1a1a Ashkenazi Levite on the list. The spreadsheet pages provide estimates that are 50% likely to be greater than the actual number of years to an MRCA. The fourth through sixth pages of the spreadsheet, named “MRCA – years (50%) (@111),” “MRCA – years (50%) (@67),” and “MRCA – years (50%) (@37),” provide the same information in years (assuming that one generation is equal to 30 years).
[3] 

 
[1] The spreadsheet includes information only through 67 markers; in theory, the Y-Utility spreadsheet will accommodate values for 111 markers. 

[2] The number of genetic steps on this spreadsheet may differ from that reported by Family Tree DNA because the Y-Utility software apparently does not incorporate Family Tree DNA’s new adjustment to count RecLOH mutations as a single step’s difference. 

[3] The calculations are based upon composite mutation rates provided by Family Tree DNA for ranges of markers, rather than marker-specific mutation rates. Although it may seem that it would be more accurate to use marker-specific mutation rates, analyses indicate that such use often tends to overstate the time to an MRCA; using an average mutation rate is appropriate to counteract the “black swan” effect of a single mutation on a marker that mutates very rarely.

Tombstone of Yechezkel Landau (1713 - 1793), from the Prague Cemetery