Question

How many DNA Y matches are needed for a confirmation of distant ancestors where the RCA is 8th Generation?

Answer 1

I'm not 100% sure if this is what you are asking, but if 2 men had good genealogical evidence back to the MRCMA (most recent common male ancestor) 8 generations ago, I would feel comfortable saying that the genealogy was supported by the YDNA results as long as they matched on at least 33/37, 60/67 or 101/111 STRs, depending on the highest number of STRs that both men tested at.

If, on the other hand, the genealogical support was weak or non-existent for one of the men, I'd probably want deep SNP testing to confirm.

Comments

That is exactly what I found. I know that we need 2 matches (with mine) that are more distant than 3rd cousin with autosomal. But, using the Y  match, got confused. Is one match enough to confirm with Y match or do you need 2?

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2 is enough for YDNA confirmation. See the example for YDNA at: https://www.wikitree.com/wiki/Help:DNA_Confirmation#Y-Chromosome_Confirmation

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Thank you Chase. I did read the link you sent. I didn't think to read the suggested entry. I'll blame that on my age. 80. God Bless You

Answer 2

I would say it would be better from two different sons of the MRCA.  If you have two yDNA tests from the same line, that does not show a connection 8 generations back.  For instance, if two tests track their paternal lines back to the same Great-Great Grandfather, that is the most recent common ancestor, even if one of the lines goes back farther to the immigrant forefather.

In this instance, we have matching yDNA tests from Christopher Smith's sons, William, Simon, Joseph, Benjamin and Edward.  These matching tests proved that Christopher, William, Simon, Joseph, Benjamin and Edward had a common yDNA forefather.  It wasn't until our Wonderful WikiTreers discovered the church registers of Stratford Upon Avon that we knew Christopher was the father and the common ancestor for William, Simon, Joseph, Benjamin, and Edward.  Please see William Shakespeare and the Christopher Smith Family for details.  Like a magazine, you have to drag the page up and down to see the full page, and drag right to left to "turn" the page.  

Comments

If the two tests track their paternal line back to the same Great Great Grandfather, then, by definition, the MRCA is only 4 generations back, not 8. You only need 2 test takers for an MRCA up either the YDNA or MTDNA lines. I agree that if the MRCA is 4 generations back, that doesn't say anything about prior generations.