Hard to say as the development phase of modern surnames lasted centuries and it's difficult to lay your hands on true contemporary sources for the period. Second hand annals can't be relied on to reproduce name forms (never mind spellings) as they were originally. Also a single record in isolation may not really indicate whether you are looking at a true hereditary surname or just a tribal name. I am looking at the emergence of the Kennedy surname in Irish records at the moment. The earliest contemporary record in Munster is this one: AI1123.2 Donn Cuan Ua Cennetich quieuit Is that a 'surname'? Impossible to say, on its own. If his father and brothers and sons and nephews are also named maybe you can get somewhere. Iain > Date: Mon, 1 Aug 2011 14:06:01 -0400 > From: cain@eecs.umich.edu > To: dna-r1b1c7@rootsweb.com > Subject: Re: [R-M222] 111-Marker results > > > Incidentally, I was struck by how unrelated we (M222) all are...a > relative concept, I know. How many generations do we go back before > surnames were uncommon? I expect 15 or 20 (?) and that depends on where > you look. Most of us are related in TMRCA terms back further in time > than the use of surnames if you look at typical values, 30 or so, in > your table. > > Charles > > >