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Were Cormac Cas and Eógan Mór really brothers? Testing traditional Irish stories with Y DNA

In searching for the exact roots of the Dál gCais/Dalcassians, I found a lot of mixed information.

The early Dál gCais carried on their banners the Claíomh Solais of Nuada. One of the Four Treasures of the Tuatha Dé Danann. From Wikipedia.

Perhaps the most persistent story put forward is that Ailill Ollamh (aka Oilioll Olum, King of Munster, who lived in the 1st or 2nd century AD… though I’ve also seen the 3rd century as another possibility) was the father of both Cormac Cas and Éogan Mór… the Dál gCais claim descent from Cas, and the Eóganachta were either founded by Eógan Mór, or the people used his name in their identity. 

As I’ve pointed out in an earlier post, in terms of Y DNA, the Dál gCais are Type III Irish (Haplogroup L226), and the Eóganachta are Type II Irish (Haplogroup CTS4466). Overlaying the timeline of the Y DNA haplogroups and the timeline of the story of “brothers” Cormac Cas and Eógan Mór poses a problem, however. In fact, the last time L226 and CTS4466 shared a common ancestor is in Haplogroup DF13. Specifically, two branches of DF13 are ZZ10 (ancestor of L226) and FGC11134 (ancestor of CTS4466). Using the aging method developed by Iain McDonald, the median age of DF13 (theoretically, Ailill Ollamh) is 4094.42 YBP (2145 BC). The 95% confidence interval is 2636 BC to 1741 BC. Therefore, at a minimum, there is an 1,800 year gap between the Y DNA split and the timeline in the traditional story for Ailill Ollamh.

So, I’ve got a bit of work ahead of me in trying to see if one of the other tales of Dál gCais origins might work with the age timeline of Y DNA.

Interestingly, I also ran across a resource for descendant lines within the Dál gCais, via a link within Library Ireland, which laid out John O’Hart’s Irish Pedigrees: or the Origin and Stem of the Irish Nation (1892, 5th edition). In this instance, I looked for the Nolan/Noland name… or O’Neylon, etc, etc. Having no luck, I resorted to checking on the closest kin in the haplotree… the Lynch/O’Loingsigh family of Thomond, and ran across this page:

AONGUS, a brother of Eochaidh Ball-dearg who is No. 94 on the “O’Brien” (Princes of Thomond) pedigree, was the ancestor of this branch of that family. The family derives its name from Longseach (“longseach:” Irish, a mariner), a descendant of that Aongus; and were after him called O’Loingsigh, or anglice, O’Lynch, and Lynch. It would appear that the “O’Lynches’ Country” was that portion of territory lying around Castleconnell, in the barony of Owny and Ara, with portion of the lands comprised in the county of the City of Limerick.

Now, as I mentioned in my post yesterday, the Lynch line of Thomond is one of the lines that breaks from haplogroup DC50. They are DC246 and DC245, while the Nolan/Noland line is DC55. As I also noted yesterday, using the aging method developed by Iain McDonald, the median age of DC50 is 1798.39 YBP (152 AD). The 95% confidence interval is 196 BC to 477 AD.*

Interestingly, Haplogroup DC50 actually falls into this range of birth dates. Additionally, looking at the rest of the haplotree, from DC55, back to L226…

Remarkably, even L226 is in the window [using the aging method developed by Iain McDonald, the median age of L226 is 1915.79 YBP (35 AD). The 95% confidence interval is 446 BC to 379 AD]. Overlaying O’Hart’s 1892 book with the Y DNA, there certainly seems to be a potential fit.

Since it fits, to wrap things up, I thought I’d throw in the rest of what O’Hart had to say about all those folks in the ancestral tree, above (though, once again, it’s suggested that Cormac Cas is brother of Eógan Mór)…

The following is the Stem [1] of this family, from Cormac Cas, who was the ancestor of O’Briain of Thomond (anglicised O’Brien, Bernard, Brien, Bryan, and Bryant), and a younger brother of Owen Mor, who is No. 85 on the “Line of Heber”;” down to Henry O’Brien, the eighth Early of Thomond, who d. in 1741.

85. Cormac Cas: second son of Olioll Olum, King of Munster, by his wife Sabh or Sabina, daughter of Conn of the Hundred Battles, and relict of MacNiadh; he was one of the most distinguished champions of his time, and “remarkable for strength of body, dexterity, and courage.” He defeated the Lagenians (or Leinster men) in the battle of Iorras Damhsa, Carmen (or Wexford), Liamhan (or Dunlaven), Tara, Teltown, and Samhna Hill; and the Conacians in the famous battle of Cruachan, in the county of Roscommon. Cormac d. at Dun-tri-Liag, (or the Fort of the Stone Slabs), now “Duntrileague,” in the county of Limerick, of wounds received in the battle of Samhna Hill, from the spear of Eochy of the Red Eyebrows, King of Leinster. He was m. to Samer, dau. of Fionn MacCumhal (Fionn MacCoole), and sister of the poet Oisin, by whom he left, with other children:

86. Mogha Corb (or Mogha of the Chariots), who was b. A.D. 167, and attained a very old age. This Prince, who became King of Munster, which he governed for the space of twenty years, fought the memorable battle of Gabhra or Garristown, near Dublin, against the monarch Cairbre Liffechar, A.D. 284.

87. Fear Corb: his son; b. 198, governed Munster for seven years; fought the battles of Tlachtga and Teltown against the Lagenians, in the latter of which he slew Tinne the son of Triun, a distinguished warrior; and defeated the Conacians in the battle of Ceara, Corann, and Rathcruaghan, with great slaughter.

88. Aeneas Tireach: his son; b. 232; was distinguished for his patriotism and courage, particularly in the battle of Cliodhna, near Clonakilty; and was remarkable for the strictness of his laws, as well as for his impartial judgements.

89. Lughaidh Meann: his son; b. 286; dispossessed the Firbolgs of the tract known as the county Clare (which had in his time formed part of Connaught), and attached it to Munster.

90. Conall Each-luath (“each:” Irish, Lat. “eq-uus,” Gr. “ik-kos” a horse; “luath:” Irish, agile, Welsh “lludw,” nimble), or Conall of the Swift Steeds: his son; b. 312. Had two sons – 1. Cas; 2. Eana Arighthach.

91. Cas: the elder son; a quo the Dal Cais or “Dalcassians;”, b. 347. Had twelve sons: – 1. Blad, 2. Caisin, 3. Lughaidh, 4. Seana, 5. Aengus Cinathrach, 6. Carthann Fionn, 7. Cainioch, 8. Aengus Cinaithin, 9. Aodh, 10. Nae, 11. Loisgeann, and 12. Dealbheath.

92. Blad (“bladair:” Irish, to coax; Lat. “blater-o,” to flatter): the eldest son of Cas; a quo O’Bladair, anglicised Blair, Flattery, and Blood (of Munster); b. 388; left four sons: – 1. Carthann Fionn Oge Mor; 2. Carthann Dubh; 3. Eochaidh; 4. Brennan Ban, ancestor of O’Brennan (of Thomond), Glinn, Glynn, Maglin, Magan, Muldowney (now “Downey”), O’Hurley, etc.

93. Carthann Fionn Oge Mor: eldest son of Blad. Had two sons: 1. Eochaidh Ball-dearg; 2. Aengus, who was the progenitor of O’Curry, O’Cormacan, O’Seasnain, etc.

94. Eochaidh Ball-dearg: son of Carthann Fionn Oge Mor. Recieved Baptism at the hands of St. Patrick, and d. at an advanced age…

*There are two lines of Lynch test takers under L226. One is under DC50 > DC246 > DC 245 (as shown above); the other (not shown above) is under L226 > FGC5660 > Z17699 > ZZ31 > FGC5623 > FGC5659 > BY4103 > DC269 > FT77685 > FT100291. The Hillyard/Hilliard line which I descend from on my maternal father’s side, is a NPE Nolan/Noland line, traceable to County Tipperary in the early 1600s. Of the Hilliard/Noland test takers to test at the Big Y-700 level, all are currently at Haplogroup DC55. 


Published by Robert Moore

Historian, writer, hypertext & Web literacy theorist

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