McCoss

A narrative history reconstructs the origins and continuity of Clann Mhic Eòs’ across more than twelve centuries, integrating onomastic analysis, archival research, oral tradition, and Y-DNA evidence. The name MacEòs’ derives from MacEòsaiph (“son of Joseph”), with Gaelic forms Eòis, Eòs’, and possibly the Flemish Joos, reflected in historical spellings such as Yowish, MacEòs’, McCose, and ultimately McCoss. Its evolution was shaped by Gaelic grammatical structures, regional pronunciation, and later adaptation into Scots orthography.

Genetic evidence anchors the lineage to a Danish-Viking primogenitor active around the Irish Sea (Most Recent Common Ancestor, or MRCA c.800). A working model links Viking-age Strathclyde settlers to later Stewart-aligned and Erskine-affiliated networks along the River Clyde, facilitating late-medieval / early-modern migration into Upper Deeside and onward — alongside Farquharson allies — into Upper Strathdon under the patronage of the Stewart and Erskine Earls of Mar. A Grampian MRCA (c.1555) is plausibly identified as a respected Brabant-trained military veteran, Eòs’ or Joos. While necessarily inferential, the model through the mid-seventeenth century rests on converging lines of evidence and remains open to refinement as new sources emerge.

The earliest clearly documented bearer of the patronymic is Alaster MacEòs’ (c.1655–c.1720), a Highlander in Glen Nochty, Strathdon, whose family endured famine, religious tension, and Jacobite upheaval. A central later figure is William “Auld MacEòsaidh” (b.1715), a blacksmith, Jacobite, and Highland soldier in overseas service. Subsequent generations served in the American Revolutionary War, established skilled trades in Huntly and Aberdeen, and carried the lineage into the modern era.