This project investigates the detailed Y-chromosome tree structure showing both recent and historical (from the Bronze Age forwards) connections for those who test positive for SNP R-Z16526 or one of its equivalents, and offering a timeline for its key nodes. It was formerly known as the R-P314 Haplogroup Project. P314 (aka P314.2) occurs in a second bottleneck group of 'equivalent' SNPs further down the tree than Z16526 and its own 'equivalents'. Membership is divided into four principal groups. Group 1 (negative for SNP P314) shows names of both Welsh and German origin, breaking away from the remainder about 1000 B.C. Group 2, leading to present day Ogans, a Heaney (there are likely more) but also a Swedish participant then splinters off an estimated 500 years later. Then beyond a further block of SNPs in which Z16534 occurs, the tree splits into Groups 3 and 4 about 140 B.C. The latter includes two Munster subgroups - the names Denn(eh)y, Kennedy, Leahy, Lyons, and O'Meara appear here - as well as names associated with Scotland and more northerly Irish regions - Campbell, Chisholm, Higgins, Keenan, Martin, McAllister, Porter - alongside the name Eubank(s), of uncertain provenance. Within Group 3, the project embraces all McCarthys and O'Callaghans (and variants) who have tested or are predicted positive for SNP L362. In the McCarthy Surname Study it is argued these share descent from Ceallachán of Cashel (d. 954 A.D.).