The McCarthy Surname Study seeks through Y-DNA analysis to place the various M(a)cCarthy lineages on its series of Y-DNA phylogenetic trees and to identify any genetic markers which might single out groups of M(a)cCart(h)ys or their immediate predecessors. Apart from facilitating family connections among M(a)cCart(h)ys throughout the world, the Study is identifying Y-DNA profiles associated with the leading families of the various MacCarthy septs and with other supplementary agnomina adopted subsequently to distinguish one M(a)cCarthy family grouping from another. Material such as charts, trees and presentations which cannot be accommodated within the webpages provided by FTDNA will be found on our supplementary website at https://mccarthydna.wordpress.com. MEMBERSHIP CRITERIA As indicated on our Results page, only about 30% of M(a)cCarthys can count themselves as paternal descendants of the eponymous Cárthach (d. 1045). These test positive for SNP ZS4606, or usually one of its two apparent 'sons', SNPs A5813 and ZS4598, or any SNPs which have occurred subsequent to these and belong in our 'R-L21 Group B'. Those of other surnames who test positive for any of these SNPs are now considered as progeny of Cárthach's paternal lineages and are welcome to join the Study. However the Study is investigating the origins of all M(a)cCar(t)hys who have acquired this surname through association with Cárthach's male progeny, and thus welcomes any participant who can supply a y-chromosome test sample representing a M(a)cCarthy family not known to have acquired the surname through a recent non-paternity event (NPE) or by corruption of another name, such as MacArthur. McAuliffe, Cremin (and variants) and certain other surnames are also claimed in historical texts to have arisen from Cárthach's male progeny or from association with M(a)cCarthys early in the second millenium. There is as yet no genetic evidence to validate these; however even if their haplotype is not consistent with their placement in the aforementioned R-L21 Group B, the Study continues to welcome, for the time being, McAuliffes with an Irish Type II haplotype (our 'R-L21 Group A') and those Cremins who belong in our R-L21 Group E. Carty is likely to derive from one of a number of independent O'Carty septs scattered around Ireland, while McCartney is usually of an independent origin outside Munster. However, if participants of these names have haplotypes which are arguably representative of McCarthys they will be welcome to join the Study. In a few cases Carty and even Carter has been found to be a corruption of MacCarthy with their Y-DNA profiles placing them among Cárthach's paternal progeny. From the above it will be appreciated that this Study is not concerned with mtDNA profiles. Female McCarthys with an interest in their McCarthy ancestry should persuade their McCarthy husbands, fathers, brothers, male cousins or uncles to participate by taking a Y-DNA test. Autosomal testing (such as Family Finder) is only pertinent to the Study as background information which potentially enhances genealogy implied in a Y-DNA test data. Our Administrator Zena is maintaining a 'Library' of McCarthy pedigrees, published on our Wordpress site. This facility is intended for all project members, but a condition of our accepting autosomal only participants is that they provide, and are willing to have published on this sister site, a verifiable pedigree going back to (and hopefully beyond) a McCarthy male whose name, birthplace and approximate birth date is recorded within the last eight generations. (By default, records pertaining to births less than 100 years ago will be suppressed). The Study also has a public Facebook presence (see below) and a members only forum (the Activity Feed accessed with members' kit numbers and passwords). Potential new members are required to submit a Join Request. Those who have taken, or intend to take, a Y-DNA test in respect of a McCarthy male, or have tested or are suspected positive for SNP ZS4606 irrespective of current surname, will normally be admitted without further ado. Others will need to satisfy, within a month of applying, the criteria stated above relating to the McCarthy Pedigree Library. A condition of membership for those who have tested 37 STR markers and are placed in McCarthy R-L21 Group B is that they will not object to being also joined to the R Z16526 and Subclades Project. This focuses on their pre-second millenium paternal ancestry. Those placed in McCarthy R-L21 Group A will be asked also to join the R1b-CTS4466 Plus Project. ADMINISTRATION The Study is jointly administered by Zena McCarty Paice and Nigel McCarthy. To share the workload and ensure the future of the Study, four Co-administrators also support this Study as indicated below. Please send any queries relating to their specific areas of expertise directly to them, with copy to both Administrators. All other queries should be sent to one of the Administrators with copy to the other. Responsibilities are currently broadly as follows - Zena McCarty Paice - Administrator: Membership, Haplogroup R-U152 genealogy, McCarthy pedigrees, and (where time permits) autosomal DNA queries. - Nigel McCarthy - Administrator: websites content, Y-data analysis and phylogenetic tree development, in 2020 the latter are being shared with his successor in this respect: - Colette O'Sullivan-Nguyen - Co-Administrator: Y-data analysis and phylogenetic tree development. - Matthew McCarty - Co-administrator: McCarthy Y-DNA Facebook moderator (https://www.facebook.com/McCarthyYDNA/) / McCarthy R-L21 Group C genealogy / liaison with MacCarthy Clan Foundation. - Fintan MacCarthy - Co-administrator: maintains the Wordpress website and supports the Administrators in undertaking ad hoc research projects delving deep into lesser used Irish records. - Pádraig Mac Cárthaigh - Co-Administrator: Irish language matters pertaining to the Study.