In the Map tab, type in a SNP or surname and press the Enter key or the Go button. Use the Options choices to see more detail.
Select from the Examples menu or click for a random SNP. Option-click for a random surname.

This tool may give you hints about where and when your paternal ancestors lived but it cannot be definitive because it relies on probabilities, incomplete data, and often fine differences. To reduce visual clutter the map may show just one path, but always review the table(s) under the Details tab and draw your own conclusions about the likelihood of one county or one SNP versus another.

Treat SNP and path locations as hints and possibilities but not genealogical fact. A quality control study of nearly 500 users who have entered precise ancestral coordinates suggests that the average error in SNP location is about 160 km; see http://scaledinnovation.com/gg/gg.html?rr=biMapping#h8. Sometimes the oddities of statistics imply wild paths through Wales or the Shetlands (see below), and remember that while your surname may have been most prevalent in one county, a specific ancestor could always have lived somewhere else.

Combining Y SNP data with comprehensive census data can be powerful -- and confusing. The table below highlights to indicate what the map shows, according to your choices.

Type of Input	Options Choice	Detail Level	Resulting Display
one SNP	Show ancestors	low	Paternal ancestry path shown as green line ending at labeled SNP origin; ancestor SNPs color-coded by epoch.
		medium	As above, with branch arrows showing paths of other descendant lines from common ancestors, and dashed circles showing location uncertainty.
		high	Alternative input SNP locations shown as pie charts showing surnames used to estimate location and size proportionate to total surname prevalence.
	Show descendants	low	Heatmap shows general location of descendant SNPs.
		medium	All descendant SNPs shown as triangles, color-coded by epoch.
		high	As above plus paths from input SNP to descendant SNPs.
multiple SNPs	Show ancestors	low	Same as above but paths color-coded by SNP
		medium	As above, color-coded by SNP.
		high	Alternative input SNP locations shown as pie charts with slice sizes proportionate to total surname prevalence.
	Show descendants	low	Heatmap shows general location of all descendant SNPs.
		medium	All descendant SNPs shown as triangles, color-coded by parent SNP.
		high	As above plus paths to descendant SNPs.
one surname		low	Heatmap showing general surname prevalence, by percent in county or total as selected.
		medium	Surname prevalence proportionate to county dot areas. Dashed circle encloses 80% of total prevalence.
		high	Possible SNPs associated with this surname shown with ancestral path; also see Details tab for SNP names, dates, data, and link to full tree.
multiple surnames, or one surname with wildcard spelling		low	Heatmap showing total surname prevalence, by percent in county or total as selected.
		medium	County pie charts with area proportionate to prevalence and segments color-coded by surname.
		high	As above, SNPs deduced from multiple surnames.

The choice of prevalence by percent in county or by total applies to all surname displays.

Names here are geographic and not political, thus 'British Isles' refers to Great Britain, Ireland, the Isle of Man, Hebrides, Orkneys, Shetlands, and Channel Islands. Ireland is used here as the name of the island, not the country, especially since the surname-by-county data used here, Griffith's Valuation of 1825-1865, was completed before the political partition of 1921.

Many thanks to Maurice Gleeson and Keith MacGregor for continuous ideas, patience, and feedback. This project began with Keith's invitation and manual efforts to match up Y DNA with Scottish clan history for a conference. Early experiments showed that the scope could be far broader, and given the very high Anglo-Scots-Irish participation at FTDNA, and when Covid19 canceled the conference, there was suddenly time and reason to build the tool. Thanks also to Shane Wilson for Irish census data, Tom Patterson for the Natural Earth background map, FTDNA for making the Y haplotree accessible, and all of the crowd at David Langton's England-EIJ FTDNA project for early feedback about the maps and methods.

The methods here are different from those used in SNP Tracker. In SNP Tracker, older SNPs are located by the archaeological literature and post-Bronze Age SNPs are generally located as weighted averages of user-entered national origins. In this tool, again a handful of older SNPs are hand-placed based on historic evidence, but the majority of locations are based on matches between surnames in the Y haplotree and surnames in 19th century British and Irish census data. See details at http://scaledinnovation.com/gg/gg.html?rr=biMapping

Single Surnames: The most common situation is a search with a single surname, or with a SNP associated with a single surname which is increasingly common as BigY identifies recent terminal SNPs originating long after surnames arose in the 11th-13th centuries. The census data is searched for just that name: in fortunate cases the name is rare and uniquely located, like Keig, Cretney, or Kermode from the Isle of Man, and it's easy to suggest a possible ancestral location. But if the name was widespread, like Smith or Taylor, there is really no sure way to say where this lineage arose, even though one country will have always the highest prevalence.

Multiple Surnames with Common Y Ancestry: A SNP's place of origin can be much better estimated when there are two or more surnames associated with it, either by known history or by surnames added to the Y tree. This is well illustrated by several clan-related SNPs that spawn their own websites and societies; click these examples and look at the surnames in the Details tab: R-L226 (Ua Briain), R-M222 (Uí Néill), R-L1335 (Alpin), I-L126 (Isles), R-CTS2187 (Little Scottish).

This power of coincidence can also be used to find which SNP(s) may attach to two or more surnames. Because of the sparseness of DNA testing and the high likelihood of lineage extinction, most SNPs originating around 3000 years ago are still single-surname http://scaledinnovation.com/gg/gg.html?rr=biMapping . Examples where two or three surnames define a SNP and its location are Morrison and McCown, Skaggs and Keig, Newman and Potter, Frame, Hamilton, and Scruggs, O'Leary and Cotter, Black,McFarlane, Hughes,McDaniel,Duffy. The Morrison-McCown case is written up in detail here http://scaledinnovation.com/gg/gg.html?rr=snpClans#h5

Boundary Identification: SNP Tracker relies on user-entered national origins for its post-Bronze Age locations. These data are too coarse-grained for location to the county level, but they can be used to estimate the SNPs that come immediately before and after a given Y lineage's migration to the British Isles, or when an R-L21 descendant line crossed from England into Scotland or Ireland. The pruning and bias that this offers greatly simplifies and improves the results of the census-based methods above. Details and examples are written up here http://scaledinnovation.com/gg/gg.html?rr=findingBoundaries .

Thanks to BigY DNA testing the Y SNP tree has grown to the point where many terminal SNPs now overlap the timescale of paper genealogy; this means that some men are able to pinpoint their SNP origins within one or two generations. I can add a precise location for you if the following conditions are met:

• You have a SNP of known location in Britain or Ireland and formation date after 1600.
• This SNP does not conflict with any other surnames or families unknown to you.
• In your FTDNA profile, you have entered your paternal surname at Account Settings > Genealogy > Surnames.
• Your email includes the SNP name, your paternal surname, the SNP formation date, and SNP origin latitude and longitude in decimal degrees, not degrees/minutes/seconds.
• You agree that anyone else may view this information.

This tool is entirely free and it comes with no guarantees. I have tried to make the maps fair and accurate but there will always be gaps and biases in the data. Results can change as new DNA data arrives, especially if users enter ancestal surnames where there were none before.

Please tell me about your ideas for improvement and stories where this tool has been of particular interest to you.

Rob Spencer