We are particularly interested in working with men who show an unusual YDNA marker, called a STR marker, which represents an historical mutation that defines one very small branch of the YDNA tree.  This mutation appears to have emerged in Europe over 1400 years before present. This STR marker can be identified with a 37-marker or larger YDNA test on FTDNA.  The STR marker is DYS438 and has a value of 8 rather than the usual value of 10. It is found in a tiny percentage of men of European origin including families with variations of the surname Tilley and Tilly. 

Another Group Project, L38, will cover a much larger range of information and we recommend you join them also, if you are in the haplogroup heading, or have interest in that haplogroup.