R1b1a (R-P297)
R1b1a is defined by the presence of SNP marker P297. In 2008 this polymorphism was recognised to combine M73 and M269 into one R1b1a cluster. The majority of Eurasian R1b is within this clade, representing a very large modern population. Although P297 itself has not yet been much tested for, the same population has been relatively well studied in terms of other markers. Therefore the branching within this clade can be explained in relatively high detail below.
Read more about this topic: Haplogroup R1b (Y-DNA), R1b (R-M343)