Haplogroup K2b1 (Y-DNA)  Haplogroup K2b1, known sometimes as haplogroup MS, is a human Y-DNA haplogroup, defined by SNPs P397 and P399. It has a complex, diverse and not-yet fully understood internal structure; its downstream descendants include the major haplogroups Haplogroup M (P256) and Haplogroup S (M230). It is not clear at present whether the basal paragroup K2b1* is carried by any living males. Individuals carrying subclades of K2b1 are found primarily among Papuan peoples, Micronesian peoples, indigenous Australians, and Polynesians. K2b1 is a direct descendant of K2b – known previously as Haplogroup MPS. Its only primary branches are: the major haplogroups S (B254), also known as K2b1a (and previously known as Haplogroup S1 or K2b1a4) and M (P256), also known as K2b1b (previously K2b1d). K2b1 is strongly associated with the indigenous peoples of Melanesia (especially the island of New Guinea) and Micronesia, and to a lesser extent Polynesia, where it is generally found only among 5–10% of males. It is found in 83% of males in Papua New Guinea, and up to 60% in the Aeta of the Philippines. The vast majority of living males carrying K2b1 are members of downstream subclades within the major haplogroups M (also known as K2b1b) and S (K2b1a). Studies of indigenous Australian Y-DNA published in 2014 and 2015, suggest that, before contact with Europeans, about 29% of Australian Aboriginal or Torres Strait Islander males belonged to downstream subclades of K2b1. That is, up to 27% indigenous Australian males carry haplogroup S1a1a1 (S-P308; previously known as K2b1a1 or K-P308), and one study found that approximately 2.0% – i.e. 0.9% (11 individuals) of the sample in a study in which 45% of the total was deemed to be non-indigenous – belonged to haplogroup M1 (M-M4; also known as M-M186 and known previously as haplogroup K2b1d1).