Haplogroups
 

There have been at least seven systems in use in the scientific community for defining and naming Haplogroups. These various systems, which assigned different names to Haplogroups, often led to confusion. Depending on which system was utilized in the literature you read, Haplogroups had different names and definitions.  To solve this problem, the Y Chromosome Consortium developed a new system to name Haplogroups and subgroups.

The new naming system developed by the Y Chromosome Consortium was designed to easily accommodate expansion, as new Haplogroups are discovered.  This new system identifies and names the current known Y-Haplogroups that have been discovered.

A Haplogroup is defined as all the male descendants of the single person who first showed a SNP (Single Nucleotide Polymorphism) mutation.  A SNP mutation identifies a group of people who had a common ancestor far back in time, since SNP's rarely mutate.  Each member of a Haplogroup would have the same SNP mutation as the common ancestor.  These mutations are extremely rare, and identify a group of people over a period of tens of thousands of years.

The Y Chromosome Consortium has defined 18 major Haplogroups, called A through R, using capital letters. Each of these major Haplogroups, which are also called clades, can have subgroups, which are called subclades. The 18 major groups at the top level, A through R, represent the major divisions of human diversity based on SNPs on the Y chromosome.

Subgroups have a numeric name, which follows the Haplogroup name.  For example, Haplogroup E has 3 subgroups, called E1, E2, and E3.  There is also a subgroup E*, which are those that belong to Haplogroup E, but do not belong to one of the 3 defined subgroups, E1, E2, or E3.

If a subgroup has subgroups, they would be labeled with a lower case alphabetic character, such as E1b1a or E1b1b.

The new Haplogroup database at FamilyTreeDNA.com utilizes this new naming system developed by the Y Chromosome Consortium.  On your search results page for Haplogroup, you will see the Haplogroup of those who match or are a close match to your Y chromosome test result.  Depending on your Haplogroup search results, you will see Haplogroups such as I, J2, I1b, R1b.  All Family Tree DNA explanations and terminology will utilize the
emerging standard defined in the Y Chromosome Consortium paper.

The Y Chromosome Consortium scientific paper, which describes the Haplogroup naming system, can be found at the link below:

http://ycc.biosci.arizona.edu/nomenclature_system/frontpage.html

For a single page graphic representation of the Y Chromosome Haplogroup tree, please see:

http://www.familytreedna.com/haplotree.html or http://ycc.biosci.arizona.edu/nomenclature_system/fig1.html