The chart displayed to the right represents the Y chromosome family tree of mankind,
called a phylogenetic tree. Each major branch is named with a letter, and deeper
branches within the tree are labeled with numbers and letters to note their relationship
to one another. Each branch is thousands or tens of thousands of years old. Because
members of a branch tend to be found in the same region of the world, your haplogroup
assignment identifies your deep ancestral origins.
What is a haplogroup?
The haplogroups are the major branches on the Y chromosome tree, defined single
nucleotide polymorphisms (SNPs), which have accumulated along different lineages
as Y chromosomes are passed from father to son over many generations. All haplogroups
ultimately descend from a single Y chromosome carried by a male that lived in the
distant past. The topology of the Y chromosome tree can be reconstructed by typing
mutations in different human populations – as more SNPs are discovered (e.g., M254),
the structure of the tree changes. Originally, the Y Chromosome Consortium (YCC)
arbitrarily defined 18 haplogroups (A-R), which represent the major divisions of
human diversity based on Y chromosome SNPs. Currently there are 20 haplogroups (A-T).
In turn, each of these major haplogroups has numbered subgroups, or subclades, that
are named with alternating letters and numbers.