B Haplogroup Project Page- Background

Background

Welcome to the web page of Haplogroup B at FTDNA.

This page groups DNA profiles from individuals that have been assigned to haplogroup B, but it is also open to members of other haplogroups who have an interest in furthering our knowledge of the human Y Chromosome Tree.

Haplogroup B is an ancient Y chromosome clade that is almost entirely restricted to Africa. It is the second oldest clade after A, and it is spread very thinly throughout the continent. Today, the highest frequencies of B are found among small hunter-gather populations, and very rarely among populations of African descent outside of Africa. Clues about their ancient origins are also suggested by the fact that members of clades A and B possess click languages, which some anthropologists argue is a remnant of the oldest form of spoken language, belonging, perhaps, to all of our ancestors before their migration out of Africa.

Our knowledge of the genetic origin of this clade, however, is still in flux, given the steady number of mutations being discovered every year, and the renewed interest in studying the basal (African) clades of the human phylogenetic tree. An example of this is the conflicting accounts of the origins of haplogroups A and B in the recent literature.

According to the evidence discussed in a paper by Karafet et al, Clade A is“defined by two mutations (M91 and P97) and contains 12 branches marked with 45 (internal) mutations. This compares with a single defining mutation and a total of 28 internal mutations associated with this clade on the Y Chromosome Consortium (2002) tree. Haplogroup B, according to the same authors, “is defined by four mutations (M60, M181, P85, and P90) and contains 17 branches with 28 internal markers. Like haplogroup A, the B clade is almost entirely restricted to sub-Saharan Africa. B chromosomes are found at their highest frequency among Pygmies, with some lineages being virtually restricted to these ethnic groups”(Karafet, et al, 2008).

In a recent paper, on the other hand, Cruziani et al. refute this view and report that the root of the human phylogenetic tree goes deeper in time, and contains far more diversity that previously thought—including the assertion that clades within haplogroup A cannot be considered as descended from a single common ancestor. In regards to haplogroup B, they contend that it branched out of an earlier clade of A, and is defined by mutation “P97 and, possibly, M91 [which] should be considered to be phylogenetically equivalent to the markers that define haplogroup BT” (Cruziani, et al, 2011). As it is plainly clear, both papers assign conflicting defining genetic markers to clades A and B.

This controversy only reveals that we are living through very exciting times. The studies discussed above show that we should expect more information about our haplogroup and human genetic origins in the years to come. For that reason it is necessary to increase the scope of this project, in terms of membership and exposure, and contribute to the search for our genetic origins.