Haplogroup BT

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Haplogroup BT
Y-DNA tree.GIF
Possible time of origin 70,000-80,000 years BP[citation needed]
Possible place of origin Africa
Ancestor A2-T
Descendants B-M60, CT
Defining mutations Page65.1/SRY1532.1/SRY10831.1, M42, M91, M94, M139, M299, P97, V21, V29, V31, V59, V64, V102, V187, V202, V216, V235

Haplogroup BT M91, also known as Haplogroup A1b2 (and formerly as A4, BR and BCDEF), is a Y-chromosome haplogroup. BT is a subclade of haplogroup A1b (P108) and a sibling of the haplogroup A1b1 (L419/PF712).

Macrohaplogroup BT has been found in populations on every continent, since prehistoric times. It is the progenitor clade of the paternal haplogroups B and CT.

Haplogroup BT has been found in various fossils that were analysed for ancient DNA. Individuals excavated in Malawi at Fingira Rock, which have been dated to 6175-5923 years ago, carried BT (2/2 males; 100%). This paragroup was also observed in a Later Stone Age skeleton at Hora (1/1 males; 100%), dated to 10000-5000 years before present.[1]


The ISOGG tree since 2014 has treated M91 as the defining mutation of BT.[2]

  • B M60, M181, P85, P90
  • CT P9.1, M168, M294

Prior to 2002, there were in academic literature at least seven naming systems for the Y-Chromosome Phylogenetic tree. This led to considerable confusion. In 2002, the major research groups came together and formed the Y-Chromosome Consortium (YCC). They published a joint paper that created a single new tree that all agreed to use.

The revised y-chromosome family tree by Cruciani et al. (2011) compared with the family tree from Karafet et al. (2008). Cruciani et al. (2011) define BT via M91 and P97, and as a consequence, ISOGG has listed BT since February 2012, and treated M91 as defining mutation for BT since 2014.[3]

See also[edit]

Phylogenetic tree of human Y-chromosome DNA haplogroups [χ 1][χ 2]
"Y-chromosomal Adam"
A00 A0-T [χ 3]
A0 A1 [χ 4]
A1a A1b
A1b1 BT
F1  F2  F3  GHIJK
IJ   K
I J     LT [χ 5]  K2
L     T [χ 6] K2a [χ 7] K2b [χ 8]   K2c   K2d  K2e [χ 9]  
K-M2313                K2b1 [χ 10]    P [χ 11]
NO S [χ 12]  M [χ 13]    P1     P2
N O Q     R


  1. ^ Skoglund; et al. (September 21, 2017). "Reconstructing Prehistoric African Population Structure". Cell. 171: 59–71. doi:10.1016/j.cell.2017.08.049. Retrieved 22 September 2017. 
  2. ^ Y-DNA Haplogroup A and its Subclades - 2012 (BT as subclade of A1b-P108) Y-DNA Haplogroup A and its Subclades - 2014 (BT as subclade of A1b-P108); Y-DNA Haplogroup Tree 2015 (BT-M91 listed as subclade of A1a-M31). ISOGG has listed M42 as a mutation characteristic (but not defining) of BT since 2012.
  3. ^ ISOGG Haplogroup A (2012): "BT is shown on this tree, though it is not considered to be a part of Haplogroup A, in order to make it clear that, as a sibling clade of A1b1, BT and all other haplogroups are downstream of A1b. Listed 15 February 2012." (also note that the group labelled "A1b" in the image is the "A0" of ISOGG (2012)).