Human Y Chromosome Haplogroup R-V88: A Paternal Genetic Record of Early Mid Holocene trans-Saharan Connections and the Spread of Chadic Languages

Eur J Hum Genet. 2010 Jul;18(7):800-7. doi: 10.1038/ejhg.2009.231. Epub 2010 Jan 6.

Abstract

Although human Y chromosomes belonging to haplogroup R1b are quite rare in Africa, being found mainly in Asia and Europe, a group of chromosomes within the paragroup R-P25(*) are found concentrated in the central-western part of the African continent, where they can be detected at frequencies as high as 95%. Phylogenetic evidence and coalescence time estimates suggest that R-P25(*) chromosomes (or their phylogenetic ancestor) may have been carried to Africa by an Asia-to-Africa back migration in prehistoric times. Here, we describe six new mutations that define the relationships among the African R-P25(*) Y chromosomes and between these African chromosomes and earlier reported R-P25 Eurasian sub-lineages. The incorporation of these new mutations into a phylogeny of the R1b haplogroup led to the identification of a new clade (R1b1a or R-V88) encompassing all the African R-P25(*) and about half of the few European/west Asian R-P25(*) chromosomes. A worldwide phylogeographic analysis of the R1b haplogroup provided strong support to the Asia-to-Africa back-migration hypothesis. The analysis of the distribution of the R-V88 haplogroup in >1800 males from 69 African populations revealed a striking genetic contiguity between the Chadic-speaking peoples from the central Sahel and several other Afroasiatic-speaking groups from North Africa. The R-V88 coalescence time was estimated at 9.2-5.6 [corrected] kya, in the early mid Holocene. We suggest that R-V88 is a paternal genetic record of the proposed mid-Holocene migration of proto-Chadic Afroasiatic speakers through the Central Sahara into the Lake Chad Basin, and geomorphological evidence is consistent with this view.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Africa, Northern
  • Asia
  • Chad
  • Chromosomes, Human, Y / genetics*
  • Emigration and Immigration*
  • Fathers*
  • Geography
  • Haplotypes / genetics*
  • Humans
  • Language*
  • Male
  • Microsatellite Repeats / genetics
  • Phylogeny*
  • Time Factors