MITOCHONDRIAL DIVERSITY AND THE ORIGINS OF AFRICAN AND EUROPEAN CATTLE

The nature of domestic cattle origins in Africa are unclear as archaeo logical data are relatively sparse. The earliest domesticates were hum pless, or Bos taurus, in morphology and may have shared a common origi n with the ancestors of European cattle in the Near East. Alternativel y, local strains of the wild ox, the aurochs, may have been adopted by peoples in either continent either before or after cultural influence from the Levant. This study examines mitochondrial DNA displacement l oop sequence variation in 90 extant bovines drawn from Africa, Europe, and India. Phylogeny estimation and analysis of molecular variance ve rify that sequences cluster significantly into continental groups. The Indian Bos indicus samples are most markedly distinct from the others , which is indicative of a B. taurus nature for both European and Afri can ancestors. When a calibration of sequence divergence is performed using comparisons with bison sequences and an estimate of 1 Myr since the Bison/Bos Leptobos common ancestor, estimates of 117-275,000 B.P. and 22-26,000 B.P. are obtained for the separation between Indians and others and between African and European ancestors, respectively. As c attle domestication is thought to have occurred approximately 10,000 B .P., these estimates suggest the domestication of genetically discrete aurochsen strains as the origins of each continental population. Addi tionally, patterns of variation that are indicative of population expa nsions (probably associated with the domestication process) are discer nible in Africa and Europe. Notably, the genetic signatures of these e xpansions are clearly younger than the corresponding signature of Afri can/European divergence.