mtDNA analysis in ancient Nubians supports the existence of gene flow between sub-Sahara and North Africa in the Nile Valley

Abstract

The Hpal (np3,592) mitochondrial DNA marker is a selectively neutral mutation that is very common in sub-Saharan Africa and is almost absent in North African and European populations. It has been screened in a Meroitic sample from ancient Nubia through PCR amplification and posterior enzyme digestion, to evaluate the sub-Saharan genetic influences in this population. From 29 individuals analysed, only 15 yield positive amplifications, four of them (26.7%) displaying the sub-Saharan African marker. Hpa 1 (np3,592) marker is present in the sub-Saharan populations at a frequency of 68.7 on average. Thus, the frequency of genes from this area in the Merotic Nubian population can be estimated at around 39% (with a confidence interval from 22% to 55%). The frequency obtained fits in a south-north decreasing gradient of Hpa I (np3,592) along the African continent. Results suggest that morphological changes observed historically in the Nubian populations are more likely to be due to the existence of south-north gene flow through the Nile Valley than to in-situ evolution.