The history of the North African mitochondrial DNA haplogroup U6 gene flow into the African, Eurasian and American continents: "Human mitochondrial DNA haplogroup U6 has been considered as a molecular signal of a Paleolithic return to North Africa of modern humans from southwestern Asia." "As secondary branch of the Eurasian macro-haplogroup N, phylogenetically, U6 is a non-African lineage and represents a back-migration to Africa. [...] Our own estimate of the time to the most recent common ancestor (TMRCA) for U6, using the current enlarged set of complete sequences, is 35.3 (24.6 - 46.4) ky. This period coincides with the Early Upper Paleolithic (EUP) period, prior to the Last Glacial Maximum, but cold and dry enough to force a North African coastal route."
