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Mitochondrial DNAMitochondrial DNA has properties which enable it to give useful insights into evolution. [Cann et al. 1987] published an important paper describing the results and interpretation of their mtDNA analysis of different living human populations. They found significantly more variation among the African population than among others, and less variation than is found in African Ape populations.
They proposed a phylogenetic tree of human relationships that has proved highly controversial, with the line leading back to one African woman ("Eve") who lived between 100-200,000 years ago. Critics have argued, among other criticisms, that the techniques used by Rebecca Cann and her associates were inaccurate. Alternative trees have also been constructed to show that an African origin is not the only possibility. The debate goes on. See Chapter 4 in [Lewin 1993] and [Boyd & Silk 1997] , pp 491-498, for more discussion. The important point to note here is that there may have been successive waves of colonisation of the Old World from Africa. Thus an initial widespread population of Homo erectus which migrated out of Africa might have been replaced by a later wave of Homo sapiens colonists originating in Africa. |