In the body cell, there are two kinds of DNA that are specifically inherited from mother to child, namely one of the X chromosomes in the cell nucleus, and mitochondrial DNA. However, only boys inherit X chromosomes exclusively from their mothers, which makes it of little use to determine biological relationships along lines spanning several generations. X chromosomes will not be further covered here.
Each cell contains up to a thousand mitochondria carrying their own DNA, called mitochondrial DNA, or mtDNA for short. Since each child inherits mtDNA from its mother only, without recombining with mtDNA from the father, the base sequence can pass unchanged for hundreds or even thousands of generations along a direct maternal line. Mutations occur with statistically predictable intervals in parts of the mtDNA without affecting the essential functions of the mitochondria or the cell as a whole, which allows the modified part to be used as an indicator of the genetic distance between two individuals. With numerous samples, mutation patterns can show relationships within and between large populations. A group of individuals sharing identical or similar mtDNA, and thus a common maternal ancestor, is called a clan, and the most recent maternal ancestor of all the members of the clan is defined as the clan mother.
Based on analysis of mtDNA mutations and archaelogical evidence, it has been determined that all human beings alive today descend along maternal lines from a single woman, living in Africa approximately 150,000 years ago, and for this reason dubbed Mitochondrial Eve. The following are the maternal clans of the world as identified and named by Bryan Sykes, Oxford University, arranged by similarity in mtDNA mutations (for clans outside Africa, see Lara).
Updated 2002-12-17
Anders Andersson
