Tracing Mitochondrial DNA

In the January 2007 issue of Scientific American, M. Sivak of Irvington, NY asked the experts:

How do researchers trace mitochondrial DNA over centuries?

Ber Ely, a biologist at the University of South Carolina, responded:

Mitochondrial DNA (mtDNA) does not change very much, if at all, from generation to generation. The mtDNA passes only from a mother to her children; fathers cannot impart their mtDNA.

Mutations (changes) do occur in mtDNA but not often—less frequently than once per 100 descendants. Therefore, a person’s mtDNA is probably identical to that of his or her direct maternal ancestor a dozen generations back, and this shared inheritance can be used to connect people across large spans of time. For example, if a particular type of mtDNA were found primarily in Africa, then we could conclude that people from elsewhere in the world who had that type of mtDNA had a maternal ancestor from Africa.

This was an excerpt of the answer which will probably be online for nonsubscribers soon. Read more about mitochondrial DNA in genetics quiz #14.

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