Mitochondria are the power plants of cells and have their own DNA. Mitochondrial DNA (mtDNA) is inherited only from the mother, and defects in mtDNA can cause a multitude of problems. In his research, Dr. Douglas C. Wallace has shown that mutations in mtDNA can cause certain forms of diabetes mellitus, cardiac and muscle disease, blindness, deafness, seizures, movement disorders, and dementias. mtDNA mutations can accumulate in our tissue with age, and this may make up part of our internal aging clock. Moreover, the levels of these age-related mtDNA mutations are higher in brains of those with Alzheimer disease and Huntington's disease, suggesting that mtDNA mutations may be a common feature of degenerative diseases.
In studying mitochondrial genetic evolution, Wallace's research group has used mtDNA variation to reconstruct the origins and ancient migrations of women. His group has found a single mtDNA tree that arose in southern African some 200,000 years ago, with descendants migrating out of Africa evolving into specific mtDNA lineages in Europe, Asia, and the Americas. The realization that all mtDNA lineages trace back to a single African origin has been popularly called the "Mitochondrial Eve" theory.