The high mtDNA mutation rate means that there is considerable naturally occurring mtDNA variation in human populations. Using this variation, Dr. Wallace and colleagues have been able reconstruct the ancient migrations of women as they migrated out of Africa and populated the various continents. Among other insights, these studies have revealed that Homo sapiens originated about 130,000 years ago. Through the study of maternally transmitted diseases, Dr. Wallace's group has shown that a variety of rare and common diseases can result from mtDNA mutations.
Additional studies focus on the accumulation of somatic mtDNA mutation in post-mitotic tissues.
The results of these investigations have suggested that the accumulation of somatic mtDNA mutations may play an important role in human aging and the progression of degenerative diseases. These mice develop heart and muscle disease. These animals die within 8 days of birth from heart failure. However, injection of chemical mimics of SOD can rescue the animals. However, if the drug does not cross the blood brain barrier, the animals develop neurodegenerative disease.