Mitochondrial DNA Mutation Rates David A. Plaisted Recently an attempt was made to estimate the age of the human race using mitochondrial DNA. This material is inherited always from mother to children only. By measuring the difference in mitochondrial DNA among many individuals, the age of the common maternal ancestor of humanity was estimated at about 200,000 years. A problem is that rates of mutation are not known by direct measurement, and are often computed based on assumed evolutionary time scales. Thus all of these age estimates could be greatly in error. In fact, many different rates of mutation are...