Mitochondrial Eve as she is called, lived about 200,000 years ago most likely somewhere in Africa. Mitochondrial Eve refers to the most recent common matrilineal ancestor from whom all living humans are descended. Mitochondrial genomes can be used to measure modern humans' genetic links back to "Mitochondrial Eve" because mitochondria are inherited only through females and in this way humans' genetic past can be traced. However, mutations accumulate over time and therefore, people descending from a common ancestor will have increasingly different DNA. This accounts for the vast variety in people of the world today as seen below.