Mitochondrial Eve (mt-mrca) is the name given by researchers to the woman who is defined as the matrilineal most recent common ancestor (MRCA) for all currently living humans. Passed down from mothers to offspring for over a hundred thousand years, her mitochondrial DNA (mtDNA) is now found in all living humans: every mtDNA in every living person is derived from hers. Mitochondrial Eve is the female counterpart of Y-chromosomal Adam, the patrilineal most recent common ancestor, although they lived at different times.
She is believed to have lived about 140,000 years ago in what is now Ethiopia, Kenya or Tanzania. The time she lived is calculated based on the molecular clock technique of correlating elapsed time with observed genetic drift.
Mitochondrial Eve is the most recent common ancestor (MRCA) of all humans via the mitochondrial DNA pathway, not the unqualified MRCA of all humanity. All living humans can trace their ancestry back to the MRCA via at least one of their parents, but Mitochondrial Eve can only be reached via the maternal line. Therefore, she necessarily lived much longer ago than the MRCA of all humanity.
The existence of Mitochondrial Eve and Y-chromosomal Adam does not imply the existence of population bottlenecks or a first couple. They each lived within a large human population at a different time. Some of their contemporaries have no living descendants today, and others are ancestors of all people alive today. No contemporary of Mitochondrial Eve or Y-chromosomal Adam is an ancestor of only a subset of people alive today, because both of them lived much longer ago than the identical ancestors point.
