Mitochondrial Eve is the most recent common matrilineal ancestor, not the most recent common ancestor (MRCA) of all humans. The MRCA's offspring have led to all living humans via sons and daughters, but Mitochondrial Eve must be traced only through female lineages, so she is estimated to have lived much longer ago than the MRCA. While Mitochondrial Eve is thought to have been living around 140,000 years ago, according to probabilistic studies,[2] the MRCA could have been living as recently as 3,000 years ago.[3]
Allan Wilson's naming Mitochondrial Eve[4] after Eve of the Genesis creation story has led to some misunderstandings among the general public. A common misconception is that Mitochondrial Eve was the only living human female of her time. While it is theoretically possible that she was the only human female of her time; had she been the only living female of her time, humanity would most likely have become extinct due to an extreme population bottleneck.
Indeed, not only were many women alive at the same time as Mitochondrial Eve but many of them have descendants alive today. They may have left descendants via either son or daughters (and grandsons or granddaughters, and so on). Nuclear genes from these contemporary women of Mitochondrial Eve are present in today's population, but mitochondrial DNA from them is not.[1]
What distinguishes Mitochondrial Eve (and her matrilineal ancestors) from all her female contemporaries is that she has a purely matrilineal line of descent to all humans alive today, whereas all her female contemporaries with descendants alive today have at least one male in every line of descent. Because mitochondrial DNA is only passed through matrilineal descent, all humans alive today have mitochondrial DNA that is traceable back to Mitochondrial Eve.
Furthermore, it can be shown that every female contemporary of Mitochondrial Eve either has no living descendant today or is an ancestor to all living people. Starting with 'the' MRCA at around 3,000 years ago, one can trace all ancestors of the MRCA backward in time. At every ancestral generation, more and more ancestors (via both paternal and maternal lines) of MRCA are found. These ancestors are by definition also common ancestors of all living people. Eventually, there will be a point in past where all humans can be divided into two groups: those who left no descendants today and those who are common ancestors of all living humans today. This point in time is termed the identical ancestors point and is estimated to be between 5,000 and 15,000 years ago. Since Mitochondrial Eve is estimated to have lived more than hundred thousand years before the identical ancestors point, every woman contemporary to her is either not an ancestor of any living people, or a common ancestor of all living people.
