https://en.wikipedia.org/wiki/Mitochondrial_Eve#Common_misconceptions
Not the only woman
One misconception surrounding mitochondrial Eve is that since all women alive today descended in a direct unbroken female line from her, she must have been the only woman alive at the time.[8][33] However, nuclear DNA studies indicate that the size of the ancient human population never dropped below tens of thousands. Other women living during Eve's time have descendants alive today, but at some point in the past each of their lines of descent did not produce a female who reproduced, thereby breaking the mitochondrial DNA lines of descent.[citation needed]
Not a fixed individual over time
The definition of mitochondrial Eve is fixed, but the person in prehistory who will fit this definition can change, not only because of new discoveries, but also because of unbroken mother-daughter lines coming to an end by chance. It follows from the definition of Mitochondrial Eve that she had at least two daughters who both have unbroken female lineages that have survived to the present day. In every generation mitochondrial lineages end – when a woman with unique mtDNA dies with no daughters. When the mitochondrial lineages of daughters of mitochondrial Eve die out, then the title of "Mitochondrial Eve" shifts forward from the remaining daughter through her matrilineal descendants, until the first descendant is reached who had at least two daughters who both have living, matrilineal descendants. Once a lineage has died out it is irretrievably lost and this mechanism can thus only shift the title of "Mitochondrial Eve" forward in time.
Because mtDNA mapping of humans is very incomplete, the discovery of living mtDNA lines which predate our current concept of "Mitochondrial Eve" could result in the title moving to an earlier woman. This happened to her male counterpart, "Y-chromosomal Adam," when older Y lines from Africa were discovered.
Not necessarily a contemporary of "Y-chromosomal Adam"
Sometimes mitochondrial Eve is assumed to have lived at the same time as Y-chromosomal Adam, from whom all living people are descended patrilineally, perhaps even meeting and mating with him. Even if this were true, which is currently regarded as highly unlikely, this would only be a coincidence. Like mitochondrial "Eve", Y-chromosomal "Adam" probably lived in Africa. A recent study (March 2013) concluded however that "Eve" lived much later than "Adam" – some 140,000 years later.[10] (Earlier studies considered, conversely, that "Eve" lived earlier than "Adam".)[34] More recent studies indicate that mitochondrial Eve and Y-chromosomal Adam may indeed have lived around the same time.[35]
Not the most recent ancestor shared by all humans
Mitochondrial Eve is the most recent common matrilineal ancestor, not the most recent common ancestor. Since the mtDNA is inherited maternally and recombination is either rare or absent, it is relatively easy to track the ancestry of the lineages back to a MRCA; however, this MRCA is valid only when discussing mitochondrial DNA. An approximate sequence from newest to oldest can list various important points in the ancestry of modern human populations:
- -The human MRCA. All humans alive today share a surprisingly recent common ancestor, perhaps even within the last 5,000 years, even for people born on different continents.[36]
- -The identical ancestors point. Just a few thousand years before the most recent single ancestor shared by all living humans was the time at which all humans who were then alive either left no descendants alive today or were common ancestors of all humans alive today. In other words, "each present-day human has exactly the same set of genealogical ancestors" alive at the "identical ancestors point" in time. This is far more recent than when Mitochondrial Eve lived.[36]
- -Mitochondrial Eve, the most recent female-line common ancestor of all living people.
- -"Y-chromosomal Adam", the most recent male-line common ancestor of all living people.
Not the biblical Eve
Owing to its figurative reference to the first woman in the Biblical Book of Genesis, the Mitochondrial Eve theory initially met with enthusiastic endorsement from some young earth creationists, who viewed the theory as a validation of the biblical creation story. Some even went so far as to claim that the Mitochondrial Eve theory disproved evolution.[37][38][39] However, the theory does not suggest any relation between biblical Eve and Mitochondrial Eve because Mitochondrial Eve:
- -is not a fixed individual
- -had a mother
- -was not the only woman of her time, and
- -Y-chromosomal Adam is unlikely to have been her sexual partner, or indeed to have been contemporaneous to her.