Mitochondrial Eve: Encyclopedia II - Mitochondrial Eve - Matrilineal descent

Mitochondrial Eve - Matrilineal descent

Although Mitochondrial Eve was named after Eve of the Genesis creation myth, this has led to some misunderstandings among the general public. A common misconception is that Mitochondrial Eve was the only living female of her time — she was not (indeed, had she been, humanity would have probably become extinct). Rather, at all times during humanity's existence there has been a large population of humans. Many women alive at the same time as Mitochondrial Eve have descendants alive today. However, only Mitochondrial Eve produced an unbroken line of daughters that persists today — each of the other matrilineal lineages was broken when a woman had only sons, or no children at all.

Imagine a family tree of all humans living today. Now imagine a line from each individual to their mother, and continue those lines from each of those mothers to their mothers, and so on. Going back through time the lineages will converge as sisters share the same mother. The further back in time one goes, the fewer lineages there will be until only one lineage is left — this is the common matrilineal ancestor of all the humans we started with, i.e. Mitochondrial Eve.

Now, going in the opposite direction of the family tree (from ancient times to today), imagine the same line, which now connects mothers to their daughters. Starting with the entire human population alive around 150,000 years ago, lineages will become extinct as mothers die childless or only have male children. Eventually, only a single lineage remains, which is the same as before.

Mitochondrial Eve was the most recent matrilineal ancestor of humans alive today. However, at times in the past, as certain lineages died out, the status of common matrilineal ancestor would have been passed to a different woman. For example, the common matrilineal ancestor of the population alive at the time of our Mitochondrial Eve would have lived still further back in time.

The smaller a population, the more quickly matrilineal lineages converge.

Mitochondrial Eve - Most recent common ancestor

Mitochondrial Eve is the most recent common matrilineal (female-lineage) ancestor, not the most recent common ancestor (MRCA) of all humans. The MRCA's offspring have led to all living humans, but Mitochondrial Eve must be traced only through female lineage, so she is estimated to have lived much longer ago than the MRCA. While Mitochondrial Eve is thought to have been living around 150,000 years ago, the MRCA is estimated to have been living within historical times (3000 BC - 1000 AD), though the MRCA was probably less recent than that when accounting for long isolated peoples.

Adapted from the Wikipedia article "Matrilineal descent", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki