Mitochondrial Eve: The Ancestor We All Share
Mitochondrial Eve | Concept Art by Sam Falconer | Source
If you are interested in a specific culture, look at its creation myth. How the world was created, but most importantly — how did people come to inhabit it — , is the nucleus of our sense of identity. Around the globe, indigenous tribes and developed civilizations have always built their entire mythology on one foundation: their version of the answer to “How did it all begin?”
Creation myths have always shaped the values of the culture. And the big and small ways in which it expresses itself.
But what does science say? What is the farthest point in history that we can look into the eyes of an ancestor?
And, above all, what does this tell us about ourselves?
A Woman of Controversy
Since the concept of “Mitochondrial Eve” was presented in 1987, some scientists have called the name “regrettable.” It evokes the image of “the first woman,” a single individual who was the beginning of all.
Reality is far more nuanced.
Why Mitochondria?
A mitochondrion is a very important organelle found in cells. It’s responsible for generating most of the power for the bio-chemical reaction of its cell, along with many other vital functions.
Most of a cell’s DNA is contained in its nucleus. The mitochondrion has its own genome and so holds part of the DNA of the cell.
And it has great protection. Each mitochondrion is surrounded by a double-membrane. The genome inside remains unmixed as it gets passed down. Since it’s completely separate from the rest of the DNA, meiosis doesn’t alter it. During fertilization, there is no mixing of genetic material in the mitochondrion.
And here is the crux of the issue. Only the mother can pass down mitochondrial DNA. If a woman has a son and a daughter, they will both inherit her mitochondrial DNA. Then if each of them has a child, only the daughter will pass it down to the next generation. The son’s child will inherit the mitochondrial DNA from its own mother.
So who is Mitochondrial Eve?
She’s our most recent common female ancestor. The woman whose mitochondrial DNA has been passed down thousands of generations and currently can be found in every single human being on Earth.
She wasn’t the first woman. She was, however, the woman whose DNA line has not gone extinct.
Example chart showing the evolution of mitochondrial DNA | by C. Rottensteiner
Similarly, we have a most recent common male ancestor, “Y-Chromosomal Adam.”
But what makes Mitochondrial Eve special is the mayhem that her discovery — and its implications — caused in the culture. The creation myths of the Western world went to pieces.
Glass Shatters
For centuries people believed that they were, quite literally, created by God. Put on this Earth from above, in a state of separateness and superiority to the natural world. This concept of “divine right” underpinned many tragic episodes of human history.
By the time Charles Darwin formulated his theory of Evolution in his 1859 book “On the Origin of Species,” the Western world had spent centuries colonizing foreign lands with the claim of bringing “civilization” to “savages.” People and natural resources were exploited for the benefit of “superior” nations.
It was 50 years after the official end of slavery in the United States — an institution founded on the belief that white Europeans are inherently superior to Black Africans — that scientists found the first fossils proving the African origins of the human race.
The developed Western civilization that had spent centuries exploiting, pillaging, and subjugating the world was shown that its origins were not different, “better,” or “divine.” In fact, not a superior God, but Africa — the very place that it had ravaged the most and the very people it deemed the least human — held the spark of its creation.
Of course, this notion — known as the “Out of Africa” (OOA) theory — met massive resistance. In the early 20th century people no longer based their arguments on religion, even though the underlying belief of separateness and superiority was still dictating how they reacted.
Scientists presented two alternatives to the OOA theory. The “Candelabra” hypothesis argues — even though there is no precedent for such a phenomenon in any animal or plant on Earth — that early pre-hominid species populated the world and then evolved, in parallel, into the same species: homo sapiens. The “Multi-regional” hypothesis is a softened version of the “Candelabra.” It doesn’t argue for a parallel evolution but for a protohuman species that evolved separately with a lot of inter-breeding.
Armies of defenders rallied behind these theories. They clung to any notion that their origins are not, after all, in Africa.
And then science developed DNA research. And in 1987, Mitochondrial Eve was introduced.
What We Know
DNA research is slow and complicated. We still don’t know much about our genes and their origins. But because of the unique qualities of the mitochondrion: its own genome and how well protected it is, scientists have been able to piece together some of the puzzle.
It’s only a fraction of the picture but we can see it with crystal clarity.
Around 200,000 years ago, a woman lived in the Makgadikgadi Pan, modern-day Botswana. She had at least one daughter. And then, at least one granddaughter. In an uninterrupted matrilinial line, all women today, their mothers, grandmothers, and great-grandmothers, are her descendants. Her mitochondrial DNA exists in every single one of the 7.8 Billion people on Earth.
This woman existed just around the time of the estimated emergence of Homo sapiens and about a hundred thousand years before homo sapiens’ migration towards the rest of the continents during the Ice Age.
This means that whatever DNA research brings in the future, it is impossible to disprove our African origins. Even if we discover evidence of older DNA outside of Africa, we are still predominately homo sapiens.
And homo sapiens can irrefutably trace its matrilineal origins back to the Makgadikgadi Pan in southern Africa.
Makgadikgadi Pan National Park | Botswana | Picture by Discover Africa
Currently one of the world’s largest salt flats, the Makgadikgadi pan in modern-day Botswana used to be a vast lush wetland for tens of thousands of years. Research shows that our ancestors started moving North as more wetlands emerged due to warming weather, around a hundred thousand years ago.
Was this the birthplace and homeland of humankind?
With our limited knowledge of our DNA, a lot of scientists warn against such sentimental labels.
But once some geneticists stopped focusing their DNA research on Europe and started looking into Africa, evidence started mounting. After studying over 1,200 indigenous tribes in Southern Africa, scientists confirmed that the Khoe-San people — hunter-gatherers whose language is notable for its clicking sounds — descend from people who split off from the main homo sapiens branch around 100,000 years ago. This means their DNA did not intermix as much as the rest of us. And their genes contain higher amounts of Mitochondrial Eve’s DNA. This places her squarely in the Makgadikgadi pan.
In 2014, an even closer relative of Eve was found. The skeleton of a man who had died in 315 BC contained the highest levels of her mitochondrial DNA. Further investigation showed that his lineage diverged from the main branch 50,000 years before the Khoe-San people. A geneticist at Harvard University said, “It is the first old ancient DNA ever to be convincingly extracted from an African context.”
Many scientists still caution us that we know too little about our DNA makeup, and we shouldn’t become too fond of this one idea of the origins of the human race. And yet, the more scientists research, the more evidence for it they find.
So Who Are We?
The creation myth of the Western civilization crumbled to pieces, even though to this day many people are still working hard to artificially prop it up.
The very notion of an African Eve caused tectonic rifts in the culture. She was discovered before the advancement of Y-Chromosome research, so before we could look for an “Adam.”
Honest scientific research presented the image of the most marginalized figure —a Black African woman — as the mother of humankind.
The theory met open hostility. A notable illustration of the vitriol bubbling under the surface was the reactions during a big setback in 1992 when the research results were still shaky and contradictory. Articles spoke about the theory as if it was an actual woman who had been punished.
Science Magazine wrote, “Eve is still reeling from the blow.” USA Today wrote, “It’s time to write Eve’s obituary.” Newsweek wrote, “Eve takes another fall.” Scientists were in consensus that this also meant a setback for the “Out of Africa” theory. A paleontologist from the Natural History Museum in London was quoted saying, “Eve may have had a quick kick on the backside, but the out-of-Africa hypothesis certainly isn’t dead.” In the article, “Mitochondrial Eve: Wounded, But Not Yet Dead,” Science Magazine describes the scientific setback as Eve’s “fall from grace.”
The glee was not meant to last. With the sophistication of DNA research, Mitochondrial Eve prevailed.
It was always going to. As much as the theory of a common African female ancestor was met with disbelief, there had been evidence for it — for centuries if not millennia — in the collective psyche of humans. Even in Christianized Medieval Europe, hundreds of Black Madonna statues and pictures rose to prominence, much to the discomfort and derision of the Church.
But just like the Church handled the Black Madonnas, our modern culture seems to do only one thing when faced with the now-irrefutable reality of our common African roots: downplay it, and quickly move on to something else.
So what is the answer to the question “Who are we?” now that for a hundred years we have known more about our origins than ever before? The answer seems to be, “Something we still refuse to see.”
This piece was originally published in the magazine History of Yesterday.
