She lived between 100,000 and 200,000 years ago in southern Africa. These days she’s known as Mitochondrial Eve, but that’s a little misleading. Unlike the Biblical Eve, she wasn’t the first woman nor was she the only woman alive at the time—and there were plenty of men around as well. Still, Mitochondrial Eve was an actual person. We don’t know much about her except that she is the most recent woman to whom everyone alive today—male and female, all 7.6 billion of us—is connected through their mothers by a speck of DNA.
But as important as such a linkage may be to scientists, and despite the role that her namesake plays in Christianity, how significant is she for us? I’m not sure. See what you think.
Every cell in any organism contains small particles that keep the cell alive. The nucleus, carrying the genetic DNA masterplan of the body, is the cell’s control center. Smaller particles carry out other functions. Mitochondria produce energy for the cell. They contain their own, separate bit of DNA because millions of years ago they themselves were free-floating bacteria that were engulfed by cells, proved useful, and took a permanent place in the cell anatomy.
Over time and across countless cell divisions, the DNA in the mitochondria changed in small ways unrelated to the genetic DNA in the nucleus. As a result, the early apes, then the pre-humans, then the earliest modern Homo sapiens all carried the slight variations in mitochondrial DNA that they inherited.
But they inherited them only through he females. Males couldn’t pass theirs along. Why? Because we inherit our cellular structure from mom’s egg. While fathers may deliver their genetic DNA by sperm to the egg, it’s mom’s egg cell itself that grows into the embryo and into all human cells. Complete with the mother’s mitochondria.
Over the course of five thousand generations or so, women around the world passed their variations of mitochondrial DNA to their daughters. Along the way, though, some mothers bore only sons and other women had no children at all. Gradually, all the variations of mitochondrial DNA fizzled out, except one. We all carry it, as did a woman a long time ago, Mitochondrial Eve.
What to make of all this? Compared to the Biblical Eve and her list of firsts—first woman, first human to be curious, first mother—we have little to show for our ancestry from the other Eve, Mitochondrial Eve. And the merging of genetic DNA from our mother and father has by far a greater influence on who we are and what we’re like. By comparison, Mitochondrial Eve is just a woman a very long time ago whom we all happen to be linked with inconsequentially on our mother’s side.
Still, as Siddhartha Mukherjee writes in The Gene, without elaborating, “I find the idea of such a founding mother endlessly mesmerizing.” For Mitochondrial Eve is one of our Most Recent Common Ancestors—an MRCA. The MRCA for any group of organisms, whether the same species or not, is the individual or type after which subsequent generations evolved in different directions. The MRCA of primates (humans as well as chimps, apes, monkeys, baboons) lived 65 million years ago. The MRCA of all animals lived 600 million years ago. And the MRCA of all living things, 3.6 billion years ago. For many people, interesting to know but not so easy to imagine.
But it is possible with some effort to envision the Most Recent Common Ancestor who looked a lot like us. Maybe Mitochondrial Eve’s value lies here: by thinking about her, we may be getting better at wrapping our heads around the reality of even older ancestors who seem impossibly ancient yet who made us what we are.