by CKR
I can’t claim to have followed this sort of thing all that carefully, but a letter in the 23 September Science suggests to me that I may not be completely off base.
The BBC gives some of the background on “mitochondrial Eve.” As far as I understand, their explanation is pretty much correct. Mitochondria are organelles within cells that are passed down through the female line; similar studies can be done of the male line with the Y chromosome.
By considering the distribution of mitochondrial DNA throughout a population, conclusions can be drawn as to who our ancestors were. The distribution of mitochondrial genes seems to indicate that all humans now alive can trace their ancestry to a woman who lived in Africa about 200,000 years ago. This is the woman referred to as “mitochondrial Eve.”
I’ve got no complaint with that. [Nor, I probably should say in these contentious anti-evolution times, do I have with the theory of evolution. Everything I say in this post is based on evolution. Raising questions about the application of a theory is not the same as questioning its basis.]
I see several problems with the name, though. First, the Biblical Eve was a woman who lived with one man, no other people around until they had children. My first reaction when I heard about “mitochondrial Eve” was that the idea of a single woman, presumably accompanied by one or more men, was absurd. Our ancestors must have lived in groups.
It took me a while to recover from the metaphor and realize that “Eve” wasn’t the only woman at the time; somehow all the other female lines died out. Her children were just a little better at surviving than those of the other women who were her contemporaries. A small advantage builds up mightily over hundreds and thousands of generations.
I’m also not happy with the Biblical reference. We’re talking about a situation very different from the Bible’s, and entanglement in the Bible’s creation stories is enough of a problem right now. We could call this woman of 200,000 years ago “the great mother of us all,” too. That’s the title of the painting I posted, from the Hopi tradition. I suspect that she didn’t look like this picture, though, which is an advantage in separating the metaphorical from the real.
But a scientist can form a model first and then develop the mathematics, or she can follow the mathematics to see what kind of model the mathematics describes. Both directions are useful, but individual scientists may be more comfortable with one or the other. I tend toward model first, and it appears to me that the people doing the mitochondrial ancestry studies used the mathematics first approach.
So I’d like a model. Hominids form groups, tribes. Species can form quickly, within a few generations. Is this what happened with humans? Did hairier, slower grandparents wonder at their shorter-faced hairless, talky grandchildren? Did our ancestors, for one reason or another, take to the water like the ancestors of whales, but, unlike them, return to land? Who started talking first? Was there one strange child? Or did barks and growls slowly form into words? Were the newly competent highly sought after as mates or were they outcastes who stuck together?
I’d like to know how we became human, and perhaps that is a different question than those who study mitochondrial DNA and the Y chromosome can answer.
Many thanks to all those at 21 October's dinner party, for helping me to clarify some of my thinking.
Multi-media painting by Paaywma; photo by CKR. Private collection.