Y-Abdullah and Mitochondrial Yvonne

There’s a Dennis Venema article, and thread, over on BioLogos about Y-chromosome Adam and Mitochondrial Eve. It’s mainly factual and not particularly controversial, but has attracted a lot of discussion. That’s pretty much exclusively because it corrects claims on the Reasons to Believe website that this genetic work confirms the existence of a single couple as progenitors of the human race. For the reasons why this isn’t so, it’s a good article to read.

As you’ll know if you’ve read about this subject (or have just come back from BioLogos) the studies don’t show a single set of parents, or even near contemporaries, though they do suggest one or more population bottlenecks which autosomal studies indicate never took us lower than, maybe, ten thousand individuals.

For some reason (maybe because BioLogos has recently run his own series on vertebrate limbs) Steve Mathieson has been more active than Dennis in fielding the queries of doubters. As he rightly points out, the issue is a very straightforward one of population genetics, of how genes get fixed in a population (or in this case, large and uniquely traceable chunks of DNA like mitochondria and Y-chromosomes). It’s also about how any gene universally present can be traced to its source in an individual and, at least approximately, to a time. And of course, it also implies that all the other variants became extinct for any number of reasons. Probably the most important result was its confirmation of the “out of Africa” hypothesis.

So the real science has shown examples of two genes that date back 200K years for female mitochondria, and 60K for the Y-chromosome (or according to a 2011 paper cited in Wikipedia 142K years – the genetic clock isn’t the most accurate timepiece in the world, it seems). So the species is older than that, as the study of other genes would no doubt show, just as some genes would have become fixed much more recently.

In other words,  apart from the rough size of the poulation then, it’s taught us nothing fundamental about human origins that we didn’t broadly know in Darwin’s time. So why has it become a cause for rejoicing amongst YECs, and for at least some confusion amongst the lay-public generally? Is it, as Dennis and Steve seemed to be suggesting, because population genetics is a bit tricky for outsiders to master? Or is it another manifestation of the bad science of Creationists?

I well remember the original Cann-Stoneking-Wilson paper in Nature getting into the popular press in 1987. And when I read about it in the Daily Telegraph, or wherever, there was already reference to”Eve”. No such appellation appears in the Nature  abstract, or in the article as far as I know. Whether its origin was a quip by one of the researchers, or the work of some copy-editor at Reuters, I don’t know. But it was good publicity for what, in scientific terms, was not a world-shatteringly general interest story. “Mitochondrial DNA shown to have become fixed in humans 200,000 years ago” would hardly have had the same ring.

By the time I bought my paperback guide to palaeogenetics in 2002, though, Y-Adam had joined Mitochondrial Eve as the undisputed evolutionary  heads of humanity, even though for the minority who, like me, read the book the more modest reality became clear. Whoever coined the names, though, they have been widely, if not universally, used by the science community in communicating with the masses. And not infrequently, they have been cited in contrast to the Biblical Adam and Eve as the “real”, scientific, story. Certainly over my time reading BioLogos, discussion of the historical Adam has often lapsed seamlessly into consideration of his being genetically impossible because our most recent common ancestor was – of course – Y-Adam. Even real biologists can be woolly on pop. gen.

In over twenty years since the first article, did geneticists ever try to correct the public  misapprehensions, and point out that  these two individuals had no unusual role in human history, or that they do not represent our most recent common ancestors? Did you ever read a press article, or a Wikipedia entry, or hear a geneticist say that “Adam” and “Eve” are thoroughly misleading terms in this context, and ought to be purged for the sake of scientific truth.

I guess the popularity of the idea gave some popular kudos to the original authors of the paper, though I’ve no idea if they wanted it or welcomed it when it came – maybe not entirely. But for the science community at large, and particularly in the USA where the Science-Creationist conflict was in full swing, it was not necessarily a bad thing to have people believe that it held a more authoritative, secular, version of human origins. “You’ve got the Bible – we’ve got the fossils mitochondria” gives you the upper hand to a far greater extent than, “Sometimes we can trace the history of gene fixation.”

The trouble is, as websites like Reasons to Believe show, that sometimes people take what you say seriously.

Jon Garvey

About Jon Garvey

Training in medicine (which was my career), social psychology and theology. Interests in most things, but especially the science-faith interface. The rest of my time, though, is spent writing, playing and recording music.
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