A Bit of a Stretch

The distortion and misrepresentation of scientific research by creationists is nothing new. Even so, I feel that I rarely see a story so painfully twisted as the one in African Populations Fit Biblical History – just reading it is threatening to give me a headache. Brian Thomas has prepared a masterpiece.

The article relates to a paper (pdf) published in Cell in early August, which sequenced and compared genomes from the African Hadza, Sandawe, and Pygmy peoples. According to a physorg article:

It identifies several million previously unknown genetic mutations in humans. It finds evidence that the direct ancestors of modern humans may have interbred with members of an unknown ancestral group of hominins. It suggests that different groups evolved distinctly in order to reap nutrition from local foods and defend against infectious disease. And it identifies new candidate genes that likely play a major role in making Pygmies short in stature.

Brian opens:

What if geneticists discovered, lurking in the DNA sequences of modern humans, clues of a heritage that mirrors the historical account of the dispersion at Babel? Researchers appear to have uncovered such clues in a recent attempt “to reconstruct modern evolutionary history” of three hunter-gatherer African tribal populations.

That’s a big ask – or rather, a big twist.

Scientists sequenced the genomes of five males—representing Pygmy, Hadza, and Sandawe tribe members—over 60 times each. Such dense coverage ensured that the identities of each DNA base pair they sequenced were accurate. They compared the African DNA sequences with each other and against similar studies on Europeans.

With (arguably) one exception, this is the sole accurate paragraph in Thomas’ article – with the caveat that they also compared their sequences with other African genomes already sequenced as well as with Europeans. Onwards to the nonsense:

The geneticists published their unexpected finds in the journal Cell, providing data that accord with a rapid post-flood diversification in Genesis history. For example, they discovered an enormous number of novel DNA variations just within the three tribes. Most of the variations were “single nucleotide polymorphisms,” or SNPs, that occur as single DNA base pair differences between individuals.

Brian asserts that the findings are “unexpected.” While that’s debatable they certainly aren’t problematic, which seems to be what Brian is driving at. We’ve noticed a number of times recently where both he and Jeff Tomkins have given incorrect pictures of what evolution predicts in their articles – straw men, in other words. This time Brian doesn’t even bother with that part, never telling us what’s “unexpected” about the research. Instead, it’s in “accord” with young Earth creationism. This first sentence pre-emptively ruins the rest of the paragraph, which is fine.

Specifically, their study found 13,407,517 SNPs that differ from the human genome reference sequence. The study authors wrote, “Our sequence data substantially expand the catalog of human genetic variation.” These results add to a recent study that found that human variation is related to an explosion of genetic diversity beginning at roughly 5,100 years ago.

13,407,517 – remember that number for a later article. Of those something like 3-5 million are new, which is still quite a lot. Brian gives two citations for his “5,100 years” claim – the first to a paper, the second to a September 2012 Acts & Facts article. I last dealt with that particular claim in August, and I see no reason to revisit it here.

The Cell authors also searched for certain kinds of sequences that identify people groups. First, they did not find “shared variants between Hadze and Sandawe.” Although both tribes are hunter-gatherers who have long lived in Tanzania, each has unique DNA variants. If they had diverged only within the past several generations, they would share variations from inter-breeding with nearby groups. The lack of shared variants indicated to the authors that the populations diverged long ago, with little or no intermarriage between them. But when exactly did they diverge?

Reading the paper we find that the actual quote is:

However, despite shared language and geographic proximity, we do not observe an excess of shared variants between Hadza and Sandawe Khoesan speakers, consistent with an ancient divergence and diverse mtDNA haplogroups.

Not finding an “excess” is quite different from none at all. It’s quite amusing that Brian keeps referring to “intermarriage” throughout this article, even though that’s far from the only way to produce gene flow between populations.

Now, how long ago is “long ago”? Obviously, Mr Thomas wouldn’t want it to be too long ago, that would be problematic for his chronology. His answer is in fact rather muddled – here’s his next two paragraphs:

The team found genomic regions inherited from ancient ancestors “in the same time frame as Neandertals.” Neandertals were a variety of mankind who intermarried with modern-looking humans during the post-Flood Ice Age from between roughly 3,500 and 4,500 years ago.

The study authors found other evidence of widespread human interbreeding long ago, “predating the divergence of these [African] populations.” The researchers wrote in the journal Cell, “A striking finding in our data set is that compelling evidence exists that extant hunter-gatherer genomes contain introgressed [repeatedly interbred] archaic sequence.”

The first problem here is that the “same time frame as Neandertals” statement actually refers to the archaic human population. Here, have a hastily-drawn and oversimplified diagram:

Basic diagram

First, there was a common ancestor of all varieties of humans being considered here. One lineage from this group became modern humans, splitting up in the last hundred thousand years or so into Eurasians and Africans and other groups as some left Africa, and more recently than that you get the origins of the pygmies and other groups in this study. At some point significantly before our departure from Africa a separate lineage split off, eventually becoming the Neanderthals. This group bred with modern humans leaving Africa, and so leave a limited descent among those people, but they are themselves extinct. What this study reports is that the evidence suggests that another group of archaic humans bred with the Africans that stayed behind. It is this group that split off from our own lineage “in the same time frame as Neandertals,” not the Pygmies that came later. (I’ve left out a lot in the above diagram, including other African groups, some of which also inherited Neanderthal DNA, and the Densiovians and their associated interbreeding.)

This “time frame,” contrasting with Brian’s “between roughly 3,500 and 4,500 years ago,” is actually a little over a million years before the present. You can see why he would have left that part out. I think I’ve sorted out the problems with the above paragraphs, correct me if I’m wrong.

Though perhaps striking to evolutionists, biblical creationists expect results like this. According to biblical history, intermarriage would have occurred freely for a few hundred years within the world’s single nation at Babel. God then confused the languages and miraculously splintered humanity according to its families that would soon become 70 ancient nations.

The Babel story would suggest that all groups diverged from each other at the same time, and that there really wouldn’t have been distinct populations to interbreed before hand. Instead, we have interbreeding and divergence that isn’t all happening at the same time (or recently). The results are certainly interesting to “evolutionists” – I’ve heard rumours of African archaic intermixture before, I might add – but not problematic. But they’re not actually very helpful to the creationists, being a bit too complex for their interpretations.

He concludes:

So, according to this genomic analysis, three modern African populations first intermarried with non-African populations. They then became isolated during the Ice Age, as is consistent with their having migrated from Babel to Africa. Finally, most of their genomic variations happened recently, since their populations were established. These events, all discerned from genomic clues, are in agreement with biblical history.

Not a single one of those sentences is true.

I can’t really pin down what makes this article particularly bad. It’s a confusing mess which just seems to take the usual misinterpretation further than the usual, confident that nobody will be able to properly follow where it’s going. The research has been used and abused in order to demonstrate what it most certainly does not, but that too is normal. So what is it?

I had planned – and still do – to take November slowly, as I have a large number of important exams over the month. However the November Acts & Facts edition is very interesting, and I don’t think I can resist taking a crack at it immediately…


2 thoughts on “A Bit of a Stretch

  1. How do YECs deal with the fossil and other evidence suggesting that waves of Homo sapiens and earlier Homo species moved out of Africa rather than out of Babylon (and much earlier than the time of the Biblical flood and fictional YEC ‘post-Flood ice age’? Rhetorical question.


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