INDELs

There was no DpSU for Wednesday from the Institute for Creation Research. Instead, on there home page is a Days of Praise article called Giving Thanks for Christian Friends. From this I take it that they’re taking the time off to celebrate Thanksgiving, a holiday with all the hallmarks of a pagan Harvest Festival without actually being pagan. From what I remember they did something like this for July 4, Columbus day and Halloween as well, although in the latter case they were condemning the event and warning their followers not to take part.

As there is nothing recent in the queue this, then, is the perfect opportunity to go back and cover the DpSU I missed from last Tuesday, DNA Study Contradicts Human/Chimp Common Ancestry. That’s quite a claim – let’s see what he’s got.

Hominoid taxonomy

Evolutionary biologists argue that since human and chimp DNA are nearly identical, both species must have evolved from a common ancestor. However, creation scientists have pointed out that their DNA is, in fact, very dissimilar. The vast majority of each species’ DNA sequence is not genes, but instead regulated gene expression. A new report unmistakably confirmed that the regulatory DNA of humans is totally different from that of chimps, revealing no hint of common ancestry.

For one thing, that’s a straw man – we don’t think that humans and chimps “must have evolved from a common ancestor” just because our “DNA are nearly identical.” DNA evidence is really more used to determine which groups in the above chart are closer to each other – you know, whether the Chimp (Pan) or the Gorilla should be next to Homo etc. But that never stopped the creationists.

Biologist John F. McDonald, of the Georgia Institute of Technology’s School of Biology, and his team wrote that chimp and human genes are more than “98.5% identical,” a commonly quoted statistic. Yet humans don’t look or act 98.5 percent identical to chimps. Thus, something other than genes must be involved, and this has been overlooked in evolutionists’ efforts to establish chimp-human ancestry.

Can you actually determine that we don’t “look or act 98.5 percent identical to chimps”? In regards to our metabolism and other behind-the-scenes things that we do I wouldn’t be surprised if we were “98.5 percent” or higher on the identicality scale. Also, I must stress that the precise degree of genetic similarity between humans and chimps has no bearing on whether or not we are actually related.

In 2005, molecular biologist and creation scientist Dan Criswell wrote:

However, such sequence similarity was based only on a fraction [less than four percent] of the total genome of man and chimpanzees, and reflects only the physiological similarities of humans and chimpanzees based on their cellular protein content, not the overall genomic content. The homology [similarity] frequently reported for the human/chimpanzee genomes excluded “indels,” which are areas with zero sequence homology.

“Indels” refer to insertions (in-) and deletions (-del) of genetic material, but they are simply DNA sequence differences.

Perhaps, but that has got nothing to do with the claim – that McDonald’s study (it is not awfully clear, but that is the “DNA Study” being talked about) “Contradicts Human/Chimp Common Ancestry.”

Publishing in the open access journal Mobile DNA, the research team led by McDonald tested the hypothesis that the “substantial INDEL variation that exists between humans and chimpanzees may contribute significantly to the regulatory differences between the species.” McDonald said in a Georgia Tech press release:

Our findings are generally consistent with the notion that the morphological and behavioral differences between humans and chimpanzees are predominately due to differences in the regulation of genes rather than to differences in the sequence of the genes themselves.

The team’s analysis of indels confirmed exactly what Bible-believing biologists have been saying for years. The indels and other variously named non-gene DNA are not “junk DNA,” and they are critical to the formation of each living creature.

Blah-de-blah-de-blah. There are two things that Brian Thomas is trying to use this study to say. The first is that Junk DNA does not exist, the second is that all non-protein coding genetic material is completely different between Chimps and Humans. The study is about – and provides evidence for – neither.

The idea that there is no such thing as Junk DNA – which is popular among creationists of all stripes, who cannot believe that their creator created something truly useless – is absurd, not least because portions of the genome have a tendency to get duplicated, and it is difficult to argue that the result provides much function.

To get to that second claim we have to scroll past another quote – this time from a “Biblical geneticist” – to the last two paragraphs:

The argument that chimp-human DNA similarity is evidence of common ancestry is possible only by ignoring the 98 percent of DNA that is different! It is like arguing that an aspirin pill is identical to a cyanide pill because they are the same shape and color. When do the differences enter the conversation?

The 98 percent comes from the footnote that says that ‘Genes comprise only 1.5 percent of the human “genome.”‘ He then rounds down to 98 to be nice, I assume. This is expanded upon in the final paragraph:

Regulatory DNA—not just genes—is essential for each kind of organism, is almost entirely useful, and is different in humans than it is in chimps. How could billions of DNA differences have evolved in just four million years? It’s impossible. Humans and chimpanzees were distinctly and uniquely created after all.

The footnote to “It’s impossible” is what we are after:

Evolutionists say that humans and chimpanzees shared a common ancestor six million years ago. Then, two million years ago, modern humans supposedly diverged from a (still unidentified) ape-like ancestor. The difference equals four million years. Further, 98 percent of the human genome’s 2.9 billion DNA base pairs, roughly corresponding to its regulatory DNA, equals 2.8 billion base pairs. Therefore, evolution requires the belief that man emerged after 2.8 billion precisely placed DNA bases somehow appeared, and even more ape-specifying regulatory DNA disappeared, in only four million years, even though experiments have not found this kind of DNA appearance and disappearance in today’s genomes.

There are so many things wrong with this. The first is, obviously, that the study was not about what percentage of non-regulatory DNA is identical between humans and chimps. They certainly didn’t find that it’s all different.

But you can use their numbers to show how absurd it is to base the conclusion that there are so many differences on this study. They defined an INDEL as a gap ranging between 80 base pairs and 12,000 bp in length. They found 15,144 such sequences that humans have but chimps don’t, and 11,365 that chimps have that we don’t. Now, if humans have a genome 2.9 billion base pairs in length, and all INDELs are the maximum 12,000 bp (which is optimistic, to say the least – from my reading of the paper the frequency of INDELs decreases as they get longer) we can calculate that no more than 6% (180 million bp) of the human genome consists of INDELs that chimps don’t have, and that that the amount of INDELs that go the other way are no longer than 140 million bp, or a length equivilent to 5% of the human genome. In other words, assuming this post even makes sense, the claim that the difference between human and chimp genomes is 98% is total bunk. The claim that any of this contradicts human-chimp common ancestry isn’t even that.

Happy Holidays, where applicable.

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3 thoughts on “INDELs

  1. Pingback: Mistakes Were Made – But Not By Us « Eye on the ICR

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