More Mutations

It happens all the time, reallyAccording to Thomas, More Mutations Mean More Diseases, Less Evolution. This is the “genetic entropy” argument, which claims that the genomes of humans and other animals are denigrating from the original, perfect genome, and if life had been around for millions of years we’d be long dead. Larry Moran has a recent post at Sandwalk from which I’ll pilfer the following sarcastic summary:

According to plant geneticist, John Sanford, the human race is degenerating rapidly. It’s one of the trade secrets of biology. Every population geneticists knows that it’s true. […]

Now if humans are degenerating at the rate of 1% or so per year then this must mean that they were perfect only a short time ago—like maybe 6000 years?

Are humans doomed just as described in scripture? Yes. Is there any hope for us? Our only hope is Christ.

What has Thomas got that he’s so chuffed about?

The science of genetics continues to refute the notion that humans evolve by natural selection of beneficial mutations. One recent study used next-generation techniques to compare the detailed sequences of 202 genes in 14,002 people. They discovered that many people have rare, individual differences in their gene sequences. And those differences, or “variants,” were probably caused by mutations and arose in the last few thousand or fewer years. The variants that everybody carries raise difficult questions for evolution to answer, while they confirm biblical creation.

That summary is terrible. The abstract to the paper – An Abundance of Rare Functional Variants in 202 Drug Target Genes Sequenced in 14,002 People, in Science – claims that on average 1 in every 17 base pair is a “rare variant,” which a) shows that the “many people” line is a gross understatement, b) gives the impression that there would not have been enough time in ~6000 to build them all up, and c) also rather suggests by their abundance that they’re not all bad (we’re still alive after all). And no, genetic does not “refute the notion that humans evolve by natural selection of beneficial mutations” (this sure doesn’t), nor doe these results “confirm biblical creation” in any way shape or form.

Publishing in Science, the extensive gene survey discovered “an abundance of rare single-nucleotide variants compared with common variants.” Rare variants include those that perhaps only one or two people or a family possesses, and common variants are DNA differences that are shared by larger people groups. The vast majority of variants are rare. What does this mean?

First, it implies that gene variants developed recently. If they arose thousands of years ago, before the human population began to soar, then the descendants would have inherited them. But since the gene variants are very rare, they reflect recent and unique mutations.

There's no guarantee that a given genetic variation will even be passed down. (Oh to have been so lucky...)An important thing to realise here, however, is that the older mutations may have been lost, as mutations are more likely to fall out of the gene pool than be ‘fixed.’ That is to say, you may have a mutation in one of your chromosomes, but for it to continue indefinitely in the gene pool you must actually pass that chromosome on to your children (not guaranteed) and so must they. For a mutation to become ‘fixed’ it must not only survive but grow in prevalence to the extent that all organisms in the gene pool have it. In a specific case, and where natural selection is not involved, this is rather improbable – try it yourself. In other words, younger mutations will be naturally more common than older ones, and this does not prove a young Earth – the very existence of the older ones, on the other hand…

Why has all this population growth and mutational buildup only just occurred if humans have been on the planet for “at least 2.4 million years”? The human population should have skyrocketed long ago if evolutionary time is true. And the human population should have collapsed many times under its burden of mutational variants—each of which garbles just a tiny bit of DNA information—if evolutionary time were real.

The context for the population growth part is this sentence from the abstract:

We conclude that because of rapid population growth and weak purifying selection, human populations harbor an abundance of rare variants, many of which are deleterious and have relevance to understanding disease risk.

If a person has many (surviving) children then the chances of a mutation being past on is much higher. We see here that Thomas’ argument fundamentally rests not on genetic entropy at all, but entirely on his bogus world population claim. He links to this DpSU from October, which I covered here. The problem in brief is that the population of the world cannot rise unless conditions allow. Naturally, population is stable (if oscillating), and you really need things like the development of agriculture and fertilisers to beat the confounding factors that keep it down. Indeed, it is this idea that population growth naturally exceeds the carrying capacity of the environment, and thus not all the cute little baby birds of the world can survive, that should begin any decent explanation of evolution – that Thomas doesn’t seem to have the foggiest we have another piece of evidence that he doesn’t know what he’s talking about.

His final reference here for that last line is to a 1995 paper promisingly entitled Contamination of the genome by very slightly deleterious mutations: why have we not died 100 times over? Unfortunately, the author apparently has some solution to that little problem. Equally unfortunately, I can’t read that paper so I’m not sure how good they are.

The latest Science study calculated a rate of 1.38 x 10-8 mutations per base pair per generation. Given the almost 3.2 billion base pairs in the human genome, that means that each new generation accumulates 44 brand new mutations in their genes. Regulatory and repetitive DNA sequences accumulate even more mutations. This is very close to 60 mutations per generation, a rate based on human pedigreed DNA sequence studies, published in 2011.

“Very close” is apparently the same as “about two thirds of” – I’ll remember that next time he brings up fine tuning. That rate seems insufficient, by the way, to generate such a high portion of bases being variants in the creationist time-scale. Thomas doesn’t bother to link to his article on the 2011 paper, which I covered here back in the days when I still hadn’t worked out his posting schedule properly and thought that he didn’t post Fridays.

The 2012 Science study authors also used three methods to estimate the likelihood that the new variants would have a neutral, possibly damaging, or probably damaging effect. Why was there no category for beneficial variants? It’s because there are too few, if any, variants that would even fall into such a category. And even if beneficial mutations were real, the rate at which damaging or neutral mutations accumulate is far greater than the rate at which any beneficial mutation would accumulate in a population. And this is what causes mutational buildup after multiple generations.

It might also be because, being disease researchers, they were only interested in those things – I’m not sure how they would even have detected beneficial mutations, and it seems out of their scope. While we’re here, “there are no beneficial mutations” is on Answers in Genesis’ Arguments we don’t use list, so Brian needs to be more careful here.

In other words, natural selection cannot erase accumulating mutations fast enough for evolution to be possible.

That’s another issue which Thomas has made no attempt to demonstrate so far at all, so he certainly hasn’t earned the right to claim it here.

He concludes:

On the other hand, the biblical understanding that mankind has only inhabited the planet for about 6,000 years makes perfect sense. These study findings corroborate that abundant rare gene variations arose only within the last few thousand years.

Not in the slightest.

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4 thoughts on “More Mutations

  1. It’s typical YEC stuff. Babble on about a bunch of unrelated findings that most of your readers don’t understand (including a mere physicist such as myself) and then out of a clear blue sky announce that it proves that the Hebrew creation myth is the right model for all of the sciences.

  2. I can see the article you wanted to look at, and was going to summarise it. But its a bunch of confusing computational modelling that flies right over my head.

    • I take it you have access to Science?

      The mitochondrial mutations thing is interesting in that it’s not quite true that they can not be selected out in males – nothing is ever that simple. I think mitochondria can, in some cases, come with the sperm. Also, there is the potential for less direct things like kin selection (or whatever it is that is in vogue at the moment).

      I did read that, though I saw also that the SC had beat me to it – I’m in no rush.

      Do you mind if I quote your comment from the other week when I come around to Tomkins’ recent articles?

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