Thursday, May 19, 2011

DNA, Intelligent Design, and Theodicy, Part Two

In the previous entry I presented one of the main points that John C. Avise made in his recent book Inside the Human Genome: A Case for Non-Intelligent Design. If God designed the world, why are there so many, and such horrific, mutations in the human genome? Not only is there a huge number of different genetic diseases, but each one of these diseases can be caused by numerous different mutations. Mutations happen so often that the same diseases keep evolving over and over and over. This presents a major challenge to theodicy, which is the attempt to justify God in a world of suffering—in this case, genetically-based suffering. Thus one of Avise’s points is that, if God designed DNA, he could have made more efficient repair mechanisms to counteract the (perhaps inevitable) mutations.

Avise goes on to make another, very important challenge to theodicy: the very structure of the genome itself is inconsistent with the idea that the genome, or the human body, or the world was designed by God. Not just the mutations in the genome, but its very structure.

The human genome is full of stuff that interferes with the use of genetic information to produce healthy and functional enzymes and bodies. First, consider the fact that only about 1 percent of human DNA codes for those enzymes. About 68 percent of the DNA consists of non-coding DNA that is between the genes, and about 31 percent of the DNA consists of non-coding DNA that is inside of the genes. This is, at best, a clumsy system, because whenever a cell divides, all of this DNA is copied, not just the DNA that the cell will use. In addition, since each gene is broken into little “exon” fragments by a large amount of internal “intron” DNA, the genetic information must be spliced together in order to be put to use. That is, to get a functional enzyme, the genetic information from lots of exon fragments has to be cobbled together. If it works, there is no problem, but the whole system is so cumbersomely complex that it often fails. Not only are many genetic diseases caused by mutations in the genes themselves, but many genetic diseases are caused by (or also caused by) failures of the cell to deal properly with the non-coding DNA and the splicing.

Much of the non-coding DNA bears the clear mark of evolutionary origin. For example, there are a lot of pseudogenes, which are old genes that are not used anymore. Some of them are extra, duplicated copies of genes, complete with their introns (unprocessed pseudogenes); others are DNA copies of RNA transcripts, from which the introns have been removed (processed pseudogenes). There are also lots of mobile genetic elements, which either have or had the ability to move around among the chromosomes. Some of them are transposons, which can “cut and paste,” to use Avise’s metaphor, moving from one place to another. Some of them are retrotransposons, which can “copy and paste,” with one copy being left behind and the other going to a new place in the genome. Many of these retrotransposons are old dead viruses. We know this because they still have major chunks of the reverse transcriptase enzyme, an enzyme used only by certain kinds of viruses! Retrotransposons cannot actually become viruses anymore, because they have lost the genes that allow them to make protein capsules. Another evolutionary pattern is that species that have the most similar genetic DNA also have the most similar non-coding DNA, which makes no sense if they do not share a common evolutionary ancestry. You see, we know where much of this non-coding DNA came from, and it is not part of a system designed by a God.

There are even examples of some genes fighting against other genes. Some mutations cause a gene to over-represent itself in the next generation (“selfish genes”), which is harmful to the organism that carries it; and there are other mutations that suppress those selfish genes. So not only does the genome contain a clumsy load of non-coding DNA, but even DNA that fights against itself.

We know that such complexity of non-coding DNA is not necessary for the function of a genetic system, because bacteria do not have any of this: no introns, no pseudogenes, no transposons. They get by just fine without them.

The more we learn about DNA, the more we see that there is really no place for a Creator or Designer to fit in. It looks like, in Avise’s words, the Creator’s “primary role was to set into operation natural evolutionary forces.” Yes, you can believe that God designed evolution, and then let evolution do everything. But this would be like saying that angels push the planets around the sun by means of the laws of gravity and momentum. To slip God into an invisible realm behind the operation of natural laws, including genetic processes, seems more and more like fantasy.

And it sets God up for culpability for an immense amount of human suffering. Mutations of genes (previous essay) and malfunctions of genetic operation (this essay) cause human misery and death, in addition to killing perhaps one-third of fertilized egg cells. If God is behind the processes of human genetics, says Avise, then God is the “world’s leading abortionist and mass murderer.” Does this offend you? Then you need to reconsider what you believe about the role that God might play in the universe.

Creationists often claim that all of these mutations and flaws have occurred just since the Fall of Man. There is no Biblical basis for this belief. Genesis says, cursed is the ground, not cursed is the chromosome. Some creationists insist that the pre-Flood world had few if any mutations, which is why people lived to be over nine hundred years old. Either way, this entire burden of bad genes would have accumulated just in the last few thousand years. Mutations are not accumulating that rapidly today. Some creationists believe that Satan designed all the bad things in the genome. This is, needless to say, also without any scriptural basis. In no part of the Bible is Satan depicted as being smart enough to have redesigned the entire architecture of the human genome.

Don’t miss my new book, Life of Earth: Portrait of a Beautiful, Middle-Aged, Stressed-Out World, just published by Prometheus Books.

1 comment:

  1. What a thought-provoking essay, especially for a non-scientist (like me). I am fortunate to have my eyes opened to the science, instead of closed to the dogma that is religion.