Friday, May 13, 2011

DNA, Intelligent Design, and Theodicy, Part One

John C. Avise published a book last year entitled Inside the Human Genome: A Case for Non-Intelligent Design. I would like to share some ideas from this book for your consideration. Avise looks at the age-old question of theodicy (why a good God would permit suffering) in light of the our understanding of human genetics, especially the new revelations that have come from the Human Genome Project just in the last dozen years.

Avise's main point is that if the world were designed by a loving intelligence (which Intelligent Design proponents publicly hesitate to call God), the DNA system shared by all organisms from amoebas to humans would look a lot different from the way it is. And his first set of examples is the sheer number and horror of mutations that fill the human genome.

Many mutations are neutral, or can be easily overcome by technology. And some of them cause a great deal of psychological suffering, such as the mutation that causes trimethylaminuria, which is physically harmless but causes the victims to smell like rotten fish no matter how clean they are. But many other mutations are deadly or, worse yet, can cause a person to have a lifetime of suffering. Perhaps the most disturbing mutation is the one that causes Lesch-Nyhan syndrome. This one mutation, of a single amino acid in a protein, causes the victim to have an uncontrollable compulsion for self-mutilation: they chew their own lips and fingers, and find sharp objects to stab their faces and eyes. The victims are fully able to feel their pain and they know what they are doing, but cannot control it.

But there is more to the story. Most of these genetic syndromes have come into existence many times. Consider glycogen storage disease, in which a defective enzyme causes glycogen (animal starch) to build up in tissues throughout the body. A childhood friend of mine has this disease, which he inherited from his father; by middle age, he was almost constantly incapacitated by this disease. I do not know if he is still alive. Geneticists know of 86 different mutations that can disrupt the enzyme and cause this disease. That is, this genetic disease has mutated into existence 86 separate times. The author directs our attention to several databases, one of which is the Online Mendelian Inheritance in Man (OMIM), which lists over 18,000 genes, three-quarters of which have documented mutations. And these are just the single-gene defects!

The author's first point is that an intelligently-designed genome would not have such a stunning number of mutations. If God designed the DNA to make us adapted to the world we live in, could God not have done a better job? Evolution, in contrast, is dependent upon random mutations, upon which natural selection acts by eliminating the bad ones (that is, disfavoring and perhaps killing the individuals who express them) and favoring the good ones. The existence of a large pool of mutations, which natural selection has not completely gotten rid of, is consistent with evolution but not with Intelligent Design.

One answer that Intelligent Design proponents have to this problem is that the Designer created a mutation-free set of human DNA when our species came into existence, then abandoned the system to take care of itself. But if this is the case, the system was so poorly designed that it could not, in fact, take care of itself.

The connection to the problem of theodicy is obvious, and Avise makes it. Defenders of God (which is the meaning of theodicy) claim that God allows bad things to happen as an inevitable consequence of free will. Their platitude is that if fire did not burn, then it would not be fire. I can understand why God would not automatically give all of us a perfect set of genes; limitations, including genetic ones, are necessary for character development, to show God on judgment day what kind of people we are (from the traditional Christian viewpoint). But Lesch-Nyhan syndrome? Potentially deadly mutations in three-quarters of human genes? Isn't this a bit excessive?

I will summarize some of Avise's other points in the next entry. Please post your comments and/or send the link to this blog to others who might be interested.

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. Lesch-Nyhan syndrome? That's tortuous...I had never heard of that mutation prior to this post. Interesting premise by Avise. I'm looking forward to your next entry, as well as, reading this book for myself.