Friday, July 14, 2017

Adam and the Genome 6: Intelligent Design

In chapter 4, the last of Dennis Venema's chapters, Venema addresses intelligent design. I'm reading Venema and Scot McKnight's book, Adam and the Genome: Reading Scripture after Genetic Science.

Previous posts
Personal Preface
Forward and Introduction
1. Evolution as a Scientific Theory
2. Genomes as Language, Genomes as Books
3. Adam's Last Stand?

Chapter 4
1. Chapter 4 is titled, "What About Intelligent Design?" The first part of the chapter recounts the arguments for intelligent design advanced most powerfully by Michael Behe. Behe's fundamental idea is that of "irreducible complexity." There are aspects to biological systems that seem to involve a set of complex interrelationships, all of which have to be in place for it to work.

I think the best illustration of this idea that Venema gives is that of a stone arch. You can't build an arch by adding stones to the side one by one. They would fall over. The keystone has to be in place before they will stay in place. But you can't put the keystone in until the other stones are in place.

Bottom line is that an intelligent designer has to come alongside with scaffolding to build the thing. Human biochemistry, Behe argues, is exactly like that.

2. I lament Venema's tone a little in a few places. Most of the time he is completely under control. But clearly he has been engaged in an ongoing argument with Michael Behe and others like Stephen Meyer in the Intelligent Design community. What makes it worse is that Venema was in their camp not too long ago, so there may be a tendency to be impatient, as it were, with his former self. These are all familiar dynamics for me on other issues.

What I think I've found is that, if you have any hope of winning over those who are disposed against your position for ideological reasons, you almost have to behave perfectly for a long time while they process your arguments. You have to be a saint, and even then the odds are stacked against you. You can know you know more about the subject. You even can know that arguments against you don't hold any water and see obvious flaws in them. Your faith and character can be impugned,

But if you get cocky or lose your cool, the opposition simply says, "See, this person has a moral problem or see, this person is not behaving like a Christian, which reinforces that their ideas aren't Christian. What need of further evidence have we?"

So I probably would have written these chapters with a tiny bit more of an exploratory tone. Every once and a while, it feels like a tiny bit of sarcasm and condescension creeps in, which probably is not ultimately helpful.

3. So what I would say is that what he shows in the rest of the chapter is not a proof that Behe and Meyer are wrong, but some reason to believe that their arguments are not nearly as strong as they might appear if you do not have extended training in genetics, biochemistry, microbiology, and cell biology.

Behe argues that for new "irreducibly complex" biochemical structures to form, there would need to be new "binding sites" for them to bind to. This suggests to him that multiple mutations would need to happen all at the same time, which he considers so improbable as to be mathematically impossible.

So Venema shows evidence that these sorts of things likely happen all the time. In fruit flies, for example, it looks as if one gene has been randomly duplicated in one species (called a paralog), while not in others. All it took was then four mutations--not at once but one at a time--for this paralog to take on an essential function for the particular kind of fruit fly.

In short, an irreducibly complex, essential protein seems to be explicable as a result of six seemingly random events, each of which was unnecessary and initially non-essential to the fly: 1) the initial duplication of the gene, 2) the addition of mutation 1, 3) the addition of mutation 2, 4) the addition of mutation 3, 5) the addition of mutation 4, and 6) the ensuing dependence on the way these mutations came to function collectively.

4. A much rarer event that the current "look" of the vertebrate genome has is what is called a "whole genome duplication." Venema suggests that this sort of event has only happened twice in the history of evolution, one of which introduced the backbone. Unlike the paralog of the previous example, this sort of event would involve a move from two to four chromosomes, doubling the length of the genome, in effect.

Computers have compared non-vertebrate genomes with vertebrate ones and certainly this looks to be true. That is where the rub is. The genome looks the way we would expect it to look if it developed in this way. Indeed, it is the theory that has led the geneticists to look for these things that they have found.

This does not prove it happened that way. Perhaps we could say that either God created it to look this way or it happened this way.

5. An experiment with E. coli has provided another example of the kind of thing Behe considers irreducible complexity developing by chance. Researchers created a population of E. coli bacteria that largely did not have a binding site for a particular virus. Yet significant amounts of that virus were introduced to the environment.

Within four random mutations, a new binding site had developed to which the bacteria could bind.

6. Stephen Meyer has argued that what are called protein folds are extremely rare and irreducibly complex such that the mathematical probability of them developing by chance is an impossibility. He draws especially on a study by Douglas Axe to support this claim experimentally.

Venema finds numerous flaws in their line of argument, so much so that he believes Meyer must not fully understand the genetics (note 38). First, Venema has already suggested a number of mechanisms by which new functions come into being by chance--gene duplication, mutation, whole gene duplication. According to Venema, it is wrong in the first place to think that anything comes de novo in evolution. It is about descent with modification. Genes split, fuse, stick extra stuff in or accidentally shift the sequence.

One example is a bacteria found in Japan that "eats" nylon, which has only existed since the 1930s. This new bacteria popped into existence in a moment when a single mutation shifted all the codons after it by one place. By coincidence, this shift created a bacteria that could weakly draw carbon and nitrogen from nylon for its "food."

Since other bacteria cannot do this, we know this bacterium has only existed for some time since the 1930s. And this bacterium has a number of the protein folds that Meyer says cannot happen mathematically by chance. Certainly God could have decided to mutate this bacteria for the good of Japan right before they bombed Pearl Harbor. Or it could be random. :-)

7. Venema also points out a number of problems with extending Axe's study beyond its original limits. Axe started with a barely functional bacterium with a specific enzyme that performed a specific function. He comes up with a mathematical impossibility that this bacterium would produce that enzyme to do that function by chance.

But Venema argues it doesn't work this way. Most bacteria have multiple back-up systems that were intentionally kept out of this study so that the study would be able to show failure. And evolution is not about the likelihood of a specific chain of events but the likelihood that some random chain of events will unfold.

As Venema's chapters close, here is his sense of design: "Evolution may be God's chosen design to bring about biodiversity on earth" (89). "I view evolution as God's grand design for creating life" (90).

I look forward to what McKnight has to say about these things theologically, starting next week.

1 comment:

Martin LaBar said...

You are right in what you say about arguing.

But what Venema (and others) have to say seem to be strong scientific arguments against ID.