Friday, August 28, 2009

Intelligent Design, Irreducible Complexity and Exaptation

Wired Magazine has an article on science that puts another nail in the coffin of irreducible complexity. The article, by Brandon Keim has this to offer:

Mitochondria are descended from free-living bacteria, which several billion years ago were swallowed by complex cells. The mitochondria soon became central to the cells’ function.

Mitochondria couldn’t have lasted in their new home without the help of a protein machine called TIM23, which delivers other proteins harvested from the cell’s body. Bacteria don’t possess TIM23, suggesting that it evolved in mitochondria. This seems to pose a cellular chicken-and-egg question: How could protein transport evolve when it was necessary to survive in the first place?

The essential paradox applies to other protein-transporting cell systems, providing disbelievers of evolution with a key part of their critique. As articulated by intelligent design proponent Michael Behe, “This constant, regulated traffic flow in the cell comprises another remarkably complex, irreducible system. All parts must function or the system breaks down.”

According to evolutionary theory, however, cellular complexity is reducible. It requires only that existing components be repurposed, with inevitable mutations providing extra ingredients as needed. Flagella, the hairlike propellers used by bacteria to move, are one example of this. Their component parts are found throughout cells, performing other tasks.

Intelligent design mavens once cited flagella as evidence of their theory. Scientific fact dispelled that illusion. The mitochondria study does the same for protein transport.

Kenneth Miller once upon a time said "Never bet against science. You will lose." So, how did the researchers figure it out?

When they analyzed the genomes of proteobacteria, the family that spawned the ancestors of mitochondria, Lithgow’s team found two of the protein parts used in mitochondria to make TIM23.

The parts are located on bacterial cell membranes, making them ideally positioned for TIM23’s eventual protein-delivering role. Only one other part, a molecule called LivH, would make a rudimentary protein-transporting machine — and LivH is commonly found in proteobacteria.

The process by which parts accumulate until they’re ready to snap together is called preadaptation[or cooption or exaptation].It’s a form of “neutral evolution,” in which the buildup of the parts provides no immediate advantage or disadvantage. Neutral evolution falls outside the descriptions of Charles Darwin. But once the pieces gather, mutation and natural selection can take care of the rest, ultimately resulting in the now-complex form of TIM23.
There are many other examples of exaptation (Google Scholar showed over 6 thousand papers on the subject). This is another example of how crippling Intelligent Design is as a scientific construct. ID purveyors were content to say that the protein transport was "designed" in place. Real scientists, by continuing to do research, found out otherwise.


  1. Can God can change the outcome of an event after the world has knowledge of it? For example, lotto numbers after the drawing is over?

    I don't understand the relationship between natural processes and God's design. Why is God inferred in natural processes? Indeed, how does one jump from that inference to Christianity?

    I think the answer is a tautology.

    Why is faith used by christians? Because you are a christian. Why are you a Christian? Because you have faith. I don't see how you jump from design to Christianity. I also find it difficult to see God in a flawed universe that can be improved.

    Exapation, randomness, natural selection. None are the artifice of a super intergalactic species of alien let alone a super mind worthy of the name 'god' (or worship, in this flawed universe).

    No matter how different we are we both understand our temporary home needs to be fixed. I've never met a Christian who sees it as his duty to fix the world and human nature. If billions recognized this simple truth then we could change human nature. It may break the design and your faith but it's by definition better than the Christian story of the fall. If not, do you really want people to be sinful?

  2. To believe in Christianity is, as you say, exactly that: belief. Even though my wife accuses me of compartmentalization, I largely keep my scientific endeavors apart from my belief in God, simply because I don't think you can use science to show the existence of God. It is out of the realm of science. This is my problem with Paley's natural theology and Intelligent Design: they don't show the existence of a creator. They simply attempt to show what their version of a creator would be. It is a glorified argumentum ad ignorantiam. When people like Casey Luskin write that Dembski and Marks' recent paper supports Intelligent Design, it, in fact, does nothing of the kind. It consists entirely of an attack on evolution. The problem, of course, is that even if they were successful in rebutting evolution, that does not mean that ID is the best explanation for the data. This is especially true since it is not testable. Because I believe in God, I believe that He created the world the way that we see it. Our pursuit of how that world is created doesn't validate my faith in God, however. I believe in God for other reasons.