Clockwise: A bacterium retracts its pili, reeling in a piece of DNA in the environment. This action facilitates “natural transformation,” a process by which bacterium acquire new genetic traits, including antibiotic resistance.
Image courtesy the Dalia Lab, Indiana University
Creationists have a problem of their own making. The same evolutionary processes they try to rebrand as evidence for a creator god are also the processes that produce parasites, pathogens and the molecular machinery by which they exploit their hosts. If Michael J. Behe wants to claim “irreducible complexity” as evidence of design, and William A. Dembski wants to claim “complex specified information” as the signature of an intelligent designer, then they cannot confine those arguments to the parts of biology they find theologically convenient. The same kinds of complexity and genetic information are also found in organisms that make us sick and increase the suffering in the world.
Although professional creationists, including fellows of the Discovery Institute such as Behe and Dembski, are careful to avoid naming their putative designer, their audience invariably identifies it with the supposedly omnibenevolent god of the Bible, Torah and Qur’an. But that creates an obvious problem: using their own criteria, this creator god must be credited not only with designing humans and other animals, but also with designing the bacteria, viruses, parasites and molecular mechanisms that infect, disable and kill them.
The significance of this is often lost on creationists because it requires a basic understanding of biology and a willingness to follow an argument to its logical conclusion. When they cite Behe’s favourite examples, such as the E. coli flagellum or anti-malarial drug resistance in Plasmodium falciparum, as evidence for their god, they are in effect crediting that god with designing mechanisms that help microbes move, invade, survive and evade our attempts to stop them. Point this out, however, and the same evidence that was allegedly scientific evidence for intelligent design is suddenly reinterpreted as evidence for “The Fall” and “Original Sin”. The pretence that creationism is science is abandoned in a hasty retreat into fundamentalist theology, where the same facts are repurposed to reach a more comfortable conclusion.
In addition to the two examples I recently discussed here and here, another example has now been reported — and this one involves a powerful molecular motor that should, by creationist standards, look very much like the sort of thing they would normally call “designed”. It is the type IV pilus retraction system, recently reported in Proceedings of the National Academy of Sciences of the USA (PNAS), which many bacteria use to retract tiny hair-like surface structures called pili. These pili act like microscopic grappling hooks, helping bacteria attach to surfaces and tissues, form antibiotic-resistant biofilms, and pull in fragments of DNA from their surroundings, including genes for drug resistance acquired from other bacteria.
