If he only had a brain...
This came to mind recently when I was reading Uncommon Descent, the blog of Wild Bill Dembski, and came across a rather fascinating set of assertions by Dembski's henchman, DaveScot.* They begin as follows:
A recent disagreement about the critical importance of gut flora to animal health led me to look for research into germ-free animals. GF animals have been available for research for about 50 years and initially they lived very short lives. The decrease in longevity was eventually traced to lack of critical enzymes in their diet. In order to remain GF their food was sterilized at high temperatures (essentially autoclaved) which caused the needed enzymes to break down. Once their dietary requirements were established an unexpected result emerged - GF animals live twice as long as controls receiving the same complete diet but not housed in sterile conditions.
So, in essence, he's claiming that animals raised so as to be entirely lacking in microbes and viruses can be kept alive for considerable periods if they are given a diet containing the proper kinds and amounts of nutrients- nutrients which are sometimes destroyed by the sterilization process. More than that, DaveScot is claiming that they live twice as long! He then continues:
This got me thinking about evolution vs. design. The animals raised germ-free could not have evolved in the natural world without exposure to bacteria but they could have been designed for GF life. The fact that they live twice as long in a GF environment when eating a diet that is nutritionally complete except for being sterile seems to be favorable evidence that animals were created in and for a germ-free world.
So, what he's really trying to argue is, "Evolution says animals evolved alongside bacteria. Biology says we use bacteria to help us digest food but, since germ free animals can live longer than non-germ free animals, evolution and biology must be wrong." Or, to break it down more simply, "Hey! We're really designed for the Garden of Eden! Take that science!" This is an interesting claim, but is, of course, trivially incorrect. Indeed, it passes incorrect and goes straight into entirely foolish. We can, for example, note that DaveScot is factually incorrect about the extention of animal lifespans- the average extension is six months.** The rat, one of the most common laboratory animals in the world, and one for which germ free animals are available, has an average lifespan of 2-5 years, so a six month increase in life is hardly "twice as long." Among larger types of germ free animals, like rabbits, increases would have to be even longer than 6 months to even approach doubling total lifespan.
Leaving that aside, however, we have another basic definitional problem. Many biologists claim that bacteria commonly found in the gut and other locations in the human body are useful for two reasons: they aid digestion and they inhibit the growth of harmful bacteria. In the latter case, the inhibition of other microorganisms, if we existed in a world without the possibility of infection we would not need symbiotic bacteria to protect us. So, under those circumstances, it's hardly surprising that the lack of symbiotic bacteria isn't an issue- the useful function they serve is no longer necessary. However, DaveScot overlooks something in this: if we were designed for an environment lacking bacteria we also wouldn't need an immune system. So, in other words, our "design" includes a very sophisticated and metabolically expensive feature that was entirely unnecessary. This is a little like building a helicopter out of solid gold: it becomes too expensive to buy and too heavy to fly. In the former case, the aiding of digestion, DaveScot is also overlooking a fundamental point. While a considerable body of work indicates that intestinal flora are useful in breaking down food, it doesn't usually*** indicate that they are indispensable. Humans can, and do, survive without these helpful assistants but life is considerably easier with them.
Even if they were indispensable, however, the germ free animals DaveScot refers to are being fed a diet tailored with the understanding that there are no germs, helpful or otherwise, in their environment. This diet is constructed to compensate for this lack in order to allow these animals to live as long as possible. Thus, using the success of said animals as an argument that they were "designed for a germ free environment" is a little like using the success of someone limited to intravenous feeding as an argument that humans were designed for an environment without eating. The success of artificial support is not an argument against the necessity of the natural function that support replaces.
And, of course, there's DaveScot's final**** idiocy: the misguided belief that intestinal flora we consider beneficial are beneficial in all circumstances. It is well-known, for example, that a perforated bowel allows beneficial bacteria to leave their assigned places and enter the body cavity. Once there their replication can prove very harmful to the host- even fatal. Similarly, beneficial bacteria are kept in check by an animal's immune system. Failures or deficiencies in immunity can result in unchecked bacterial growth also leading to the harm. Thus, while beneficial bacteria are beneficial, they don't come without their own unique costs.
Ultimately, the issue is that evolution doesn't predict, and biology doesn't argue for, a perfectly beneficial relationship between intestinal flora and an organism. Instead it is one of somewhat tense cooperation, good enough to keep everyone alive most of the time, but not by any means perfect. Yet DaveScot ignores all this, happy to take a set of organisms living in a completely unnatural environment, supported by advanced human science and technology, as evidence that animals are designed to live that way. Thus, much as in the Wizard of Oz, we have yet another strawman dancing brainlessly before us, hoping to entertain us with each ludicrous kick and leap.
Only this time, he's failing miserably.
* Whom Uncyclopedia refers to as "the Darth Maul to Dembski's Palpatine." I think the analogy is rather apt.
** Wostmann BS (1996) Germfree and Gnotobiotic Animal Models. Boca Raton: CRC Press.
*** There are exceptions in other species, such as the ruminant animals, which are quite dependant on microorganisms.
**** Not really. I'm sure he will continue to be an abundant font of foolishness.
As a side note: I'm rather excited that Tom posted earlier this week on intelligent design.