Creationism and the Bombardier Beetle
Creationism believes that all life looks designed, and an often used example of this intelligent design is a creature known as the Bombardier Beetle. Defending this claim requires a careful examination of the bombardier beetle and of the definition of the word “design”. Under scrutiny, however, the bombardier beetle can be a proof of evolution and seriously challenges the design argument.
What Makes Bombardier Beetles Special?
Bombardier beetles are so-called ground beetles in the four groups Brachinini, Paussini, Ozaenini, and Metriini and comprise over 500 species. The group Brachinus is the most common group.
Bombardier beetles are amazing creatures. They are so called due to their ferocious ability to defend themselves against predators by shooting a mixture of scalding hot and toxic chemicals from glands in their behinds.
This is how their defensive squirting action works. Secreting cells produce hydroquinones and hydrogen peroxide which collect in a bladderlike vessel. This vessel is opened through a muscle-controlled sphincter onto a thick-walled reaction chamber. This chamber is lined with cells secreting catalases and peroxidases. As the contents of the bladder are forced into the reaction chamber, the catalases and peroxidases quickly break the hydrogen peroxide down and catalyze the oxidation of the hydroquinones into p-quinones. This releases free oxygen and generates sufficient heat to bring the mixture to the level of boiling which vaporizes a fifth of it. Under pressure of the released gasses, the sphincter is automatically shut which forces the chemicals through openings found in the abdomen.
Unfortunately, and making real debate and communication almost impossible, creationists offer an un faithful account of the process. The creationist Duane Gish made the claim that hydrogen peroxide and hydroquinones would explode spontaneously when mixed without a chemical inhibitor, and that the beetle starts with a mix of all three and adds an anti-inhibitor when he wants the explosion.
In reality, the two simply do not explode when mixed, as has been frequently demonstrated. Gish stubbornly still used the mistaken scenario after being corrected by Kofahl in 1978. Why let the truth get in the way of a good story? The same mistake is also repeated in books by Hitching in 1981, Huse in 1983 and 1993, and twice in a creationist magazine in 1990.
How strong is an argument of design if the people making it don’t know what the design looks like?
Irreducible Complexity: The Design Argument’s Best Buddy that Never Calls Back
Just knowing what something looks like doesn’t reveal whether it is designed; for that, we must define “design”.
Although it’s rarely defined, the most important aspect of design as it relates to creationism appears to be complexity. Richard Lumsden says,
Systems that are of high complexity, that is functionally integrated multicomponent systems, systems that are of high specificity where only one or very few of many possible arrangements of these components works, and systems which are of low probability, at least spontaneous occurrence . . . these are the hallmarks of purposefully designed engineered systems. [Lumsden, 1995]
The problem for proponents of intelligent design and the design argument is that the theory of evolution already allows that complex, functionally integrated, low-probability systems can arise via gradual variation and selection. Darwin’sntheory explains how a few photosensitive cells might evolve gradually into human eyes. In order for complexity to be a problem for the concept of evolution, it must demonstrate some property that rules out gradual development. Michael Behe proposes such a property with the concept he calls “irreducible complexity,” which he defines as “a single system composed of several well-matched, interacting parts that contribute to the basic function, wherein the removal of any one of the parts causes the system to effectively cease functioning.” Although Behe leaves open the questions of whether bombardier beetles are irreducibly complex, Gish expresses the concept with reference to them when he says, “How are you going to explain that step-by-step by evolution by natural selection? It cannot be done!”.
Gish is obviously not as right as he believes himself to be; a step-by-step evolution of the bombardier system is not hard to imagine.
In a future post I will show a potential step-by-step evolution of the bombardier beetle mechanism all the way from a primitive arthropod.
The Bombardier Beetles – Nothing is Real
