Bad Design in Nature, or Simply Bad Code Review?

As the biological sciences continue to unveil the incredible intricaies of life at the molecular level, claims of "bad design" sound increasily hollow.

I am a programmer by trade, and one of the trickest things you can do as a programmer is review (and particularly rewrite!) code that you didn’t write in the first place. In some cases, the code may be executing a very complex sequence of tasks that involve a lot of extra components working together in obtuse ways. Following the “rabbit” trail of logic can be an exercise in frustration, or at the very least time-consuming. The biggest danger is in misunderstanding the overall point of the code or why the original programmer chose to write it the way he/she did. In the biological sciences, “reverse engineering” the building blocks of life can raise similar issues, and–unfortunately–some scientists have committed the same error of misunderstanding why certain biological features are the way they are.

Nowhere does this become more controversial than in the debate between Darwinian evolution and intelligent design. For an evolutionist committed to a purely materialist explanation of biological development, it’s only natural to assume the “illusion” of design in nature will present both good “designs” and less-than-ideal or even bad “designs”. Natural selection may be an incredible thing but it’s not a miracle-worker. In a sea of random mutations, one can hardly expect perfection at every turn.

For an intelligent design advocate, one doesn’t necessarily need to expect perfect designs either (after all, it is basically a method of identifying products of intelligence in the natural order, not identifying the exact nature of the intelligence per se). However, the bias certainly leans in favor of assuming that biological systems are well-designed and generally accomplish what they are intended to do (barring genetic or developmental defect, injury, disease, or the like–and actually it’s remarkable just how resilient biological systems are against negative influence).

A good example is in the structure of the vertebrate eye. For years, I have been aware of charges that the eye exhibits “bad design” because of the fact that the “wires” connecting the individual photocells to the main optic nerve stick out “over” the cells instead of coming up from behind, therby blocking or distorting incoming light to a small degree. In an initial summary, any decent engineer would look at the “backwards” wiring of the eye and wonder why it’s done that way–similar to how I might review some code written by someone else and scoff at the strange and ineffecient logic and algorithms employed (even though the output, oddly enough, seems to be just fine).

However, as I have discovered numerous times, code review requires a certain degree of humility, as there are many times I or others have thought some code was badly written, only to discover after further review or conversation with the original author that it was written in a certain manner for good reasons, and in fact “obvious optimizations” one could make might interfere with the proper working of the code and introduce additional problems.

And so it is with the eye as well. To illustrate the issue, a blog post on Uncommon Decent quotes from The Blind Watchmaker by preeminent evolutionary biologist Richard Dawkins, where he states:

…light, instead of being granted an unrestricted passage to the photocells, has to pass through a forest of connecting wires, presumably suffering at least some attenuation and distortion (actually probably not much but, still, it is the principle of the thing that would offend any tidy-minded engineer!).

Some evolutionists have also pointed out that other eye designs found in nature, such as in squids, appear to be wired the “right way”, so in fact nature did eventually arrive at a seemingly “optimal” design but not in vertebrates. (Too bad for us!)

One of the counterarguments to this claim of bad vertebrate eye design, articulated most notably by Michael Benton, was that this particular arrangement of connections increased blood flow in the retina thereby supplying additional oxygen to the photocells. So maybe in the end it’s not a bad design but more of a comprise design. However, recent studies indicate that there’s more to it than meets the eye (pardon the pun)–that, in fact, certain cells surrounding the connecting wires act as fiber-optic cables which direct photons more clearly to the underlying rods and cones. The aformentioned post on Uncommon Decent quotes from a 2007 study on the nature of these cells:

Although biological cells are mostly transparent, they are phase objects that differ in shape and refractive index. Any image that is projected through layers of randomly oriented cells will normally be distorted by refraction, reflection, and scattering. Counterintuitively, the retina of the vertebrate eye is inverted with respect to its optical function and light must pass through several tissue layers before reaching the light-detecting photoreceptor cells. Here we report on the specific optical properties of glial cells present in the retina, which might contribute to optimize this apparently unfavorable situation. We investigated intact retinal tissue and individual Müller cells, which are radial glial cells spanning the entire retinal thickness. Müller cells have an extended funnel shape, a higher refractive index than their surrounding tissue, and are oriented along the direction of light propagation. Transmission and reflection confocal microscopy of retinal tissue in vitro and in vivo showed that these cells provide a low-scattering passage for light from the retinal surface to the photoreceptor cells. Using a modified dual-beam laser trap we could also demonstrate that individual Müller cells act as optical fibers. Furthermore, their parallel array in the retina is reminiscent of fiberoptic plates used for low-distortion image transfer. Thus, Müller cells seem to mediate the image transfer through the vertebrate retina with minimal distortion and low loss. This finding elucidates a fundamental feature of the inverted retina as an optical system and ascribes a new function to glial cells.

Subsequent findings are indicating that these Müller cells are highly specialized, directing light along specific wavelengths to the appropriate photocells (rods or cones).

In short, not only is the vertebrate eye not an example of bad or suboptimal design but is increasily looking like an example of excellent and rather ingenious design. It would seem that scientists are also susceptible to misguided “code reviews” and a certain degree of humility is required in the study of biology. I won’t be very surprised if future discoveries uncover even more well-engineered features inherent in the design of the vertebrate eye.  

While this may not come as welcome news to the camp of hardline evolutionary scientists who gain an advantage whenever examples of “bad design” in nature are presented, to those of us who are confident in the intelligent origin of biological systems, it is simply another reminder that life–by its very existence–is a miracle and an unfolding story of incredible complexity and intricate beauty.

Jared White