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Squeezing Out the Mystery: Final Comments on Strickberger’s Evolution

Robert F. Shedinger
chambered nautilus
Photo: Gaze into the eye of a chambered nautilus, © Hans Hillewaert.

Squeezing Out the Mystery: Final Comments on Strickberger’s Evolution

Editor’s noteDr. Shedinger is a Professor of Religion at Luther College in Decorah, Iowa. He is the author of a recent book critiquing Darwinian triumphalism, The Mystery of Evolutionary Mechanisms. See also the earlier entries in this series:

In my previous post analyzing Strickberger’s Evolution, a prominent textbook by Brian K. Hall and Benedikt Hallgrimsson, I focused on the phenomenon of convergent evolution. One of the most amazing examples of convergence is the repeated evolution of the camera eye. I will begin this final post by considering Strickberger’s treatment of eye evolution along with comments on a few other problematic aspects of the textbook. 

On eye evolution, Hall and Hallgrimsson write: 

As explained by the process of convergent evolution, the structural similarity of squid and vertebrate eyes does not come from an ancestral visual structure in a recent common ancestor of mollusks and vertebrates, but rather from convergent evolution as similar selective pressures led to similar organs that enhance visual acuity. Such morphological convergences may have arisen independently in numerous other animal lineages subject to similar selective visual pressures. [Emphasis in the original.]

But how could a similar series of mutations of the sort necessary to produce similarly structured eyes in different lineages occur so many times independently if the mutations are randomly produced? Hall and Hallgrimsson are not bothered by this question, but in order to convince the reader that such a thing is possible, they appeal to the well-known work of Dan-Eric Nilsson and Susanne Pelger.

Caveats in Nilsson and Pelger’s Paper

In 1994, Nilsson and Pelger published an article in the Proceedings of the Royal Society of London demonstrating how a light-sensitive patch of pigment could develop into a complex camera eye in a relatively short period of time, a sequence of steps that supposedly has occurred multiple times in the history of life. What Hall and Hallgrimsson fail to report, unfortunately, are the important caveats contained in Nilsson and Pelger’s paper. 

First, Nilsson and Pelger point out that an eye makes little sense on its own. A patch of light-sensitive pigment absent the simultaneous development of neural networks and processing centers to produce the subjective experience of sight would not confer a selective advantage on an organism. One can have fully functioning eyes and yet be blind due to disruptions in the visual centers of the brain. Based on this fact Nilsson and Pelger conclude:

Because eyes cannot evolve on their own, our calculations do not say how long it actually took for eyes to evolve in their various animal groups. However, the estimate demonstrates that eye evolution would be extremely fast if selection for eye geometry and optical structures imposed the only limit. [Emphasis in the original.]

Of course, they have just argued that eye geometry and optical structure do not impose the only limit! Their scenario therefore does not solve the problem of convergent eye evolution. Hall and Hallgrimsson’s summary of Nilsson and Pelger’s work is disingenuous at best. Biology education must encourage students to read original papers and not uncritically accept the summaries found in textbooks.

A Common Analogy

Nevertheless, Hall and Hallgrimsson do believe that natural selection can string together the mutations necessary to produce complex new structures. They attempt to demonstrate this with a common analogy. Suppose, they say, we have a bowl full of ten different letters (A, C, E, I, N, O, T, U, V) with each letter present in equal frequency. The chance of drawing nine letters at random that happen to spell EVOLUTION is only 1 in 109. These are long odds. But if we assume E is the only letter that can survive by itself, it will be preserved when drawn. Then if we assume EV is an adaptive combination, the chance of drawing V and thus getting EV is only 1 in 10 (not 1 in 100). In this way, “the entire word, EVOLUTION, can eventually be selected with relatively high probability without the intervention of any agent other than the strictly opportunistic one of what is adaptive at each separate stage.”

The problem here is obvious. The adaptive advantage of EV is based on knowing that the final target is EVOLUTION. But by definition, natural selection has no foresight and cannot know what the final complex structure is supposed to be. Adaptability is determined only by present conditions, not some future goal or purpose. This hypothetical problem is later repeated in a real-world example.

The Meaning of “Correct”

Say we want a protein that is 100 amino acids long. The odds against stringing the amino acids together in the correct order randomly is 1 in 10130. But at each link in the chain there is a 1 in 20 chance of getting the correct amino acid. Therefore:

This stepwise procedure would entail perhaps 20 trials to achieve the correct amino acid at one position, another 20 trials to achieve the correct amino acid at one position, and so on. In sum, a succession of only 95 x 20=1900 trials may be necessary for selection to elicit a functional amino acid sequence for a chain 100 amino acids long.

Here Hall and Hallgrimsson fail to reflect on the meaning of the word correct. How will natural selection know which amino acid is “correct” in each position without knowing the whole correct sequence from the start? The textbook fails miserably in its attempt to address the problem of combinatorial inflation. The authors would have been well served to read the papers produced at the famous Wistar Institute conference of the 1960s!

Perhaps the issue isn’t so much the small variations in DNA sequences that affect amino acid and protein synthesis. Perhaps gene regulation is the important dynamic in generating variation. Strickberger’s Evolution explains:

In a seminal paper credited with directing many researchers to enter molecular biology, Francois Jacob (1977) saw the importance of regulation (which he named tinkering) in both development and evolution and as the ultimate target of natural selection.

We are then told that:

Natural selection does not work as an engineer works. It works like a tinkerer — a tinkerer who does not know exactly what [s]he is going to produce.

The reference is to Francois Jacob’s famous paper “Evolution and Tinkering” that appeared in Science. As we just saw with the article by Nilsson and Pelger, the textbook authors would have benefitted from a careful reading of Jacob’s paper. 

Engineering and Tinkering

According to Jacob, engineering and tinkering differ in the following important way:

When different engineers tackle the same problem, they are likely to end up with very nearly the same solution: all cars look alike, as do all cameras and all fountain pens. In contrast, different tinkerers interested in the same problem will reach different solutions, depending on the opportunities available to each of them. 

If Jacob is right, the phenomenon of convergent evolution suggests that natural selection fits better with the analogy of the engineer than it does the tinkerer! Moreover, just because a tinkerer is relegated to materials readily at hand doesn’t mean that the tinkerer doesn’t know in advance what he is trying to produce. Why tinker if you don’t have some idea of what you want to accomplish? Perhaps this is why Jacob, who wrote an entire paper based on drawing an analogy between natural selection and a human process, still concluded, “natural selection has no analogy with any aspect of human behavior.”

Distorting Evolution to Indoctrinate Students

In this post and the five that preceded it I have tried to highlight some of the more egregious ways Strickberger’s Evolution fundamentally distorts the science of evolutionary biology in service to its real intention to indoctrinate students into the Darwinian worldview. Clearly this textbook is not alone. Many of the errors and distortions outlined in this series of posts could be found in many other evolutionary biology textbooks. 

It is a great irony that one of the biological establishment’s chief complaints about intelligent design is the charge that ID proponents want to undermine science and turn the science classroom into an arena of religious indoctrination. In reality, however, it is the biological establishment that appears guilty of the crime of indoctrination and the undermining of real scientific inquiry and science education. The origin and development of life on earth presents us with some of the most profound mysteries we can face. The science classroom should be a place where students are brought fully into the presence of this mystery, not indoctrinated into a philosophical worldview that attempts to squeeze the mystery out. Strickberger’s Evolution, unfortunately, is a prime example of the latter.