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Theistic Evolution: Creative Power

Posted By Randall D. Isaac, Sunday, January 7, 2018

One of the major scientific critiques of theistic evolution offered by the authors is that the theory of evolution does not include mechanisms with adequate creative power to explain the complex and diverse biosphere. Therefore, they say, theistic evolutionists inappropriately attempt to reconcile Christianity with an inadequate scientific theory.

To assess the creative power of evolution, the authors ask, in effect, “What is the probability that random mutations, as proposed by the theory of evolution, could account for the existence of all the biomolecules, such as proteins, that are necessary for life?” In chapter 3, Matti Leisola writes: “Twenty amino acids are the building blocks of the proteins present in all living organisms, from bacteria to humans. The average protein is about 300 amino acids in length, more precisely, 267 for bacterial and 361 for eukaryotic proteins. These 300 amino acids can be ordered in 20300 (10390) different ways.” (p. 150-151) Using a multitude of detailed examples, the various authors calculate the enormous number of combinations of amino acids that are possible. They show that the fraction of those combinations that are functional is a vanishingly small number. To illustrate the argument, they offer examples such as bike locks, Shakespeare, and language. Hence, the probability that random mutations, even those starting from a known functioning biomolecule, could result in a complete set of the necessary biomolecules is effectively zero.

This argument is repeated in many different ways but the underlying principle is always the same. A probability of life based on the number of possible combinations of the building blocks of life is zero. Therefore, the theory of evolution has inadequate creative power to explain life.

I would suggest that the authors are considering the wrong question. It is well known that a posteriori probabilities are notoriously tricky. In evolution, we only know the a posteriori result and any probability must be treated with care. Dealing with this issue involves teleology which will be discussed in future posts.

The most important reason why this is the wrong question is that valid probabilities cannot be calculated, particularly using combinations, if the possible combinations aren’t all equally probable, or nearly so. In dealing a deck of cards, this is accomplished with a reshuffle before dealing each hand. In evolution, there is no reshuffle. Instead, there is active feedback at every generation that influences which combinations will continue to be pursued. With this feedback, probabilities can only be assessed if all known feedback processes can be identified and evaluated in detail. This cannot be done for evolution. The mutation processes we observe in nature are not just simple nucleotide or amino acid changes but large-scale changes such as chromosomal crossover in gamete formation, horizontal gene transfer, transposons, retroviruses, and many more, and most likely some we have yet to identify. Survival provides feedback at each generation about which combination will be sustained. As a result, probabilities are very weak arguments for or against the theory of evolution. 

Combination approaches to probability are known to scale exponentially with the number of components. This means, as in the quote above, that even average sized proteins involve an extremely large number of possible combinations. It can be shown mathematically that when feedback exists, probabilities scale much more slowly, perhaps as a power law or even logarithmically, depending on the type of feedback. This changes the outlook from impossible to the realm of possibility. This is the case for evolution. When the feedback from natural selection at each generation is taken into account, the probabilities no longer scale exponentially. The claim that evolution does not have the requisite creative power is not compelling.l.

It is nevertheless a mind-boggling claim to think that today’s diversity of life could ever have come from a simple population of primitive life. The right question to ask is not about the probabilities of evolution but to ask about evidence of what actually did happen. This is the topic of other claims in the book that we will discuss in future posts.

Tags:  theistic evolution 

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Keith C. Furman says...
Posted Sunday, January 7, 2018
Great points, Randy. I used to rely on those same protein complexity arguments. However, they mistakenly assume that the particular protein sequences we have are critical to particular function when there’s no reason that there couldn’t be an ocean of undiscovered totally different and unrelated sequences/folds that provide the same function—nature just happened to land on the ones we have. If intellectually unbiased and honest about it they would only need to imagine how many ways a string would fold each time it is shoved inside a thick hollow plastic key, for example. It would be an almost unlimited number of ways even though each folding solution would fill and assume the exact shape of the key each time.

Carbonic anhydrase, for example, has evolved independently multiple times with unrelated sequences. See http://www.pnas.org/content/96/26/15184.full.pdf

Further, with very rare exceptions, the sequences we do have are almost always remarkably tolerant of amino acid substitution as can be seen in cross-species sequence alignments, i.e., an ocean of alternative variants.

For the rare quite intolerant exceptions, like certain histone protein subunits, there could be an ocean of undiscovered unrelated sequences that would work, as in our string and hollow key analogy. We just don’t know what they are.

All-in-all, there are almost limitless ways that Created nature has to skin that cat to land upon the needed function.

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Randall D. Isaac says...
Posted Monday, January 8, 2018
Keith,
I agree with you that there is a remarkable degree of robustness and resilience in the recipe for proteins with many variations possible that retain the requisite function. The authors of this book recognize it as well. On page 151, Leisola says "But scientists still debate the size of the fraction of functional protein molecules among nonfunctional ones, as well as how best to describe the functional information residing in proteins. The difficulty is confounded by experimental findings showing that there are protein families with more than 100,000 members having related but different sequences and, most likely, essentially the same structure and function. Moreover, proteins having different sequences and structures but similar functions are also known. How can one address this difficult issue?" He devotes the rest of his chapter to detailed assessments such as the rarity of function in protein space.
I am suggesting in this post that relying on ratios of functional to nonfunctional combinations of nucleotides or amino acids is irrelevant to the question of the creative power of evolution. Such ratios may be helpful if all combinations are nearly equally probable. In evolutionary processes, they most decidedly are not. The use of the term "random mutations" is too often misunderstood to mean that all combinations are equally likely. But it really means that changes are made independent from the outcome. The combinations resulting from mutations are constrained by the numerous types of genomic changes that can occur. These are then selected for their contribution to survival. The result is a finely tuned feedback system that greatly enhances the probability of achieving the functions necessary for survival. This is extraordinary creative power.
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Craig M. Story says...
Posted Tuesday, January 9, 2018
Well said Randy, you must have a good biology teacher.
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