Protein Probability – Dr. Brian Miller, guest blog post

Doug Axe determined experimentally that the probability for a random sequence of amino acids to correspond to just one section of a working protein is 1 chance in 10 to the power of 77. That number is a 1 with 77 zeros behind it. It is approximately the number of atoms in a billion galaxies the size of the Milky Way. Some have argued that the odds of a random sequence corresponding to a functional protein might be very small, but given enough trials, a functional sequence would eventually emerge.
 
This objection fails to appreciate that the chance of a successful search depends on the maximum possible number of trials.  An example would be a thief attempting to steal a bike by guessing the correct combination to a five-digit lock. The thief would have to attempt half of the 10,000 possible combinations to have a 50% chance of success. A diligent thief could likely try a sufficient number to find the correct combination in less than a day. In contrast, a ten-digit combination corresponds to 100 billion possibilities. A thief would not likely find the correct combination even if he searched for his entire lifetime.
 
In the case of proteins, the total number of organisms that have existed in the entire history of the earth is roughly 10 to the power of 40. That number is approximately the number of atoms in the Rocky Mountains, which is much smaller than the previous number. The chance of any organism ever stumbling upon a working protein would then be less than the total number of organisms (the smaller number) divided by number of trials needed to find a functional protein with high likelihood (the larger number). That probability is less than 1 chance in a trillion, trillion, trillion.
 
A second objection is that the particular protein Doug Axe studied might correspond to very rare sequences, but most other proteins might be much easier to evolve. In reality, the protein Axe studied performs the relatively simple task of breaking apart an antibiotic molecule. A large portion of proteins perform much more complex tasks, so they should be even more difficult to evolve. In addition, later research demonstrated that a wide range of proteins respond to mutations very similarly in terms of how they degrade the protein’s stability. This result further supports the view that extreme rarity applies to most proteins.
 
Guest Blog Post: Brian Miller, Research Coordinator, Center for Science and Culture, Discovery Institute
Dr. Brian Miller is Research Coordinator for the Center for Science and Culture at Discovery Institute. He holds a B.S. in physics with a minor in engineering from MIT and a Ph.D. in physics from Duke University. He speaks internationally on the topics of intelligent design and the impact of worldviews on society. He also has consulted on organizational development and strategic planning, and he is a technical consultant for TheStartup, a virtual incubator dedicated to bringing innovation to the marketplace.

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