This is a WordPress repost of another excellent article originally authored by Kirk Durston at p2c.com (Power to Change Student Ministry) and is reposted with his permission. Dr. Kirk Durston has a Ph.D in Biophysics. While this post may be a tad on the technical side for some of us, it clearly speaks to the highly improbable, if not down right impossibly of life originating by chance. Be sure to click on the internal links within his post for additional supportive information.
Reposting: As requested by the author, please ensure that “Reposted with Permission” is included and that a link back to the originators site is included.
Two days ago I received a message from a second year medical student. She wrote, “We are currently in our neuroanatomy and physiology block in school, and … [our class is] collectively in awe of the structure of the human brain … which leads me to wonder about the total probability of all the conditions necessary for the existence of life on earth coming about by random chance alone. Would you be able to shed any insight on this?”
I certainly can. Let’s begin with estimating the probability P of obtaining an average-size (300 amino acids) protein. I will choose RecA because it is a universal protein and is only slightly smaller than average size with 240 amino acids. We can procede using an equation published by Hazen et al.
I (Ex) = – log2 [M(Ex)/N] (1)
Where I (Ex) is the functional information required to code for the protein and [M(Ex)/N] represents the number of functional sequences divided by the total number of possible sequences, which is equivalent to the probability P of obtaining a functional sequence in a single sampling. Unfortunately, we have two unknowns, M(Ex) and I(Ex). Fortunately, we can obtain a minimum value for I (Ex) using a method published by Durston et al. using actual data from Pfam for RecA and the published result (Table 1) is 832 functional bits of information.
Plugging that value into Eqn. (1) and solving for P = M(Ex)/N, the probability of obtaining RecA in a single sampling is, at best, 1 chance in 10^250 (1 with 250 zeros after it). Using a fast mutation and replication rate, a large genome size and a population of 10^30 prokaryotes, an upper limit for the total number of samplings over 10 billion years is somewhere around 10^42 to 10^43 … more than 200 orders of magnitude inadequate for obtaining even one average protein. Already, we can see that just getting one average functional, folding protein is a no-go, but we need a lot more for the first life form.
The simplest possible life form is thought to require roughly 382 protein-coding genes. Using published results from 35 protein families or domains, an average of 2.18 functional bits of information is required per site for a biological protein. Taking 382 protein families with an average of 300 sites each, the minimum amount of information required to code for the simplest life form would be 164,000 bits. Using Eqn. (1) to solve for P, the probability of obtaining the simplest life form is, at best, 1 chance in 10^250,000.
I would suggest that the belief that the elements in the periodic table can self-assemble into even the simplest life form has been about as scientifically successful as alchemy (see also here) and should not be confused with science. Evolutionary biologist Eugene Koonin, however, has another explanation. He concedes that obtaining something even simpler like the machinery for RNA replication is so improbable that it will not happen in the history of this universe, but suggests an infinite number of universes as the obvious solution. This, however, should not be mistaken for a scientific explanation but an appeal to science’s own ‘god-of-the-gaps’.