Many believe that the Theory of Evolution scientifically confirms a strictly materialistic view of the origin of life. I, like most Americans, am profoundly skeptical of this claim. But, unlike most Americans, my reasons do not stem from religion. They are, in fact, much more closely related to elementary probability theory and a family of proteins called aminoacyl tRNA synthetase.
Most of the machinery of cells is made up of long strings of amino acids called proteins. The order of the amino acids in a protein determines its structure and function. Pearson’s “Campbell Biology” notes that because there are 20 different kinds of biological amino acids there is a 1/20th chance of getting the correct amino acid at any particular point in a protein — making it unlikely that functional proteins could be randomly assembled.
Of course, Pearson oversimplified. Just like any mechanical structure, individual proteins still “work” with a number of “wrong” amino acids in their sequences. On average, six different kinds of amino acids can be placed at any given site in a protein without inhibiting function. So the likelihood of randomly assembling a protein properly is 6/20 x 6/20 x 6/20 ... and so on, as many times as there are amino acids in the protein.
Since most proteins are hundreds of amino acids long, these probabilities become vanishingly small. For example, even doubling the 6/20 chance above, the probability of getting a functional 400 amino acid protein from scratch is less than one chance in 10 to the 80th.
Biochemical evolutionary theory purportedly explains how such probabilities could have been overcome in little steps via natural selection. Such explanations are often disappointing because the probabilities assigned to each of these “little steps” either have nothing to do with biochemical reality (as in the pop-culture works of Richard Dawkins) or are ignored.
But there is one type of protein that unquestionably could not have been developed by Darwinian evolution: aminoacyl tRNA synthetase.
The aaRS are a family of proteins that “charge” tRNA blocks so that they can be used in protein synthesis. Each particular aaRS binds to one of the 20 biological amino acids. Then when a tRNA block with a particular three-base code floats by, the aaRS protein binds to it, checks that it has the correct set of three bases, and “fuses” its amino acid to the tRNA block. This “charged” tRNA now has RNA bases on one side and the amino acid which corresponds to them on the other. Ribosomes reading strips of mRNA can use charged tRNA blocks to accurately assemble proteins which reflect the information in the cell’s genes.
If the materialistic assumption is to account for the origin of life, it must account for this system — found in every known life form.
But the aaRS protein family — or some version of that family — must have been randomly assembled without the aid of natural selection. After all, without a functional aaRS (or something doing its job), the proteins synthesized by a cell would have nothing to do with the DNA in that cell. Without a way of at least somewhat accurately linking specific amino acids to specific RNA bases, the proteins assembled by a cell would be an entirely random function of whatever amino acids happened to be lying around.
Thus, we are forced to ask the probability of obtaining by pure chance a version of the aaRS that “works” — that could at least, loosely speaking, link specific amino acids to specific tRNA blocks. But — given the fact that most aaRS proteins (even in bacteria) are 800-900 amino acids long — the math explained above yields a probability even less than one in 10 to the 80th.
Such probabilities are beyond the point of possibility. Even assuming the entire surface of the earth were covered with mutation hubs, each about the size of a bacterium, feverishly reshuffling 400 amino acids every second, there could only be about 1 x 10^40 attempts at getting the aaRS in 13.5 billion years. This is over 40 orders of magnitude below the expected waiting time for getting a functional aaRS — even under the most generous of assumptions.
Such a thing simply could not have happened. An increasing number of scientists are coming to recognize this problem, and I think the average Penn student should too. Evolutionary theory does not provide a plausible materialistic explanation for the origin of life.
JEREMIAH KEENAN is a College junior from China studying mathematics and classical studies. His email address is firstname.lastname@example.org. “Keen on the Truth” appears every other Wednesday.
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