If you have been paying attention, you might have notices a striking contrast in several of my previous postings about evolution and the genetic code. Let me see if I can make it more clear.
1. Some traits are easy to evolve — formed by many different combinations of mutations. Others are hard to evolve — made from an unlikely genetic recipe. Evolution gives us the easy ones, even when they are not the best.
2. For example, in 1991, evolutionary biologists Laurence Hurst of the University of Bath in England and David Haig of Harvard University showed that of all the possible codes made from the four bases and the 20 amino acids, the natural code is among the best at minimizing the effect of mutations.
3. Furthermore, just as a tinkerer’s creations seem jury-rigged, so too do the products of natural selection.
4. Thus, termination codon sequences are resistant or well-adapted to TM resulting from not only guanine lesions but also cytosine deamination.
5. evolution does not produce rational, perfect, finely-tuned beings. It makes organisms that are good enough.
6. Here, we consider whether robustness to translational frame-shift errors may be linked to the structure of the genetic code. We tested all alternative codes for the mean probability of encountering a stop in a frame-shifted protein-coding message. We find that the real genetic code encounters a stop more rapidly on average than 99.3% of the alternative codes.
It would seem clear to me that an intellectually honest and open-ended approach would have to acknowledge that these rational features of the genetic code count as evidence for its design. Not proof. Not even powerful evidence. Just evidence.
And there is a lot more to come…..