The reason why this protein cannot go home, evolutionarily speaking, is due to five mutations that are supposed to have occurred. While these five mutations refined the protein's ability to find and bind cortisol, they also would destabilize the ancestral structure. In other words, if the protein were to revert to its ancestral structure, it would first need to reverse those five mutations. But, the evolutionists say, reversing those mutations would not help improve the ancestral function. They write:
we demonstrate that five subsequent ‘restrictive’ mutations, which optimized the new specificity of the glucocorticoid receptor, also destabilized elements of the protein structure that were required to support the ancestral conformation. Unless these ratchet-like epistatic substitutions are restored to their ancestral states, reversing the key function-switching mutations yields a non-functional protein. Reversing the restrictive substitutions first, however, does nothing to enhance the ancestral function.
Anyone familiar with the evolution genre knows the extreme heroics they routinely employ to make their theory work. When necessary evolutionists do not hesitate to make a mockery of science to avoid admitting the obvious--that evolution does not explain the evidence very well.
But when the adequacy of evolution is not at stake, when only the more esoteric issue of evolution's reversibility is under consideration, then evolutionists suddenly are free to point to obvious barriers.
They tell us that evolution created everything we have discovered: The DNA code, all of the genomes, the factory that makes glucocorticoid receptor and the other proteins, and a thousand other marvels. They cannot tell us just how this occurred, but they assure us that it is a fact. To deny any of this would be to deny evolution.
And yet when evolution is not at stake, then a mere five mutations halts the magic. Unbelievable.