An article in Nature seems to say that inconsequential mutations within our genes and proteins can be as significant as extinction in determining the evolutionary path we living creatures have taken since the beginning.

Michael J. Harms & Joseph W. Thornton published

Historical contingency and its biophysical basis in glucocorticoid receptor evolution

here http://www.nature.com/nature/journal/v512/n7513/full/nature13410.html

They say their “findings demonstrate that GR evolution depended strongly on improbable, non-deterministic events, and this contingency arose from intrinsic biophysical properties of the protein.”

My friends with “design” leanings will assert that God directed these highly improbable events. It is interesting to contemplate, along with all the other improbable constraints that coalesced to bring us to where we are, but the fact remains, these events are natural, not supernatural. The fact remains, it is impossible to please God without faith; it is impossible to come to God without first belief that he is and that he is a rewarder of them who diligently seek him.

The article, being at Nature, is expensive, and I won’t be buying it, so I’ll quote the editor’s summary,

Can evolutionary biology become a predictive science? The answer to that question depends largely on whether it proves possible to develop a quantitative measure of the role of chance historical events in shaping evolutionary paths. With that objective in mind, Michael Harms and Joseph Thornton start from a database of thousands of variants of an ancestral form of the glucocorticoid receptor to look for mutations paving the way for the appearance of a larger-effect mutation creating a new ligand specificity, and they find none besides the historical permissive mutations. Their result shows that the evolution of this class of hormone receptors is critically dependent on rare non-deterministic events, constrained by protein biophysics. Evolutionary contingency is often seen in terms of chance external forces such as extinction by asteroid impact or climate change, but this work points to the internal organization of biological systems as a further powerful source of contingency.

Just an annoying aside: I don’t know why editors allow “non” to be needlessly hyphenated.

As to the use of “predictive” in the editor’s first sentence, I suppose he is indicating the use of predictive models based on our understanding of evolutionary biology and mutation in order direct evolutionary change in organisms in order to get new ones with specific characteristics and traits. I think he mainly means we have to understand a lot better before we really move beyond trial and error in these regards.

I’ll add that there is plenty of references on the Nature page to keep someone busy for a long time, and many libraries will have free [to use] access to many of the resources. So, you can check it all out expending only your time.

One last comment from my studies long ago, a researcher once found that E. coli could consistently beat extreme odds of starving [and surviving] by mutating to eat an alternative food in their culture dish. The story goes that the researcher forgot to add the nutrient to a set of culture dishes one night, and he was disappointed to see his failed experiment the next morning. However, a couple of the cultures had survived. He investigated and found they had mutated such that they could eat an organic component of the culture gel, something that was not supposed to be able to happen. Odds against it were several million to one. So, he tried again with the same results. Then he tried various directed experiments along those lines and kept finding that the E. coli could consistently be extremely long odds. One experiment necessitated a contingent mutation, as the authors of the article here cited discuss. That is, the E. coli had to mutate ineffectively before a useful mutation was possible–a two step mutation pair. The E. coli managed. That is, while starving they mutated in a way that didn’t help them eat, yet that mutation allowed them to make a mutation that did enable them to eat and survive.

I’ve never managed to find again the specific references when I’ve tried. Perhaps the information is readily available now, but it will still require the right search. Regardless, such research continues, and the almost limitless variations and abilities of life grow more astonishing as we understand it better.

 

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