Thanks very much. What a great explanation! I think that I completely understand and the analogy was helpful. If you would not mind, can you please also clarify this:
You seem to differentiate between mutations that occur and mutations that stick (those that are “vital”…) Is that true?
In this quote, you are only referring to the vitality aspect here, right? You are not saying that one mutation has an effect upon another mutation occurring or not occurring, correct?
There is often a mix of categories, so I don’t know if it would be helpful to differentiate between them. There are mutations that happen, and some of those become common in the population through reproduction and common ancestry. Of those that become common, some are vital, some make no difference (i.e. neutral), and some can even be slightly deleterious. As time passes, the same mutation can switch between those categories, going from neutral to deleterious, slightly deleterious to beneficial, and so on.
I am saying that one mutation can have an effect on how beneficial, neutral, or deleterious other mutations are. I am talking more about the chances of a mutation being kept through natural selection. We could also include neutral drift resulting in a mutation becoming common in a population that later becomes beneficial when it interacts with future mutations.
@evograd @T_aquaticus Thanks to both for the explanations!
Thanks… it is helpful, maybe only to me so as to ensure that I was understanding you correctly. I believe that I was and thanks for the clarification. I see what you are saying in that the roles that any particular mutations are playing at any given time could change based upon the direction the object (enzyme, species, cell, etc.) is evolving.
So, the experiment was a bad one because, potentially, the pathway that they were expecting from enzyme1 to enzyme2 may not have been the way in which it would have evolved, if enzyme1 were to evolve into enzyme2? They calculated seven separate mutations to get from one to the other, but are you saying this could be a “you can’t get there from here” kind of scenario because the history brought to the experiment by the original enzyme was not included?
If that is so, and in light of the fact that we have such a diversity today, can we not imagine that X1 might evolve into X2? What would have been a good experiment for them to run that would explore the “evolvability” of an existing enzyme into another, vital enzyme?
Did anyone ever successfully engage with Axe on these questions?
Imagine you persuaded Axe that he should test an inferred ancestor of two extant enzymes, instead of attempting direct conversion. The result now has the potential to substantiate the reality of inferred phylogenies, basically proving extant sequences have a long and shared evolutionary history. How are IDcreationists now supposed to be dismissing phylogenetics as nothing but fantasies?
Studious avoidance is perhaps a good description.
Unfortunate.