My colleagues and I worked on this problem of getting a new function for an existing protein fold, A to B transitions is what we call them. You have the same overall folded structure that can do both function A and B, but you need to do some modification to get it to go from A to B. Can evolution do it? When we went to the lab, we found that for the particular one that we examined, you can’t get from A to B by any evolutionarily plausible means. When we published that and described that in technical papers, the critique has been “In the history of life, that particular A that you studied never did evolve to B, so you’re studying a change that never actually happened in history.” We anticipated that that would be the critique and this is why we think that that’s a false critique of our work. We think that in order to say that evolution works, it must be true generally that you can get new functions for existing structures. So A to B transitions of some kind have to happen readily all the time in order for these new protein functions to appear. When we go to the lab and look at a particular A to B transition, we’re testing the general idea that these transitions are easy. However, we find that they aren’t, that A to B transitions are very difficult, in fact impossible, for the evolutionary mechanism, at least in the case that we’ve studied. So the claim that our particular demonstration of failure doesn’t apply is fallacious. People are trying to say A to B transitions happen all the time but the one you looked at didn’t work, whereas no one has shown that any of these transitions can work.
There’s another way in which the critique of our work goes wrong. We’ve shown that a particular A to B functional transition for enzymes doesn’t work and instead of people saying “Yes it does”, a lot of people who’ve critiqued our work have said “Of course it doesn’t work. These enzymes no longer evolve, they’re stuck on their functions and A enzyme is an A enzyme and a B enzyme is a B enzyme and it’s silly for you to think that you could get one to evolve to another because it has become so perfected by evolution that they’re no longer pliable.” This is basically an admission that evolution doesn’t work and it’s dreaming up a world where things were pliable and we’re scratching our heads thinking “Show us this world, show us these enzymes that can move from A to B.” It really has removed evolution from the realm of science, where you can go and test things in the lab, to “dreamed up in a fairy tale world” where you can’t even find the things that you would do the experiments on. It really has turned the whole thing into something of a joke.