I hate it that they always take words and change the meanings!! "It's only a theory".
It's unfortunate when words have two very different meanings in a technical and casual context. Some Creationist sites (like Answers In Genesis) go out of their way to outline this difference, so it's unclear to me to what extent they do this intentionally and to what extent it's simple misunderstanding of the context in which the word is used. Remember, most of these people are hearing about evolution for the first time at their churches, in which a simple misunderstanding 20 years ago may still be propagated to each new generation.
But yes, it is frustrating.
Yes!! This is the exact question I have! Where is the barrier, where does it stop exactly?!? Anything that I've read on this has never clarified. I should have known when he started mentioning Michael Behe though.
Unfortunately for him, nature doesn't play by our rules. Draw any line in development, and you'll almost certainly find at least one thing that straddles it. Divide organisms into species, and you'll find populations that meet some parts of the definition but not all. Divide into kingdoms, and you'll find something that doesn't quite fit into any kingdom. If you Google around you'll find multiple versions of the classification system out there, because nature cares so little about these things that we can't even agree on what the best categories
are, let alone trying to fit things in.
So if all the lines are blurry when you look close enough, how can we point to one and say, "Nature can't cross it?" I think you'll be hard pressed to find an answer that doesn't invoke the Biblical "kinds," ask whether dogs can evolve into cats, or invoke some variation of the watchmaker analogy. I've yet to hear a direct, concrete answer to the question, and that's probably because such a barrier is not known to exist.
However he did say something that I was wondering about. He states "mutations have never been found to create new protein-to-protein binding sites as would be necessary for the formation of novel molecular machinery within the cell". In other words, he's saying that no new biological structures are ever formed. I get lost on that one.
Yeah, I'm not sure what he's trying to say, either. Is he alluding to Michael Behe's criticism of the bacteria flagella? (I know Behe likes to refer to the flagellum as a piece of "machinery.") Is there anything in the context that makes this more clear?
For example, when talking about natural selection he used rabbits vs foxes and described a way where rabbits survived because of a gene that made them faster. He then says that in order for the foxes to survive, they would too aquire a running gene because the slower foxes would die out so the rabbits wouldn't have an advantage anymore. He described this as an arms race. So in his mind, it doesn't really work.
He is describing coevolution, where evolutionary changes in one organism results in changes in another organism. This can happen in many different interactions: cooperation, competition, predation, etc. With predation, it is indeed an arms race. However, I'm not seeing why it wouldn't work.
He is likely oversimplifying. Taking it a step further, what does a "gene to run faster" mean in real world terms? Is it like a part to make your car fun faster?
Just looking at the wall of text on that page should tip you off that it's definitely not that simple. What does running faster mean in terms of leg muscles, bone density, overall weight, size, shape, etc? Intuition tells us that stronger leg muscles will make us run faster, but that losing weight will also make us run faster. So let's increase our rabbit's leg muscles, trim some weight from the belly, lighten the bones a bit, and crank up the metabolism for good measure.
Ok, so we've now increased our energy consumption while decreasing our energy stores. So now we need to eat twice as often to stay healthy. Of course, that means we're in the open twice as long, so we're more vulnerable to attacks, and have less time for mating.
Are we optimizing for sprinting or long distance, or are we going to do a moderately good job at both? Do we want to grow larger so we can store a bit more food, or get smaller so we can find more hiding places? Do we want to focus our muscles on blind speed so we can outrun our predators, or agility so we can outmaneuver them? Do we want to make you smarter so you can be less predictable, or reduce some brain mass to save some energy? And will adding more leg muscles make you look more tasty?
And then once we find the best match, the fox evolves to match it. Maybe they get stronger legs to go faster, or maybe they increase their mobility, or they get smaller so they can follow more easily, or they get smarter so they can predict behavior, or they get quieter so they can ambush better (which means more delicate movements, smaller size, change in body proportions, etc.), or they optimize for sprinting, or they optimize for endurance...
So while it's definitely an arms race, I think he's picturing this as each side becoming like The Flash. But every improvement comes with a price, and the goal isn't to maximize one thing but rather to stay one step ahead of the other. So what this really amounts to is a complex evolutionary version of rock-paper-scissors.
And yeah, that's not even factoring in all the other stuff you mentioned.