I was looking at Ken Ham's blog this afternoon because, well, I'd just cleaned up two piles of puke at work* and figured that reading a few of the Hamster's offerings wouldn't be that bad by comparison. As usual, the power of the Young Earth Creationists to be stupid is something that I shouldn't have underestimated. Apparently the Creation Museum here in Kentucky has a petting zoo (almost everything in Kentucky has a petting zoo) and the petting zoo recently succeeded in breeding a zonkey. Readers may remember our friend the zonkey, which is a sterile hybrid of a zebra and a donkey, from this post about artificial insemination pioneer Ilya Ivanov. While zonkeys sometimes occur in the wild, Ivanov could make the things on demand. (You know, in case we need thousands of them for...something.)
In any event, Ham holds up the zonkey as a triumph of the idea of "kinds". That is to say, the Young Earthers, forced to retreat from absolute anti-evolution rhetoric by the forces of obvious and observable reality, have now come up with an idea of limited evolution wherein basic body plans denote what can and cannot interbreed. Donkeys, horses, and zonkeys belong to the "horse kind"; tigers, lions, and Big Fluffy Puss-Puss belong to the "cat kind"; humans are their own "kind" apart from other primates (of course); and vampires, werewolves, and mummies are all part of the "monster kind". The creationists have even made up a field of "study", baraminology (which is so new that my spell check won't accept it), that is devoted to talking about "kinds" without, to my knowledge, actually publishing any peer reviewed research on the subject. Curiously, one of the things they've never really gotten around to is actually defining what a "kind" is. By ignoring secular taxonomy in favor of Biblical "baramins", Young Earthers have the luxury of adjusting the definition of "kind" to narrow it down to the species level (as with humans) or to broaden it out to include entire orders and beyond as it suits them.
Basically, this YEC concept is used to explain away observable evolution, visible changes within populations, and genetic similarities between certain animals. It creates certain difficulties, however, for those of us who are prone to thinking too hard about such things. For one thing, while it's touted as an anti-evolution concept, it requires (in the 6,000 year-old Earth context in which it is couched) super-fast hyperevolution to work. For example, AiG says that there were originally only 50 "kinds" of dinosaurs, and yet science has documented approximately 700 species of dinosaurs. Let's examine what those two numbers mean: AiG maintains that the story of Noah's Ark actually happened, and that it happened around 2300 BC. They further maintain that every "kind" of dinosaur was represented on the ark. These "kinds" of dinosaurs must therefore have undergone a ludicrously rapid speciation in order to get from 50 "kinds" to 700 species and then die off without a trace before, say, the birth of Christ. That's around 650 new species of megafauna appearing in less than 2500 years - hardly an anti-evolution position, but rather a pseudo-evolutionary one!
The point isn't really to try and make any sense or advance any understanding of the natural world. The point behind all this wrangling about "kinds" is to figure out some way to keep humans separate from all other animals. Using it as a sensible opposition to evolution (which it isn't) is a distantly secondary concern to the true goal: trying to set humans apart from all other lifeforms. As far as I can tell, humans are the only organisms with a "kind" all their own. Even the giraffe, which is often held up by creationists as being so bizarre as to be incapable of having evolved naturally, is acknowledged by AiG to share a common ancestor with the okapi. Talking about kinds lets the Young Earthers admit the reality of evolution without having to say it out loud - it's like a kid standing in his parents' living room with a baseball bat and admitting that he "might" have been responsible for the broken lamp.
Easily observable and repeatedly verified phenomenon like the appearance of drug resistant tuberculosis can only be explained in evolutionary terms, and deep down the Young Earthers know that. They have to own up to at least some evolution, so they try to invent new concepts like "microevolution" and "kinds" to downplay the significance of observed evolution. When they can't lie outright about the findings they're uncomfortable with (See this picture from AiG in which the shaded area is purported to represent the only bones found of ambulocetus, a transitional whale, then look at this picture of the actual skeleton.), they retreat to their weak "evolution-but-not-evolution" positions and try to stall out the discussion.
Even so, I don't think the point of "kinds" is to legitimately oppose evolution, not in the end. It just doesn't do a good job of it, and it admits far too much when you read between the lines. No, the main point of all so-called "bariminology" is undeniably the human "kind" sitting high atop its lonely throne. Separating us from our primate cousins is the ultimate purpose. Reality forces the Young Earthers to admit common ancestry in the animal kingdom, but as long as they can sequester humans in their own kind, they remain special, the God-created focal point of the universe. After all, once you've established yourself as the ultimate purpose of the existence of the entire cosmos, everything else is small potatoes.
*Good ol' direct care social services, man.