Thanks for your well-informed comment. The definition of species that I was taught, and that I still see in books, is that two organisms are considered to be of different species if they cannot interbreed and produce fertile offspring. What is the source for your definition? I wouldn’t be surprised if there are several definitions, each with its own cadre of backers. The diversity of life is a continuum. We like to put sharp borders around things, but nature is seldom that distinct. That’s just begging to have competing definitions.

The bit about the groups being separated for only a few millennia is hard to figure out. We’re dealing with a strange hybrid here. I am referring, of course, to the Intelligent Design creationism people. They’re a strange mix of young-Earth and old-Earth ideas. On the one hand, they’re looking for every opportunity to bash the process of evolution. Then in the same breath, they claim that evolution works, it was just occasionally goosed by God to make it work.

I wonder if ID creationists can interbreed with young-Earth creationists. Wait! What am I saying? Of course they can! They’re almost identical!

You’re right about how her “conclusion” doesn’t follow from her observation, but you’ve made some incorrect oversimplifications in your rebuttal.

The main one is the notion that different species “can’t” interbreed. Actually, they often can. A better simple description (although again, too simple to fully capture the real complexity of the term in biology) of what makes two groups different species is that they *don’t* interbreed, not that they “can’t”. It’s a statement of genetic isolation of two groups, not necessarily genetic incompatibility.

It’s true that in *some* cases the “don’t” is because they “can’t”, due to some genetic incompatibility. But there are many other reasons for genetic isolation, such as individuals of each group having mate-choice preferences toward their own group and against members of the other group, or separating into different ecological niches where they no longer encounter each other, or geographic isolation (i.e. some physical barrier between them), etc.

And over time, such genetic isolation has a strong likelihood of producing some degree of genetic incompatibility and/or noticeable difference in phenotype/morphology/appearance, the traits the layman most often thinks of as being what makes one species distinct from another. This is why it’s usually safe to deduce genetic isolation when one finds distinct groupings of different kinds of dinosaur fossils, for example, even though one obviously can’t try to crossbreed extinct groups or do genetic testing on them or watch and see if they mate with each other. Groups that retain traits distinct from each other clearly weren’t interbreeding, at least to any significant degree, for if they were there’d be many individuals who had mix-and-match combinations of the traits, we wouldn’t find say T-Rex style fossils and Daspletosaurus style fossils with distinct traits from each other.

Getting back to bison and non-bison, they’ve clearly been shaped independently of each other by the requirements of their ecological niches, and haven’t interbred with each other for quite a while, or else they’d have “blended” their traits and remained more similar to each other and not become so distinctive that they’re instantly recognizable as different. Even kids can tell a “buffalo” from a regular “cow”. All this remains true even under the YEC scenario (since they think that all these came from one set of ancestral “cow kind”), so even the creationists are going to have to agree that the different cattle varieties have been genetically isolated for a significant amount of time. So once one corrects their misunderstanding of the biological definition of “species”, they’ve got nothing to whine about, because even in their notion of the origin of bison vs non-bison cattle, they qualify as different species. QED.

Another thing that didn’t get jumped on as much as it should is the creationists’ mention of these groups being separated “for millennia”. You know, a few thousand years is a *really* short time in an evolutionary history. Do they *really* expect to see genetic incompatibility (not just isolation) occur after only a few thousand years? Really? Biologists don’t make any such claim (except in special cases — sometimes genetic incompatibility can arise suddenly, but that’s not the norm), so why are the creationists stupidly going “neener neener” at the biologists over a case of separation for only a few “millennia”? (A “millennium”, remember, is only 1000 years). Hey, many human subgroups have been isolated for more than 10,000 years (e.g. Europeans vs Native Americans), yet we all interbreed just fine. It usually takes a lot longer than that to diverge far enough to have problems interbreeding, for both us, and the bison.

As usual, the things the creationists fling around as “problems” for evolution are instead just examples of things that the creationists don’t properly understand about what evolutionary biology (or biology or science in general) does and does not say.

I actually have no delusions about convincing the retarded. This blog has two goals:
1. Entertain the non-retarded.
2. (This one is important) Provide information to people who aren’t necessarily fundies, but who are confused by all of the smoke and noise coming out of the fundie camp. Some of the creationist arguments sound plausible on the surface (”teach the controversy”, etc.). I want to show those people that those arguments are false and empty. We need to help those on the fence to come down into the pasture of facts and reality, and not fall over backward into the pasture of lies and delusions.

While I do so LOVE your style, I fear that you’re only going to entertain our (the non-retarded) community and your arguments will be lost on any dissenters. Of course…most arguments are lost on them, even if they’re politer and have pretty pictures, so…keep up the good work!

If you haven’t heard it already, P.Z. Myers ran creationist Geoffrey Simmons up and down the street on the radio the other day. MP3 here. (link from Bad Astronomy.)

I just checked their site. They still haven’t approved your comment. Don’t sit around waiting. They know their article can’t stand up to scrutiny, so they aren’t going to allow any dissent. Funny. That’s what they always accuse “Darwinists” of!

Keep up the good work.

They seem to spend about 95% of their time trying to disprove evolution. They’re wasting their time. If tens of thousands of real scientists have been unable to do so over many decades, what chance do they (most of them scientific illiterates) think they have?

They should put all of that effort into coming up with real statements on just what their theory predicts, and on coming up with the data to suppport that. But I guess finding any real data to support their crazy idea is even more unlikely than disproving evolution.

My major objection to ID/creationism is that it’s not falsifiable, but that’s a whole other topic.