One of the major fallacies of intelligent design creationism is that so many structures appear to be haphazardly designed. Case in point: polyadenylation in Giardia lamblia. ScienceBlogling Carl Zimmer, in an excellent post about the recently published Giardia genome, describes the system:
There’s all sorts of fascinating stuff lurking in Giardia‘s genome. As they surveyed its 6470 genes, the genome team was struck by how simple Giardia is, compared to other eukaryotes. I think this diagram in particular does a nice job of illustrating Giardia’s simplicity. The top drawing shows what happens when Giardia is done copying a gene from DNA into a messenger molecule of RNA. The parasite has to lop off the end of the RNA molecule when it reaches the end of the gene. (It’s a process known as polyadenylation.) Four proteins (the small white circles) come to the aid of the RNA-building machine (marked here as RNAPII) when it reaches the end of a gene.
Below the diagram of Giardia‘s proteins is one showing the proteins that yeast uses to lop off its RNA. While yeast is single-celled eukaryote like Giardia, it’s much more typical as eukaryotes go. Along with the same four proteins Giardia uses (marked in green), yeast needs another 20 proteins to do the same job.
Same job, six times more proteins.
If you just looked at the polyadenylation complex of yeast (or humans), you might think that it was a marvelously complex system that could not work if any part was missing. But it turns out that it still works in Giardia with most of those proteins missing.
Why yeast would need 24 proteins when Giardia gets by with four isn’t deducible from intelligent design creationism. However, an ID creationist could try to argue that each polyadenylation system is adapted to each organism. Of course, the counter-argument is that if one claims that there are organism-specific polyadenylation systems, then why would there be any similar proteins–why not use a completely different system with no common proteins? In other words, the intelligent designer likes to use the same bits over and over again in a manner that could fool us heathens into thinking that the similarities evolved via common descent. To put it gently, that’s adding a weak ad-hoc supporting hypothesis to buttress the inadequacies of a weak ‘research programme.’
It’s also called fucking stupid.
Nonetheless, this does highlight the difference between biblical (young earth) creationism and intelligent design. Biblical creationism is completely anti-science in that it simply claims that the Bible supercedes all material evidence. Intelligent design creationism, on the other hand, proposes untestable hypotheses and is bad science–the kind that would earn a seventh-grader an F.
Now go read Carl’s description of some good science.