Giardia: Suck on It, ID Creationists!

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:

giardia%20polyadenylation%20313.jpgThere’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.

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8 Responses to Giardia: Suck on It, ID Creationists!

  1. Jason Failes says:

    Hear, hear.
    You would think, however, that by not totally ignoring scientific research, by reading some studies (if only to quote mine them) the IDers would learn some actual biological science by accident and…then…just…go…away, shamed they ever thought such nonsense and took so long to grasp the multitudes of contradicting evidence.

  2. CRM-114 says:

    I forget where it was, but recently I ran into some interesting speculation about a species of parasite which has in its DNA coding for brain structures while the present species has no brain and seems to be doing splendidly without one.
    Not only does this make ID look Monty Python silly-buggers idiotic, but it puts the kack on those who insist evolution has a teleological aspect.

  3. Luna_the_cat says:

    In one of my first conversations with an ID-er, in which I was trying to diagram out for them a Wnt signalling pathway, they tried to claim that the complexity and interlocking parts of the system meant that it had to be “intelligently designed”. I thought, yeah, in much the same way that something designed at 2am in an undergraduate dorm after a great deal of alcohol is “intelligently designed”…or perhaps something farmed out to a subcommittee’s subcommittee after the whole project has gone horribly over deadline and over budget, and which ends up being finished in a final rush of “oh, just kludge something together so we can get out of here” at 4:30pm on Friday so that everyone can get to the pub.
    Any sober 3rd-year engineering student could surely have come up with a better design. What on earth do they mean to imply about their proposed “designer”?

  4. Chris Anderson says:

    You have what should be a valid point, Jason, except for one critical piece. IDers look at anything through a tremendously limiting filter. They only really see the pieces which they feel they can use to their own advantage, everything else is obviously either misinterpreted or flat out lies.
    As for intelligent design, Luna, I have long said that knees backs and teeth are all positive evidence that there cannot be an omnipotent omnibenevolent creator. You get three choices: bad design through incompetence, bad design through malice, or bad design through natural evolutionary processes. Which seems least appalling to you?

  5. David Marjanović says:

    I’m not the first to say “two words: Stupid Design”.

  6. Justin Moretti says:

    Are there not five proteins (five white circles)? Or do the overlapping Ysh1 and Yth1 count as one? Or perhaps either Pab1 or Pap1 have been mislabelled as the other?
    If only the ID creationists WOULD suck on some Giardia! They might be less full-of-shit afterwards…

  7. Luna_the_cat says:

    Chris Anderson: I will see your knees, backs and teeth, and raise you eyes, the esophagus/trachea intersection, and testicles.

  8. David Harmon says:

    Why yeast would need 24 proteins when Giardia gets by with four…
    Is it reasonable to guess that the parasite’s version would be much more vulnerable to environmental disruptions? (Which, of course, are less of a problem for an internal parasite than for a free-living organism.)

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