Handing Ammunition to the Creationists
by MikeGeneOver at the Panda's Thumb, PZ Myers declared that the human appendix was useless:
Here's an excellent and useful summary of the appendix from a surgeon's perspective. Creationists dislike the idea that we bear useless organs, remnants of past function that are non-functional or even hazardous to our health; they make up stories about the importance of these vestiges. Sid Schwab has cut out a lot of appendices, and backs up its non-utility with evidence.
Yet it now looks like both Myers and Schwab are wrong:
Some scientists think they have figured out the real job of the troublesome and seemingly useless appendix: It produces and protects good germs for your gut. That's the theory from surgeons and immunologists at Duke University Medical School, published online in a scientific journal this week"¦.. But sometimes the flora of bacteria in the intestines die or are purged. Diseases such as cholera or amoebic dysentery would clear the gut of useful bacteria. The appendix's job is to reboot the digestive system in that case.
This hypothesis is also built on an interesting observation:
In less developed countries, where the appendix may be still useful, the rate of appendicitis is lower than in the U.S., other studies have shown, Parker said.
He said the appendix may be another case of an overly hygienic society triggering an overreaction by the body's immune system.
So where did Myers go wrong?
It is possible that Myers simply overlooked the role that symbiosis has played in evolution. For example, gut flora do not merely graze off the intestinal fluids, but "play important roles in shaping the postnatal development of the mammalian digestive tract, immune system and vasculature." (Cheesman, SE and Guillemin, K. 2007. We know you are in there: Conversing with the indigenous gut microbiota. Research in Microbiology 158: 2-9.) That the appendix may "reboot the digestive system" not only makes evolutionary sense, but the symbiotic nature of these bacteria among all vertebrates suggests this rebooting-function may even be the ancestral role of the appendix (or appendix-like structures). I'll try to address this in more detail later.
But I think the primary cause of Myers error was his anti-creationist chest-thumping. There is nothing in evolutionary theory that mandates the appendix would be useless and non-functional. On the contrary, that prediction is tied to an attempt to discredit the view of the human body being designed without evolution. By crowing about a non-functional organ that is also responsible for disease and death, Myers was trying to "disembowel" yet another creationist claim.
Of course, Myers now pays the price for all that chest-thumping, as I suspect it will not be long before creationists everywhere use his own words to claim victory. If he had stayed close to evolutionary theory and exhibited a scientific spirit, he would not have handed such useful ammunition to the creationists.
October 7th, 2007 at 9:26 pm
Yeah, PZ really jumped the gun on that one.
It's sad, because the real message should be that organs can be vestigial even if they're functional.
Comment by keiths — October 7, 2007 @ 9:26 pm
October 7th, 2007 at 9:30 pm
Hi keiths,
Well, it finally looks like we agree on something.
Comment by MikeGene — October 7, 2007 @ 9:30 pm
October 7th, 2007 at 9:39 pm
You're right. Let's go have a beer — this might not happen again for a while.
Comment by keiths — October 7, 2007 @ 9:39 pm
October 7th, 2007 at 10:06 pm
Comment by MikeGene — October 7, 2007 @ 10:06 pm
October 7th, 2007 at 10:22 pm
Nick Matzke in comment #4 said
It's not just for creationists anymore, Nick.
Comment by Lurker — October 7, 2007 @ 10:22 pm
October 8th, 2007 at 10:12 am
The appendix remains vestigial to its original function for digesting leaf matter even if it has been *coopted* for other functions; just as ostrich wings are vestigial to their original function of flight, but are important for balance in running.
That PZ may have overstated his position is rather irrelevant to the science. There is no scientific support for creationism in this report. I suppose it might have some minor effect on the cultural debate.
Comment by Zachriel — October 8, 2007 @ 10:12 am
October 8th, 2007 at 11:02 am
No one said there was. The problem is that, in his zeal to argue against creationism, PZ labelled the appendix useless and non-functional. Creationists (and others, I'm sure) apparently argued for an immune-system role of the appendix. 'Non-functional and useless' now seems like the incorrect claim. There's the ammunition he handed over. And the sad fact is, it wasn't necessary for him to do it - he should be chided for letting emotion and devotion to metaphysics over science turn him into, let's face it, a creationism accomplice.
Comment by nullasalus — October 8, 2007 @ 11:02 am
October 8th, 2007 at 7:45 pm
Don't be too surprised. After all, PZ like Dawkins is not immune to behaving in exactly the way they claim creationists do. If anything they are worse than the most sterotypical creationist you could possibly imagine.
Incidentally if anybody doubts this, read The God Delusion and PZ Myers defense of the same.
Comment by thesciphishow — October 8, 2007 @ 7:45 pm
October 9th, 2007 at 1:43 am
Darwinists will only reluctantly admit that the appendix gets progressively larger as you move from monkeys to humans. New world monkeys have no appendix. Some old world monkeys have an appendix. Apes have a smaller appendix than humans. Humans have the largest appendix of all primates. That doesn't exactly fit the predicted model of a vestigal organ. It fits the model of an organ that is coming rather than going.
Comment by Jehu — October 9, 2007 @ 1:43 am
October 9th, 2007 at 3:08 am
Um, this is tenditious because you are leaving out the caecum in all of these relatives: http://www.talkorigins.org/faq...
Um, the new paper doesn't even propose an immune function, not that anyone ever proved that there really was an immune function anyway (there is lymphatic immune tissue distributed throughout the gut), except perhaps the idea that the appendix immune cells represented a lame attempt to keep infected appendixes from killing several percent of the healthy adult population every generation.
And by the way, until someone explains some function (not "effect" or "possible effect") that has some benefit that outweighs the substantial selective cost imposed by appendicitis, they haven't really shown that the appendix has a useful function.
Comment by Nick Matzke — October 9, 2007 @ 3:08 am
October 9th, 2007 at 5:00 pm
Nick wrote:
"And by the way, until someone explains some function (not "effect" or "possible effect") that has some benefit that outweighs the substantial selective cost imposed by appendicitis, they haven't really shown that the appendix has a useful function."
Hmmm. So, are you suggesting that the appendix does not have a useful function, and thereby, can be a good example of evolutionary cobbling or bad design? Or do you believe we are still learning about the appendix and that it may in fact turn out to be "useful," whatever that definition is? Surely the default should not be that it has no useful function while the jury is still out?
Seems like the trend is definitely against the bad/useless design (or frankly, vestigal organs) school of thought: the panda's thumb, the inverted retina, junk DNA . . . Now the appendix may follow suit.
It's a tough time to be a proponent of design-by-evolutionary-cobbling.
Comment by Eric Anderson — October 9, 2007 @ 5:00 pm
October 9th, 2007 at 7:52 pm
Hi Nick,
As I mentioned above, you are not thinking in terms of symbiosis. Here is a more detailed summary of the study that should make this more clear:
The immune function in this case would be to protect the good bacteria.
You also note:
The "substantial selective cost imposed by appendicitis" seems to be more of a problem in industrialized societies (where the reach of selection is minimized by such artificial environments, BTW):
Here is some more on the hygiene hypothesis.
Comment by MikeGene — October 9, 2007 @ 7:52 pm
October 9th, 2007 at 10:34 pm
Douglas Theobald addresses the topic here in his usual thorough and sensible way.
Comment by keiths — October 9, 2007 @ 10:34 pm
October 10th, 2007 at 12:57 am
I have a few issues with the PT link. In trying to decide what side makes more sense in this whole deal, I'm worried about the attitude of those at sites like PT and others. The fact that ID is considered "anti-evolution" by most at these sites is very telling. Clearly, men like Michael Behe, who calls himself a theistic evolutionist is not a creationist, unless creationism simply means the belief that ANY intelligence started the process of evolution off and guided it in ANY manner whatsoever. Also- I've noticed the need for these sites to declare "good news" when they think something shows a lack of teleology. The post linked above even talks about how it's "good news" that the appendix might still be without purpose.
What's the quote I've read about the guy who is so bewildered by the fact that so many scientists spend so much of their lives trying their best to prove that their lives have no real purpose?
That's what I constantly see with these sites. It seems if they were truly interested in the truth, they'd follow it and it wouldn't automatically be good news to find that A, B, and C body parts are pointless. The obsession with calling anyone who doesn't see the world as blind, unguided, and lacking any and all teleology "anti-evolution" or "creationist" is also disturbing.
The fact is- it seems as if most of these posters and those who comment on these sites are outright atheists, and want merely to push that with their "science." Why else would you constantly attack a theistic evolutionist like (again I will use Behe as an example)?? I notice that TE's like Ken Miller get a pass. Is that because Miller denies that there's ANY scientific evidence for TE (which makes me wonder why he labels himself a TE at all)? Why are TEs who deny there's any evidence to back up their beliefs in that sense are given a pass by people like those at the NSCE?
Point is- it seems like a big heaping of politics and trying to push a very liberal point of view rather than doing too much science. (I mention that, because I've also noticed a common theme among most of the folks at sites like PT that they're usually of a fairly liberal bent socially, so it seems there's a connection.)
When it's all said and done- going to the link above seems fairly pointless unless you're already on board with the "your life is purposeless" idea and you're already fairly liberal socially. If you're not on board, then it feels like you're going to be labeled "anti-evolution" or "creationist" or maybe downright evil if you let them know it. Maybe I'm way off?
Comment by HaroldJenkins — October 10, 2007 @ 12:57 am
October 10th, 2007 at 2:32 pm
"Here's an excellent and useful summary of the appendix from a surgeon's perspective. Creationists dislike the idea that we bear useless organs, remnants of past function that are non-functional or even hazardous to our health; they make up stories about the importance of these vestiges. Sid Schwab has cut out a lot of appendices, and backs up its non-utility with evidence."
What creationists dislike the idea? I've read some creationists' peculiarly dysgenic theories of de-evolution, in which forces operating on the genome (as identified in evolutionary theory) are cumulatively destructive, randomizing, compromising functionality, etc. Life is degenerating from its originally created pristine state. Wouldn't seem to be such an alien idea, remnants, vestiges, useless organs, etc. We are the tattered remains of what we once were.
So creationists aren't consistent. So what? No one else is either.
And Sid Schwab, I can chop down a tree but that doesn't make me an expert on botany.
Seems to me the real ammunition being provided the creationists is not just another PZMyer flub, but that we so casually have accepted the teleological language and conceptions of the creationists (w/o crediting them of course) when we talk about biological functions at all.
Of course the appendix has no "function." Nothing has a "function." It makes as much sense to speculate about the appendix's function as it does to argue over the disposition of its soul.
Comment by Rock — October 10, 2007 @ 2:32 pm
October 11th, 2007 at 5:41 pm
I have to admit that the surgeon's argument was annoying to me. Someone (Martin?) recounted research implicating the appendix in the embryological development of the immune system. Schwab dismisses that by observing that the immune system suffuses the digestive tract. (Most of the Bamboo-Gobblers dismissed or ignored it too.)
It is not some sort of teleological prediction on my part, but maybe the appendix is a developmental vestige and not really an "evolutionary" vestige. (Of course, development is teleogical.)
The difference is that I didn't reject such a possibility, which Schwab, assuming an "anti-teleological" perspective, dismissed"”w/o even thinking of the possible alternative explanation.
Even if accepting teleology isn't productive of science, rejecting it clearly leads to problems.
Comment by Rock — October 11, 2007 @ 5:41 pm