Posted on 06/18/2008 9:12:40 PM PDT by neverdem
Everyone is born with one, but no one knows what it’s for. The human appendix is a small dead-end tube connected to the cecum, or ascending colon, one section of the large intestine. Everyone lives happily with it until it becomes painfully inflamed, when the only treatment is to remove it surgically.
Then everyone lives happily without it. So why is it there in the first place?
Some experts have guessed that it is a vestige of the evolutionary development of some other organ, but there is little evidence for an appendix in our evolutionary ancestors. Few mammals have any appendix at all, and the appendices of those that do bears little resemblance to the human one.
Last December, researchers published a novel explanation in The Journal of Theoretical Biology. The appendix, they suggest, is a “safe house” for commensal bacteria, the symbiotic germs that aid digestion and help protect against disease-causing germs.
Structurally, the appendix is isolated from the rest of the gut, with an opening smaller than a pencil lead, protected from the fecal stream that might be carrying pathogens. In times of trouble like a diarrheal infection that flushes the system, these commensal bacteria could hide out there, ready to repopulate the gut when the coast is clear.
William Parker, the senior author of the study and an assistant professor of surgery at Duke, emphasized that this was a hypothesis, not experimental proof. “At this point,” Dr. Parker said, “this is a deduction based on a lot of information that we’ve had for many years and some key pieces of information that have only been uncovered recently by our lab and others. It does make sense.
“But an experiment to prove this theory would be very expensive...?”
(Excerpt) Read more at nytimes.com ...
What an interesting idea.
btt
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Darwin strikes out again...
I hate it when they hide in the footnotes, though.
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Thanks neverdem.there is little evidence for an appendix in our evolutionary ancestors. Few mammals have any appendix at all, and the appendices of those that do bears little resemblance to the human one.To all -- please ping me to other topics which are appropriate for the GGG list. |
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How so?
It would be rather easy to compare two groups; those with appendix and those that have removed them with respect to intestinal infections etc.
“Helpful Bacteria May Hide in Appendix”
Yeah, well, *I’m* not going in after them!
Yakult
“long thought vestigial”
Yes. That's how they eventually figured out that the spleen actually does occasionally matter.
That took decades.
This might take longer, as societies with enough of an understanding of basic sanitation to allow people to survive an appendectomy also have much, much lower rates of bouts of severe diarrhea.
The other end of that same stick is we still have appendices (well, maybe you do, I don't) because we still need them. If they were truly vestigial they would eventually go away especially since they do case often lethal problems.
For example, left untreated my appendicitis would have prevented me from passing on my genes. There must be some offsetting advantage to compensate for the losses caused by appendices, or the occasional freak born without one would take over the gene pool.
Die of appendicitis? Die of the after effects of diarrhea? Multiple bouts of diarrhea remains a very popular way for small children to die world wide, even with an appendix to repopulate the gut after the first mild case.
Like Perfect Creation, Evolution predicts that everything has a function. We may occasionally discover the function where it isn't glaringly obvious. This looks like one of those cases.
“An experiment to prove this would be very expensive.”
Perhaps it would be possible to check the infection rates of people with and without their appendix to see if having it removed causes an increase in various types and duration and frequency of illness after appendix removal.
Interesting. I have wondered what function the appendix performs. This theory, after it is studied, just might tell us what its function is.
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