Slashdot Mirror
Purpose of Appendix Believed Found
CambodiaSam sent in this story, which opens: "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.
For generations the appendix has been dismissed as superfluous. Doctors figured it had no function. Surgeons removed them routinely. People live fine without them.
The function of the appendix seems related to the massive amount of bacteria populating the human digestive system, according to the study in the Journal of Theoretical Biology. There are more bacteria than human cells in the typical body. Most are good and help digest food.
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."
I have studied little biology or medical subjects though I've read studies about this same sort of thing happening with asthma, polio & allergies. I think I've posted about this before but anecdotally I noticed there were no farmers who had allergies or asthma as I grew up and worked on farms with them. The young kids would play in hay and run around in the mud outside when it rained. So it seems that a problem with being an overly hygienic society today (as the article notes) is that we don't expose our young to these pathogens early on so they never adapt to them and suffer exposure to them later. This is why I recommend against anyone installing an air purifier in their home. It's a great idea--if you never plan on leaving your home.
I can't find the research but I thought a long time ago that a German study was done to find out why polio was "a middle class disease." If I recall they found that poor children were exposed to it since birth and rarely suffered from it since they were exposed to it always. The middle class children would be protected as infants but once exposed to it, their bodies would not be able to fight it. The upper class would take all costs to reduce exposure to it at all times--and they could.
Now this research is interestingly related in that appendicitis may be something that occurs due to our lack of exposure to diseases that destroy all the germs in our body (cholera & certain types of dysentery). Should something happen that would threaten this, our bodies respond poorly to it and the appendix flares up. As this article notes, appendicitis occurs less frequently in underdeveloped countries. Perhaps this is more reinforcement for the idea that protecting your children from germs is a double edged sword.
My work here is dung.
The abstract, for those who don't have access to the journal (article DOI doi:10.1016/j.jtbi.2007.08.032):
The human vermiform ("worm-like") appendix is a 5 to 10 cm long and 0.5 to 1
cm wide pouch that extends from the cecum of the large bowel. The architecture of the
human appendix is unique among mammals, and few mammals other than humans have
an appendix at all. The function of the human appendix has long been a matter of debate,
with the structure often considered to be a vestige of evolutionary development despite
evidence to the contrary based on comparative primate anatomy. The appendix is thought
to have some immune function based on its association with substantial lymphatic tissue,
although the specific nature of that putative function is unknown. Based (a) on a recently
acquired understanding of immune-mediated biofilm formation by commensal bacteria in
the mammalian gut, (b) on biofilm distribution in the large bowel, (c) the association of
lymphoid tissue with the appendix, (d) the potential for biofilms to protect and support
colonization by commensal bacteria, and (e) on the architecture of the human bowel, we
propose that the human appendix is well suited as a "safe house" for commensal bacteria,
providing support for bacterial growth and potentially facilitating re-inoculation of the
colon in the event that the contents of the intestinal tract are purged following exposure to a pathogen.
On the evening of the sixth day of creation, God had an argument with his editors about what to do with some material that all agreed was clever but not an especially great fit. So they decided to move it to the appendix.
Gives a new meaning to the term "stack dump". I myself am currently suffering from a stop error. :-(
-Rob
Biblical fiscal responsibility
Just like leaving meat out in the sun "produces" flies? Didn't we sort all this out back in the 17th century or whatever? Oh wait, its CNN, that paragon of quality journalism.
I want to delete my account but Slashdot doesn't allow it.
Evolution would have gotten rid of it if this part were useless.
It is not exactly true that evolution would get rid of a part that has become useless. Evolution through natural selection would tend to remove mainly deleterous (harmful) structures, but structures that are neither harmful nor helpful are masked from natural selection. To explain the loss of the vestigial structures, we must realize that the individual organism has only so many resources (energy, molecules, etc) with which to survive. This causes natural selection to select against structures that use up the organism's resources without contributing to its survival (for example in whales, who still have vestigial hips and leg bones, which serve no function and are much reduced in size).
This leads to the question of why the structure is still present. There are two major reasons why we would still observe the structure today: time and cost.
If natural selection only started working on removing the structure in recent time (geologically speaking), it would not be finished instantly in one generation, as natural selection works by tiny modifications that are build on generation after generation. Hence the canon of natural history: Natura non facit saltum (nature makes no leap).
A second possibility for its continued presence is that further reduction in its size or its total absence would be more disadvantageous the organism's fitness than its presence. This seems to be what the study is suggesting, that even though it is not used to the full extent it once was, there is some tiny function that is still useful enough to justify the resources the organism spends on it.
We are made wise not by the collection of our past, but by the responsibility for our future. -George Bernard Shaw
Want to give your offspring the best chance?
1. Breastfeed. Not just for 6 weeks either. Worldwide average weaning age is 3-4yrs. U.S. is about the worst at this.
2. Let your kids eat dirt. No, don't encourage it. Just don't freak when it happens.
3. Be very conservative with immunizations. How many middle class US children are really going to get exposed to Hep? And since thermerisol has finally been removed from vaccination products, the autism rate has finally stopped exploding (despite the fact that studies show no link between the two).
4. LOTS of physical contact! Breastfed babies get this. It stimulates brain development.
5. Love the little knuckleheads despite everything.
6. Learn basic biology and medicine yourself. Your offspring, your responsibility. Knowledge and common sense go a long way towards health.
We're still learning about biology and medicine. Oh shit, you mean bacteria can evolve to become resistant to antibiotics, and that blanketing the population with antibiotics (antibaterical handsoap, anyone?) causes bigger problems than it solves? I've never heard of a staph infection from a home birth. When women give birth at home around all the same germs they are exposed to anyway, postpartum infections are almost nonexistent.
OTOH, I will take exception to the idea that there were no allergies and less sickness among rural populations 2 generations ago. There were. The difference is that those kids were just labeled "sickly" and often died back then. Is it a bad thing that those kids have a chance now?
All pass beyond reach of medicine. None pass beyond the reach of love.