The appendix is not, in fact, useless

https://www.npr.org/sections/health-shots/2024/02/02/1228474984/appendix-function-appendicitis-gut-health

by Digit-Al • 2 years ago

309 140 2 years ago

Even when I was a kid they were starting to understand this. I'm old enough to remember people believing it was useless, maybe even I was told it from a figure of authority at some point, but definitely as a child my memory was "people used to think it was useless, but now we know it isn't ".

It's kind if interesting to me that I continually see stories titled like the article over the years. It goes to show that undoing incorrect common knowledge is a long process that isn't really ever completed, because an editor somewhere decided that a title like this would grab people's attention, but to someone like me, this is like a headline that reads "brushing your teeth confirmed to be effective treatment in fighting tooth decay".

I've noticed a surge in articles letting me know that the appendix isn't useless, so I assume we figured out a bit better what it actually does, but to me the most interesting part is about knowledge dissemination.

Talanes• 2 years ago

I had a similar thing with whether Giant Pandas were actual bears or not when I was a kid. The genetic tests that determined they were definitely bears happened five years before I was born, but I still got taught the "We used to think they were bears, but they're actually more closely related to raccoons" version until high school.

readthenotes12• 2 years ago

It was a weird article. The latest study date was 2007. Maybe since then they found the c. Difícils difference??

tamaharbor• 2 years ago

Jupiter used to “have” twelve moons.

taeric2• 2 years ago

To this day, I still have family that think ulcers are strictly a stress and diet related thing.

I also get a bit of a smirk out of the example you use. Brushing teeth is almost certainly effective at fighting tooth problems. However, I have grown wary of it as a goto example, as I think it has long been assumed as the only thing of note there. It seems far more likely, to me, that diet and genetics play far more of an active role in tooth health. Maybe I've just had bad luck with dentists, but I swear my tooth woes only ever get significantly worse every time I see one. :(

SuperNinKenDo2• 2 years ago

Interesting. That said, you would expect your teeth to basically get worse over time, there's rarely anything you can do to make them actually better, assuming you're not heavily deficient in something important to them. Only thing I can think of is that I believe it's possible to regrow enamel, but don't quote me on that. Otherwise teeth just basically get worse, and it's just a question of how quickly that happens.

kirse• 2 years ago

It goes to show that undoing incorrect common knowledge

It's because the appendix-is-useless "belief" comes with decades of evolution vs. intelligent design emotion behind it, starting with Darwin himself.

tsimionescu• 2 years ago

Part of it is also that, while it does seem to help, it doesn't really have a major role in your body, and you can live a very happy and healthy life without an appendix. So, compared to virtually every other organ a regular person would know by name, saying "it doesn't have a role" is a quite good approximation. Even tonsils have a better defined and more measurable role.

RandomLensman3• 2 years ago

Appendicitis was around in ancient times, too, so I am not sure I understand the reference only to industrialized nations in that respect.

readthenotes12• 2 years ago

"Appendicitis is predominantly happening in the industrialized nations of the world — areas where fiber content of the diet tends to be lower. "

I saw it as a reference to fiber poor diets....

RandomLensman3• 2 years ago

Perhaps, but I am somewhat surprised to see rates of appendicitis lower in the US than in Europe, for example.

arp242• 2 years ago

It doesn't say "only", it said "predominantly" and "more likely".

RandomLensman3• 2 years ago

Not sure the data is that clear:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9758930/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9945388/

Bangladesh and Bhutan have the highest age-standardized prevalence rates, for example. One of the lower SDI cohorts seems to lead now.

IAmNotACellist• 2 years ago

Story begins:

The appendix is not, in fact, useless
It was the first day of spring break in 1992 in Phoenix, and 12-year-old Heather Smith was excited for her family's upcoming ski trip...

Immediate skip.

sva_• 2 years ago

Almost like they were going to suggest their cooking recipe 20 paragraphs later.

adolph2• 2 years ago

The human appendix averages 9 cm (3.5 in) in length . . . . The diameter of the appendix is 6 mm (0.24 in) . . .

You'd need a bunch of appendii for a meal. Maybe one could pan fry them with mushrooms and serve atop pasta.

dvsfish• 2 years ago

That's very funny, thanks for that one haha :)

fngjdflmdflg• 2 years ago

+1. I was bit by an article yesterday[0] whose content begins 13 paragraphs in. Seems like this article starts only seven, shorter paragraphs in, which is more tolerable but still annoying.

[0] https://news.ycombinator.com/item?id=39248326

delecti• 2 years ago

At least that one presented itself as a story they were telling, rather than a simple factual answer. A headline about an anatomy professor detailing the uses of the appendix doesn't seem like it'll be a meandering tale about that professor's personal experience suffering with appendicitis more than 30 years ago.

notfed• 2 years ago

This is why many of us are excited about LLMs. This.

knodi123• 2 years ago

"Finally, I'll be able to automate turning a short science paragraph into a 10 page story with human interest content!"

avg_dev• 2 years ago

I wish an LLM had obviated this thread from the discussion

leptons• 2 years ago

So you won't have to write 10 paragraphs of inane filler, a computer will do it for you?

shortrounddev2• 2 years ago

Humans retain knowledge better if it's attached to a story

sidlls2• 2 years ago

I must not be human. For factual information of this sort I just prefer the information. The story is irrelevant and usually too mundane to be bothered with

lupire• 2 years ago

Only if the story relates to the knowledge. Not a distracting tangent.

jedberg• 2 years ago

Luckily they labeled the sections so I just skipped to the middle with all the good stuff.

pentae• 2 years ago

This is what happens when content is curated for Google and not human beings

pcchristie• 2 years ago

How does Google preference articles with these sorts of framings/intros?

ghosty141• 2 years ago

Whats the issue? Its just 1 small paragraph that goves a bit of background about the researcher. This isnt a scientific paper so a tiny bit of fluff isnt so bad.

lapetitejort• 2 years ago

I remember two or three times in my early life where I felt appendicitis-like symptoms only for them to go away after a few hours. That was until one night when the pains persisted past midnight. My roommate insisted on taking me to the ER. After several hours there I finally got checked in, had a CT scan, and prepped for surgery. The docs said I did indeed have appendicitis, and in fact had scarring from past episodes. Before the surgery the pain actually started to subside. I wonder if I could have moved past that episode, and if it would have hit me years later.

cyberax3• 2 years ago

Yes. Appendicitis can go away on its own, and it can also be treated with antibiotics.

Doctors prefer surgery because it's a definite cure, without negative effects of a long antibiotic course.

maximinus_thrax2• 2 years ago

Yes, it is possible but not likely for appendicitis to go away on its own. I mean the idea here is the likelihood of it going away on its own vs the possibility of it to burst and cause peritonitis. Doctors prefer surgery because peritonitis has a mortality rate of ~13% for < 50yo and ~30% otherwise, assuming immediate medical care and of course the surgery to clean up the burst organ.

Appendicitis going away without surgery is a common trope I heard from antivaxxers over the years. It's a very dangerous train of thought.

(someone who no longer has an appendix)

outime• 2 years ago

For what it's worth, I can relate to your story very much, albeit with a slight twist. The last time I experienced such intense pain, I ended up fainting (first and only instance in my life) in the ER. Consequently, surgery became a must.

IMHO, considering your past experiences with similar symptoms and existing scarring, it seems advisable to forgo the appendix, especially given your susceptibility to infection. If you hadn't done it, perhaps one of the future occasions could have ended much worse.

meindnoch• 2 years ago

My brother had the same. Except the second time it hit, it almost perforated, then he got peritonitis after the surgery, so he had a second emergency surgery where they had to remove 12cm of his bowel to save his life.

Don't hesitate going to the ER if you suspect your appendix.

cogman10• 2 years ago

It turns out that the appendix appears to have two related functions. The first function is supporting the immune system. The appendix has a high concentration of immune tissue, so it's acting to help the immune system fight any bad things in the gut.
The second function that it serves is what we refer to as the safe house. So this was a hypothesis that was put forward by a team from Duke University in 2007. And they argued that the appendix may serve as a safe reservoir for the beneficial gut bacteria that we have.

I have to question if the first function is valid. How can the appendix "help fight bad things in the gut" when it's basically a minor piece hanging off the large intestine. It's not like a lot of stuff passes through it or that it really secretes anything (AFAIK). In fact, wouldn't it make a little more sense that the high amount of immune tissue is there because of appendicitis? After all, people that don't die from sepsis tend to have more options to procreate and a less infect-able appendix would tend to make people live longer.

The second thing is pretty interesting though. Sort of makes sense. Though I'd imagine that more often than not the "bad bacteria" is going to infest the safe haven and kill the good gut bacteria. I can't see how that wouldn't often happen.

ramraj07• 2 years ago

The immune system in the gut has a complicated roll: it doesn’t just find bacteria and yell “bacteria! We have an infection!” Thus it needs to be able to tell the good bacteria from the bad. How does it? It constantly surveils the gut flora and builds a tolerance to the regular players. When something changes then it has the opportunity figure out if this is worrisome.

Thus you can see how the appendix could be part of this surveillance mechanism. Of course we still don’t fully understand this entire system so this is all hypotheses at best.

alan-hn2• 2 years ago

Bacteria need to compete for resources, usually when a new bacterial strain is introduced to an environment where there's already a ton of different bacteria, the ones that are already there have adapted to live in balance with the nutrients available and the other members of the community.

A new bacterial strain must either find an open niche in that community or somehow outcompete what's already there. The ones already there generally outnumber newcomers to a significant extent.

There is no "good" or "bad" in nature, those are words that describe the human perspective and there aren't necessarily bacteria that could come in with small numbers and somehow wipe out an existing population. Its all about competition and resources

killjoywashere7• 2 years ago

Once you understand the embryology, there are actually a variety of things like the appendix: they're just the ends of things that come together. The uvula is a great example: embryologically, the two sides of the face separate very early as an opening, then develop a lot of complicated anatomy and fuse back together. The uvula is where that fusion completes and the fusion process completes (returns 0) when the microenvironment variables get to a certain state.

The vermiform appendix is where the three tiniae coli come together. Unsurprisingly, the other, rectal, end the tiniea coli don't so much end as they spread out into the longitudinal muscular layer of the rectosigmoid.

And of course the wall of the vermiform appendix is full of lymphoid tissue. The whole colonic wall is full of lymphoid tissue!

Source: I'm a pathologist. I have looked at way too much colon. And uvula, and pretty much every other bit of tissue you can imagine, under gross exam, under a microscope, and in situ (live in ORs and dead in autopsy suites).

This idea that the vermiform appendix is some deep evolutionary mystery is sort of a low point of medicine that occasionally pokes its head up. It ranks up there with male pregnancy, and various birth defects that have given rise to stories of monsters, like Cyclops. Fun stories, completely useless. Please don't invest in anything related to any of those. If you have money burning a hole in your biomedical investment pocket, feel free to reach out.

ProjectArcturis• 2 years ago

I believe Cyclops myths were inspired by the skulls of dwarf elephants who lived on the island of Sardinia. https://greekcitytimes.com/2023/01/28/cyclops-ancient-greeks...

adolph2• 2 years ago

At first I thought the dwarf elephants would have come as a result of the Zanclean megaflood [0] of 5m years ago, which did cause some odd sized animals like the small dog sized rabbit Nuralagus [1], but the Mediterranean dwarf elephants did not appear until 2.5m years ago [2].

0. https://unchartedterritories.tomaspueyo.com/p/the-zanclean-m...

1. https://en.wikipedia.org/wiki/Nuralagus

2. https://en.wikipedia.org/wiki/Dwarf_elephant

Mordisquitos2• 2 years ago

In support of your scepticism I have to say there is something I'm always missing in these discussions about the alleged function of the appendix. That thing that I'm missing is a straightforward description of what are the consequences of patients losing these functions after an appendectomy. Surely there is more than enough population over which to do a case-study observational analysis? So, where is it? What happens to the immunity or gut flora of people who have had their appendices removed? Anything?

lo_zamoyski2• 2 years ago

This seems similar to asking what happens if you loose a number of parts whose loss does not produce immediately discernible detriment, or perhaps parts whose function may be approximated by something else in the event of a failure.

Of course, it is a perfectly valid question to ask what the effects of losing a part are.

starmftronajoll• 2 years ago

The article touches on this:

Studies have shown that infections with the really bad, nasty bacteria C. diff tend to be higher in people who have had their appendix removed.

cco• 2 years ago

Though I tend to agree with your train of thought, I'm always reminded of the French man who lost 90% of his brain mass yet still had a family a job and lived a normal life by all accounts. The human body can confound expectations for sure.

__MatrixMan__• 2 years ago

So it's like how knit hats often have pompoms to hide the lumpy part where all the threads come together, but like... for bodies?

alan-hn2• 2 years ago

More like the lumpy part where the threads come together that the pompom is hiding

hinkley• 2 years ago

Is this part of why everyone is so anxious to hear of the baby's first bowel movement? I know it's a sign the plumbing works, but I am not sure I would have included "the plumbing is connected" under 'works'.

sidlls2• 2 years ago

I always thought this was for two reasons: one as you say is to show the plumbing works, the other is because not passing the meconium (combination of stuff ingested while in the uterus) indicates other more serious conditions might exist

glfharris3• 2 years ago

There are lots of ways things don't work. The plumbing can be connected up wrong or the pumps can not work.

uulu• 2 years ago

Pathologist ... returns 0 when the microenvironment variables ...

Wow, and also informative and funny. This is HN in its full glory!

Sorry for the off-topic.

stavros• 2 years ago

Looks like it returns 1, to me.

keepamovin• 2 years ago

Awesome! Anatomy is so cool. Watching anatomy videos on YT, to me it seems like human bodies are composed of layers of biopolymers. The way all the structures are arranged and the intricacy and clean distinctness of the different layers is incredibly well organized. The human body is an amazing marvel, more so in than out in many ways.

Regarding gut bacteria, can you actually see biofilms of bacteria in the gut? Where do they reside? Or you can't tell with the eye?

pazimzadeh4• 2 years ago

Nothing you said convinces me that the uvula and appendix have no purpose. I assume that ends of things do come together a lot during development, but why does that imply no importance? Sounds like a classic case of chesterton's fence. and I hate to say it but argument from authority is pretty boring.

prometheon1• 2 years ago

Is it an argument from authority or an argument from experience?

baxtr• 2 years ago

And there is nothing in the article either that convinced you?

pegasus2• 2 years ago

I think you misread GP, they only said the appendix is not an evolutionary mystery, not that it doesn't serve a purpose. In fact, he noted the presence of lymphoid tissue, which makes is useful to the organism, as stated by the article as well.

wilgertvelinga• 2 years ago

I've got the proof of the embryology in my throat. My uvula is partially split. See: https://my.clevelandclinic.org/health/diseases/23943-bifid-u...

picadores• 2 years ago

As you described, nature just joints the pieces in a best effort and when it goes wrong, its never very likely to grow up to have appendictis. So the absence of anecdotes about failure is a indication of vitality of an element not of any designs.

My question: Did you discover during discection differences on the appendix depending on nutrition? Of course, people usually do have hospital meals in them when they drop by on the stainless steel desk.. none the less.. there might be bits stuck to the inflamed material..

GuB-42• 2 years ago

Even if that's just a seam, so to speak, it doesn't mean it can't evolve, I guess.

So the question is: why do we have a part of the body that seems to serve no purpose besides getting infected? And if it is not, in fact, useless, what purpose does it serve? Logically it should improve survivability more than the occasional infection decreases it, otherwise it should have disappeared, or at least, be different than it is now.

Unless appendicitis is a relatively modern disease and didn't affect survivability significantly and for long enough for evolution to do its work, which is a common hypothesis.

killjoywashere7• 2 years ago

The appendix does not evolve. The organism evolves. Logically, the genes encode proteins that respond to the local microenvironment. And that's it. The cells have no idea where they are, other than subtle cues from their neighbors. Imagine trying to build a city with no localization input except accelerometry. Theoretically, works fine. In practice, eh, there are some odds and ends left over.

jdonaldson• 2 years ago

Can you put the colon on the blockchain? I might know a guy.

lo_zamoyski2• 2 years ago

Natura nihil frustra facit.

quickthrower23• 2 years ago

Is an assumption. There is no evidence to say we are 100% optimised . Although I think it is likely.

maxbond• 2 years ago

What about vestigial stuff, like leg bones on whales?

https://www.icr.org/i/stage_248/whalelegs_stage.jpg

Similarly, what about things like congenital diseases? Why does sickle cell anemia seem to be an imperfect answer to malaria? Etc.

My suspicion is that evolution satisfices rather than optimizes, because once a trait which is in the process of changing ceases to be the limiting factor in reproduction it ceases to change rapidly. So unlike an optimizer, evolution often doesn't take free variables to extremes (eg remove the leg bones entirely) and doesn't find a global minimum, it finds a satisfactory location in phase space close to it's previous position.

Or maybe it optimizes on a higher level, and satisficing is more advantageous because optimizing to local conditions will leave you unprepared for future environmental changes, and tolerating things like vestigial traits creates opportunities for advantageous mutations. I think both explanations could coexist. This is all speculation, to be clear.

forgotmypw176• 2 years ago

https://www.sciencedaily.com/releases/2007/10/071008102334.h...

Date: October 8, 2007 Source: Duke University Medical Center Summary: Long denigrated as vestigial or useless, the appendix now appears to have a reason to be - as a "safe house" for the beneficial bacteria living in the human gut. The gut is populated with different microbes that help the digestive system break down the foods we eat. In return, the gut provides nourishment and safety to the bacteria. Parker now believes that the immune system cells found in the appendix are there to protect, rather than harm, the good bacteria.

feedsmgmt• 2 years ago

A reserve of good bacteria to repopulate your guts in case you consume something bad that needs to get flushed out. Aren't tonsils something similar?

forgotmypw176• 2 years ago

Yes, tonsils are another organ that was at one point declared useless but proved to be important.

wly_cdgr• 2 years ago

Well yeah. Half the time that's like, the best part of the book.

dinkleberg• 2 years ago

Haha that is how I interpreted the title too. Was thinking who in their right mind would question the value of an appendix?

kmoser• 2 years ago

It took me until the third paragraph to understand the actual topic.

jongjong• 2 years ago

I heard that tonsils also have an immune function.

stubish2• 2 years ago

Yes, last I heard they seemed designed to catch infection and be a training ground for the immune system, so it can deal with the issue faster if that particular pathogen infects a more critical organ. Also similar to one of the reasons babies stick everything in their mouths, so they get samples of pathogens while they are healthy and can deal with it, rather than getting exposed later when they are sick and their immune system already stressed.

ornel• 2 years ago

Primary source here:

https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.2...

jojobas• 2 years ago

The immune role of the appendix has been known for decades.

cryptonector• 2 years ago

I wonder whether exploratory surgery to try to "squeeze clear" any blockage might be a good idea, though it could easily be a terrible idea, no doubt.

fargle• 2 years ago

it is, in fact, usually the most interesting part of the document

denton-scratch3• 2 years ago

What purpose is served by the little toe?

I suspect it provides some (very) marginal help with balancing, at the cost of a microlimb that is particularly exposed to breakage by stubbing. Having broken each of my little toes by stubbing (on different occasions), I can attest that a broken little toe definitely makes it harder to balance. Hell, it makes it hard to stand.

I seriously doubt that there's enough strength in a little toe to provide much help with balancing. So given its propensity for injury, why have little toes not evolved away in large bipeds? (I don't think birds or quadripeds are prone to toe-stubbing)

Ekaros• 2 years ago

It is probably linked to fingers in some gene expressions. And 5 fingers I would say is more effective than 4. So changing of number of toes might also affect fingers. So better just to keep the extra. After all it is marginal.

lloeki• 2 years ago

Doesn't necessarily need to be effective motor function: it's a probe that provides tactile feedback, both for posture and balance, as well as being the one who gets hit often - being on the outer edge - possibly saving more critical foot areas from irreparable damage. By way of consequence it's helpful when fully functional but not essential as you are prone to hit it by "design" and make it temporarily nonfunctional every so often, all without impairing the whole foot function critical for bipedal walk as humans do it. Also, redundancy: when you break some other toe you're super glad there's a pinky, however comparatively small and weak.

Anecdata: as a skateboarder it's obvious (sometimes painfully so) how every toe matters to get the most information from beneath one's feet.

adammarples• 2 years ago

Little toes significantly widen your base. Yours probably don't because you've forced them into shoes your whole life and they are crushed against the others.

Fire-Dragon-DoL• 2 years ago

When I used to windsurf, it was pretty obvious how important the little toe is for balance, it drives where to push. I can't tell you why, but it was the toe that gave back the most feedback and told me how to push with my feet

bshacklett• 2 years ago

The little toe’s most important function is to remind its owner that even the most advanced being on earth can be thwarted by an inanimate object, such as the leg of a coffee table.

searchingalways• 2 years ago

I really thought this was going to be about a book appendix.

ArunRaja• 2 years ago

My theory:

Appendix acts like a fuse in an electric circuit.

As we get appendix infected, gotta iron out the root cause, it's a doorway to finding the lifestyle problem. Instead getting it removed (unless rarely necessary) means, certain first line of defence is taken away.

The appendix is not, in fact, useless

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