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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
by killjoywashere 3y 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 3y agoI 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-myth/ https://greekcitytimes.com/2023/01/28/cyclops-ancient-greeks...
- deleted 3y ago[deleted]
- adolph 3y agoAt 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-megaflood https://unchartedterritories.tomaspueyo.com/p/the-zanclean-m... 1. https://en.wikipedia.org/wiki/Nuralagus https://en.wikipedia.org/wiki/Nuralagus 2. https://en.wikipedia.org/wiki/Dwarf_elephant https://en.wikipedia.org/wiki/Dwarf_elephant
- jacobolus 3y agoDwarf elephants have appeared separately in multiple places and times when full-sized elephants got stranded somewhere and their habitat / food supply was restricted. There were dwarf mammoths in the California channel islands until pretty recently (a mammoth presumably swam from the mainland when the sea level was lower and they were one big island).
- kombookcha 3y agoFor more non-elephant examples https://en.wikipedia.org/wiki/Insular_dwarfism https://en.wikipedia.org/wiki/Insular_dwarfism
- Mordisquitos 3y agoIn 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_zamoyski 3y agoThis 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.
- TeMPOraL 3y agoHence mention of a large population who lost those parts. The actual detriment may not be identifiable in a random individual, but it will show up at scale, as the noise of other confounders will average out.
- AniseAbyss 3y ago[dead]
- deleted 3y ago[deleted]
- starmftronajoll 3y agoThe 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.
- Mordisquitos 3y ago
- __MatrixMan__ 3y agoSo 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-hn 3y agoMore like the lumpy part where the threads come together that the pompom is hiding
- hinkley 3y agoIs 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'.
- sidlls 3y agoI 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
- barsonme 3y agoNewborn bowel movements are also important for preventing more serious jaundice.
- glfharris 3y agoThere are lots of ways things don't work. The plumbing can be connected up wrong or the pumps can not work.
- uulu 3y 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 3y agoLooks like it returns 1, to me.
- LocalH 3y agoNaN
- killjoywashere 3y agoReturns 1 would be cancer, autoimmune disease, or malformation.
- keepamovin 3y agoAwesome! 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?
- pazimzadeh 3y agoNothing 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.
- baxtr 3y agoAnd there is nothing in the article either that convinced you?
- pazimzadeh 3y agoYeah, it convinced me of the opposite. The appendix is probably not useless.
- prometheon1 3y agoIs it an argument from authority or an argument from experience?
- pazimzadeh 3y agoExperience would mean he's taken out a bunch of people's appendices and nothing bad has happened. Which still wouldn't prove that the appendix has no purpose at all.
- glfharris 3y agoHe's a pathologist, so if he has removed someone's appendix they'd probably be dead. Pedantry aside, your point still stands.
- killjoywashere 3y agoI've done a fair number of autopsies and have never even heard of someone ending up on the autopsy table secondary to an appendectomy. I'm sure it's happened, but, on balance, if the docs say you need an appendectomy, they're probably right.
- wilgertvelinga 3y agoI've got the proof of the embryology in my throat. My uvula is partially split. See: https://my.clevelandclinic.org/health/diseases/23943-bifid-uvula https://my.clevelandclinic.org/health/diseases/23943-bifid-u...
- picadores 3y agoAs 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 3y agoEven 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.
- killjoywashere 3y agoThe 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 3y agoCan you put the colon on the blockchain? I might know a guy.