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There's a lot of stuff that does something after we thought it didn't. I don't quite trust folk when they say "Oh, that's just there in your body but it doesn't
by nusl 2y ago
There's a lot of stuff that does something after we thought it didn't. I don't quite trust folk when they say "Oh, that's just there in your body but it doesn't do anything."
I get that some stuff genuinely doesn't because evolution deprecated it, but others we might not yet understand well enough to know this for sure.
- ajb 2y agoA lot of this comes from the assumption that our organs each have a single purpose, so if the obvious purpose is not relevant in humans then the organ is useless. But most organs serve multiple purposes.
- phkahler 2y ago>> I don't quite trust folk when they say "Oh, that's just there in your body but it doesn't do anything." If you expand that to "You don't need that" it covers the appendix, spleen, tonsils, wisdom teeth (even incisors can be removed to make room) and probably some other things. I'm in favor of keeping all your parts unless absolutely necessary, as all of these things seem to have at least marginal purpose.
- kstrauser 2y agoI generally agree, but: 1. They used to yank everyone’s tonsils at any provocation. There was a swing back to trying never to take them. I wish my pediatrician would’ve had mine removed after my nth tonsillitis so I didn’t have to have them out in my 30s. That was fun. 2. Having had an emergency appendectomy, I’m sympathetic to the notion of proactively snipping them any time you happen to be in there anyway. Getting a hernia fixed? Oh hey, let’s grab the appy while we’re at it!
- simianparrot 2y agoExcept the appendix is an important organ. It has a high concentration of immune tissue and supports the immune system in the gut, and it's also a "safe house" for beneficial bacteria in the case of food poisoning or other gut "clearing" events. It absolutely should not be just nipped out proactively.
- 1propionyl 2y agoMakes me wonder what we'd uncover with systematic longitudinal studies (within the same culture, rather than comparing populations with distinct cultures and genetic bases) on effects of male genital mutilation.
- kstrauser 2y agoThose are all true. However, appendicitis is still the most common abdominal surgery worldwide[0] and lots of people still die of it. It's easy to make the case that someone already undergoing abdominal surgery where the surgeon has ready access to it could have long-term lower health risk by removing it. If you live in a country with excellent healthcare and you're never far from a hospital, the calculus is a bit different. You'll probably be fine. If you regularly find yourself far away from modern medical clinics, it's easier to defend the idea. I had appendicitis as a kid. If you've never experienced it, trust me, you don't want it. [0] https://pmc.ncbi.nlm.nih.gov/articles/PMC9945388/ https://pmc.ncbi.nlm.nih.gov/articles/PMC9945388/
- wongarsu 2y agoIf you practice good food safety and hygiene (and live around people who do the same) then removing the appendix during unrelated surgeries or even preemptively before long stays at a place without emergency healthcare can be beneficial. It's a bit of a Chesterton's Fence situation: the appendix is really useful, but for you and me the benefit was much larger 300 years ago than it is today. Today the benefit is small enough that you can remove it with only minor considerations (like being more cautious about your gut microbiome, and having a slightly worse immune system)
- AnthonBerg 2y agoMy favorite – this is to some degree my interpretation though! – my favorite is the default mode network, a kind of constellation of brain activity. It’s called the default mode network because they found it through magnetic resonance imaging or something like this, and this activity pattern was the first pattern they saw!… A-ha! This is the default mode network! The default! The default mode! Yes!… the activity pattern in the brain of a human who has been persuaded to go into a very tight-fitting tube and is there all alone and it’s not pleasant. The default mode is activated during introspection and social isolation and among the things it does is generate the sensation of being something which is distinctly not part of the rest of the world.
- ulbu 2y agothis is so interesting. it’s not the first nor the last time wish that communities would not refrain from changing terminology. fitness is as important as accuracy and we shouldn’t be wary of dropping such inaccuracies, especially when they bring such strong connotations.
- PaulHoule 2y agoFor one thing the technology in an MRI based on a phenomenon known as nuclear magnetic resonance https://en.wikipedia.org/wiki/Nuclear_magnetic_resonance https://en.wikipedia.org/wiki/Nuclear_magnetic_resonance they dropped the "nuclear" bit because it is scary, it doesn't involve any ionizing radiation. It is all about making the nucleus wobble but not about splitting atoms. I have fond memories of doing NMR experiments in senior labs as a physics major.
- alyandon 2y agoI'm not one to typically have strong fear/anxiety responses in situations that aren't actually dangerous. However, I felt extremely uncomfortable being partially inserted into an MRI tube for a lower body scan. I couldn't imagine being shoved head first into that thing without being heavily sedated or completely knocked out.
- 2y ago
- a_c 2y agoThere is no grand design in biology. If something ain’t broke, evolution ain’t going to fix it. Retina in mammals facing backwards that gives rise to blind spot is one example. The laryngeal nerve that goes all the way down aorta and back up the neck is another
- jjk166 2y agoEh evolution will certainly try to fix things that ain't broke, indeed it will try to vary just about everything at some point or another. Bad cable management remains because no one survives the intermediate steps between functional configuration A and optimal configuration Z.
- Iolaum 2y agoNot exactly. Everything in our body needs energy to maintain itself. It has to provide some value for the energy it consumes, otherwise not having it becomes an evolutionary advantage meaning evolution will gravitate towards it.
- duskwuff 2y agoWhat a_c is getting at is that evolution can become trapped in local optima. The backwards retina in mammals is suboptimal, but it's locally optimal - the path from where we are to a better design (like the one in squid) is too long for evolution to hill-climb up to.
- Noumenon72 2y agoInformative X thread on how the recurrent laryngeal nerve path is dictated by having to develop embryos through chemotaxis: https://x.com/culpable_mink/status/1850937701518000383 https://x.com/culpable_mink/status/1850937701518000383 He mentions that even if you're a giraffe, you have nerves just as long running to the end of your spine, and from your spint to the bottoms of your feet, so the extra length of nerve isn't really a problem.
- a_c 2y agoThere is a pathway for every possible configuration. It doesn’t dictate whether a configuration is optimal. Maybe the laryngeal nerve isn’t that bad. But that doesn’t guarantee all anatomy and physiology optimal
- EvanAnderson 2y agoOn the theme: The phrase "junk" DNA always irritated me. I'm glad it is being replaced with "non-coding". Anybody who has looked at a 4kb demo can intuit that "junk" code likely has a function, even if it isn't immediately obvious machine code for the host CPU. I'm no geneticist, and I understand cells aren't CPUs, but I've read enough to know there's at least a tenuous analogy to non-coding DNA and the kind of "junk" you might find reversing a 4kb demo that procedurally generates its output.
- TeMPOraL 2y agoYup, DNA turned out to not merely be a sequence of triplets telling a dumb matter printer which hard-coded proteins to make - at least according to what little I understand of evolutionary developmental biology[0], DNA is much more like procedural generation in gamedev or demoscene. That is, there's plenty of recipes for various structures and body parts, and then there's lots of DNA that's responsible for conditionally enabling or disabling or modulating those recipes, depending on more DNA that controls when and where and how much to enable them, and then more - a complex network of logic. -- [0] - Didn't get much further than this four-minute intro to the field, but it is a good intro: https://youtu.be/ydqReeTV_vk https://youtu.be/ydqReeTV_vk. (EDIT: It's actually the second part of a trio, that starts with a four-minute bottom-up overview of organic chemistry[1], and ends on a three-minute intro to nanotechnology[2]. I recommend the series together for how well it frames humans in relation to other life and universe as a whole.) [1] - https://www.youtube.com/watch?v=f8FAJXPBdOg https://www.youtube.com/watch?v=f8FAJXPBdOg [2] - https://www.youtube.com/watch?v=ObvxPSQNMGc https://www.youtube.com/watch?v=ObvxPSQNMGc
- throwup238 2y agoThere’s also epigenetics with mechanisms like histone modification and DNA methylation that can control expression without changing the DNA, but still being heritable.
- mapt 2y agoThere are something like (in the reference diagram I'm looking at) eight levels of organization in the structure 'chromosome': https://en.wikipedia.org/wiki/Chromatin#/media/File:Chromatin_Structures.png https://en.wikipedia.org/wiki/Chromatin#/media/File:Chromati... Only the first one is DNA, and only a small portion of 'coding' DNA was initially regarded as important. My question is how? Structural organization implies information. Who thought "Nah, evolution put that in for shits and giggles"? Was it just things we couldn't observe at all without modern scanning electron micrography?
- marliechiller 2y agoTonsils are a good example of this. New studies are finding that they may be part of the immune system. Anecdotally, I had mine removed as a child due to frequent tonsilitis. As an adult, I suffer from a number of airborne allergies. Most likely a coincidence, but it does make me wonder!
- s_dev 2y agoThe Chesterton's Fence of body parts. https://en.wikipedia.org/wiki/G._K._Chesterton https://en.wikipedia.org/wiki/G._K._Chesterton
- Damogran6 2y agoMan, does THAT sum up the current political climate in America. There exists in such a case a certain institution or law; let us say, for the sake of simplicity, a fence or gate erected across a road. The more modern type of reformer goes gaily up to it and says, "I don't see the use of this; let us clear it away." To which the more intelligent type of reformer will do well to answer: "If you don't see the use of it, I certainly won't let you clear it away. Go away and think. Then, when you can come back and tell me that you do see the use of it, I may allow you to destroy it."[97]
- MrPatan 2y agoThe Chesterton fence defense (yeah!) doesn't apply. Did you care about Chesterton when the previous set of fence-smashers went around smashing (much older) fences?
- estebank 2y agoThe Chesterton fence argument is that you need to understand why the fence is there. If you do understand it, and still remove it, it doesn't say that's bad.
- card_zero 2y agoNo matter how hard I twiddle the left nipple, I can't seem to pick up Jazz FM.
- yread 2y agoMy grandfather managed to persuade me when I was 4 that beer comes out of man's nipples. Unfortunately, at the time he was supposedly too old for it to happen. And my father was too young. So, I've never seen it in action
- andrewl 2y agoAgreed. There is, or at least were, some parts of the body that were only recently discovered and not just known about and assumed to be inactive. It was only in 2015 that lymphatic vessels were discovered in the central nervous system: https://www.nih.gov/news-events/nih-research-matters/lymphatic-vessels-discovered-central-nervous-system https://www.nih.gov/news-events/nih-research-matters/lymphat... That article is about mice, but they were later found in humans, too.
- adolph 2y agoEpistemological modesty/honesty is undervalued compared to confident certainty (in my mind at least).
- pc86 2y agoI would expect at least some evolutionary pressure to get rid of unused things in your body. Let's just take the appendix as an example because it's probably the most common "you don't actually need this" thing that people know about. Some appendixes burst. Sometimes this kills people. Sometimes this happens before that person has been able to reproduce. Wouldn't this cause selection for people who at the very least don't have bursting appendixes (appendices just sounds wrong to my inner narrator in this context), but also for people who have smaller ones. Over time this pressure would decrease but shouldn't it theoretically over many many generations result in smaller and smaller, eventually disappearing, appendixes?
- grog454 2y agoI would think so. Who says that's not happening now? It seems reasonable that evolutionary pressure can be strong enough to have a significant impact in 1-2 generations (for example due to the introduction of a new environmental threat) or weak enough to take thousands of generations.
- kjkjadksj 2y agoAppendix is being appreciated these days as a reservoir of good gut bacteria. So there’s actually probably some pressure to keep it around. Appendicitis is a thing but of course not everyone suffers it. Maybe in the primitive world you were more likely to see your skull meet a rock before that happened in significant numbers of people in the population to the point it affected offspring counts.
- 4gotunameagain 2y agoCan we be sure that we don't need the appendix ? We used to think tonsils are optional as well, and there seem to have been some studies that find a link between tonsillectomy & Crohn's, Hodgkin's or even breast cancer (from wikipedia). There surely must be vestigial parts in our organisms, like the one in the article, but more often than not we have no fucking clue how they interconnect with the whole and what their function is. I think. I'm not a doctor or anything.
- evertedsphere 2y agofor me, appendix / appendixes (organ) / appendices (to a book) too, just like index / indexes (database) / indices
- arijo 2y agoTake mitochondria as an example. There has been a revolution in the understanding how this organelle works in the last few years. https://www.sciencedirect.com/science/article/pii/S0898656823002085 https://www.sciencedirect.com/science/article/pii/S089865682...
- ndr 2y agoEvolution works on a different timescale than what science divulgation headlines, and selected lineages to care about how to cross deadly valleys even though they might have appeared rarely. There's little room for baggage.
- eleveriven 2y agoYep, evolution leaves behind things that were once useful, but sometimes those traits could still have some kind of latent function that we just don’t have the tools to detect yet