These Questions Prove People Know Nothing About Human Anatomy

Home Biology These Questions Prove People Know Nothing About Human Anatomy

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By Joe Burgett - March 8, 2021

All over the internet, you will find medical questions being asked about pretty much everything. Yet there is no better outlet to find some of the most unique medical questions than Reddit. They have questions about pretty much everything from animal and plant biology to human anatomy and much more. We decided it would be pretty awesome to gather up some of the best human anatomy questions on Reddit and display them here. We also plan to give you the most popular answer that Reddit users voted for, as well as our take on the matter. Don’t worry, we’ll mark them in bold so you know which is which.

Since some of these answers can be quite massive (human anatomy is a big thing to explain), we did cut some down to display the main points the person gave. We’re also going to link you to the person who answered the question, so be sure to go to their profile and tell them that Science Sensei sent you! That said, let’s get started on our list of important questions about human anatomy, according to Reddit.

These Questions Prove People Know Nothing About Human Anatomy — *Woman Sleeping. Photo Credit: Lia Koltyrina/Shutterstock*

Why Can Your Body Have “Sleep Debt,” But Not A “Sleep Surplus?”

adp1314: Your brain is like a trash can. Throughout the day it fills up with garbage, and at night that garbage is slowly removed. If you don’t get enough sleep, only some of the garbage gets taken out. Over time, it builds up until your can is almost always full. A full can is bad and makes you fall asleep or hallucinate. However, if you sleep lots and lots, your trash-can can’t get under 0% full. It will always only hold a certain amount of garbage.

SS: Sleep is important to our bodies for numerous reasons, but the main reason is the health of our brain and body overall. If one lacks sleep, they will end up having issues such as hallucinations. Yet those can happen for other specific reasons beyond sleep. Since your brain needs sleep to function properly, specific areas of the brain will be affected. That is what brings a lot of symptoms along. You cannot have a sleep surplus because a surplus would be like having a remainder amount that you can store. But brains do not work like that. You need sleep daily, and sleep hours cannot be stored for later.

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Why Are Spinal Injuries (Even Minor Ones) Next To Impossible To Completely Fix?

NERWAL85: Take one strand of an overcooked spaghetti noodle. Break it. Now put it back together. Not so bad. That’s a nerve in your arm. Now take a whole fistful of overcooked spaghetti noodles. Rip those in half. Now reconnect them to the correct noodles without mushing any other noodles up. And do it while still holding them in your fist. That’s your spine.

SS: Basically. Of course, due to advancements in human anatomy, we’ve gotten far better at correcting spinal injuries. It used to be that even a minor spinal issue could turn into something that put you in a wheelchair for life. Now, we’re able to fix small stuff and even large problems are now a bit easier to control. There can be some major side effects, such as nerve problems, that spine surgeries can cause. However, we also now have medication to help that. While it is not perfect, things are getting better. Soon, this may no longer be an issue at all.

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Why Can You Donate More Than Half Your Liver and It’ll Grow Back In a Few Months, But Excessive Alcohol Will Permanently Scar It?

BlueShoeLover: Alcohol damages cells indiscriminately. So, I’m imagining a donated liver looks just like half of a healthy liver, and all the healthy cells can regrow normally. Then an alcohol-damaged liver is intact, but with random cells damaged. Now the cells around them can’t regrow because technically the damaged cells are still there and don’t need replacing.

SS: This is pretty much true. When you drink alcohol, your body has built-in measures to help. It’s part of our human anatomy to evolve and we’ve been drinking alcohol for thousands of years. Our livers have something called alcohol dehydrogenase, which breaks down the booze you drink. However, too much drinking will damage it. Due to the damage, your liver will not grow back those cells most of the time. When you cut a portion out, surgeons are ONLY removing healthy amounts that can grow back. It’s all down to what you remove, where alcohol is like dropping a bomb on your liver.

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If Our Brains Do Not Have Pain Receptors, How Does It Seem Like We Want To Split Our Skull When We Get Migraines or Headaches?

Fullblackhabit: While the brain itself doesn’t have pain receptors, it is surrounded by networks of muscle, membranes, blood vessels, and the like. That’s what experiences the pain instead.

SS: Essentially, that is true. Known human anatomy studies tell us that headaches are often caused by our neck or areas surrounding (often musculoskeletal), which can and will experience pain. If your neck is in a bad way, it can cause several issues that lead to headaches. This is why chiropractors are able to help with headache issues via adjustments. Migraines are different, however. They are often brought on by sensory issues, which then trigger a pain response. Like the Reddit responder said, this pain is then going to occur in other sectors.

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When a Person Receives a Limb Donation, How Do Surgeons “Wire Up” The Nerves So That The Recipient Can Use The Limb and Feel Sensation From It?

ThinImpression00: Recipient’s and new limb’s nerve fibers are connected => Recipient’s nerve fiber grows along with the new limb’s nerve fiber, and stimulates the surrounding muscles. This makes it functional (able to feel and move) => it takes months until the recipient’s nerve fibers have fully grown into the donated limb, making the whole new limb functional.

SS: Exactly true. This can be a difficult area of human anatomy to fully explain. It is an incredibly complicated surgery because it involves the ability to use a brand new limb with all nerves able to “feel” the limb. For robotic limbs, there might not be a feeling but the concept is the same. Where you need to be able to move it, you must be able to send signals from your brain to the limb. For the other, you’re able to connect and literally make it part of you once your body adjusts to the new limb.

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Why Do We Retain Memories If All Of Our Cells Replace Themselves After a Small Number of Years?

Gnonthgol: The concept that all your cells regenerate within 7-10 years is based on some misconceptions. Different types of cells regenerate at different rates. Some only last a few weeks while others last your entire life. Most of your brain cells are in the latter category. The seven years is based on an estimated average of all your cells. While we do not know much about how memories work there is some evidence suggesting that memories are refreshed when you are asleep. Even if brain cells don’t last your entire life but get damaged somehow, the memories will be restored and refreshed from time to time.

SS: This is mostly how it works. However, while we do know that cells do replace themselves, not all are replaced at the same level our skin cells are replaced. Memories are part of the brain itself, and if they did replace themselves the same way skin cells do, we’d never be able to remember things, think, move, or anything else. They do not operate in this format. Plus, cells do not fall off and restore at the same time. It’s a slow process, meaning in that 7 to 10 years, a complete area would have replaced itself. But they each did this over that specific period. That is also likely why memories are not affected.

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If The Liquids We Drink End Up In The Stomach, How Does Our Stomach Acid Not Get Thinned Down By The Constant Flow of Liquid?

Jkei: It does get diluted, but the stomach walls just add more concentrated acid back in. Even if you weren’t drinking anything, purely solid food is mixed with the acidic “liquidy” contents of the stomach and sent on to the small intestine together, so you “lose” acid over time regardless. The stomach would lose its function very, very quickly if it couldn’t maintain its contents’ proper acidity.

SS: A lot of this comes down to “pH balance” stuff. In human anatomy, we have the Acidic to Alkaline Scale or pH Scale. It goes from 0 to 14. Where 0 is Strongly Acidic and 14 is Strongly Alkaline. Stomach Acid happens to be at the 1 level. Meaning its acidic nature is incredibly high. Water is a 7, which is the neutral between acidic and alkaline. This makes stomach acid about 100 times more acidic than water. For your stomach acid to be affected, you’d have to literally drown yourself in water, drinking literal liters upon liters.

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On a Cellular Level, How Does Exercise Make Us Healthy or Improve Our Health?

bundt_chi: When your body is just sitting around, there’s still a lot of stuff your body is doing. When you exercise, your body has to be able to do those normal sitting-around things better and faster to be able to keep up with the demands of exercising. If you do that enough times, your body realizes it’s not doing a great job and needs to get better. It sends the signal to your body to start improving things. As this happens and your body gets a lot of practice operating at a higher level. In general, your body is less stressed just sitting around because it’s so much easier. [see the rest of this answer here]

SS: This is true. Our human anatomy is a tricky thing. We need to be able to handle everything life brings our way, and exercise is certainly a way to do that. Moreover, exercise is not really a cellular thing. It is mostly about the musculoskeletal system, which then affects the rest of our body. Thus, also affecting the cells in that process. When you exercise, you’re helping areas like the lungs and heart. That then helps the blood, which helps the brain. That will then help the rest of the body. Therefore, it’s a graduated scale where everything helps something else.

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In Ancient Times and Places Where Potable Water Was Scarce and People Drank Alcoholic Beverages For Substance, How Were People Not Dehydrated and Hungover All The Time?

nnelson2330: That is almost entirely a modern-day myth. There were systems in place to ensure the town’s water supply wasn’t contaminated and drinking water in most of the world was perfectly fine. They even had a system where tanners and blacksmiths and such would be fined if their cast-offs made it into the water supply. They were only allowed to operate in certain areas of town to keep the water supply clean. The laborers DID drink a lot of ale and beer while working but it was because the alcohol content was so low that it kept them hydrated and helped give them calories to keep up their energy.

SS: That is somewhat true. We’ve known that for thousands of years you could boil water to make it safer to drink. Of course, water was not filtered like today so humans did drink ale and wine a lot. The reason came down to filtration that this would go through. It was naturally safer to drink, and even kids drank wine back then. Why were they not dehydrated or hungover? Food also had water in it and bread could soak up the wine. Also, your body adjusts to the amount of alcohol you take in. Therefore, the more you have over time, the more you can consume without getting hungover.

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How Do We Think About Moving Our Body Without Actually Moving It?

TorakMcLaren: A lot of the brain activity is similar when we think about something as when we do it. Seems kinda obvious, but it goes deeper than you think. If you scan a musician’s brain when they actively listen to music, it will light up in a similar way as when they are playing the music. This differs in those who don’t play an instrument and listen to it. When you listen to someone speaking, part of your understanding comes from imagining yourself making those sounds, and working out what words you’d be saying if you did that. This is why you see some people mouthing along as they listen to someone speaking.

SS: That is mostly true. Our brain is pretty advanced. Why do you think we’ve yet to find a way to truly remove consciousness from one being to another? Why do you think brain transplants aren’t a thing? We can easily think about moving without actually moving. Meanwhile, we can also move without telling our bodies to do so. Things like twitches or other nerve-related issues can cause movements that we ourselves do not trigger. It is the same principle here. I can think about moving my leg, but it takes me actually doing it for it this to happen.

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Why Are Voices So Unique and Distinguishable? Even a Single Word Can Let You Recognize Someone?

Zomunieo: When you hear someone speak vowel sounds in particular, the timbre (resonant characteristics) is determined by the physical dimensions of a person’s body, especially their throat, mouth, and nose. Your brain learns to decode this to learn about the speaker, just as reverberations provide clues about the room you’re in.

SS: That is true. Several things impact how we sound. Many of us sound like our parents because we have recognized how they speak and copy it. This is especially true regarding vernacular and overall language. We separate to get our own distinct sound. But sound waves also operate differently when you record them or listen to them on a phone. This is why many people do not know how they truly sound without this. Some cannot even understand why they are told they cannot sing either. The way our ear catches things makes us adjust the way we speak. This is why deaf people sound as they do too.

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Why Does Everyone Have a Unique Gait When Biologically Most Of Us Are All Pretty Similar?

mrkedi: Basically, you always unconsciously walk while spending minimum energy (minimum potential energy) to do so. When they want to model someone’s gait, they model the dynamics of their body and calculate the most energy-efficient way to travel from point A to B. This will give super close results. Even when you have an injury, you will still take the minimum energy path within the limits of your injured joints. Since everyone’s body (and dynamics) is a little different, your gait will differ.

SS: To be fair here, our gaits are less unique than people assume. For women, you will likely see them walk in a way that their hips swing back and forth left to right. Men usually walk with one leg straight moving forward, then the next. The difference is due to those three things in the middle of our legs. This explains why in gender/sex form. The next reason is due to our height and weight. Larger steps are taken by larger people. Weight makes one need to use their hips to move their legs, which is why you might see overweight people moving in a waddle format.

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Why Do Older People Get Hurt More Often/Frequently/Easily Than Younger People?

DaedricHamster: Old people’s cells grow back slower than young people’s. When you’re young, your body is still set up to be growing and to be very active, your cells regenerate quickly. So do your organs, muscles, and bones. They’re kept in top condition and heal quickly when damaged. As you age, your rate of cell regeneration reduces. This means your body and organs get weaker and more susceptible to injury over time and, if they are damaged, they heal slower.

SS: Our knowledge of human anatomy tells us that as we age, our body slows down. Yet injuries are worse for the elderly because they are not keeping muscle on naturally or from working out regularly. Many also lose a lot of fat they once had. This means that without muscle or fat to break falls, bones are what’s impacted. As well as blood. Moreover, slower reflexes might cause them to have trouble bracing or stopping a fall. Some stuff happens frequently for older people due to various reasons, such as bad eyesight, bad hearing, medication, fatigue, etc.

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What Is The Anatomy Of a Boob and How Do Boob Jobs Work?

Catthew-Mahogany: [Breasts are] fatty tissue that comes equipped with glands for lactation. A breast implant involves a silicone implant being inserted into the breast to push that fatty tissue further away from the chest and make the skin of the breast stretch to become larger. Like when you make a mud pie in the backyard and your friend mushes his smaller mud pie into yours. The first mud pie is now bigger because it has more mud in it. Only it turns out your friend was using a different kind of mud than you used to make the original mud pie yourself.

SS: Breasts certainly are fatty tissue. Also, “boob jobs” are actually called “breast augmentation surgeries.” Yet what people think about breasts tends to be off-base. Women have larger breasts than men due to the estrogen hormone. When men take a lot of estrogen pills, they too will grow larger breasts. That is how many do it for gender transitioning. Also, ALL breasts can lactate… not just women’s. It is easier for women to do, especially naturally, because pregnancy will help trigger lactation (again, estrogen). Men do not have larger breasts or nipples for the baby to latch onto, making it harder to breastfeed.

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From Neanderthal To Homo sapiens: Did The Human Brain Develop In Order To Make People Think More or Did People Think More So That Their Anatomy Changed?

ipatimo: [The] Brain accidentally changed multiple times due to mutations in DNA. Species with changed brains had a small advantage to think better, which helped them to outlive others. And again, and again.

SS: The reason our brains changed was certainly evolutionary. All versions of human beings from the small spec to what we are today would develop and adjust for millions of years. The real major change in our brains developed during the Ardipithecus Era just under 6 million years ago. This was when we first began walking on two legs. We used stone tools in the Australopithecus Era around 2 million years ago. Our brains altered here the most which took us into the Neanderthal Era. Brains have since actually gotten smaller but more efficient, a lot like cell phones. All due to evolutionary adjustments. For a frame of reference, scholars generally agree that the earliest form of writing appeared almost 5,500 years ago in Mesopotamia.

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How Is Everyone’s Smile So Different Yet Everyone Has Relatively The Same Facial Muscular Anatomy?

mikeofarabia17: Everyone’s smile is incredibly similar, it’s just that our brains are set up to detect the small differences in human faces quickly and easily. Similarly, we can pick up on minute muscle tensions in faces to quickly assess the thoughts/moods/intentions of others.

SS: Exactly. This is just like the “gait” question. We’re more similar in our human anatomy than we assume. A smile is something that will differ a bit. However, faces look different more often than not. Therefore, we assume that a person’s smile is very different because we connect their face to their smile too. You and a friend could have the same smile but look different doing it, yet people might say your smiles differ when they really don’t. Your faces differ; the smile is the same. However, when they do differ, this is often due to the teeth and jaw. They are what truly determines a smile.

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What Happens When Fat Is Burned?

Verence17: Oxygen (which you gain from breathing) plus organic matter (which mainly consists of carbon and hydrogen atoms) produces water (oxygen plus hydrogen) and carbon dioxide (oxygen plus carbon). The former is used in your body alongside the water you drink, and excess water is ejected as urine. The latter is ejected when you breathe.

SS: Sooo… fat burning is often misunderstood. Fat cells actually give us our energy to fuel new activities and even work out. When you use a lot of this by working out or exercising regularly, fat cells cannot be stored as frequently. Obviously, you’re using them up. Since you are not storing fat as much, you begin to lose the fat you have on your body. This is good but it also means you need to eat more to give yourself the energy you used to get from stored fat. This is why you might see people like The Rock eat a lot, and somehow remain extremely muscular. He must eat a lot, there’s very little fat stored up to use.

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Why Do Most Animals (including humans) Have Some Duplicate Organs (lungs, kidneys) But Only One Of Our Most Important Organ (heart)?

stecarr1: Your most important organ would most likely be your brain and central nervous system as it’s the only part that can’t be replaced. For the sake of the argument, the heart is almost a duplicate organ in itself. It has two sides that provide blood to different parts of the body. These two sides are separated by the septum. Why do we have two of some organs? Evolution, having two of some organs has given us an evolutionary survival advantage over having one. These genes are more likely to survive and get passed down to offspring. Human anatomy today is the anatomy that was most likely to survive throughout our evolution.

SS: This is true. We even have proof of this. From an evolutionary perspective, we developed these extra organs as back-ups or to lead to efficiency. Many believe we developed two lungs as part of our beginning stage to help us grow. Considering oxygen levels were much higher millions of years ago, developing duplicate lungs only ensured we’d grow into larger beings. It worked, obviously. We then realized we needed two kidneys to help filter out potential problems, like poisons we might drink accidentally. However, humans can live normal lives with just one kidney and live just fine with one lung too!

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Why Do People Pass Out On Thrill Rides Like Slingshots or Roller Coasters?

Skusci: The main reason is due to Vasovagal syncope, which is where your heart rate and blood pressure suddenly drops from certain triggers. Anxiety/fear/excitement that comes with roller coasters tends to set it off. With the sudden drop in blood pressure, your brain gets less blood, and that leads to unconsciousness. G-force alone causing blood to rush to your feet doesn’t usually do it (unless you aren’t healthy), but a smaller drop in blood pressure is needed for you to pass out.

SS: This is pretty much on the mark. We pass out for numerous reasons, but it is almost always related to blood pressure. There are times our heart rate will cause this, but that in turn still triggers blood pressure differences. A person’s brain has randomly caused them to pass out, but this is extremely rare. A neurally-mediated syncope is almost the reverse of Vasovagal, as it lowers the heart rate and blood pressure. Yet it, too, triggers a pass-out or fainting episode. This tends to be something people can experience under G-Force pressure compared to thrill rides that raise both heart rate and blood pressure.

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What Are T-Cells and B-Cells In Medical Or Anatomy Terms and How Are They Different When Dealing With Viruses?

gamevideo113: B and T-cells are part of the adaptive immune system. They are lymphocytes that are activated to fight infection. T-cells can be divided into three main kinds: cytotoxic T-cells, which recognize and kill infected cells, T helper cells, which produce molecules called cytokines to control the immune response to a pathogen, and T reg cells, which inhibit the immune response. B-cells instead only produce antibodies, which can neutralize a pathogen and help macrophages in killing it. Some of these belong to innate immunity, others belong to adaptive immunity, while others allow an intersection between the two.

SS: Very spot on here. B-Cells are at the very center of the adaptive humoral immune system. They are responsible for being the middleman in our production of antigen-specific immunoglobulin, which is then directed to face off with invasive pathogens. T-Cells are responsible for trying to kill the infected host cells and then activate other immune cells with the hope of regulating our immune response in the body. Both are important to our immune system and help to keep us alive, literally.

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What Happens If Our Internal Organs Get Rearranged?

Tomato_On_Uranus: As long as nothing is damaged or twisted up, it’ll basically go right back where it was. Your organs don’t flop around loose in your torso, they’re attached all over the place to the inside of your thoracic cavity. If an organ is permanently removed from the torso, the others just kinda shift around to fill the space. A kidney specifically is different because it’s in a separate “pocket” than the rest, but end result is similar. There’s not an empty hole or anything.

SS: We know the person asking the question was asking it specifically in reference to c-sections. When you have one, it is true that surgeons will need to remove your organs to take out the child. For many, they are actually awake during this but are incredibly numbed up. Naturally, removing organs to get a child out is dangerous. Of course, this is why surgeons and nurses are so well trained. They know where to put them back. But even if they put them back in the wrong place, it’s not exactly a bad thing. Some people are born with their organs on the opposite side, it’s called Situs Inversus.

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How Does The Anatomy Of Conjoined Twins Work?

Straight-faced_solo: It’s different depending on each case. Usually, they have separate organs but share a circulatory system. It’s not uncommon for them to only have one heart and liver shared between the two.

SS: This is true, and the human anatomy of conjoined twins can be wildly different depending on the case. In fact, many conjoined twins are able to be separated without it causing an issue these days. The ones that cannot be “detached” are those who share an important organ such as a brain or heart. Other stuff can be cut in half and grow back or they can live with just half. This includes both having one lung, one kidney, or half a liver. Regarding those sharing a heart, they’ll be added to a transplant list. But this can take years and there is no guarantee a new heart will work. So splitting is very risky.

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Why, After a Good Long Cry, Can’t We Take A Big Deep Breath Without That Huh-Huh-Huh Tracheal Contraction?

Gynoceros: Those “tracheal contractions” are probably either diaphragmatic or congressional intra-abdominal muscle spasms, due to the strain that had been placed on them during the crying jag. Do you know how your legs get wobbly after doing a bunch of squats? Your breathing muscles get wobbly after being worked hard too.

SS: It essentially works exactly like this. A great example was given here. Yes, your diaphragm or other areas of your throat are working overtime when you cry a lot. On top of this, so are your lungs and even your sinuses. This is why when you cry, you might see a lot of “green stuff” come out. The human anatomy is interesting in this area, as we do not all cry the same but we ALL have an affected sinus or breathing issue. The same sort of thing can occur when we laugh very hard too. You’ve likely seen people who laugh so hard they cry or cough before. It’s the same principle involved.

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Why Does It Hurt When You Can’t Start/Finish a Sneeze?

AtlasTradeM: When you sneeze, it’s because your body detected bad stuff that it wants to remove from the body. This could be something irritating or something you’re allergic to. Sometimes your body tries to sneeze but fails because bodies aren’t perfect. When this happens, that sneezing feeling stays and can be painful because the allergen never left.

SS: This is mostly true. Basically, and your human anatomy textbooks will tell you this too, your sinus cavity affects a ton of things. As a result, if you feel you have to sneeze then you will very well end up sneezing usually. Some people like to stop themselves from doing so and that stoppage will hurt pretty bad. If you hurt when you’re about to sneeze but stop, it is all down to the nerves you have throughout your face and sinus cavity. These will be activated and that sends pain signals to the brain.

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Before We Had a Basic Concept Of Human Anatomy, Did We Use To Think That “Thought” Came From Our Heads?

[deleted-user] No. According to my psych book, across history, different cultures have thought that the “mind” existed in the liver or the heart. I would say that yes it is just placebo (to your 2nd question). I have no idea why we think love comes from the heart, maybe someone else can help?

SS: Human Anatomy assumptions were pretty wild. Socrates notably claimed the heart was the center of thought. We wrote a big article about how the human heart works and killed off some assumptions. In that, we referenced how Hippocrates was genius with his original assumptions of the heart and never believed it held thought. That said, we did not really believe the brain was the center of thought until after 100 AD. Yet people like Pythagorean Alcmaeon of Croton claimed in the 5th Century BCE that the brain was the center of thought. It just took a while for the rest of us to catch on.

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