49 Facts I Learned This Year That — Surprisingly — Like, A Lot Of People Don't Know

Several times this year, I shared lists of "little-known facts" — aka facts BuzzFeed readers and Redditors alike revealed that most people either get wrong or, for whatever reason, are simply never taught.

Person with light hair wearing a textured jacket, holding tissue, and gesturing. Appears engaged in a conversation or interview setting
First We Feast / BuzzFeed

So you can enter 2025 even smarter than you were in the beginning of 2024 (which I'm willing to bet is already pretty dang smart!), I rounded up the commonly unknown facts people taught us this year:

As always, to keep this list from being ten thousand pages long, these are only summaries and by no means exhaustive explanations on all these topics. If you'd like to do a deep dive of your own, sources are linked out for each fact. Happy learning! 🤓

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1."The human body glows in the dark. No, seriously. It emits visible light at all times, but our eyes are too weak to see it. So yeah, you’re glowing right now, but no one can appreciate it."

Embarrassed_Honey711

2."It took a long time for the Giant Tortoise to be scientifically recognized because to be catalogued, a sample had to reach London. Turtles turn out to be really, really good to eat."

Giant tortoise walking on grass with palm trees in the background

3."Your skin doesn't have receptors to let you know if it's wet or not. This is why those sensory deprivation tanks have you floating in it. When the water is warm enough, your skin stops sensing the 'wetness' and you just feel like you're floating in the air."

Water droplets on a person's bare shoulder and upper back, with their hand gently touching their skin

4."The difference between less and fewer. 'Fewer' is used when something is countable, ie: Bob has fewer apples than Sally. 'Less' is used when it’s not, ie: Bob shows less kindness to horses than Sally.'"

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u/trigunnerd and u/not_thrilled

5."That butterflies retain memories from their larval (caterpillar) form. So while it is all goo in the pupa form, something is keeping some memories intact."

Butterflies emerging from chrysalises on a branch, showcasing stages of metamorphosis against a plain background

6."If there are 23 people in a room, the probability that two people have the same birthday is over 50%."

—u/MrLevi123This is called the birthday paradox. It involves a bit of math, so bear with me here. If every single person compares their birthday with each of the 22 other people in the room on a 1-on-1 basis, there are 253 possible combinations of people. In general, any two people have about a 99.7% chance of not having the same birthday. To calculate the likelihood of no birthday matches in that group overall, you'd multiply that percentage by itself (99.7% x 99.7%) 253 times (aka the number of possible combos), which ends up being 49.95%. If there's a 49.95% chance of them not having the same birthday, that means there's about a 50% chance of them having the same birthday! You can take a closer look at the math yourself here.

7."There's a thing called the Royal Order of Adjectives. This rule dictates the specific order in which adjectives should be arranged in a sentence, and native speakers follow it instinctively without being taught."

The order is: quantity, opinion, size, age, shape, color, origin/material, and qualifier. For example: A lovely small old square brown French leather handbag. It sounds wrong if you deviate from this order, but many people aren’t consciously aware of it! When you say something like 'A lovely small old square French leather brown handbag,' other naive speakers will wonder what French leather is. "

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jared_number_two

8."I remember reading that if you look at pictures of sick people, your immune system will automatically give itself a little boost just by looking at the pictures."

Person sneezing, holding a tissue, with eyes closed and wearing a casual black hoodie

9."The story of Humpty Dumpty doesn’t explicitly state that he is an egg."

Humpty Dumpty stands on a stool, shouting at a man in historical clothing. A teapot is on the ground nearby

10."UTIs in the elderly can cause them to hallucinate or be disoriented."

u/silly-billy-goat

Older patients with UTIs tend to have untraditional symptoms. They often experience symptoms such as delirium, tachycardia, frequent falling, or — in more extreme cases — hallucinations.

11."Rabbits don't have paw pads like cats or dogs. They've got nothing but fluffy feet. If you see a cartoon rabbit with paw pads, it's all lies."

—FOTBWN

12."Sign language isn't universal. Sign languages are their own unique languages, not just a signed version of spoken language."

Hands in various positions with a translucent red motion blur, emphasizing movement and artistic expression

13.Humans have stripes. We just can't usually see them. They're called Blaschko's lines, and according to the American Osteopathic College of Dermatology, they're patterns on "the skin that represent the developmental growth pattern during epidermal cell migration."

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Suggested by: Probablynotspiders

14.St. Patrick was not, in fact, Irish. Despite being the patron Saint of Ireland (and St. Patrick's Day generally being a celebration of Irish pride and culture), St. Patrick was actually born in Scotland. He ended up in Ireland after being kidnapped by Irish pirates and kept as a shepherd.

A man wearing a green "Ireland" shirt and a sparkly hat holds two pints of stout, celebrating outdoors with a crowd in the background

15."The first English scientists to receive a preserved platypus were so absolutely 100% convinced it was a hoax that he nearly took the specimen apart trying to find evidence that it had been assembled from multiple different animals."

—u/SoldMySoulForHairDyeIt's true! In 1799, zoologist George Shaw — the first to publish a description of a platypus — said of the animal,

16."The fax machine was invented in the 1800s, well before the telephone."

Exciting-Half3577

It's not the fax machine we know today, but the "original" fax machine (aka the electric printing telegraph)  was invented in 1843 by Alexander Baine. In contrast, the telephone was invented decades later in 1876 by Alexander Graham Bell. Big century for Alexanders, it seems!

17."A pony is not a baby horse. A baby horse is called a foal. A pony is a horse that as an adult is below a certain height."

Three horses stand in a scenic landscape of rolling hills and purple heather under a partly cloudy sky

18."Zebras are black with white stripes."

Zebra standing in a natural habitat, facing the camera with ears perked up and black and white stripes clearly visible

19."Words that are spelled the same but pronounced with emphasis on different syllables are actually indicative of the part of speech they are. Stress on the first syllable is a noun. Stress on the last syllable is a verb. Examples: CON-tract and con-TRACT. The former is a noun (sign this contract), whereas the latter is a verb (the muscles contract). Same with record, address, impact, object, and a few others."

Glittering-Cat4009

20."There's a jellyfish that doesn't have an anus! Whenever too much waste product builds up in its body, it simply makes a hole somewhere on its body, discharges the waste, and then the hole closes back up again."

A translucent jellyfish with shimmering bioluminescent lights floats in deep water, showcasing intricate patterns and delicate tentacles

21."The fact there are multiple ski resorts in Australia. Always seems to blow people's minds."

Person skiing down a snowy slope in New South Wales, surrounded by rocky outcrops and sparse vegetation under a partly cloudy sky

22."We all know the dinosaurs died out a long time ago (~65 million years ago). But what's even longer: they roamed the Earth for 165 million years. The Stegosaurus went extinct 66 million years before the T-Rex even existed."

despenser412

23."The Children's Crusade was a Holy Crusade made up nearly entirely of children. Their goal was to siege and take the Holy Lands for the Catholics, fixing their fathers' and brothers' perceived failures and taking the city. Most of them died before getting anywhere out of Europe."

—u/Upright_EeyoreThe Children’s Crusade of 1212, led by 12-year-old Stephen of Cloyes, was approved by neither King Philip nor the Pope, but that didn't stop Stephen and his army of children (which, according to legend, was as large as 30,000 people). Another similar group of child crusaders formed in Germany, led by Nicholas of Cologne. They supposedly carried crosses and banners instead of weapons and optimistically believed they could convert people through their words and divine intervention. As OP mentioned, the Crusaders hit a wall, so to speak, around the time they made it to Genoa, Italy, as many grew tired, hungry, and did not speak the language. The groups fell apart when they hit the coastal cities, where they were supposed to wait for boats to the Holy Land. You can read about them more in-depth here.

24."Poison dart frogs are only poisonous if you feed them toxic bugs. They are perfectly safe to handle if you feed them crickets."

A small, brightly patterned frog with orange and blue markings sits on a leaf

25."Babies have more bones than adults. A lot more."

u/SandSurfSubpoena

Babies are born with about 300 bones, whereas adults have 206 bones. As babies get older, some of their bones begin to fuse together. For instance, babies tend to have soft spots on their heads, which feel a lot different than the hard heads we adults have. Well, as babies age, those soft spots "close up" as the bones in their head fuse, giving them the skulls we have as adults. You can read more about the process here.

26."Froot Loops are all just one flavor."

Close-up of a pile of colorful cereal loops, including orange, purple, green, blue, and red, arranged in a random fashion

27."Animals can see completely different colors than us. Pretty wild when you think about it."

—u/InovoxMany animals can see colors that we as humans cannot. For instance, birds, reptiles, honeybees, and some bony fish have the ability to see ultraviolet light, which is outside our range of

28."Previously fish-free lakes and ponds can be populated by fish thanks to migrating ducks. When ducks eat fish eggs, some of them can pass through the digestive system unharmed and hatch in new waterways."

u/sola_clamoris

29."Uppercase letters are called that because they could be found in the upper drawer of a printing press, lowercase could be found in the lower case of the printing press."

A hand selects a small letter block from a drawer filled with various metal typesetting pieces

30."Rollercoasters are built to shake! I’ve seen so many people decide not to get on because of the swaying, but it’s important! If the support beams and tracks didn’t shake, they’d simply snap with all the force from the coaster cars roaring over them."

Roller coaster loop in motion under a clear sky, showcasing the thrill and speed of the ride

31."Also, roller coasters — at least the traditional kind — don’t have any engines. Typically, there’s a slope at the start where a chain in the track pulls the cars up to the top. After that, it’s all gravity and momentum. Takes some careful design to ensure that the cars don’t run out of (metaphorical) steam before the end."

Gadget100

32."German chocolate cake was made by an American named Samuel German. Not an actual German."

A slice of chocolate and cream layered cake on a white plate with chocolate shavings

33."Flamingos get their pink color from the seafood they eat. Change the food, and they'd be a different color."

Flamingo stands on one leg in shallow water with a cloudy sky in the background

34."Deoxygenated/venous blood isn’t blue, it’s dark red."

u/hellfirepunch

You might've been taught as a child that the blood flowing through your veins is blue because it hasn't been exposed to oxygen. That, however, is a myth. It's actually a dark red color. When you look at a vein in your arm, for instance, it only appears blue or purple-ish because you're viewing it through layers of fat and skin.

35."That your car’s fuel gauge has a little arrow next to the gas pump icon indicating which side your gas cap is on. Super handy when driving a rental or a new car."

—u/Weak_Rule_595

36."There are more bones in gummy worms than real worms."

Close-up of colorful gummy worms scattered randomly on a surface

37."The term 'bug' in computing has been around for a long time. The term was not commonly used until an actual bug landed on an electrical switch, causing the computer to malfunction. The term bug grew in popularity afterward and landed us where we are today. Also, when we find a bug in software, we apply a 'patch.' This comes from old cardex/punch card systems. If a punch card was punched in the wrong spot, you could fix it by applying a patch to the hole."

afristralian

The use of the term 'bug' to refer to an error or glitch can be traced all the way back to Thomas Edison in the early 1800s. As OP said above, it gained popularity in computer science after 1947, when a team at Harvard discovered that the reason their computer (Mark II) was having consistent errors was because an actual bug — a moth — had gotten inside the hardware and was messing with its functionality.

38."There is a jellyfish that is 'immortal.' It returns back to pupa state and then again grows and repeats the cycle!"

Glowing jellyfish with long, delicate tentacles floating in dark water

39."I recently learned that goodbye is a shortened form of 'God Be With You,' which people in Ye Olde England would say to each other."

Definition and etymology of "goodbye," derived from "God be with you," and similar phrases like farewell and adieu

40."The word 'set' holds the record for having the most definitions of any single word."

santyare

According to Guinness World Records, there are 430 different definitions for the word 'set' in the 1989 Second Edition of the Oxford English Dictionary. In fact, the entry is 60k words.

41."The release of all of the original Star Wars trilogy is closer in time to WWII than the present day."

Actor in a sci-fi movie scene wearing futuristic armor. Appears focused and determined amidst a high-tech background

42."Water towers are for water pressure, not just a town putting its name on a tank and saying, 'Hey, look how much dang water WE have.'"

—u/agreeswithfishpal

43."Your pee is filtered out of your BLOOD by your kidneys. There's no direct route for that glass of water from swallow to kidneys to pee (like food/feces has it's own set of pipes, from in to out). Water goes into your blood circulation (absorbed through the gut) and at some point, it gets lifted by your kidneys (along with other waste products) via your blood."

"It probably sounds breathtakingly obvious to many of you, but I teach A&P as part of my job, and many people don't initially realize that. They assume that there's some separate tube that takes fluids direct to the kidneys because they've just never really thought about it."

FeyGreen

44."Trees get the vast majority of their mass from the air. All that wood? That was once carbon dioxide and sunlight."

Tall trees seen from below with sunlight filtering through the branches

45."The component parts of the word helicopter are not 'heli' and 'copter.' It’s 'helico,' meaning 'spiral-shaped' like the word 'helix,' and 'pter' meaning 'wing' as in 'pterodactyl.'"

A helicopter flying in a cloudy sky with rotor blades spinning, as seen in an article on Internet Finds

46."The tune of the ‘Alphabet Song’ is actually the ‘Twinkle Twinkle Little Star’ tune."

Anonymous

47."Plumbing comes from the root Latin word of 'plumbum', which means lead, and is the reason it's Pb on the Periodic table. The Romans made water pipes out of lead."

Man under sink fixing pipes with a wrench, catching water in a bucket, focused expression

48.Most of the oxygen we breathe doesn't actually come from trees. When you were in school, you probably learned about how trees and other plants use carbon dioxide — what we breathe out — in the process of photosynthesis, which creates oxygen — what we breathe in — as a byproduct. People often assume that most of the oxygen we breathe comes from trees or other plant-dense forests, but that's not true. According to National Geographic, only about 28% of oxygen on Earth comes from rainforests.

Underwater scene with diverse seaweed and marine plants swaying in the ocean current

49.And lastly, "That sharks are older than the rings of Saturn."

u/CaBBaGe_isLaND

Saturn's rings are estimated to be no more than 400 million years old. Comparatively, sharks date back to the Late Ordovician Period, or about 450 million years ago.

Do you know any little-known facts like these? If so, please share them with us in the comments below! They just might end up in a future BuzzFeed Community post!