Humans Glow

Bioluminescence, the strange biology that causes certain creatures to glow, is usually found at the darkest depths of the ocean where the sun’s light doesn’t reach. While these light-emitting animals seem otherworldly, the trait is actually pretty common — in fact, you’re probably glowing right now.

According to researchers at Tohoku Institute of Technology in Japan, humans have their own bioluminescence, but at levels 1,000 times less than our eyes can detect. This subtle human light show, viewable thanks to ultra-sensitive cameras, is tied to our metabolism. Free radicals produced as part of our cell respiration interact with lipids and proteins in our bodies, and if they come in contact with a fluorescent chemical compound known as fluorophores, they can produce photons of light. This glow is mostly concentrated around our cheeks, forehead, and neck, and most common during the early afternoon hours, when our metabolism is at its busiest.

Cats Can Be Allergic to People

If you love cats but can’t have one of your own because you’re allergic, the feeling may be mutual. It isn’t common, but cats can be allergic to people. The condition is rare in part because we humans usually bathe regularly and thus don’t shed as much dead skin or hair as other animals (and it’s somewhat unclear how much of a problem human dander may be for felines). That said, cats are fairly sensitive to chemicals and sometimes have a negative reaction to certain perfumes, laundry detergents, and soaps. Cat allergic reactions look much the same as the ones humans get — they may manifest as sneezing, runny noses, rashes, hives, or other uncomfortable symptoms. In rare cases, cats can even be allergic to dogs. (Maybe that’s why some of them don’t get along.)

Reindeer Eyes Change Color With the Seasons

Rudolph’s nose may have been red, but his eyes were blue — except in the summer, when they would have been golden. That’s because reindeer eyes change color depending on the time of year, which helps them see better in different light levels. Their blue eyes are approximately 1,000 times more sensitive to light than their golden counterparts, a crucial adaptation in the dark days of winter. Only one part changes color, however: the tapetum lucidum, a mirrored layer situated behind the retina. Cats have it, too — it’s why their eyes appear to glow in the dark.

Chocolate Chips Were Invented After Chocolate Chip Cookies

Ruth Wakefield was no cookie-cutter baker. In fact, she is widely credited with developing the world’s first recipe for chocolate chip cookies. In 1937, Wakefield and her husband, Kenneth, owned the popular Toll House Inn in Whitman, Massachusetts. While mulling new desserts to serve at the inn’s restaurant, she decided to make Butter Drop Do pecan cookies (a thin butterscotch treat) with an alteration, using semisweet chocolate instead of baker’s chocolate. Rather than melting in the baker’s chocolate, she used an ice pick to cut the semisweet chocolate into tiny pieces. Upon removing the cookies from the oven, Wakefield found that the semisweet chocolate had held its shape much better than baker’s chocolate, which tended to spread throughout the dough during baking to create a chocolate-flavored cookie. These cookies, instead, had sweet little nuggets of chocolate studded throughout. The recipe for the treats — known as Toll House Chocolate Crunch Cookies — was included in a late 1930s edition of her cookbook, Ruth Wakefield’s Tried and True Recipes.

The cookies were a huge success, and Nestlé hired Wakefield as a recipe consultant in 1939, the same year they bought the rights to print her recipe on packages of their semisweet chocolate bars. To help customers create their own bits of chocolate, the bars came prescored in 160 segments, with an enclosed cutting tool. Around 1940 — three years after that first batch of chocolate chip cookies appeared fresh out of the oven — Nestlé began selling bags of Toll House Real Semi-Sweet Chocolate Morsels, which some dubbed “chocolate chips.” By 1941, “chocolate chip cookies” was the universally recognized name for the delicious treat. For her contributions to Nestlé, Wakefield reportedly received a lifetime supply of chocolate.

Bulls Can’t Actually See the Color Red

If the very idea of bullfights makes you see red, you’re not alone — even though bulls themselves can’t actually see the color. As is the case with other cattle and grazing animals such as sheep and horses, bulls' eyes have two types of color receptor cells (as opposed to the three types that humans have) and are most attuned to yellows, greens, blues, and purples. This condition, a kind of colorblindness known as dichromatism, makes a bullfighter’s muleta (red cape) look yellowish-gray to the animals.

So why are bulls enraged by the sight of matadors waving their muletas? The answer is simple: motion. The muleta isn’t even brought out until the third and final stage of a bullfight. The reason it’s red is a little unsavory — it’s actually because the color masks bloodstains. In 2007, the TV show MythBusters even devoted a segment to the idea that bulls are angered by the color red, finding zero evidence that the charging animals care what color is being waved at them and ample evidence that sudden movements are what really aggravate the poor creatures.

Ketchup Was Originally Made Out of Fish

If you asked for ketchup thousands of years ago in Asia, you might have been handed something that looks more like today’s soy sauce. Texts as old as 300 BCE show that southern Chinese cooks were mixing together salty, fermented pastes made from fish entrails, meat byproducts, and soybeans. These easily shipped and stored concoctions — known in different dialects as ge-thcup, koe-cheup, kêtsiap, or kicap — were shared along Southeast Asian trade routes. By the early 18th century, they had become popular with British traders. Yet the recipe was tricky to recreate back in England because the country lacked soybeans. Instead, countless ketchup varieties were made by boiling down other ingredients, sometimes including anchovies or oysters, or marinating them in large quantities of salt. One crop that the English avoided in their ketchup experiments was tomatoes, which for centuries were thought to be poisonous.

Across the Atlantic, Philadelphia scientist James Mease created the first tomato-based ketchup recipe in 1812. More than half a century later, Henry J. Heinz founded his food company in Sharpsburg, Pennsylvania, initially selling pickles, horseradish, and more. The first commercial tomato ketchups — including Heinz’s 1876 product — relied on chemicals to preserve their freshness and color, including formalin and coal tar. But around 1904, chief Heinz food scientist G.F. Mason devised an all-natural blend that included tomatoes, distilled vinegar, brown sugar, salt, and spices. With the signature formula now established, the brand was able to meet the growing U.S. demand for hot dogs, french fries, and hamburgers.

The Inventor of the Stop Sign Never Learned How To Drive

Few people have had a larger or more positive impact on the way we drive than William Phelps Eno, sometimes called the “father of traffic safety.” The New York City-born Eno — who invented the stop sign around the dawn of the 20th century — once traced the inspiration for his career to a horse-drawn-carriage traffic jam he experienced as a child in Manhattan in 1867: “There were only about a dozen horses and carriages involved, and all that was needed was a little order to keep the traffic moving,” he later wrote. “Yet nobody knew exactly what to do; neither the drivers nor the police knew anything about the control of traffic.”

After his father’s death in 1898 left him with a multimillion-dollar inheritance, Eno devoted himself to creating a field that didn’t otherwise exist: traffic management. He developed the first traffic plans for New York, Paris, and London. In 1921, he founded the Washington, D.C.-based Eno Center for Transportation, a research foundation on multimodal transportation issues that still exists. One thing Eno didn’t do, however, is learn how to drive. Perhaps because he had such extensive knowledge of them, Eno distrusted automobiles and preferred riding horses. He died in Connecticut at the age of 86 in 1945 having never driven a car.

The National Animal of Scotland Is the Unicorn

America has the eagle, England has the lion, and Scotland has the unicorn. And while the horned mythological creature may not actually exist, the traits it represents certainly do: Purity, independence, and an untamable spirit are all qualities Scotland has long cherished. Unicorns appeared on the country’s coat of arms starting in the 12th century, and were ​​officially adopted as Scotland’s national animal by King Robert I in the late 14th century. For many years, the coat of arms included two of the legendary beings, but in 1603 one was replaced by a lion to mark the Union of the Crowns. Fittingly for the then-newly united England and Scotland, folklore had long depicted the two creatures as butting heads to determine which one was truly the “king of beasts.”

Scottish kings also displayed that fighting spirit, which may be why unicorns were generally depicted in Scottish heraldry as wearing gold chains — only the land’s mighty monarchs could tame them. Unicorns remain popular in Scotland to this day, with renditions found on palaces, universities, castles, and even Scotland’s oldest surviving wooden warship.

Green Bell Peppers Are Just Unripe Red Bell Peppers

If you’ve ever found yourself in the grocery store struggling to decide between red and green bell peppers — or even just wondering what the difference is between them — you may be interested to learn that they’re the very same vegetable. In fact, green bell peppers are just red bell peppers that haven’t ripened yet, while orange and yellow peppers are somewhere in between the two stages. As they ripen, bell peppers don’t just change color — they also become sweeter and drastically increase their beta-carotene, vitamin A, and vitamin C content. So while the green variety isn’t quite as nutritious as its red counterpart, the good news is that one eventually becomes the other.

A Dentist Helped Invent the Cotton Candy Machine

When folks learn that one of cotton candy’s creators cleaned teeth for a living, jaws inevitably drop. Born in 1860, dentist William J. Morrison became president of the Tennessee State Dental Association in 1894. But Morrison was something of a polymath and a dabbler, and his varied interests also included writing children’s books and designing scientific processes: He patented methods for both turning cottonseed oil into a lard substitute and purifying Nashville’s public drinking water. In 1897, Morrison and a fellow Nashvillian — confectioner John C. Wharton — collaborated on an “electric candy machine,” which received a patent within two years. Their device melted sugar into a whirling central chamber and then used air to push the sugar through a screen into a metal bowl, where wisps of the treat accumulated. Morrison and Wharton debuted their snack, “fairy floss,” at the Louisiana Purchase Exposition of 1904 (better known as the St. Louis World’s Fair). Over the seven-month event, at least 65,000 people purchased a wooden box of the stuff, netting Morrison and Wharton the modern equivalent of more than $500,000.

Human Hair Contains Traces of Gold

Gold is present in low levels throughout the Earth. It’s been found on every continent except Antarctica, as well as in the planet’s core, the oceans, plants, and in humans, too. The average human body of about 150 pounds is said to contain about .2 milligrams of gold, which we excrete through our skin and hair. Babies less than 3 months old tend to have more gold in their manes than older people, thanks to the precious metal being passed along in human breast milk. And while no one’s suggesting we should mine the gold in hair or breast milk (as far as we know), researchers are studying whether gold — and other metals — might be recovered from human waste.

Bananas Are Technically Berries

Berry classification is a confusing business. People began referring to some fruits as “berries” thousands of years before scientists established their own definitions, some of which are still debated. Today, little effort is made to teach the public about what botanically constitutes a berry, so here’s a bit of help. It’s generally accepted that all berries meet three standards: First, they have a trio of distinct fleshy layers (the outer exocarp, middle mesocarp, and innermost endocarp); second, their endocarps house multiple seeds; third, berries are simple fruits, meaning they develop from flowers with a single ovary.  

Blueberries and cranberries are true berries, as their names imply. Other berries may surprise you: Avocados, eggplants, grapes, guava, kiwis, papayas, peppers, pomegranates, and tomatoes are all, botanically speaking, berries. Bananas are berries, too, since they meet all three requirements. The exocarp of a banana is its peel, while the mesocarp is the creamy middle surrounding the seedy, also-edible endocarp. With seeds growing on the outside, blackberries, raspberries, and strawberries are, confusingly given their names, neither berries nor simple fruits. Instead, they are called aggregate fruits, because they grow from multiple ovaries of the same flower.

Grand Central Terminal Is Radioactive

Next time you find yourself arriving at Grand Central Terminal, feel free to inform the person sitting next to you that the architectural landmark is radioactive — and, once their expression changes, be sure to also tell them that it’s only by a harmless amount. Located in midtown Manhattan, New York’s most-beloved transportation hub (sorry, not sorry, Penn Station) was built between 1903 and 1913 out of granite, which contains higher levels of uranium than most other stones. Still, the levels aren’t all that high: The average person is exposed to 360 millirems of radiation per year, 300 of which come from natural sources, and Grand Central employees would absorb about 120 millirems at work over the course of a year.

Bees Can Recognize Human Faces

Humans have known about bees for a long time: 8,000-year-old cave paintings in Bicorp, Spain, show early humans scaling trees to collect honey. But modern scientists wanted to know if bees recognize us, which is why researchers have put the insects’ microscopic brains to the test. In a 2005 study, honey bees were trained to memorize pictures of human faces by scientists who rewarded them for correct matches with droplets of sugar water. While a bee’s-eye view isn’t as clear as our own gaze, the buzzing insects were able to correctly differentiate between faces up to 90% of the time — even two days after first seeing them, and when the sweet incentives were removed.

The emerging research into bee brains shows that not all living creatures need the complex brain systems humans have in order to recognize and recall environmental differences, but some researchers say that’s not entirely shocking. The Apis mellifera (aka the European honey bee) can visit up to 5,000 flowers in one day, distinguishing between buds that give off beaucoup nectar and those that don’t. So, it makes sense that bees have some form of working memory. And unlocking how bee brains work has practical applications for both us and them: Tech developers may be able to fine-tune artificial intelligence systems (in part by understanding how such tiny brains work so efficiently), and entomologists can better focus on supporting these crucial insects, which are responsible for an estimated 80% of food crop pollination.

There’s Only One Species of Cactus Found Wild Outside the Americas

There are nearly 2,000 known species of cacti, all of which are native to the Americas alone — except for one. That would be Rhipsalis baccifera, also known as the spaghetti cactus or the mistletoe cactus, which grows wild in India, Sri Lanka, and Africa, as well as parts of the Americas. Even stranger than the idea of a single cactus species thousands of miles away from its prickly relatives is the fact that scientists aren’t exactly sure how R. baccifera ended up in the Eastern Hemisphere to begin with. The epiphytes (also called air plants) are remarkably resilient, able to survive without soil by drawing moisture from the air, and the many theories attempting to explain their broad distribution fit their strange nature.

One explanation is that birds snacked on the white berries containing R. baccifera’s seeds somewhere in South America before flying all the way to Africa, where they passed those seeds and essentially planted the cactus on the other side of the world. Problem is, scientists don’t know of any berry-snacking birds that could have actually made that journey. Another theory suggests that sailors used the cactus, with its fetching long green branches, to decorate their living quarters while journeying across the Atlantic from Brazil, then left them behind upon arriving in Africa. Yet another theory posits that the plant could have existed way back when Africa and the Americas were part of one supercontinent called Gondwana — which then broke up around 184 million years ago, leaving a little cactus on both sides. However, it’s unlikely the plant existed all those years ago. The truth is, we’ll probably just have to embrace the mystery of it all.

Lemons Float, but Limes Sink

Few flavors complement each other like lemon and lime, with many a refreshing treat (hello, Sprite!) combining both for maximum effect. The two citrus fruits have some key differences, however, including the fact that limes sink while lemons float. You may have noticed this if you’ve ever put lime and lemon slices in a glass of water or cocktail, and the reason is simple: Objects only float if they’re less dense than the liquid they're placed in, and while both limes and lemons have densities close to that of water, limes are denser than their yellow counterparts. That remains true whether the lemon or lime in question is whole, peeled, or sliced — a lemon will always float, and a lime will always sink.

That's not the only difference between these citrus fruits, of course. Whereas lemons grow well in moderate climates, limes fare better in tropical and subtropical areas. Limes also tend to be smaller, which helps distinguish them from lemons even when they sometimes take on a yellowish hue as they ripen. And though the two are almost identical on a nutritional level, lemons are sweeter — which is probably why you can think of a lot more lemon-flavored candies than lime-flavored ones.

Palm Trees Are Not Native to L.A.

There are an estimated 75,000 palm trees in Los Angeles, all of which have one thing in common: They aren’t native there. Despite being an L.A. icon on par with the Hollywood sign and Dodger Stadium, the tropical tree is no more a native Angeleno than, well, the Dodgers. Not unlike the Hollywood sign, palms were originally a marketing technique for developers hoping to attract newcomers to the area in the late 19th century. They got the idea from the French Riviera — another area palms aren’t actually native to — where like-minded developers had successfully used them just a few decades before to cultivate an image of glitz and glamour. In addition to being beautiful, palms are surprisingly easy to uproot and transport from their native tropical and subtropical environments in the Middle East, Mexico, and elsewhere, so tens of thousands of them were planted all across the California city that had once been desert scrubland.

It seems fitting that one of Los Angeles’ most enduring symbols was essentially a branding strategy chosen for its aesthetic appeal, doubly so because palm trees’ association with the city was (and is) further cemented by their ubiquity in the many films shot there. After all, most of the directors, actors, and studio executives who made Hollywood what it is today weren’t originally from the City of Angels either.

Dung Beetles Navigate Using the Milky Way

We tend to think of dung beetles as lowly creatures, right down to their name. In spite of their earthbound status, however, they do something downright cosmic that no other animal we know of does: navigate using the Milky Way. While “dancing” atop their balls of dung, they orient themselves by looking up at the night sky, catching a glimpse of the bright strip of light our humble galaxy generates, and then moving relative to its position. They do this by taking what scientists call “celestial snapshots” and storing the images in their tiny little dung-beetle minds, a surprisingly fast process that allows them to hightail it away from the dung piles they scavenge. (As for daytime gathering, they move using special photoreceptors in their eyes that allow them to see a symmetrical pattern of polarized light emanating from the sun.) Doing so quickly is imperative — there’s a lot of competition for dung out there, and daddy dung beetles need to move quickly to bury the excrement, which they later feed to their babies. The insects move rapidly in straight lines away from the dung piles, which seems to minimize the likelihood of meeting other creatures of the same kind and getting into a dung-related squabble.

There are around 8,000 species of dung beetles on Earth, 600 of which roll such balls; the others burrow directly beneath the piles of dung and store their quarry in tunnels. Most of them prefer the dung of herbivores, who tend not to digest their food that well. And while most dung beetles are lucky enough to live under dark skies that help them see the Milky Way, light pollution is a growing concern that could throw off their celestial compasses — that is, unless we become more considerate of our dung-rolling neighbors.

The Scientific Name for the Western Lowland Gorilla Is “Gorilla Gorilla Gorilla”

Living things are categorized by a taxonomy system you may have learned about in school, starting with kingdom (e.g., animals, plants) and ending with species (e.g., Homo sapiens). Scientific names are usually expressed using their last two or three categories: genus, species, and, if there is one, subspecies. The western lowland gorilla is in the genus Gorilla, which contains the largest apes. It’s also the species gorilla, which refers to western gorillas (the eastern gorillas are G. beringei). (Western gorillas aren’t the only creatures to have an identical genus and species name; a red fox is Vulpes vulpes.)

Gorilla gorilla also contains two subspecies: G. gorilla diehli, the Cross River gorilla, and G. gorilla gorilla, the western lowland gorilla. You might say the western lowland gorilla is the most gorilla: It’s in the genus gorilla, the species gorilla, and the subspecies gorilla, making its scientific name Gorilla gorilla gorilla.

The Eiffel Tower Grows a Little Each Summer

When the Eiffel Tower was first built in 1889, it was the tallest building in the world at 312 meters tall, or a little more than 1,023 feet. Today, it’s around 60 feet taller because of the radio and TV antennas at its peak, and while nothing’s going to make it the tallest building in the world again, its exact height varies by a few inches depending on the time of year. That’s thanks to a scientific phenomenon called thermal expansion. In general, when a substance heats up, its atoms become more active and move farther apart, making its volume larger. Some substances are more sensitive to thermal expansion than others, including metals like iron. Because the Eiffel Tower is made up of almost pure iron — and there’s a lot of it — hot weather leads to some different measurements. In the summer, the tower not only grows (by as much as 6 inches), but also gets a little lopsided; because the sun only hits one side, it tilts ever-so-slightly away from the sun.

It’s Illegal to Own Just One Guinea Pig in Switzerland

The “dignity of living beings,” including animals, is enshrined in the Swiss Constitution, so Switzerland has some incredibly detailed animal protection laws, including a provision that social creatures cannot be kept alone. This includes not only guinea pigs, but many other animals, including mice, chinchillas, parrots, and lovebirds. Other animal no-gos in Switzerland include extreme breeding, cropping dog ears, and, with very few exceptions, animal testing.

So what happens if you have two guinea pigs and one dies? You could get another guinea pig, which would require buying a ton of subsequent guinea pigs as each one dies, or just hope nobody rats you out. Alternatively, one Swiss animal lover actually started a service that lets you rent a friend to keep your remaining guinea pig company for the rest of its life.

The Dot Over the Small Letter “I” Is Called a “Tittle”

Remember to cross your t’s and tittle your i’s! Those little dots over letters such as the lowercase “j” are called “tittles,” a term that dates back to the 12th century. It can also refer to any other modifying marks on a letter, known as diacritic marks — that includes things like the two dots of an umlaut, the accent over the “e” in fiancé, the squiggly line (also known as a cedilla) under the “c” in façade, or the tilde over the “n” in piñata or jalapeño. In its earliest use, it referred specifically to the character ÷, which was once used as an abbreviation for the Latin word est, but is now often used as a division sign.

Sad Puppy Face Evolved Separately in Dogs

You know that look dogs get when they’re requesting attention, some of your dinner, or just a little eye contact — the one that pulls at your heartstrings? That look requires two muscles that connect the brow to either edge of the eye. Most domesticated dogs have these muscles, but their closest wolf relatives don’t. Older breeds that are a little closer to wolves may just have one.

Humans respond much more positively when animals have features, such as widening eyes, that remind us of human infants, and dogs use those muscles far more often when a human is paying attention. Dogs branched away from wolves 33,000 years ago when they started their relationship with humans, so it’s likely that those muscles evolved specifically because they gave dogs an advantage when interacting with human beings.

Thousands of Plastic Yellow Duckies Were Lost at Sea — and Found All Over the World

One day in January 1992, a crate slipped off a cargo ship into the Pacific Ocean while en route to Tacoma, Washington, from Hong Kong. This isn’t particularly unusual — thousands of shipping containers fall into the ocean each year — except that it was full of roughly 29,000 floating bath toys in four shapes and colors. Blue turtles, red beavers, green frogs, and yellow ducks, each around 3 inches long, emerged from their disintegrating cardboard packages and started drifting.

Ten months later, hundreds of them started washing up in Alaska, but many of them continued their oceanic journey. In the early 2000s, they hit the shores of New England. Some took a southern turn early on and ended up in Hawaii, while others traveled as far as Europe. Researchers ended up using them to study current patterns, and according to calculations by oceanic scientists, some of them may have circumnavigated the globe, while others likely became part of a Texas-sized convergence of lost plastic known as the Great Pacific Garbage Patch.

“OMG” Predates the Internet

After decades of text messaging and home internet use, acronyms like “LOL" (“laughing out loud”), “IMO” (“in my opinion”), and “FTW” (“for the win”) have made their way into “IRL” (“in real life”) speech — but it may surprise you to know that one of the most common ones, “OMG,” predates even the earliest forms of the Internet. It even had the same meaning: “Oh my God.”

Its first recorded use dates back to 1917 in a letter to Winston Churchill from British admiral and former sea lord John Fisher, who was expressing some annoyance around naval tactics. “I hear a new order of Knighthood is on the tapis,” he wrote. “OMG (Oh! My! God!) — Shower it on the Admiralty!!”

It’s worth noting that, while “OMG” usage tends to be associated with younger people, Fisher was in his mid-70s when he authored the letter.