Some deaf people have been known to continue signing even after they drift into sleep, through unconscious movements of the hands. The phenomenon is similar to talking in your sleep: The brain’s language and motor circuits remain active while you snooze, though they are suppressed, and during sleep-talking episodes, brain activity more closely resembles the awake state, allowing speech to slip out.
Sign and spoken languages involve similar neural processes, so while hearing people may talk in their sleep, this subconscious impulse takes the form of sleep signing or involuntary hand movements for deaf people. Sleep signing has been documented since as early as 1935, when electrophysiology studies found deaf people made signing motions while asleep. Bursts of activity were observed in the fingers and arms, a pattern not seen in hearing sleepers.
American Sign Language (ASL) came before French Sign Language (FSL).
FSL was standardized by French priest Charles-Michel de l’Épée in the 1750s and ultimately influenced ASL, which was standardized throughout the 19th century.
In one widely cited 2017 case, a 71-year-old deaf man with REM sleep behavior disorder was observed signing fluently in his sleep. Because that disorder prevents the usual temporary paralysis that occurs during REM (rapid eye movement) sleep, he was able to sign so clearly that researchers could even decode aspects of his dreams.
This same mind-body link may also explain why dogs sometimes bark or twitch their paws during REM sleep and why some chimpanzees who know sign language have also been observed signing as they snooze.
On average, people spend one-third of their life sleeping.
Advertisement
Martha’s Vineyard once had its own sign language.
In the 18th and 19th centuries, Martha’s Vineyard, Massachusetts, was home to a surprisingly high number of deaf residents. At its peak, about one in 155 of the island’s residents were born completely deaf, a ratio much higher than in the general U.S. population, in which about one in 5,700 people are deaf. The higher rate in Martha’s Vineyard is believed to have been caused by a hereditary form of deafness traced to settlers from Kent, England.
To communicate, the islanders developed Martha’s Vineyard Sign Language (MVSL), a fully functional language. Many hearing residents also learned and used it daily, making communication seamless across the community. MVSL declined in the late 19th and early 20th centuries when American Sign Language gradually replaced it. It wasn’t rediscovered until the 1970s, when anthropologist Nora Ellen Groce traced the island’s unusually large deaf population and uncovered the language.
Nicole Villeneuve
Writer
Nicole is a writer, thrift store lover, and group-chat meme spammer based in Ontario, Canada.
Advertisement
top picks from the Inbox Studio network
Interesting Facts is part of Inbox Studio, which publishes content that uplifts, informs, and inspires.
When seawater freezes, it undergoes a remarkable natural desalination process — known as brine rejection — that expels much of its salt content. So when that seawater ice melts, the result is almost pure fresh water. It may seem impossible, but it all comes down to what happens at the molecular level when the salty water freezes.
As ocean temperatures drop below freezing, water molecules begin forming ice crystals with a highly organized structure. That structure cannot incorporate salt ions, so those ions are largely excluded, pushing the salt out of the ice. Initially, not all of the salt is rejected; some of it is trapped in the ice, forming pockets of concentrated brine. The brine remains in a liquid state because it requires lower temperatures to freeze. So at that stage, the sea ice still has a high salt content, but over time, the ice continues to eject the brine.
About 70% of the world’s freshwater reserves are frozen in Antarctica.
The massive Antarctic ice sheet contains a vast amount of frozen fresh water. More fresh water is added to the ocean as the ice sheet melts, making the water less salty and less dense — potentially disrupting global ocean circulation and affecting climate patterns worldwide.
Thanks to this phenomenon, sea ice contains significantly less salt than the water it came from. In liquid form, ocean water has an average salinity of 35 parts per thousand, while newly formed seawater ice has a salinity of between 12 and 15 parts per thousand. As the ice grows thicker and brine rejection takes place, the salinity decreases significantly: Arctic first-year ice has an average salinity of 4 to 6 parts per thousand, and sea ice four years or older is nearly free of brine.
When seawater that has been frozen for years eventually melts, the water released is dramatically fresher than the ocean around it. In these cases, when nearly all the brine is gone, the ice can be fresh enough to provide drinking water when melted — something that’s often done during polar expeditions.
In his 1911 book, Polar Exploration, the British polar scientist and explorer William Speirs Bruce described how whalers and exploring ships in the Arctic extracted water from pools on the ice, which was often drinkable fresh water. Today, polar expedition members still take an occasional drink from these pools.
The largest moon in the solar system is Ganymede. Its ocean may contain more water than all of Earth’s oceans combined.
Advertisement
The world’s largest waterfall is underwater.
When we think of the world’s mightiest waterfalls, we normally picture them cascading majestically over cliffs to a turbulent plunge pool far below. But the world’s largest waterfall is actually located in the ocean. Known as the Denmark Strait cataract, it flows beneath the Denmark Strait, which separates Iceland and Greenland. At the bottom of that strait, a series of cataracts — beginning some 2,000 feet beneath the surface — plunge to a depth of 10,000 feet, a drop of nearly 2 miles.
This underwater waterfall exists due to density differences between the two water masses on either side of the Denmark Strait. When the southward-flowing cold water from the Nordic Seas meets the warmer water from the Irminger Sea, the cold, dense water quickly sinks below the warmer, less dense water, and plunges over a huge drop in the ocean floor. The resulting downward flow is estimated to well exceed 123 million cubic feet per second. By comparison, the discharge of the Amazon River into the Atlantic Ocean is just 7.74 million cubic feet per second.
Tony Dunnell
Writer
Tony is an English writer of nonfiction and fiction living on the edge of the Amazon jungle.
Advertisement
top picks from the Inbox Studio network
Interesting Facts is part of Inbox Studio, which publishes content that uplifts, informs, and inspires.
Original photo by IanDagnall Computing/ Alamy Stock Photo
In his 100 years on Earth, Jimmy Carter set a number of records and achieved almost as many firsts. In addition to being the longest-living president in U.S. history, he was also the first one born in a hospital — an event that occurred on October 1, 1924, in Plains, Georgia. It was much more common for babies to be born at home in the early 20th century than it is now, but Carter’s mother was a nurse at what was then known as Wise Sanitarium, and there happened to be a room available on that fateful October night.
One president never married: James Buchanan, who held the highest office in the land from 1857 to 1861. Grover Cleveland was a bachelor when he was elected in 1884, but later tied the knot (to Frances Folsom) in the White House — the only president to do so.
All five presidents born after Carter — Joe Biden (1942), Donald Trump (1946), George W. Bush (1946), Bill Clinton (1946), and Barack Obama (1961) — were likewise born in hospitals. George H. W. Bush, who was born less than four months before Carter and assumed the presidency 12 years after Carter, was born at home in Milton, Massachusetts.
Jimmy Carter’s favorite president was Harry S. Truman.
Advertisement
Martin Van Buren was the first president born a U.S. citizen.
Though his seven predecessors were also born in what’s now the United States of America, Martin Van Buren was the first president born a U.S. citizen. His predecessors all came into the world as British subjects, but Van Buren was born on December 5, 1782 — six years after the Declaration of Independence was signed and less than a year before the Revolutionary War officially ended. He was also the only president not to learn English as a first language, as he was raised in the Dutch community of Kinderhook, New York, and learned Dutch first. English was his second language.
Michael Nordine
Staff Writer
Michael Nordine is a writer and editor living in Denver. A native Angeleno, he has two cats and wishes he had more.
Advertisement
top picks from the Inbox Studio network
Interesting Facts is part of Inbox Studio, which publishes content that uplifts, informs, and inspires.
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. (Jane Austen was said to be partial to mushroom ketchup.) One crop that the English avoided in their ketchup experiments was tomatoes, which for centuries were thought to be poisonous.
Although the company’s slogan was “57 varieties,” it makes way more than 57 products (and did even when the slogan was first created). Henry Heinz is said to have chosen the number because it combined his and his wife’s lucky numbers (5 and 7, respectively).
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. 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 forhot dogs, french fries, and hamburgers.
There’s a museum in Wisconsin entirely devoted to mustard.
At this Midwestern attraction, the showpiece is the Great Wall of Mustard, an assortment of more than 5,600 bottles and jars. Exhibits on the wall have been sourced from every U.S. state as well as 70 countries. The museum’s founder and curator is Barry Levenson, who began collecting mustard in 1986. The following year, while working for the Wisconsin Department of Justice, Levenson successfully argued a case before the U.S. Supreme Court — with a jar of hotel mustard in his pocket. In the early ’90s, he left law to open the original iteration of his museum, which is now in Middleton. Tickets to the National Mustard Museum are always free, and include entry to the Mustardpiece Theatre.
Jenna Marotta
Writer
Jenna is a writer whose work has appeared in The New York Times, The Hollywood Reporter, and New York Magazine.
Advertisement
top picks from the Inbox Studio network
Interesting Facts is part of Inbox Studio, which publishes content that uplifts, informs, and inspires.
The human nose is a biological wonder. It can smell up to 1 trillion odors, trap harmful debris in the air before it enters your lungs, and even help regulate emotion. But arguably its most important job is to condition the air you breathe before that air enters your respiratory tract. This means warming and humidifying the air before it passes to your throat and beyond. To do this, the nose undergoes a nasal cycle in which one nostril sucks in the majority of the air while the other nostril takes in the remaining portion. A few hours later (on average), the nostrils switch roles. This cycle is regulated by the body’s autonomic nervous system, which swells or deflates erectile tissue found in the nose. Although we don’t notice this switch throughout the day, if you cover your nostrils with your thumb one at a time, you’ll likely observe that air flow through one is significantly higher than in the other. This is also why one nostril tends to be more congested than the other when you have a cold (the nondominant one gets more filled with mucus).
The human nose is unique among primates because of our brains.
Our ancestors’ skulls underwent a massive change some 2 million to 3 million years ago. As our brains grew, facial features shrank to make room. Unlike the flush nose of a chimpanzee, our nose likely took its current, protruding shape to give the brain some extra space.
There are a few possible reasons for this nasal back-and-forth. Some scientists theorize that the cycle actually improves our sense of smell. Because scent molecules degrade at differing rates, some smells are easier to identify through fast-moving air (in the dominant nostril), while others are more easily picked out in slower currents of the nondominant, usually more congested, nostril. Very few smells can get past our nose undetected thanks to this alternating nasal superpower.
The nose with the most sensitive sense of smell in the animal kingdom belongs to the African elephant.
Advertisement
The size of a human nostril is determined by climate.
Nostrils come in all shapes and sizes, and like most other parts of the human body, that’s the result of millions of years of evolution. In 2017, scientists confirmed a long-held theory that climate plays a vital role in determining the size of our nostrils. People whose ancestors hail from warm, humid climates have little need for nostrils to humidify air before it enters the lungs. As a result, their nostrils are wider. But in cold, dry climates — where air easily irritates the lining of the nose and throat — smaller nostrils create a more “turbulent” air flow, causing the air to mix in the nose. This turbulent mixing interacts with the nose’s mucus-covered lining, which warms and humidifies the air before it passes to the lungs. Over the long, grinding process of evolution, as humans traveled farther from the equator, smaller nostrils were naturally selected as better-suited for the cold and dry areas of the world.
Darren Orf
Writer
Darren Orf lives in Portland, has a cat, and writes about all things science and climate. You can find his previous work at Popular Mechanics, Inverse, Gizmodo, and Paste, among others.
Advertisement
top picks from the Inbox Studio network
Interesting Facts is part of Inbox Studio, which publishes content that uplifts, informs, and inspires.
One small step for man took place before astronauts could even roll their suitcases across the spaceport. The first wheeled suitcase was invented in 1970, a year after the moon landing. It was the brainchild of inventor Bernard D. Sadow, who called it one of his best ideas, despite the fact that the product wasn’t immediately popular.
Mind you, this wasn’t the upright luggage we know today. “The Luggage That Glides,” as Macy’s marketed the product after buying it, rolled on its side and was pulled with a strap attached to the top. The innovation may not have been very sophisticated, but it nonetheless improved ease and convenience by adding wheels to something that could certainly use them.
That title belongs to the humble fruit fly, which the U.S. launched 68 miles into space on February 20, 1947, to study high-altitude radiation exposure.
Sadow applied for a patent in 1970 and received it in 1972. “Whereas formerly, luggage would be handled by porters and be loaded or unloaded at points convenient to the street, the large terminals of today, particularly air terminals, have increased the difficulty of baggage-handling,” the patent stated. “Baggage-handling has become perhaps the biggest single difficulty encountered by an air passenger.” That remains true today, even with the 1987 invention of the vertical Rollaboard, the now-ubiquitous style of vertical wheeled suitcases.
The world’s bestselling luggage brand is Samsonite.
Advertisement
No one has walked on the moon in more than 50 years.
A dozen people have walked on the moon, but no one has done it in more than half a century. Eugene A. Cernan was the last astronaut on the lunar surface, a feat he achieved as part of the Apollo 17 mission in December 1972. He previously served as the lunar module pilot of Apollo 10.
Cernan logged 566 hours and 15 minutes in space throughout his NASA career, 73 hours of which were spent on the surface of the moon. “As I take man’s last step from the surface, back home for some time to come … America’s challenge of today has forged man’s destiny of tomorrow,” he said as he climbed the ladder for the final time.
Michael Nordine
Staff Writer
Michael Nordine is a writer and editor living in Denver. A native Angeleno, he has two cats and wishes he had more.
Advertisement
top picks from the Inbox Studio network
Interesting Facts is part of Inbox Studio, which publishes content that uplifts, informs, and inspires.
Pepsi has been nearly synonymous with cola for more than a century, but it wasn’t always called that. We have pharmacist Caleb Bradham to thank for the bubbly beverage, as well as its original name: Brad's Drink. Believing that his concoction had digestive benefits, Bradham sold it at his pharmacy in New Bern, North Carolina. Brad’s Drink didn’t last long, however — it was renamed Pepsi-Cola in 1898.
That honor belongs to its fierce rival, Coca-Cola, which consistently outsells Pepsi. In fact, in 2025, Pepsi came in fourth, behind Coke, Dr. Pepper, and Sprite.
The new name was partly derived from the word “dyspepsia,” a technical term for indigestion, and was meant to convey the tasty beverage’s supposed medicinal properties. Bradham trademarked the name in 1903, and the company grew exponentially over the next few years, with 240 franchises opening across 24 states by 1910. Pepsi isn’t the only major company to undergo a name change, of course — 7-Eleven used to be known as Tote’m Stores, Nike was founded as Blue Ribbon Sports, and Canon was originally called Precision Optical Instruments Laboratory, among others.
In 1989, Pepsi paid Madonna $5 million to appear in a commercial that was quickly taken off the air.
Advertisement
Dr. Pepper used to be served warm.
Dr. Pepper used to be advertised as a hot holiday drink, a response to declining sales in the winter months. The original ad from the 1960s even came with helpful instructions: Simply warm the beverage in a saucepan until it steams, then pour it over a lemon slice. The result was a “distinctively different hot Dr. Pepper” and “the holiday favorite of the proud crowd,” per the festive commercial. Heating the drink to 180 degrees Fahrenheit eliminated the carbonation, leaving behind a sweet, flat flavor that was especially popular in the South.
Michael Nordine
Staff Writer
Michael Nordine is a writer and editor living in Denver. A native Angeleno, he has two cats and wishes he had more.
Advertisement
top picks from the Inbox Studio network
Interesting Facts is part of Inbox Studio, which publishes content that uplifts, informs, and inspires.
While there are a few human-made objects visible from space, there’s only one known example constructed by beavers: the world’s largest beaver dam, located in the Peace-Athabasca Delta of Canada’s Wood Buffalo National Park. You can’t see it from space with the naked eye, but the dam was discovered on October 2, 2007, using satellite imagery provided by Google Earth. It appears to have been built during the last five decades, as photographs taken of the same location in 1975 show limited beaver activity.
Estimates put the length of the dam at more than 2,600 feet, and based on satellite imagery, it’s been measured to cover an approximate surface area of roughly 750,000 square feet. The pond created by the dam is estimated to hold nearly 2.5 million cubic feet of water. To use an analogy Canadians would surely approve of, that’s roughly the same amount of water needed to fill 1,600 standard ice hockey rinks.
The Hoover Dam got its name in 1930, but it didn’t sit well with Franklin D. Roosevelt, Herbert Hoover’s rival and successor. At the dam’s 1935 dedication, Roosevelt referred to it as the Boulder Dam. That name stuck until after FDR’s death in 1945.
Given its remote location miles from any paved road or trail, accessing the dam requires a multiday trek through wetlands and forest. That inaccessibility poses such a challenge that only one known individual has ever visited the dam itself. In July 2014, adventurer Rob Mark completed the perilous trek, snapping a celebratory selfie with the beaver lodge behind him. Upon his arrival, he noted how difficult it is to grasp the dam’s enormity from up close, and how its sheer size is better appreciated with the photographs taken from space.
Beavers are the second-largest rodents, behind capybaras.
Advertisement
China’s Three Gorges Dam slowed the Earth’s rotation.
Depending on their enormity, it’s possible for massive infrastructure projects to impact the Earth’s rotation. One such example is China’s Three Gorges Dam, which measures 600 feet tall and 7,500 feet long and spans the Yangtze River. When filled, the dam’s reservoir is able to hold 10 trillion gallons of water.
In 2005, NASA scientist Benjamin Fong Chao calculated that a completely filled reservoir would slow the Earth’s spin, increasing the length of each day by 0.06 microseconds (or 60 billionths of a second). This is caused by the redistribution of mass away from the center of Earth’s rotation, which makes the planet twirl less fluidly. As water is raised higher above sea level, it impacts the Earth’s moment of inertia and causes the planet’s rotation to slow.
Bennett Kleinman
Staff Writer
Bennett Kleinman is a New York City-based staff writer for Inbox Studio, and previously contributed to television programs such as "Late Show With David Letterman" and "Impractical Jokers." Bennett is also a devoted New York Yankees and New Jersey Devils fan, and thinks plain seltzer is the best drink ever invented.
Advertisement
top picks from the Inbox Studio network
Interesting Facts is part of Inbox Studio, which publishes content that uplifts, informs, and inspires.
The City of Brotherly Love has clear-cut claims on many food origins — cheesesteaks, stromboli, and even root beer. But ironically, Philadelphia Cream Cheese is not from Philly. The iconic dairy brand secured its misleading name (and gold-standard status) thanks to a marketing ploy that’s been working for more than 150 years … and it’s all because of Pennsylvania’s reputation for impeccable dairy. Small Pennsylvania dairies of the 18th and early 19th centuries were known for using full-fat milk and cream to make rich cheeses — in contrast to New York dairies, which mostly used skim milk — and because the perishables couldn’t be easily transported, they gained a reputation as expensive luxury foods. So when upstate New York entrepreneur William Lawrence began making his skim milk and (for richness) lard-based cream cheese in the 1870s, he needed a name that would entice customers and convey quality despite it being made in Chester, New York, and not Philadelphia. Together with cheese broker and marketing mastermind Alvah Reynolds, Lawrence’s cheese was branded under the Philadelphia name in 1880, which boosted sales and promoted its popularity with home cooks well into the early 1900s.
Cream cheese and Neufchâtel cheese are the same spread.
Both kinds of cheese are white, soft, and come in foil-wrapped blocks, but they’re not the same. Neufchâtel (named for a town in France) has less fat, giving it a slightly tangier flavor.
Lawrence is often credited with inventing cream cheese, and culinary lore frequently cites its creation as an accident. But some food historians say he wasn’t the first person to concoct the cheesy spread — recipes for it had been circulating for some time in newspapers and magazines. Lawrence did, however, create the first commercial cream cheese factory, which made the product accessible to home cooks. Lawrence eventually left the dairy industry for politics, becoming the mayor of Chester, but his legacy remains in every foil-wrapped block found in an American fridge.
Famed Philadelphian Benjamin Franklin once drafted a recipe for milk punch, a curdled alcoholic drink.
Advertisement
Cream cheese has been wrapped in foil since the 1880s.
Besides the whipped or flavored versions that usually come in plastic tubs, most American cream cheese comes in a foil-wrapped block — and it’s almost always been that way. William Lawrence’s first mass-produced cream cheeses were wrapped in thick tissue paper commonly used by cheesemongers. But a few years into production, the rebranded Philadelphia Cream Cheese of the 1880s opted for foil packaging that helped the moldable cheese keep its shape — and more importantly, provided a firm wrapper that was an easier surface on which to print the brand name. Today, Kraft (the current owner of the Philadelphia brand) says the foil helps retain moisture and freshness.
Nicole Garner Meeker
Writer
Nicole Garner Meeker is a writer and editor based in St. Louis. Her history, nature, and food stories have also appeared at Mental Floss and Better Report.
Advertisement
top picks from the Inbox Studio network
Interesting Facts is part of Inbox Studio, which publishes content that uplifts, informs, and inspires.
Tomatoes: so easy a potato can grow them. Well, not quite, but the two do occasionally join forces and result in the aptly named “pomato” plant. That two-for-the-price-of-one hybrid occurs when a tomato plant is grafted onto a potato plant, which is relatively easy to do since both belong to the Solanum genus of the nightshade family.
The pomato isn’t its own fruit, however — it’s a plant that grows both foods at the same time: tomatoes on the vine and potatoes under the soil. Peppers, eggplants, and tobacco are also members of the Solanum genus, and tomato plants can be grafted onto them as well.
They really are easy to grow, hence why residents of all 50 states — not to mention more than 125 countries — do so.
Nicknamed the “ketchup ’n’ fries” plant and sometimes called “tomtatoes,” these plants have been grown since at least 1833. In addition to the novelty of growing two things at once, pomatoes can benefit from both plants’ natural advantages: potatoes’ cold resistance and tomatoes’ heat resistance. The potatoes and tomatoes grown from these hybrid plants don’t taste any different than their normal counterparts, but they are more convenient to grow.
Tomatoes are believed to have originated in Peru and Ecuador.
Advertisement
Heinz ketchup has a speed limit.
As the brand practically synonymous with ketchup, Heinz has a reputation to uphold. A big part of that image is the consistency and viscosity of its flagship product, which is meant to be thick enough to pour onto your fries at a diner by turning the bottle upside down but not so smooth that the ketchup splatters everywhere.
As part of its quality control process, the company has even imposed a speed limit on the condiment of 0.028 mph, which is checked at its factories. That’s the exact speed at which Heinz ketchup should move when poured upside down from its bottles. This speed limit even inspired a promotional campaign in collaboration with Waze, in which anyone forced to go 0.028 mph while stuck in traffic could get a free bottle of ketchup.
Michael Nordine
Staff Writer
Michael Nordine is a writer and editor living in Denver. A native Angeleno, he has two cats and wishes he had more.
Advertisement
top picks from the Inbox Studio network
Interesting Facts is part of Inbox Studio, which publishes content that uplifts, informs, and inspires.
Enter your email to receive facts so astonishing you’ll have a hard time believing they’re true. They are. Each email is packed with fascinating information that will prove it.
Sorry, your email address is not valid. Please try again.
Sorry, your email address is not valid. Please try again.