Lists and Stories

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  Why Have So Many World Leaders Married Their Cousins? A crown. A ring. Your cousin. What else do you need for a royal wedding? At this point, the fact that so many royals through history wed relatives in what are now termed consanguineous marriages is something of a history joke. But why did they do it in the first place? Before we begin, an...
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  Why Have There Been Plans to Build a New Colossus of Rhodes? The Colossus of Rhodes graced the main harbour of the ancient city of Rhodes, both as a monument to the sun god Helios, the patron of the island of Rhodes, and as a testament to the city’s independence after the long siege of Demetrius I Poliorcetes. But the mighty statue, standing 105 feet (32...
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  Why Is a Baker’s Dozen 13? Request a dozen eggs from a farmer, a dozen steaks from a butcher, or a dozen pencils from a traveling office supplies salesman, and you will almost certainly receive 12 of your chosen item (counting errors do happen). But a baker’s dozen is commonly understood to mean 13. Are bakers just bad at...
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  Why Is a Group of Molecules Called a Mole? It’s one of the first things you learn in chemistry: Atoms and molecules are so small that even a few grams of a substance contains so many atoms or molecules that counting them by the billions or trillions is just as pointless as counting them one by one. Chemists therefore use a unit called the...
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  Why Is Alcohol Measured by Proof? If you get a bottle of vodka from your local liquor store, you’ll probably see two different numbers telling you how much alcohol it contains. The first is an alcohol by volume (ABV) percentage, which is relatively intuitive to understand: it’s the percentage of alcohol in the overall liquid and is...
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  Why Is Bird Poop White? Actually, bird poop, per se, is not white. Birds, unlike mammals, do not have separate exits for urine and feces. Both waste products are eliminated simultaneously through the cloaca. While mammals excrete nitrogenous wastes mostly in the form of urea, birds convert it to uric acid or guanine,...
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  Why Is Black History Month Celebrated in February? “February is Black History Month.” Since the 1970s that familiar declaration has introduced countless celebrations of African American history and achievement, from Black History Minutes on local television stations to the pronouncements of U.S. presidents. But why is February designated as the...
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  Why Is Charles I Buried with Henry VIII and Jane Seymour? In St. George’s Chapel at Windsor Castle, an innocuous marble floor tile hides more than the building’s foundation. Four oddly matched royals are buried beneath: King Henry VIII, Jane Seymour, King Charles I, and an infant child of Queen Anne. Originally, the vault was intended as only a temporary...
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  Why Is Christmas in December? Christmas, the holiday commemorating the birth of Jesus Christ, is celebrated by a majority of Christians on December 25 in the Gregorian calendar. But early Christians did not celebrate his birth, and no one knows on which date Jesus was actually born (some scholars believe that the actual date...
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  Why Is Eating Protein Important? There are three basic macronutrients that the body needs to survive: fats, carbohydrates, and proteins. Proteins are directly involved with the chemical processes that support life, and proteins help compose the enzymes, hormones, and tissues that form our bodies and keep them running smoothly....
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  Why Is Elvis Called “the King of Rock ’n’ Roll”? “The Hillbilly Cat.” “Elvis the Pelvis.” “The Memphis Flash.” The renowned singer and dominant performer Elvis Presley has had no shortage of nicknames, but his most memorable moniker is also his grandest: “the King of Rock ’n’ Roll,” or simply “the King.” Although its exact debut is unknown, that...
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  Why Is Grass Green? Grass is green because of the presence of chlorophyll throughout the leaves and stems. Chlorophyll is a pigment that allows plants to capture energy from the Sun in order to power the process of photosynthesis. Given that most grasses lack trunks or woody stems like trees or shrubs, their...
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  Why Is Ireland Two Countries? The island of Ireland comprises the Republic of Ireland, which is a sovereign country, and Northern Ireland, which is part of the United Kingdom. The Republic of Ireland endured a hard-fought birth. Ruled from Great Britain since the 13th century, its citizens, many of them suppressed Catholics,...
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  Why Is It Called Black Friday? The day following Thanksgiving—commonly referred to as Black Friday—has become one of the busiest shopping days of the year in the United States. National chain stores traditionally offer limited money-saving specials on a wide variety of goods in an effort to lure shoppers into stores while...
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  Why Is It Important to Know the Incubation Period of a Disease? This article was originally published on March 19, 2020. Knowing the incubation period of an infectious disease—the time from exposure to the causative agent to when symptoms first appear—can provide important information during an outbreak, including when infected individuals will be symptomatic...
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  Why Is Labor Day Celebrated in September? The origins of Labor Day can be traced to the labor movement of the late 19th century in the United States. There is some uncertainty as to who deserves credit for the idea; most cite either Peter J. McGuire, a union leader who founded the United Brotherhood of Carpenters in 1881, or Matthew...
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  Why Is Marijuana Illegal in the U.S.? Since the late 20th century, there has been a growing movement in the United States to legalize marijuana. In 1996 California made news as the first U.S. state to approve the decriminalization of pot for medical use, and medical marijuana was later allowed in other states. Then in 2012 Washington...
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  Why Is Missouri Called the Show Me State? Missouri has long been known as the Show Me state, but the origins of that nickname aren’t entirely clear. Perhaps the best-known story involves a Missouri representative named Willard Duncan Vandiver. After a tour of the Philadelphia Navy Yard in 1899, the congressman was invited to a meeting of...
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  Why Is Pizza So Popular in the U.S.? An easy group dinner or a tasty midnight snack, pizza is a staple in the U.S. Americans love pizza so much that they eat 100 acres of pizza a day. (If you don’t measure your pizza consumption in acres, that’s about 350 slices of pizza per second!) Did you ever wonder how this Italian flatbread—now...
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  Why Is Pluto No Longer a Planet? In 2006 the International Astronomical Union (IAU) demoted the much-loved Pluto from its position as the ninth planet from the Sun to one of five “dwarf planets.” The IAU had likely not anticipated the widespread outrage that followed the change in the solar system’s lineup. When the announcement...