Lists and Stories

• 
  Why Is Kim Such a Common Surname in Korea? About 20 percent of South Korea’s population of 49.3 million (2015 est.) has the family name Kim. That’s about 10 million people. Lee is the second most common name, and Park (or Pak) is the third. All told, about 45 percent of Koreans have one of these three names! But why are Kims so particularly...
• 
  Why Are Some Metals More Conductive than Others? All metals can conduct heat and electric current, but some are more effective conductors than others. What are some factors that influence a metal’s electrical conductivity? Metals are usually crystalline solids. In most cases, they have a relatively simple crystal structure distinguished by a...
• 
  Why Are Some Time Zones 30 Minutes Off Instead of an Hour? Ideally, time zones would be slices of Earth’s surface 15 degrees of longitude wide that keep the same time. However, some countries and parts of countries have decided that being within a specific time zone is not preferable and have chosen offsets of 30 minutes or even 45 minutes. Why? Consider...
• 
  Why Are the Babies of Mammals Cute? Although cuteness can be a matter of personal preference, people tend to find young mammals cute and adorable, and this is likely part of an evolutionary development. Cuteness serves a purpose in species whose young cannot live on their own right away. People are drawn to babies, and it’s their...
• 
  Why Are There Nine Justices on the U.S. Supreme Court? The Supreme Court of the United States (SCOTUS) was established by Congress in 1789 and acts as the head of the U.S.’s federal court system. The Supreme Court is the court of last resort, and most of its significance arises from its being an appellate body—that is, a body that has the power to...
• 
  Why Are There Only 28 Days in February? Each month in the modern Gregorian calendar consists of at least 28 days. That number would be a nicely rounded 30 were it not for February. While every month besides the second in the calendar contains at least 30 days, February falls short with 28 (and 29 on a leap year). So why is the most...
• 
  Why Are There So Few HBCU Medical Schools? At the turn of the 20th century, there were seven medical schools focused on training and sending Black doctors into the various medical professions. In 1910, however, a report titled Medical Education in the United States and Canada was largely responsible for closing all but two of the...
• 
  Why Are Tomatoes Red? Most tomatoes are red when they are ripe, because of the presence of lycopene, which is a phytochemical (a biologically active compound produced by plants). Immature tomatoes are rich in chlorophyll, another phytochemical, which gives them their green colour. As the seeds inside mature, the fruits...
• 
  Why Are Two Political Parties Dominant in the U.S.? Two parties dominate the U.S. political system in large part because the U.S. system of representation is based on the top vote getter in each district. Multiparty democracies typically use a system in which representation is proportional to the number of votes received. The U.S. system leaves...
• 
  Why Are U.S. Elections Held on Tuesdays? For decades, federal elections in the United States have been held on the Tuesday after the first Monday in November. Why this date? Originally, election days varied by state, but in 1845 a law was passed to set a single election day for the entire country. (At first, it applied only to...
• 
  Why Can’t You Tickle Yourself? At some point in your life you’ve probably been tickled—repeatedly touched in a way that induced smiling, laughter, and involuntary movements. Ticklishness can occur in many places on the body, but the most common are the ribcage, the armpit, and the sole of the foot. Tickling usually occurs in the...
• 
  Why Did Adult Humans Start Drinking Milk? Most adult humans around the world are lactose-intolerant, meaning that, once they were weaned from breast milk, they gradually lost the ability to consume animal milk and certain other dairy products without having digestive problems. However, the majority of people of European descent, especially...
• 
  Why did Joseph McCarthy’s influence decline? Wisconsin Sen. Joseph McCarthy catapulted to national prominence in the United States after his claim in February 1950 that 205 communists were at that time employed by the State Department. Over the next few years, McCarthy capitalized on existing Cold War fears that Soviet communist subversion...
• 
  Why Did the Soviet Union Collapse? On January 1, 1991, the Soviet Union was the largest country in the world, covering some 8,650,000 square miles (22,400,000 square km), nearly one-sixth of Earth’s land surface. Its population numbered more than 290 million, and 100 distinct nationalities lived within its borders. It also boasted...
• 
  Why Did We Start Wearing Makeup? Here’s a question for makeup users and nonusers alike: Would you believe that philosophers once determined makeup trends? What about poets? To understand the origin of makeup, we must travel back in time about 6,000 years. We get our first glimpse of cosmetics in ancient Egypt, where makeup served...
• 
  Why Do Airlines Overbook Seats on Flights? Traveling by air can be a stressful activity. There’s turbulence, baggage limitations, intrusions by airport security, and the overhyped fear of plane crashes. If these annoyances weren’t enough, once a passenger finally makes it to their gate, they face the possibility of being “bumped”—that is,...
• 
  Why Do Americans Celebrate the Fourth of July with Fireworks? Fireworks have been part and parcel of U.S. Independence Day, the anniversary of the signing of the Declaration of Independence, since its first celebration in July 1777. That celebration took place in the midst of the Revolutionary War, however, and explosions, artillery fire, and “bombs bursting...
• 
  Why Do Animals Have Tails? There are numerous reasons why many animals have a tail. One answer is that a tail of some kind has helped different kinds of animals—whether an insect, a fish, a lizard, or a mammal, among others—survive long enough to reproduce successfully. Invoking natural selection as an answer might seem...
• 
  Why Do Athletes Wear Numbered Jerseys? “The new and enterprising Cleveland Club management has taken the bull by the horns and numbered its players,” proclaimed Sporting Life magazine on July 8, 1916. A weekly sports journal based in Philadelphia Sporting Life had recommended that teams adopt numbering “years ago”—a suggestion that...
• 
  Why Do Bananas Turn Brown? The life cycle of a banana is a colorful one—it starts with a deep green, changes to a delicious yellow, and ends (if it’s not eaten beforehand) at an unappetizing brown. But what causes this color change, and what makes a banana go from green all the way to the dark side? As it turns out, bananas...