25 Amazing Facts About the Human Body

iStock.com/kali9
iStock.com/kali9

The human body is an amazing piece of machinery—with a few weird quirks.

  1. It’s possible to brush your teeth too aggressively. Doing so can wear down enamel and make teeth sensitive to hot and cold foods.

  2. Goose bumps evolved to make our ancestors’ hair stand up, making them appear more threatening to predators.

Woman's legs with goosebumps
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  1. Wisdom teeth serve no purpose. They’re left over from hundreds of thousands of years ago. As early humans’ brains grew bigger, it reduced space in the mouth, crowding out this third set of molars.

  2. Scientists aren't exactly sure why we yawn, but it may help regulate body temperature.

  3. Your fingernails don’t actually grow after you’re dead.

  4. If they were laid end to end, all of the blood vessels in the human body would encircle the Earth four times.

  5. Humans are the only animals with chins.

    An older woman's chin
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    1. As you breathe, most of the air is going in and out of one nostril. Every few hours, the workload shifts to the other nostril.

    2. Blood makes up about 8 percent of your total body weight.

    3. The human nose can detect about 1 trillion smells.

    4. You have two kidneys, but only one is necessary to live.

    5. Belly buttons grow special hairs to catch lint.

      A woman putting her hands in a heart shape around her belly button
      iStock.com/PeopleImages
      1. The satisfying sound of cracking your knuckles comes from gas bubbles bursting in your joints.

      2. Skin is the body’s largest organ and can comprise 15 percent of a person’s total weight.

      3. Thumbs have their own pulse.

      4. Your tongue is made up of eight interwoven muscles, similar in structure to an elephant’s trunk or an octopus’s tentacle.

      5. On a genetic level, all human beings are more than 99 percent identical.

        Identical twin baby boys in striped shirts
        iStock.com/BorupFoto
        1. The foot is one of the most ticklish parts of the body.

        2. Extraocular muscles in the eye are the body’s fastest muscles. They allow both of your eyes to flick in the same direction in a single 50-millisecond movement.

        3. A surgical procedure called a selective amygdalohippocampectomy removes half of the brain’s amygdala—and with it, the patient’s sense of fear.

        4. The pineal gland, which secretes the hormone melatonin, got its name from its shape, which resembles a pine nut.

        5. Hair grows fast—about 6 inches per year. The only thing in the body that grows faster is bone marrow.

          An African-American woman drying her hair with a towel and laughing
          iStock.com/GlobalStock
          1. No one really knows what fingerprints are for, but they might help wick water away from our hands, prevent blisters, or improve touch.

          2. The heart beats more than 3 billion times in the average human lifespan.

          3. Blushing is caused by a rush of adrenaline.

14 Things You Might Not Have Known About James K. Polk

Matthew Brady/Getty Images
Matthew Brady/Getty Images

James K. Polk may have served just one term, but he was one of history’s most consequential U.S. presidents. Polish up on Young Hickory, America's 11th Commander in Chief.

1. James K. Polk had surgery to remove urinary bladder stones when he was 16.

Born on November 2, 1795, James Knox Polk was the oldest of 10 children born to Samuel Polk, a farmer and surveyor, and his wife, Jane. When James was 10, the family moved to Tennessee and settled on a farm in Maury County. As a child, James was too ill to attend formal school; just before he turned 17, he had urinary bladder stones surgically removed by Ephraim McDowell, a prominent Kentucky surgeon. Anesthesia wasn’t available at that time, so the future president reportedly dulled the pain with brandy. The surgery allowed the formerly ill Polk to attend formal schooling for the first time. He entered the University of North Carolina as a sophomore after just 2.5 years of formal schooling. According to Britannica, "as a graduating senior in 1818 he was the Latin salutatorian of his class—a preeminent scholar in both the classics and mathematics." After graduation, he returned to Tennessee to study law and eventually opened up his own practice.

2. James K. Polk won a seat on the Tennessee Legislature at 27, and the U.S. House of Representatives at 29.

During his time in the state legislature, he met—and befriended—future president Andrew Jackson. He also began courting his future wife, Sarah Childress. The daughter of a prominent planter, she had been educated at the prestigious Moravian Female Academy in Salem, North Carolina, and was an eager and active participant in his political campaigns. Polk and Sarah married in 1824. In 1825, Polk was elected to the U.S. House of Representatives; he was speaker of the House from 1835 until he left in 1839 to become governor of Tennessee.

3. James K. Polk's nomination for president surprised everyone—including himself.

Months before the democratic national convention of 1844, Polk was at a low point. He had just lost his bid to be re-elected governor of Tennessee (he had been voted out of office in 1841 and tried—and failed—to be elected again in 1843). But when the delegates at the convention couldn’t agree on a nominee—the party was deadlocked between Martin Van Buren and Lewis Cass—they eventually decided to compromise by picking a “dark horse” candidate: Polk.

4. Everyone thought James K. Polk would lose his bid for the presidency.

Despite being a seven-time congressman, a former Speaker of the House, and an ex-governor, Polk was a relative nobody. His opponent Henry Clay lamented that Democrats had failed to choose someone “more worthy of a contest.” Despite the doubts, Polk won the popular vote by nearly 40,000 and the Electoral College 170-105.

5. During James K. Polk's White House "office hours," any American could stop by.

During Polk’s day, anybody was permitted to visit the White House for “office hours.” For two days every week, concerned citizens and lobbyists could drop by to vouch for a cause or ask for political favors. “Job seekers were the worst, in Polk’s view, and he found their incessant interruptions far more annoying than his Whig opponents in Congress,” writes Walter R. Borneman in his book Polk: The Man Who Transformed the Presidency and America.

6. James K. Polk was remarkably boring.

Polk had as much charisma as a puddle of mud. He was straight-laced, somber, and humorless. As Speaker, an editor in Washington called him the "most unpretending man, for his talents, this, or perhaps any country, has ever seen." Some attributed Polk’s boringness to his refusal to drink socially. The politician Sam Houston supposedly called him “a victim of the use of water as a beverage.” (Sarah banned hard liquor—and dancing—from the White House.)

7. James K. Polk worked 12 hour days and didn't take much time off from the presidency.

Polk regularly spent 12 hours a day at the office. He rarely left Washington, took advice, or delegated. When he wanted to lobby for policy, he’d visit Congress and do it himself. Over the course of his single term, Polk took a total of just 27 days off. “No President who performs his duty faithfully and conscientiously can have any leisure,” Polk wrote.

8. James K. Polk acquired America's first patch of Pacific coastline.

In the early 19th century, the Pacific Northwest was jointly occupied by British and American settlers. But as the century progressed, Americans began to outnumber the British, and they increasingly felt like the rightful owners of the “Oregon Country.” Thankfully, neither country was interested in battling over the land. In 1846, Polk and the British drew a border at the 49th parallel (with some adjustment for Vancouver Island)—what is now Washington State’s boundary with Canada. With that, the United States obtained its first uncontested patch of Pacific coastline.

9. James K. Polk waged a controversial—and consequential—war with Mexico.

In the 1840s, Mexico’s border encompassed California, the American southwest, and even parts of Colorado and Wyoming. Polk wanted this land. In 1845, he offered to buy some disputed territory near the Texas-Mexico border, as well as land in California; when Mexico refused, Polk sent troops into the disputed territory. Mexico retaliated. Polk then requested Congress to declare war. His critics (including a young Abraham Lincoln) complained that Polk had deliberately provoked Mexico. Whatever Polk’s motivations, the United States lost 13,000 men and approximately $100 million in the ensuing war—but succeeded in taking one-third of Mexico’s land.

10. James K. Polk is the reason the United States stretches from the Atlantic Ocean to the Pacific Ocean.

In the course of just one term, Polk oversaw one of the greatest territorial expansions of any president—an increase of 1.2 million square miles. His administration extended the United States boundary to the Pacific Ocean and laid the groundwork for states such as California, Utah, Nevada, Arizona, New Mexico, Colorado, Washington, Idaho, Oregon, and Montana.

11. James K. Polk's ambivalence toward the issue of slavery may have sparked the Civil War.

When Polk’s administration began pushing westward, debate raged over how these new territories could alter the power balance between free and slave states. Polk, who considered slavery a side issue, refused to give the rancor much time or attention. (No doubt because of his own relationship with slavery. He owned more than 20 enslaved people and brought them to the White House.) Polk’s ambivalence helped sow so much discord that historians now consider his rapid expansion westward as the first steps toward the Civil War.

12. James K. Polk signed bills that reshaped Washington, D.C.

Polk accomplished a lot in just four years. During his tenure, he signed the Smithsonian Institution into law. He was instrumental to the construction of the Washington Monument and helped establish the U.S. Naval Academy in Annapolis, Maryland. He also re-established an independent U.S. Treasury, which was partly intended to reduce the role of speculation in the economy.

13. James K. Polk's administration introduced Americans to the postage stamp.

One of Polk’s unofficial campaign managers was a Nosferatu-lookalike named Cave Johnson, who Polk rewarded with a job as Postmaster General. It was a tough gig. The post office’s budget was swimming in red ink. (At the time, mail recipients paid postage: If a mail carrier failed to find a recipient, no money was made. This happened a lot.) Johnson fixed the financial problem by introducing the prepaid postage stamp, which flipped the responsibility of paying to senders. According to historian C. L. Grant, in 1845, Johnson estimated that the department would have a deficit of over a million dollars. By the time he left that was down to $30,000.

14. The location of James K. Polk's grave is causing a stir in Tennessee.

Polk died, likely of cholera, in 1849, just months after leaving office. Because he died of an infectious disease, the president was hastily buried in a city cemetery near the outskirts of Nashville. Months later, he was re-interred near his Nashville mansion, Polk Place. In 1893, his tomb was moved again to the state Capitol grounds. Today, Tennessee legislators are actively debating whether to move Polk’s bones a fourth time, this time to his old family home in Columbia, Tennessee.

10 Complicated Facts About Shaft

Richard Roundtree stars in Shaft (1971).
Richard Roundtree stars in Shaft (1971).
MGM

On July 2, 1971, moviegoers caught their first glimpse of John Shaft, the "black private dick that’s a sex machine to all the chicks." Today, Shaft is considered one of the grandfathers of the blaxploitation genre—and it’s got one of the most recognizable soundtracks of all time. While Samuel L. Jackson has taken on the role for a new generation here are some interesting facts about the original film's creation and release. If you picked up on why Shaft and his associates call everyone "mother," you’re smarter than at least one unfortunate reporter.

1. A white newspaper reporter created Shaft.

John Shaft made his debut in Shaft, a novel by Ernest Tidyman. Tidyman was a reporter for The Cleveland News, The New York Post, and The New York Times before he began writing the Shaft series, which included seven detective stories. Along with John D.F. Black, he adapted his first Shaft book into the screenplay for the first film. He would later go on to write the screenplays for The French Connection (1971) and High Plains Drifter (1973) as well as Shaft’s Big Score! (1972) and the Shaft TV series (1973-1974). His work earned him an NAACP Image Award.

2. The studio wanted to shoot Shaft in Los Angeles.

Shaft was filmed entirely in New York City, which is clearly illustrated by the shots of Times Square and Greenwich Village. But it nearly wasn’t. In his autobiography, Voices in the Mirror, director Gordon Parks recalled how he received word from MGM mere hours before he was set to commence filming that he was to return to Los Angeles and shoot the movie there. Apparently it was a budgetary issue, but Parks wasn’t having it. He flew back to the West Coast and essentially told the studio heads he would quit if he couldn’t shoot in Manhattan. "It has to have the smell of New York," Parks insisted. The director won out, and his nightmare of a Harlem in Hollywood was never realized.

3. Shaft's mustache was non-negotiable.

The Los Angeles fiasco was behind him, but Parks immediately faced another scare when he spied his star, Richard Roundtree, heading to the bathroom with a towel and razor. Producer Joel Freeman had asked him to get rid of his soon-to-be legendary mustache. Parks told Roundtree emphatically, “Shave it off and you’re out of a job.” And with that, the ‘stache stayed in the picture.

4. Gordon Parks put his magazine in the movie.

In the movie’s opening sequence, Shaft stops to talk to a blind newsstand vendor. The magazine Essence is prominently displayed—and that’s no accident; Parks helped found the publication and served as its editorial director for its first three years in print.

5. Bumpy Jonas was based on a real mobster.

Shaft spends most of the movie tracking down a kidnapped girl. She’s the daughter of Harlem crime kingpin Bumpy Jonas, and Bumpy was not a Hollywood invention. He was based on Ellsworth “Bumpy” Johnson, who ruled the Harlem crime scene from the 1930s through the 1960s. He had ties to the infamous murder of Dutch Schultz and mentored Frank Lucas, the notorious heroin dealer Denzel Washington played in American Gangster. Fictionalized versions of Johnson have also appeared in movies like The Cotton Club and Hoodlum.

6. Gordon Parks made a cameo.

Parks appears briefly in the montage of Shaft searching for Ben Buford. He’s the landlord with the pipe, who complains that he’s also looking for Buford, who owes him six months of rent.

7. Muhammad Ali's trainer had a bit role.

Drew Bundini Brown was a well-known member of Muhammad Ali’s entourage. He worked as an assistant trainer, and was famous for the “float like a butterfly, sting like a bee” bit he performed with Ali for the cameras. But when he wasn’t in Ali’s corner, Brown was busy racking up movie credits. His first was Shaft, where he played one of Bumpy Jonas's men.

8. "Skloot Insurance" was a nod to a crew member.

Shaft’s office is sandwiched in between Acme Imports Exports Inc. and Skloot Insurance. The latter is a reference to Steven P. Skloot, the movie’s unit production manager.

9. Parks had to explain what "shaft" and "mother" meant to a reporter.

When Parks flew to London to do publicity for the film, he ended up giving an impromptu vocabulary lesson. At a press screening, a confused British reporter asked the director what “shaft” really meant. Parks replied by smiling and sticking his middle finger up in the air, explaining that was “the most honest answer” he could give. But the reporter was persistent and followed up by asking why the characters called each other “mother.” Parks really didn’t know how to answer that one, but luckily, a woman in the audience swooped in. “You’ve heard of Smucker’s jam, young man,” she said. “Just snip out the first two letters and add an ‘f’ and you’ll get the message.”

10. Isaac Hayes was the first black composer to win an Oscar.

Isaac Hayes’s ubiquitous “Theme from Shaft” earned him a 1972 Academy Award for Best Original Song. This win was historic for many reasons: For one, Hayes was the first black composer to score an Oscar. But he was also only the third African American to win an Oscar, period. Prior to 1973, the only other black Academy Award winners were Hattie McDaniel (Best Supporting Actress for Gone with the Wind) and Sidney Poitier (Best Actor for Lilies of the Field).

This story has been updated for 2019.

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