iStock
iStock

Blame Leap Year on Mismatched Solar, Lunar, and Seasonal Cycles

iStock
iStock

It’s hard to think of anything as complex, and yet as humdrum, as the calendar. These days, clocks and calendars are so ubiquitous—the screen you’re looking at right now can instantly tell you the time and date—that we’re blissfully unaware of the centuries-old intellectual struggle involved in their creation. What better day than February 29—a day that comes only once every four years—to reflect on the story behind our seemingly esoteric method of counting the days of the year.

BLAME IT ON THE SUN, MOON, AND SEASONS

The complexity of our timekeeping systems isn’t really humanity’s fault. If you’re looking for a scapegoat, I’d blame the solar system. The urge to keep track of time is probably as old as our species, and the most obvious signs of time’s passage are the cycles we observe in nature, especially the regularities we see in the night sky.

Most obvious are the day (measured by the rising or setting of the Sun); the month (measured by tracking the phases of the Moon); and the year (the annual cycle of the seasons). But timekeeping soon gets complicated, because none of these cycles fit neatly into one another: The lunar month is about 29.5 days long (actually 29.5306); the average year as defined by the seasons—also known as the “solar” or “tropical” year—is about 365.25 days long (actually a smidgeon less, at 365.2422 days). And the month refuses to fit neatly into the year, too, for that matter (there are more than 12, but less than 13, lunar cycles in a year). Over the centuries, different civilizations tried every possible trick to try to reconcile these incongruent cycles.

It would have been nice if there were 360 days in a year: The math would be wonderfully simple, since 360 can be divided by 2, 3, 4, 5, 6, 8, 9, 10, and—well, I won’t list them all, but 360 has 22 divisors in all (not counting 1 and 360). But no such luck; the year actually has a bit more than 365 days.

FROM THE EGYPTIANS' FIVE-DAY PARTY TO POPE GREGORY VIII'S MISSING 11 DAYS

The ancient Egyptians had a fairly elegant solution: Use a 360-day calendar, with 12 months of 30 days each, and then enjoy five days of feasts and celebrations at the end of each year. But it still wasn’t perfect: The resulting year of 365 days is still about a quarter-day short of the true solar year.

The Egyptians recognized this discrepancy early on, and realized that adding an extra day every four years would bring the average length of the year to within just a few minutes of the true solar (tropical) year. It wasn’t until 238 BCE, however, that the Egyptian king Ptolemy III pushed for the adoption of a leap-year system. The Romans—whose empire would eventually encompass Egypt—tried a variety of calendar systems, eventually adopting the now-familiar leap year system, in which every fourth year has 366 days, instead of the usual 365. They’re also responsible for the peculiar lengths of the months. Initially, the idea was to have alternating 30-day and 31-day months, but successive rulers fiddled with those lengths. (For example: July, named for Julius Caesar, had 31 days; naturally, his successor, Augustus, demanded that August must have 31 also—the extra day being taken away from lowly February.)

The Roman calendar wasn’t perfect. Its average year of 365.25 days was just slightly shorter—by about 11 minutes—than the true solar year. By the time of Pope Gregory XIII, in the late 1500s, that discrepancy added up to 10 full days. Springtime holidays like Easter were drifting awkwardly into summer. Gregory convened a council of mathematicians and astronomers, who eventually found a way to make the average year just slightly longer: In the old system, “century years” like 1500, 1600, and 1700 would be leap years because they’re divisible by 4; under the new plan, only those century years divisible by 400 (such as 1600 and 2000) would be leap years.

The proposed reform was adopted in 1582—at which point 10 days were dropped from the calendar to let it “synch up” with the seasons (and so October 4, 1582, was followed by October 15). Some people were distressed at what seemed to be “lost” time. Merchants puzzled over the calculation of profits and losses; bankers were befuddled by interest rates.

CATHOLICS AND PROTESTANTS ALSO FOUGHT OVER THE CALENDAR

While Catholic countries quickly adopted the Gregorian calendar, Protestant countries held off. In Britain, the new calendar wasn’t adopted until 1752—at which point 11 days had to be dropped from the year, in order to “catch up.” Protests broke out in London and Bristol, with workers shouting, “Give us back our 11 days!” Interestingly, such tensions have not entirely disappeared; as The Telegraph points out, some people resent having to work an extra day for no pay in leap years.

Leap years, which have been a part of our timekeeping system for more than 2000 years, barely warrant notice these days— although today’s Google Doodle serves as a cute reminder. Of course, if you’re one of the 4 million or so living leap day babies, known as “leaplings” or “leapers,” you’re likely hyper-aware of leap years. (Calculating the number of people with a February 29 birthday is tricky, by the way: The fraction of babies born on February 29 isn’t 1 in 365, but rather, about one in 1460, since February 29 occurs only once every four years—or, to be precise, 97 times every 400 years.) Famous leap-babies include motivational speaker Tony Robbins, rapper Ja Rule, and the 16th-century pope Paul III. Intriguingly, two major events—the Summer Olympics and U.S. national elections—are always held in leap years.

Dan Falk (@danfalk) is a science journalist based in Toronto. He explored time and timekeeping in his 2008 book, In Search of Time.

nextArticle.image_alt|e
iStock
Interactive Map Shows Where Your House Would Have Been 750 Million Years Ago
iStock
iStock

Your neighborhood traveled a long way over several hundred million years to reach the spot it occupies today. To trace that journey over the ages, check out Ancient Earth, an interactive digital map spotted by Co.Design.

Ancient Earth, a collaboration between engineer and Google alum Ian Webster and Paleomap Project creator C.R. Scotese, contains geographical information for the past 750 million years. Start at the beginning and you'll see unrecognizable blobs of land. As you progress through the ages, the land mass Pangaea gradually breaks apart to form the world map we're all familiar with.

To make the transition even more personal, you can enter your street address to see where it would have been located in each period. Five hundred million years ago, for example, New York City was a small island in the southern hemisphere isolated from any major land mass. Around the same time, London was still a part of Pangaea, and it was practically on top of the South Pole. You can use the arrows on your keyboard to flip through the eras or jump from event to event, like the first appearance of multicellular life or the dinosaur extinction.

As you can see from the visualization, Pangaea didn't break into the seven continents seamlessly. Many of the long-gone continents that formed in the process even have names.

[h/t Co.Design]

nextArticle.image_alt|e
Illustration by Mental Floss / Images: iStock
11 Facts About the Appendix
Illustration by Mental Floss / Images: iStock
Illustration by Mental Floss / Images: iStock

Despite some 500 years of study, the appendix might be one of the least understood structures in the human body. Here's what we know about this mysterious organ.

1. THE ANCIENT EGYPTIANS CALLED IT THE "WORM" OF THE BOWEL.

The human appendix is small, tube-shaped, and squishy, giving ancient Egyptians, who encountered it when preparing bodies for funerary rites, the impression of a worm. Even today, some medical texts refer to the organ as vermiform—Latin for "worm-like."

2. THE APPENDIX SHOWS UP IN LEONARDO DA VINCI’S DRAWINGS.

The earliest description of a human appendix was written by the Renaissance physician-anatomist Jacopo Berengario da Carpi in 1521. But before that, Leonardo da Vinci is believed to drawn the first depiction of the organ in his anatomical drawings in 1492. Leonardo claimed to have dissected 30 human corpses in his effort to understand the way the body worked from mechanical and physiological perspectives.

3. IT'S ABOUT THE SIZE OF A PINKY FINGER.

The appendix is a small pouch connected to the cecum—the beginning of the large intestine in the lower right-hand corner of your abdomen. The cecum’s job is to receive undigested food from the small intestine, absorb fluids and salts that remain after food is digested, and mix them with mucus for easier elimination; according to Mohamad Abouzeid, M.D., assistant professor and attending surgeon at NYU Langone Medical Center, the cecum and appendix have similar tissue structures.

4. CHARLES DARWIN THOUGHT IT WAS A VESTIGIAL ORGAN …

The appendix has an ill-deserved reputation as a vestigial organ—meaning that it allegedly evolved without a detectable function—and we can blame Charles Darwin for that. In the mid-19th century, the appendix had been identified only in humans and great apes. Darwin thought that our earlier ancestors ate mostly plants, and thus needed a large cecum in which to break down the tough fibers. He hypothesized that over time, apes and humans evolved to eat a more varied and easier-to-digest diet, and the cecum shrank accordingly. The appendix itself, Darwin believed, emerged from the folds of the wizened cecum without its own special purpose.

5. … BUT THE APPENDIX PROBABLY EVOLVED TO HELP IMMUNE FUNCTION.

The proximity and tissue similarities between the cecum and appendix suggest that the latter plays a part in the digestive process. But there’s one noticeable difference in the appendix that you can see only under a microscope. “[The appendix] has a high concentration of the immune cells within its walls,” Abouzeid tells Mental Floss.

Recent research into the appendix's connection to the immune system has suggested a few theories. In a 2015 study in Nature Immunology, Australian researchers discovered that a type of immune cells called innate lymphoid cells (ILCs) proliferate in the appendix and seem to encourage the repopulation of symbiotic bacteria in the gut. This action may help the gut recover from infections, which tend to wipe out fluids, nutrients, and good bacteria.

For a 2013 study examining the evolutionary rationale for the appendix in mammal species, researchers at Midwestern University and Duke University Medical Center concluded that the organ evolved at least 32 times among different lineages, but not in response to dietary or environmental factors.

The same researchers analyzed 533 mammal species for a 2017 study and found that those with appendices had more lymphatic (immune) tissue in the cecum. That suggests that the nearby appendix could serve as "a secondary immune organ," the researchers said in a statement. "Lymphatic tissue can also stimulate growth of some types of beneficial gut bacteria, providing further evidence that the appendix may serve as a 'safe house' for helpful gut bacteria." This good bacteria may help to replenish healthy flora in the gut after infection or illness.

6. ABOUT 7 PERCENT OF AMERICANS WILL GET APPENDICITIS DURING THEIR LIFETIMES.

For such a tiny organ, the appendix gets infected easily. According to Abouzeid, appendicitis occurs when the appendix gets plugged by hardened feces (called a fecalith or appendicolith), too much mucus, or the buildup of immune cells after a viral or bacterial infection. In the United States, the lifetime risk of getting appendicitis is one in 15, and incidence in newly developed countries is rising. It's most common in young adults, and most dangerous in the elderly.

When infected, the appendix swells up as pus fills its interior cavity. It can grow several times larger than its average 3-inch size: One inflamed appendix removed from a British man in 2004 measured just over 8 inches, while another specimen, reported in 2007 in the Journal of Clinical Pathology, measured 8.6 inches. People with appendicitis might feel generalized pain around the bellybutton that localizes on the right side of the abdomen, and experience nausea or vomiting, fever, or body aches. Some people also get diarrhea.

7. APPENDECTOMIES ARE ALMOST 100 PERCENT EFFECTIVE FOR TREATING APPENDICITIS.

Treatment for appendicitis can go two ways: appendectomy, a.k.a. surgical removal of the appendix, or a first line of antibiotics to treat the underlying infection. Appendectomies are more than 99 percent effective against recurring infection, since the organ itself is removed. (There have been cases of "stump appendicitis," where an incompletely removed appendix becomes infected, which often require further surgery.)

Studies show that antibiotics produce about a 72 percent initial success rate. “However, if you follow these patients out for about a year, they often get recurrent appendicitis,” Abouzeid says. One 2017 study in the World Journal of Surgery followed 710 appendicitis patients for a year after antibiotic treatment and found a 26.5 percent recurrence rate for subsequent infections.

8. AN INFECTED APPENDIX DOESN’T ACTUALLY BURST.

You might imagine a ruptured appendix, known formally as a perforation, being akin to the "chestbuster" scene in Alien. Abouzeid says it's not quite that dramatic, though it can be dangerous. When the appendix gets clogged, pressure builds inside the cavity of the appendix, called the lumen. That chokes off blood supply to certain tissues. “The tissue dies off and falls apart, and you get perforation,” Abouzeid says. But rather than exploding, the organ leaks fluids that can infect other tissues.

A burst appendix is a medical emergency. Sometimes the body can contain the infection in an abscess, Abouzeid says, which may be identified through CT scans or X-rays and treated with IV antibiotics. But if the infection is left untreated, it can spread to other parts of the abdomen, a serious condition called peritonitis. At that point, the infection can become life-threatening.

9. SURGEONS CAN REMOVE AN APPENDIX THROUGH A TINY INCISION.

In 1894, Charles McBurney, a surgeon at New York's Roosevelt Hospital, popularized an open-cavity, muscle-splitting technique [PDF] to remove an infected appendix, which is now called an open appendectomy. Surgeons continued to use McBurney's method until the advent of laparoscopic surgery, a less invasive method in which the doctor makes small cuts in the patient's abdomen and threads a thin tube with a camera and surgical tools into the incisions. The appendix is removed through one of those incisions, which are usually less than an inch in length.

The first laparoscopic appendectomies were performed by German physician Kurt Semm in the early 1980s. Since then, laparoscopic appendectomies have become the standard treatment for uncomplicated appendicitis. For more serious infections, open appendectomies are still performed.

10. AN APPENDIX ONCE POSTPONED A ROYAL CORONATION.

When the future King Edward VII of Great Britain came down with appendicitis (or "perityphlitis," as it was called back then) in June 1902, mortality rates for the disease were as high as 26 percent. It was about two weeks before his scheduled coronation on June 26, 1902, and Edward resisted having an appendectomy, which was then a relatively new procedure. But surgeon and appendicitis expert Frederick Treves made clear that Edward would probably die without it. Treves drained Edward's infected abscess, without removing the organ, at Buckingham Palace; Edward recovered and was crowned on August 9, 1902.

11. THE WORLD'S LONGEST APPENDIX MEASURED MORE THAN 10 INCHES.

On August 26, 2006, during an autopsy at a Zagreb, Croatia hospital, surgeons obtained a 10.24-inch appendix from 72-year-old Safranco August. The deceased currently holds the Guinness World Record for "largest appendix removed."

SECTIONS

arrow
LIVE SMARTER
More from mental floss studios