Sidewalk crack addict

Debunking urban myths is part of Flip Side's journalistic mission. Last year we revealed that drinking eight glasses of water a day provided no health benefit. Today we explode seven widely believed urban myths.

Step on a crack, break your mother's back: Attribution error plus confirmation bias propels this erroneous belief.

When a mother breaks her back, an offspring usually recalls stepping on a crack. Wracked with guilt, he confesses to everyone, "I stepped on a crack and broke my mother's back."

His observation is passed on, perpetuating the myth and confirming the belief that if one steps on a crack, one will break one's mother's back. (Broken-back mothers universally blame their affliction on negligent offspring.)

People fail to observe the false positives (offspring do not step on a crack, but mother breaks her back anyway) and false negatives (daughter steps on a crack, but the mother does not break her back).

When these data are included, the link between stepping on a crack and breaking your mother's back is very weak and may be due to random fluctuations. Researchers at Cal Tech concluded that stepping on a crack increased the chances of your mother breaking her back by only 3.6 percent.

An apple a day keeps the doctor away: A University of Wisconsin study tested this theory by establishing three groups:

Group 1 ate apples every day. Group 2 thought they ate apples every day, but, in fact, were given a tofu substitute. Group 3 ate no apples.

Researchers recorded all visits to doctors for 10 months. The study concluded that apples had no effect on keeping the doctor away.

Lack of health insurance and low reimbursement rates were the most effective methods of keeping the doctor away.

No two snowflakes are alike: In Pullman, Wash., on Jan. 7, 1993, Alison Karp noticed that two snowflakes were exact replicas. Startled, she began to closely observe snowflakes. Since then she has reported more than 120 examples of two or more snowflakes being the same.

"Most people believe that no two are the same, so they don't bother to look," she explains. "If you look closely, you find matches all the time. It's obvious, if you think about it. There a are a lot of snowflakes and not that many shapes."

Because Carp's samples always melted, scientists were initially skeptical. However, a 2006 NASA study proved Carp's contention. NASA determined that in any given year, snowflakes outnumbered all possible shapes by at least 14 to 1. Ergo, some snowflakes had to be alike.

All roads lead to Rome: This notion retains currency because it has been repeated so often in literature, opera, and film. In the Aeneid, Anchises directs his son Aeneas to Rome, saying, "Where all roads converge, there you shall found Rome." When Aeneas asks how to get there, Anchises replies, "Take any road, you blockhead. They all go there. You can't miss it."

In the Opera Tosca, Angelotti escapes to Rome explaining, "I could not go anywhere else. Every road led here."

In the movie Gladiator, General Maximus Decimus Meridius (Russell Crowe) dispatches troops to Rome with the order, "Take any road. It doesn't matter. All roads lead to Rome. Don't sweat it."

But all roads do not lead to Rome! For example, Madison Street in Seattle runs from Lake Washington to Puget Sound. A road that starts and ends at water does not lead to Rome.

Numerous roads in Missouri end at the Mississippi River. Most roads in Detroit do not lead anywhere.

Cleanliness is next to godliness: While many things are next to godliness, cleanliness is not one of them. Search the Bible, the Koran, and the New Testament and you will find little praise for cleanliness. Jesus, Muhammad, and Moses displayed a Gallic view of bathing.

None of the Ten Commandments pertains to flossing, washing behind the ears, or shampooing.

God himself found concerns about cleanliness hopelessly middle class, remarking, "They break my commandments and then obsess about underarm odor. What a bunch of losers."

The early bird gets the worm: This may have been true at some point in the distant past. However, for generations the early worm got eaten. Therefore, through natural selection, worms have evolved to be late risers, often staying in bed until noon.

A recent study revealed that birds do not bother to look for worms until the sun is over yardarm.

Every dog has its day: My dog, a Bichon Frise, has never had its day. My neighbors, the Roaches, have two dogs. To my knowledge, neither has had its day.

The Greater Cleveland area (pop. 2,250,871) is home to 437,159 dogs. Can you name a single dog in Greater Cleveland who has had its day? If every dog had its day, more than 1,000 dogs would be having their day this very day in Greater Cleveland alone. Wouldn't someone notice?

Updates: Life imitates art

Esprit de core competency, July 21: Last week, The Wall Street Journal explained that while the earnings of the S&P 500 were off 17.9 percent for the quarter, "core" earnings excluding financials and energy were up 2.8 percent. "Lose the troubled home builders and auto makers for an even more finely tuned measure of 'core' profits, and the gain improves to 5.4 percent," the Journal noted.

The Fearmongers, Definers, Swiftboaters, and Borkers square off, July 27: Last Thursday, July 31, The New York Times ran the front-page headline, "McCain Tries to Define Obama as Out of Touch."

• Steve Clifford writes humor for Crosscut. In his unhumorous life, he was CEO of King Broadcasting and once played a role in saving New York City from bankruptcy.