A 2011 study found that Chinese consumers are charged more due to “superstitious manipulations” of retail prices—fives and sixes appear more often than unlucky fours, eights and nines more than unlucky sevens. “Retailers,” the study reported, “are the clear winners.”

A twelfth-century-bc Chinese king consulted an oracle and was told his lucky charm would not be a tiger, dragon, bear, or leopard but rather a wise counselor. He soon came upon a sagacious old man fishing in the river and conscripted him into service. It is said the man’s virtue was such that he fished not with a hook but with a straight piece of iron; acknowledging his integrity, fish impaled themselves voluntarily.

In November 1934 a team of American baseball stars, including Babe Ruth, toured Japan. When they arrived for a game in the town of Narashino, each man was presented with a horseshoe-shaped flower wreath. Ruth detested the gift; he later told a Japanese baseball magazine that he considered such wreaths bad luck and had never hit a home run after receiving one.

When Apple released its Shuffle feature for iPods, users were deceived by the true randomness of its playback; songs from the same album or artist were often grouped by chance. Complaints led Steve Jobs to alter the device’s programming and begin offering Smart Shuffle, which allowed users to adjust the likelihood of hearing similar songs in a row. “We’re making it less random,” he said, “to make it feel more random.”

In July 2003 details leaked of a new venture from the Defense Advanced Research Projects Agency: an online market for financial speculation on possible terrorist attacks, assassinations, and coups. “Futures markets have proven themselves to be good at predicting such things as elections results,” the Defense Department argued. “They are often better than expert opinions.” DARPA—already under fire for its proposed Total Information Awareness program—was forced to abandon the idea.

Sailors’ fear of bananas may extend back to seventeenth-century Spanish ships trading in the Caribbean. Crew members would often purchase wooden crates of the fruit, and when their vessels sailed north to pick up the Gulf Stream in the Straits of Florida, hazards of the passage shipwrecked many, leaving behind stray clumps of bananas floating ominously on the water’s surface for later ships to see.