English cobblers first created “left” and “right” shoes in 1785. Before that, pairs of shoes were identical.

Octopuses have been taught to count to five, distinguish shapes and unscrew jar lids.

The South American paradoxical frog (Pseudis paradoxa) shrinks as it matures. As a tadpole it can be 10 inches long, but is only about 3 inches long as an adult.

The Sarawak Chamber in Malaysia is the largest known underground cave in the world. It is 2,300 feet long, 1,300 feet wide and 230 feet high. That’s about 19 football fields long, 11 football fields wide and as tall as a 14-story office building.

UK scientists have invented the darkest color ever. Called “superblack,” it has almost no reflectivity and absorbs 99.6% of all light.

Epilepsy sufferers should avoid episode 38 of the Japanese cartoon Pokémon. Especially a scene featuring rapidly flashing red and blue lights. A 1997 broadcast caused more than 600 Japanese viewers, mostly children, to suffer epileptic seizures. Many had to be hospitalized.

Life spans of body cells: Bone marrow—12 hours, white blood cell—2 weeks, skin cell—1 month, red blood cell—3 months, liver cell—18 months, nerve cell—almost an entire lifetime.

Number of muscles utilized: 6 to move an eyeball, 20 to purse lips, 25 to smile, 45 to frown (the adage is true!), 50 to take a step forward, 75 to speak.

The human eye can distinguish more than 7 million different colors—more than 500 shades of gray alone.

Sherlock Holmes’ iconic hat is called a deerstalker, and as the name indicates, it is traditionally worn as deer-hunting headgear.

Marrying a love of literature with megalomania: Saheb Ibn Abad, the 10th century Grand Vizier of Persia, always traveled and went to war with his collection of 117,000 books. The volumes were carried by 400 camels in alphabetical order.

Longest alphabet: Khmer, used in Cambodia, has 74 letters. Shortest alphabet: Rotokas, used in Papua New Guinea, has 11 letters. Note: Letters in the Chinese alphabet are technically symbols, and there are around 50,000, but knowledge of 4,000 is enough to get by.