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Even identical twins with the same genes can differ in handedness: one may be left-handed and the other right-handed. Such discordance in twin studies shows that although genes influence handedness, they do not determine it alone.

About 10% of people worldwide are left-handed. A 2020 meta-analysis covering more than two million people estimated the best overall prevalence at 10.6%—confirming the familiar figure of roughly one person in ten.

In 1907, biologist Henry Van Peters Wilson pushed a sponge through silk mesh into loose cells. They regrouped in seawater and regrew into a sponge. Later experiments mixing two species found that cells sorted by species and formed separate sponges.

One reason airplane meals taste flat is cabin pressure. Cabins mimic 1,800–2,400 m altitude and dry nasal passages. A 2010 Fraunhofer experiment found sweet and salty taste sensitivity fell ~30%, so airlines emphasize umami and tomato juice.

More than 90% of the methane cattle produce escapes through belching, not flatulence. Anaerobic microbes in the rumen ferment grass and generate methane, which exits primarily through the mouth.

Schrödinger's cat was made to criticize quantum mechanics, not explain it. In 1935, Erwin Schrödinger argued that the Copenhagen interpretation absurdly leaves an everyday cat both alive and dead. His critique became quantum theory's best-known illustration.

Earth reaches its farthest point from the Sun, aphelion, in early July—the Northern Hemisphere's summer. At ~152 million km, it is 5 million km farther than in January. Seasons come from axial tilt, not distance: Earth is farthest from the Sun in midsummer.

On August 9, 1945, atomic bomb Fat Man's primary target was Kokura, not Nagasaki. Smoke and clouds obscured the target through 50 minutes and three failed runs. With fuel critically low, the B-29 Bockscar diverted to Nagasaki, its secondary target.

In 1897, the Indiana House passed a bill that effectively made pi 3.2, 67–0. Its author, an amateur mathematician, thought he had squared the circle and offered free school rights. Purdue professor Clarence Waldo saw it in the Senate, explained the error, and the bill was tabled.

Sterile fly maggots are an FDA-approved medical device. They eat only dead tissue and secrete compounds that clean wounds and kill drug-resistant bacteria. Where antibiotics fail against chronic infections, maggot therapy can work. The FDA cleared it in 2004.

One gram of DNA can theoretically hold 215 petabytes — roughly 200 million movies. Its four bases act as a base-4 storage medium. In 2017, George Church's Harvard team stored a short film and images in DNA and retrieved them without errors. Properly stored, DNA can last millennia.

People with red-green color blindness can see green camouflage in finer detail. Less distracted by color, they rely on brightness and texture, making concealment easier to spot. Wartime accounts say Allied forces used colorblind soldiers as photo interpreters.

Humans are the only primate with obvious white sclera. Apes have darker sclera that hide gaze direction, but human eyes broadcast where someone is looking. The Cooperative Eye Hypothesis says this 'eye that cannot lie' helped early coordination and group hunting.

In 1696, Britain taxed houses by window count. Homeowners bricked up windows to cut the bill, leaving rooms without enough light or ventilation. Doctors opposed the health effects; the tax was repealed in 1851. Bricked-up window outlines remain on old buildings.

During sleep, the brain not only stores memories — it erases them. Research from 2022–2023 found Arc and Homer1a can weaken less-active synapse connections. Forgetting is a feature, not a bug: clearing space helps encode new memories.

In 2005, Yale researchers taught capuchin monkeys to use metal tokens as currency. The monkeys developed gambling and loss aversion spontaneously. Some males exchanged tokens with females for food.

At Mount Everest's summit (~8,849 m), air pressure is only ~33% of sea level, so water boils at about 70 °C. Since bubbles form well below 100 °C, pasta stays undercooked and eggs won't hard-boil — no matter how long you heat them on the world's highest peak.

Marie Curie's notebooks remain in lead-lined boxes 90+ years after her death — still dangerously radioactive. Soaked in radium and polonium she handled bare-handed, readers must sign a waiver and wear protective gear. Radium's half-life is 1,600 years.

An Ostrich eye is about 5 cm across and 60 g — heavier than its brain. The eyes occupy more skull space than the brain, flattening it between them. This visual system helps spot predators from up to 2 km away: an evolutionary trade-off for a flightless bird.

During the 1962 Cuban Missile Crisis, Soviet sub B-59 was hit by U.S. depth charges; its captain prepared a nuclear torpedo launch. All three senior officers had to agree, but Vasili Arkhipov alone refused. His no is credited with preventing Nuclear war.