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Ancient Green Beer Contained Antibiotics

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Alexander Fleming's dodgy cleaning habits helped him discover penicillin in 1928. The bacteriologist was cleaning Petri dishes when he noticed mold growing on staphylococcus (staph) bacteria. The mold, Penicillium notatum, killed the staph around it and Fleming realized he stumbled on a treatment for bacterial infections. Fleming's discovery revolutionized medical practices, but researchers found that he wasn't the first to accidentally discover antibiotics. Ancient Nubians regularly drank antibiotics in their beer more than 2,000 years ago.

In 1963 George Armelagos, a biological anthropologist, and some colleagues uncovered Nubian mummies. The Nubians lived between 350 AD and 550 AD in modern Egypt and Sudan. Armelagos began peering into microscopes to examine Nubian bones and understand osteoporosis, when he noticed the mummies exhibited high levels of tetracycline, an antibiotic once used to treat cholera, but not available until 1950. (Now, it is mostly prescribed to treat acne.) He was curious why there were such high levels of the antibiotic and thought it came from contamination. He took bone samples and asked a lab to dissolve them, extracting tetracycline. He found that the Nubians consumed so much of the drug that remnants lingered in their bones. This was no freak contamination. (The image at left, taken under UV light, shows the tetracycline on the bones—the green is the tetracycline.)

Armelagos discovered that grain stored underground became moldy with Streptomyces, which produces tetracycline. High heat from baking bread, for example, would kill the small amounts of it. But fermenting the grains would promote rapid growth of tetracycline—Nubians prepared gruel and beer with fermented grains. Armelagos found that beer drinking started young and discovered traces of tetracycline in babies from mothers' breast milk. Armelagos suspects that the Nubians realized the beer and gruel made them feel better but had little idea why.

Some of Armelagos' students made a home-brewed beer with Strep bacteria, like the Nubian brew. It tastes sour and looks green (perfect for St. Patrick's Day and Strep throat). Don't worry about ingesting extra antibiotics when drinking beer, though—most beers undergo pasteurization, killing bacteria.

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Belly Flop Physics 101: The Science Behind the Sting
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Belly flops are the least-dignified—yet most painful—way of making a serious splash at the pool. Rarely do they result in serious physical injury, but if you’re wondering why an elegant swan dive feels better for your body than falling stomach-first into the water, you can learn the laws of physics that turn your soft torso a tender pink by watching the SciShow’s video below.

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What's the Saltiest Water in the World?
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Saltwater is common around the world—indeed, salty oceans cover more than two-thirds of the globe. Typical saltwater found in our oceans is about 3.5% salt by weight. But in some areas, we find naturally occurring saltwater that's far saltier. The saltiest water yet discovered is more than 12 times saltier than typical seawater.

Gaet’ale is a pond in Ethiopia which currently holds the record as the most saline water body on Earth. The water in that pond is 43.3% dissolved solids by weight—most of that being salt. This kind of water is called hypersaline for its extreme salt concentration.

In the video below, Professor Martyn Poliakoff explains this natural phenomenon—why it's so salty, how the temperature of the pond affects its salinity, and even why this particular saltwater has a yellow tint. Enjoy:

For the paper Poliakoff describes, check out this abstract.

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