Billion-Year-Old Rocks Reveal the First Color Ever Produced by a Living Thing

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iStock

Billions of years ago, before there were plants and animals on Earth, there were rocks, tiny organisms, water, and not much else. It’s hard to envision what our barren planet looked like back then, but scientists now have some idea of what colors dominated the landscape.

As Vice reports, a team of researchers from Australian National University (ANU) were able to pinpoint the oldest colors ever produced by a living creature: purple-red hues dating back more than 1.1 billion years. The pigments, which appear pink when diluted, were found in molecular fossils of chlorophyll that had been preserved in rocks beneath the Sahara desert. A billion years ago, though, this area was “an ancient ocean that has long since vanished,” Nur Gueneli of ANU said in a statement.

Chlorophyll may very well be green, but these pinkish pigments are a result of "fossilized porphyrins, a type of organic compound that forms an atomic ring around a magnesium ion to form a chlorophyll molecule," Vice explains.

While this provides an interesting visual, the color itself is less important than what it reveals about some of the earliest life forms on Earth. Scientists determined that the chlorophyll was produced by ancient organisms called cyanobacteria, which derived energy via photosynthesis and ruled the oceans at that time, researchers wrote in a paper published in the Proceedings of the National Academy of Sciences. Larger planktonic algae—a potential food source for bigger life forms— were scarce, which may explain why large organisms didn’t roam the Earth a billion years ago. That kind of algae was about a thousand times larger than the cyanobacteria.

“The cyanobacterial oceans started to vanish about 650 million years ago, when algae began to rapidly spread to provide the burst of energy needed for the evolution of complex ecosystems, where large animals, including humans, could thrive on Earth," ANU associate professor Jochen Brocks said.

So the next time you encounter algae, you can thank it for helping you secure a spot on this planet.

[h/t Vice]

The Science Behind Brining Your Thanksgiving Turkey

iStock.com/LazingBee
iStock.com/LazingBee

At many Thanksgiving tables, the annual roast turkey is just a vehicle for buttery mash and creamy gravy. But for those who prefer their bird be a main course that can stand on its own without accoutrements, brining is an essential prep step—despite the fact that it requires finding enough room in the fridges to immerse a 20-pound animal in gallons of salt water for days on end. To legions of brining believers, the resulting moist bird is worth the trouble.

How, exactly, does a salty soak yield juicy meat? And what about all the claims from a contingency of dry brine enthusiasts: Will merely rubbing your bird with salt give better results than a wet plunge? For a look at the science behind each process, we tracked down a couple of experts.

First, it's helpful to know why a cooked turkey might turn out dry to begin with. As David Yanisko, a culinary arts professor at the State University of New York at Cobleskill, tells Mental Floss, "Meat is basically made of bundles of muscle fibers wrapped in more muscle fibers. As they cook, they squeeze together and force moisture out," as if you were wringing a wet sock. Hence the incredibly simple equation: less moisture means more dryness. And since the converse is also true, this is where brining comes in.

Your basic brine consists of salt dissolved in water. How much salt doesn't much matter for the moistening process; its quantity only makes your meat and drippings more or less salty. When you immerse your turkey in brine—Ryan Cox, an animal science professor at the University of Minnesota, quaintly calls it a "pickling cover"—you start a process called diffusion. In diffusion, salt moves from the place of its highest concentration to the place where it's less concentrated: from the brine into the turkey.

Salt is an ionic compound—its sodium molecules have a positive charge and its chloride molecules have a negative charge, but they stick together anyway. As the brine penetrates the bird, those salt molecules meet both positively and negatively charged protein molecules in the meat, causing the meat proteins to scatter. Their rearrangement "makes more space between the muscle fibers," Cox tells Mental Floss. "That gives us a broader, more open sponge for water to move into."

The salt also dissolves some of the proteins, which, according to the book Cook's Science by the editors of Cook's Illustrated, creates "a gel that can hold onto even more water." Juiciness, here we come!

There's a catch, though. Brined turkey may be moist, but it can also taste bland—infusing it with salt water is still introducing, well, water, which is a serious flavor diluter. This is where we cue the dry briners. They claim that using salt without water both adds moisture and enhances flavor: win-win.

Turkey being prepared to cook.
iStock

In dry brining, you rub the surface of the turkey with salt and let it sit in a cold place for a few days. Some salt penetrates the meat as it sits—with both dry and wet brining, Cox says this happens at a rate of about 1 inch per week. But in this process, the salt is effective mostly because of osmosis, and that magic occurs in the oven.

"As the turkey cooks, the [contracting] proteins force the liquid out—what would normally be your pan drippings," Yanisko says. The liquid mixes with the salt, both get absorbed or reabsorbed into the turkey and, just as with wet brining, the salt disperses the proteins to make more room for the liquid. Only this time the liquid is meat juices instead of water. Moistness and flavor ensue.

Still, Yanisko admits that he personally sticks with wet brining—"It’s tradition!" His recommended ratio of 1-1/2 cups of kosher salt (which has no added iodine to gunk up the taste) to 1 gallon of water gives off pan drippings too salty for gravy, though, so he makes that separately. Cox also prefers wet brining, but he supplements it with the advanced, expert's addition of injecting some of the solution right into the turkey for what he calls "good dispersal." He likes to use 1-1/2 percent of salt per weight of the bird (the ratio of salt to water doesn't matter), which he says won't overpower the delicate turkey flavor.

Both pros also say tossing some sugar into your brine can help balance flavors—but don't bother with other spices. "Salt and sugar are water soluble," Cox says. "Things like pepper are fat soluble so they won't dissolve in water," meaning their taste will be lost.

But no matter which bird or what method you choose, make sure you don't roast past an internal temperature of 165˚F. Because no brine can save an overcooked turkey.

This piece originally ran in 2017.

Why Your Cat's Tongue Is Nature's Perfect Hairbrush

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iStock.com/takashikiji

A lick from a cat is a mixed blessing. On the one hand, cats don’t dole out affection to just anyone, so it’s a true compliment when they try to groom you. On the other hand, their tongues feel like sandpaper wrapped in barbed wire. Those sharp tongues are actually incredible tools, according to a new study published in Proceedings of the National Academy of Sciences. Their unique structure is very efficient at depositing saliva on cats' fur to help them clean themselves and keep cool. Researchers from Georgia Tech made the discovery using high-speed video, CT scans, and “grooming force measurements.”

Cats aren't just prettying themselves up when they spend all day grooming themselves, the study shows. (That’s not an exaggeration—house cats can spend up to a quarter of their waking lives grooming.) As they lick themselves, their tongues remove debris, fleas, and excess heat from their fur thanks to those sharp, curved spines—called filiform papillae—that are so unpleasant to feel on your skin.

A close-up image of a cat's tongue
Alexis Noel

These keratin-based filiform papillae have U-shaped hollows at their tips that allow cats to wick saliva from their mouths onto their fur, helping them regulate body temperature and cool down. Each of these papillae can carry one-tenth of an eyedropper’s worth of spit, half of which gets deposited on the fur. The papillae spread the saliva along the roots of each hair, allowing it to penetrate cats’ fur so that it can cool their skin. Saliva alone can provide 25 percent of a cat’s cooling needs, according to the study.

This useful adaptation isn’t limited to domestic cats. Researchers looked at tongue tissue from six different species—bobcat, cougar, snow leopard, tiger, and lion, in addition to house cats—and found similar structures.

As part of the study, the researchers also created a flexible “tongue-inspired grooming" (TIGR) brush with the help of 3D models of a house cat’s papillae. They found it was easier to clean than a typical human hairbrush—hair could be removed from it in one swipe, without the tweezers or other tools you need to get hair out of the stiff bristles of the typical hairbrush. (The wavy ridges on the roofs of cats’ mouths may do this job in the animals themselves.)

The brush has several potential uses. Because of its papillae-inspired structure, it could be used to apply liquids to cats’ skin. That could be helpful for applying topical medication, but it might also be a way to wash off some of the allergens they produce that bother humans. Potentially, there could be human uses for a papillae-like hairbrush in the future, too. You could imagine using it to brush styling products evenly through your hair, for instance. The researchers suggest the structure "may provide inspiration to soft robotics and biologically inspired technologies for sorting, cleaning, and depositing fluids into fur and arrays of flexible filaments."

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