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Why Does My Cat Bring Home Dead Animals?

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Cats are adorable, and sometimes aloof. Occasionally, they can be allergic to you, and half of them have no reaction whatsoever to catnip. They’re also hunting machines: A recent study estimated that cats kill between 1.4 billion and 3.7 billion birds and between 6.9 billion and 20.7 billion small mammals a year in the United States alone. And, as any owner of an indoor-outdoor cat knows, some of these dead (or nearly dead) animals end up on our doorsteps uneaten. Why does your cat kill something if he's not intending to eat it? And why is he leaving that dead mouse for you?

No, it's not because he's a vicious murderer. It all comes down to a cat’s natural predatory instinct. “Cats are hunters by nature,” says Dr. Stephanie Liff, a veterinarian at Brooklyn Cares Veterinary Clinic in Brooklyn, New York. “They will go out and kill their prey and then bring it home for the rest of the ‘pack’ for sustenance, and maybe to boast—but that is really anthropomorphic and probably not a real explanation.” Even if your domestic cat has no need to hunt because you’re providing food for him, he’ll still display that behavior (just look at how he stalks his toys!).

Typically, cats learn how to hunt by watching their mothers. To teach her kittens how it's done, a mother cat will bring back dead animals, and then, later, she’ll bring home injured prey that her kittens can kill on their own. Eventually, when her kittens are big enough, she’ll take them out to hunt with her.

But even without maternal interaction—in cases where the mother cat dies, or abandons her kittens—or when domesticated cats are spayed and don’t have kittens to care for, “these cats will still hunt and are very likely to bring the prey home to their human family,” Liff says. The behavior is hardwired into their systems.

So the next time you find a dead or dying mouse in your house, try to look at it this way: Your cat is trying to take care of you by providing you food and teaching you how to hunt. Isn’t that sweet? And if you find the grisly treats disgusting, the solution is simple: Keep your cats inside. The birds will thank you!

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Big Questions
Can You Really Go Blind Staring at a Solar Eclipse?
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A total solar eclipse will cut a path of totality across the United States on August 21, and eclipse mania is gripping the country. Should the wide-eyed and unprotected hazard a peek at this rare phenomenon?

NASA doesn't advise it. The truth is, a quick glance at a solar eclipse won't leave you blind. But you're not doing your peepers any favors. As NASA explains, even when 99 percent of the sun's surface is covered, the 1 percent that sneaks out around the edges is enough to damage the rod and cone cells in your retinas. As this light and radiation flood into the eye, the retina becomes trapped in a sort of solar cooker that scorches its tissue. And because your retinas don't have any pain receptors, your eyes have no way of warning you to stop.

The good news for astronomy enthusiasts is that there are ways to safely view a solar eclipse. A pair of NASA-approved eclipse glasses will block the retina-frying rays, but sunglasses or any other kind of smoked lenses cannot. (The editors at MrEclipse.com, an eclipse watchers' fan site, put shades in the "eye suicide" category.) NASA also suggests watching the eclipse indirectly through a pinhole projector, or through binoculars or a telescope fitted with special solar filters.

While it's safe to take a quick, unfiltered peek at the sun in the brief totality of a total solar eclipse, doing so during the partial phases—when the Moon is not completely covering the Sun—is much riskier.

WOULDN'T IT BE EASIER TO JUST TELL YOUR KIDS THEY WILL GO BLIND?

NASA's website tackled this question. Their short answer: that could ruin their lives.

"A student who heeds warnings from teachers and other authorities not to view the eclipse because of the danger to vision, and learns later that other students did see it safely, may feel cheated out of the experience. Having now learned that the authority figure was wrong on one occasion, how is this student going to react when other health-related advice about drugs, alcohol, AIDS, or smoking is given[?]"

This story was originally published in 2012.

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Big Questions
If Beer and Bread Use Almost the Exact Same Ingredients, Why Isn't Bread Alcoholic?
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If beer and bread use almost the exact same ingredients (minus hops) why isn't bread alcoholic?

Josh Velson:

All yeast breads contain some amount of alcohol. Have you ever smelled a rising loaf of bread or, better yet, smelled the air underneath dough that has been covered while rising? It smells really boozy. And that sweet smell that fresh-baked bread has under the yeast and nutty Maillard reaction notes? Alcohol.

However, during the baking process, most of the alcohol in the dough evaporates into the atmosphere. This is basically the same thing that happens to much of the water in the dough as well. And it’s long been known that bread contains residual alcohol—up to 1.9 percent of it. In the 1920s, the American Chemical Society even had a set of experimenters report on it.

Anecdotally, I’ve also accidentally made really boozy bread by letting a white bread dough rise for too long. The end result was that not enough of the alcohol boiled off, and the darned thing tasted like alcohol. You can also taste alcohol in the doughy bits of underbaked white bread, which I categorically do not recommend you try making.

Putting on my industrial biochemistry hat here, many [people] claim that alcohol is only the product of a “starvation process” on yeast once they run out of oxygen. That’s wrong.

The most common brewers and bread yeasts, of the Saccharomyces genus (and some of the Brettanomyces genus, also used to produce beer), will produce alcohol in both a beer wort
and in bread dough immediately, regardless of aeration. This is actually a surprising result, as it runs counter to what is most efficient for the cell (and, incidentally, the simplistic version of yeast biology that is often taught to home brewers). The expectation would be that the cell would perform aerobic respiration (full conversion of sugar and oxygen to carbon dioxide and water) until oxygen runs out, and only then revert to alcoholic fermentation, which runs without oxygen but produces less energy.

Instead, if a Saccharomyces yeast finds itself in a high-sugar environment, regardless of the presence of air it will start producing ethanol, shunting sugar into the anaerobic respiration pathway while still running the aerobic process in parallel. This phenomenon is known as the Crabtree effect, and is speculated to be an adaptation to suppress competing organisms
in the high-sugar environment because ethanol has antiseptic properties that yeasts are tolerant to but competitors are not. It’s a quirk of Saccharomyces biology that you basically only learn about if you spent a long time doing way too much yeast cell culture … like me.

This post originally appeared on Quora. Click here to view.

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