Frequent Sighing Helps Keep You Alive

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iStock

Good news for hopeless romantics and the perpetually dismayed: All that sighing is good for you. In fact, you’d die without it. Scientists have now pinpointed the region in the brain that transforms normal breathing into a life-giving sigh. They published their findings this week in the journal Nature.

Let’s start with the mechanics. Physiologically speaking, sighing is a way of keeping your lungs inflated. “A sigh is a deep breath, but not a voluntary deep breath,” study co-author Jack Feldman said in a press release. “It starts out as a normal breath, but before you exhale, you take a second breath on top of it.” Whether you realize it or not, you do this about 12 times an hour, and even more than that when you’re stressed or anxious. And it’s a good thing you do. “If you don’t sigh every five minutes of so, the alveoli will slowly collapse, causing lung failure,” Feldman said. “That’s why patients in early iron lungs had such problems, because they never sighed.” The machines had not been programmed to give patients regular deep, lung-filling breaths.

One group of researchers sifted through nearly 19,000 gene expression patterns in the active brains of mice, looking for the root of the sigh reflex. It was much smaller than they expected: just one little bundle of 200 cells in the brain stem, releasing one of two molecules called peptides. They shared their data with Feldman’s lab, and together the team found another set of 200 cells on the peptide receiving end.

A mouse's sigh clusters. Image credit: Stanford/Krasnow Lab

When the scientists prevented one peptide from reaching its goal, the rate of the mice’s sighing was cut in half. Blocking both peptides caused the mice to stop sighing altogether. “Unlike a pacemaker that regulates only how fast we breathe, the brain’s breathing center also controls the type of breath we take,” co-author Mark Krasnow noted in the press release. “It’s made up of small numbers of different kinds of neurons. Each functions like a button that turns on a different type of breath. One button programs regular breaths, another sighs, and the others could be for yawns, sniffs, coughs, and maybe even laughs and cries.”

It’s highly unusual for such small clusters of neurons to have so much power, Feldman said. “Sighing appears to be regulated by the fewest number of neurons we have seen linked to a fundamental human behavior.” The team’s findings may someday lead to treatment for people with diseases that limit their breathing. “These molecular pathways are critical regulators of sighing, and define the core of a sigh-control circuit,” Krasnow said. “It may now be possible to find drugs that target these pathways to control sighing.”

More Than Half of Wild Coffee Species Could Go Extinct

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iStock.com/Alfribeiro

Your morning cup of coffee is under threat. A study published today in Science Advances asserts that a majority of the world’s wild coffee species are at risk of extinction. The main two types we rely on for our caffeine fix—arabica and robusta beans—are both threatened by climate change and deforestation.

The team of UK-based researchers used Red List of Threatened Species criteria from the International Union for the Conservation of Nature to classify the risks facing the world’s 124 known species of wild coffee. About 60 percent of them—or 75 different species—face possible extinction in the coming decades. This represents “one of the highest levels recorded for a plant group,” researchers write in their paper.

Partly to blame are the severe droughts associated with climate change, as well as deforestation. Other threats include the spread of fungal pathogens and coffee wilt disease in Central and South America and Africa, respectively, as well as social and economic factors for growers.

“Considering threats from human encroachment and deforestation, some [coffee species] could be extinct in 10 to 20 years, particularly with the added influence of climate change," lead author Aaron P. Davis, of the Royal Botanic Gardens, Kew, tells CNN.

Davis’s previous research stressed that arabica, which is already listed as an endangered species, could be extinct within 60 years. Most of the coffee plants we rely on are farmed, but wild coffee is no less important. Some wild species are resistant to disease and have other useful genes that could be introduced to commercial crops. That way, the cultivated varieties might endure the effects of climate change better and stick around a little longer.

Consumers aren’t the only ones concerned, either. Coffee farming is an industry that supports about 100 million workers around the world. One way of conserving the plants is to store their seeds and genes, but Hanna Neuschwander, the director of communications for the industry group World Coffee Research, tells Mashable that these seed banks aren’t well established yet. For now, the focus is on preserving the plants themselves.

12 Facts About the Sense of Taste

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iStock/m-imagephotography

A lot more than your tongue is involved in the process of tasting food. Taste is not only one of the most pleasurable of the five senses, but a surprisingly complex sense that science is beginning to understand—and manipulate. Here are 12 fascinating facts about your ability to taste.

1. Everyone has a different number of taste buds.

We all have several thousand taste buds in our mouths, but the number varies from person to person. The average range is between 2000 and 10,000. And taste buds are not limited to your tongue; They can be found in the roof and walls of your mouth, throat, and esophagus. As you age, your taste buds become less sensitive, which experts believe may be why foods that you don’t like as a child become palatable to you as an adult.

2. You taste with your brain.

The moment you bite into a slice of pie, your mouth seems full of flavor. But most of that taste sensation is happening in your brain. More accurately, cranial nerves and taste bud receptors in your mouth send molecules of your food to olfactory nerve endings in the roof of your nose. The molecules bind to these nerve endings, which then signal the olfactory bulb to send smell messages directly to two important cranial nerves, the facial nerve and the glossopharyngeal nerve, which communicate with a part of the brain known as the gustatory cortex.

As taste and nerve messages move further through the brain, they join up with smell messages to give the sensation of flavor, which feels as if it comes from the mouth.

3. You can’t taste well if you can’t smell.

When you smell something through your nostrils, the brain registers these sensations as coming from the nose, while smells perceived through the back of the throat activate parts of the brain associated with signals from the mouth. Since much of taste is odor traveling to olfactory receptors in your brain, it makes sense that you won’t taste much at all if you can’t smell. If you are unable to smell for reasons that include head colds, smoking cigarettes, side effects of medications, or a broken nose, olfactory receptors may either be too damaged, blocked, or inflamed to send their signals on up to your brain.

4. Eating sweet foods helps form a memory of a meal.

Eating sweet foods causes your brain to remember the meal, according to a 2015 study in the journal Hippocampus, and researchers believe it can actually help you control eating behavior. Neurons in the dorsal hippocampus, the part of the brain central to episodic memory, are activated when you eat sweets. Episodic memory is that kind that helps you recall what you experienced at a particular time and place. "We think that episodic memory can be used to control eating behavior," said study co-author Marise Parent, of the Neuroscience Institute at Georgia State. "We make decisions like 'I probably won't eat now. I had a big breakfast.' We make decisions based on our memory of what and when we ate."

5. Scientists can turn tastes on and off by manipulating brain cells.

Dedicated taste receptors in the brain have been found for each of the five basic tastes: sweet, sour, salty, bitter, and umami (savory). In 2015, scientists outlined in the journal Nature how they were able to turn specific tastes on or off in mice, without introducing food, by stimulating and silencing neurons in the brains. For instance, when they stimulated neurons associated with “bitter,” mice made puckering expressions, and could still taste sweet, and vice versa.

6. You can tweak your taste buds.

Most of us have had the experience of drinking perfectly good orange juice after brushing our teeth, only to have it taste more like unsweetened lemon juice. Taste buds, it turns out, are sensitive enough that certain compounds in foods and medicines can alter our ability to perceive one of the five common tastes. The foaming agent sodium lauryl/laureth sulfate in most toothpaste seems to temporarily suppress sweetness receptors. This isn't so unusual. A compound called cynarin in artichokes temporarily blocks your sweet receptors. Then, when you drink water, the cynarin is washed away, making your sweet receptors “wake up” so the water tastes sweet. A compound called miraculin, found in the herb Gymnema sylvestre, toys with your sweet receptors in a similar way.

7. The smell of ham can make your food “taste” saltier.

There’s an entire industry that concocts the tastes of the food you buy at the grocery store. Working with phenomena known as phantom aromas or aroma-taste interactions, scientists found that people associate “ham” with salt. So simply adding a subtle ham-like scent or flavor to a food can make your brain perceive it as saltier than it actually is. The same concept applies to the scent of vanilla, which people perceive as sweet.

8. Your taste buds prefer savory when you fly.

A study by Cornell University food scientists found that loud, noisy environments, such as when you’re traveling on an airplane, compromise your sense of taste. The study found that people traveling on airplanes had suppressed sweet receptors and enhanced umami receptors. The German airline Lufthansa confirmed that on flights, passengers ordered nearly as much tomato juice as beer. The study opens the door to new questions about how taste is influenced by more than our own internal circuitry, including our interactions with our environments.

9. Picky eaters may be “supertasters.”

If you’re a picky eater, you may have a new excuse for your extreme dislike of eggplant or sensitivity to the slightest hint of onion. You might be a supertaster—one of 25 percent of people who have extra papillae in your tongue. That means you have a greater number of taste buds, and thus more specific taste receptors.

10. Some of your taste preferences are genetic.

While genetics may not fully explain your love of the KFC Double Down or lobster ice cream, there may be code written into your DNA that accounts for your preference for sweet foods or your aversion to certain flavors. The first discovery of a genetic underpinning to taste came in 1931, when chemist Arthur Fox was working with powdered PTC (phenylthiocarbamide), and some of the compound blew into the air. One colleague found it to have a bitter taste, while Fox did not perceive that. They conducted an experiment among friends and family and found wide variation in how (and whether) people perceived the flavor of the PTC to be bitter or tasteless. Geneticists later discovered that the perception of PTC flavor (similar to naturally occurring compounds) is based in a single gene, TAS2R38, that codes for a taste receptor on the tongue. In a 2005 study, researchers at the Monell Chemical Senses Center found that the version of this gene also predicted a child's preference for sweet foods.

11. Your genes influence whether you think cilantro tastes like soap.

There may be no flavor more hotly debated or deeply loathed than the herb cilantro (also known as coriander). Entire websites, like IHateCilantro.com, complain about its “soapy” or “perfumy” flavor, while those who like it simply think it gives a nice kick to their salsa. Researchers at the consumer genetics company 23andMe identified two common genetic variants linked to people's “soap” perceptions. A follow-up study in a separate subset of customers confirmed the associations. The most compelling variant can be found within a cluster of olfactory receptor genes, which influence our sense of smell. One of those genes, OR6A2, encodes a receptor that is highly sensitive to aldehyde chemicals, which cilantro contains.

12. Sugar cravings have a biological basis.

Your urge for more hot fudge may have little to do with a lack of self-control. Scientists think that our yearning for sweets is a biological preference that may have been designed to ensure our survival. The liking for sweet tastes in our ancient evolution may have ensured the acceptance of sweet-tasting foods, such as breast milk and vitamin-rich fruits. Moreover, recent research suggests that we crave sweets for their pain-reducing properties.

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