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6 Fascinating Facts About Oxytocin, the "Love Hormone"

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The hormone oxytocin is often referred to as the “love hormone” or the “bonding hormone” because of its observed effects on our relationships. It's released by the hypothalamus during physical intimacy, and during breastfeeding to facilitate mother-child bonding. It also helps us trust one another—as Irina Conboy, associate professor of bioengineering at UC Berkeley, puts it, “this is the hormone that makes your heart melt when you see kittens, puppies and human babies.” But it’s not that straightforward, and many of oxytocin’s effects seem to contradict the presumption that it turns us into blubbering piles of love. Here, a look at some of the many things this molecule can do.

1. It helps turn off fear.

Earlier this month, researchers at the University of Bonn Hospital discovered that oxytocin inhibits the brain’s fear center. In the study, scientists induced fear in subjects by showing them a series of images, 70 percent of which were accompanied by a small electric shock to the hand. Half the subjects then received an oxytocin nasal spray and were shown the same images again, but without the electric shock. Those treated with oxytocin were less afraid of the shock, and the areas of their brains associated with fear were less active. The finding suggests oxytocin could be used to treat anxiety disorders in the future.

2. It may be the cause of your mommy issues.

Oxytocin has been shown to influence how men remember their mother’s affection toward them as children. While under the influence of the hormone, men with strong attachments and happy memories of their mother had these memories heightened, and recalled being closer to her as a kid. This was to be expected, but researchers were surprised to find oxytocin did not enhance positive memories for men who were less attached to their mothers. Instead, the hormone brought bad memories to the forefront, causing men to remember their mothers as less caring. "The fact that oxytocin did not make all participants remember their mother as more caring, but in fact intensified the positivity or negativity of the men's pre-existing memories, suggests that oxytocin plays a more specific role in these attachment representations,” says researcher Jennifer Bartz, Assistant Professor of Psychiatry at Mount Sinai School of Medicine.

3. It makes us cheaters and liars

In one study, participants were asked to predict the outcome of a coin toss and self-report their accuracy. Correct guesses resulted in money, which would be split between team members. Predictably, a financial reward encouraged participants to lie about their success rate. But a dose of oxytocin made them lie even more, and without hesitation. “This is the best evidence yet that oxytocin is not the ‘moral molecule,’” said Carsten de Dreu from the University of Amsterdam, who co-led the study.

4. It makes your dog like you more.

Humans aren’t the only animals affected by oxytocin. One study suggests the hormone makes dogs more friendly toward their owners. Researchers administered oxytocin to 16 adult dogs of different breeds and watched their behavior, paying specific attention to “bonding” behavior like sniffing, nudging, licking, and playing. "We found that after receiving the oxytocin spray, dogs displayed more affiliative behaviors and paid more attention to their owners than during the controls," said the study’s lead author Teresa Romero. The substance may someday be useful in helping abused dogs trust their new, loving owners.

5. It helps heal age-related ailments.

As mice age, the amount of oxytocin in their blood decreases. But what does that mean for their health? Researchers injected oxytocin under the skin of elderly mice with damaged muscles and discovered the muscles healed much faster than those of mice left untreated. “The action of oxytocin was fast,” said Christian Elabd, the study’s co-author. “The repair of muscle in the old mice was at about 80 percent of what we saw in the young mice.” Researchers aren’t sure yet when oxytocin levels drop in humans, or by how much, but they hope it could be used to treat some of our age-related ailments. “Aging is a natural process,” said Irina Conboy, associate professor of bioengineering at UC Berkeley, “but I believe that we can meaningfully intervene with age-imposed organ degeneration, thereby slowing down the rate at which we become progressively unhealthy.”

6. It could help treat eating disorders.

In one study, researchers found that oxytocin nasal spray helped patients suffering from anorexia stop obsessing over things like food and body image. “Oxytocin reduces patients' unconscious tendencies to focus on food, body shape,” said Professor Youl-Ri Kim from Inje University in Seoul, South Korea. This “hints at the advent of a novel, ground-breaking treatment option for patients with anorexia."

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The Surprising Reason Why Pen Caps Have Tiny Holes at the Top
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If you’re an avid pen chewer, or even just a diehard fan of writing by hand, you’re probably well acquainted with the small hole that tops off most ballpoint pen caps, particularly those classic Bic Cristal pens. The reason it’s there has nothing to do with pen function, it turns out. As Science Alert recently reported, it’s actually designed to counter human carelessness.

Though it’s arguably unwise—not to mention unhygienic—to chomp or suck on a plastic pen cap all day, plenty of people do it, especially kids. And inevitably, that means some people end up swallowing their pen caps. Companies like Bic know this well—so they make pen caps that won’t impede breathing if they’re accidentally swallowed.

This isn’t only a Bic requirement, though the company’s Cristal pens do have particularly obvious holes. The International Organization for Standardization, a federation that sets industrial standards for 161 countries, requires it. ISO 11540 specifies that if pens must have caps, they should be designed to reduce the risk of asphyxiation if they’re swallowed.

It applies to writing instruments “which in normal or foreseeable circumstances are likely to be used by children up to the age of 14 years.” Fancy fountain pens and other writing instruments that are clearly designed for adult use don’t need to have holes in them, nor do caps that are large enough that you can’t swallow them. Any pen that could conceivably make its way into the hands of a child needs to have an air hole in the cap that provides a minimum flow of 8 liters (about 2 gallons) of air per minute, according to the standard [PDF].

Pen cap inhalation is a real danger, albeit a rare one, especially for primary school kids. A 2012 study [PDF] reported that pen caps account for somewhere between 3 and 8 percent of “foreign body aspiration,” the official term for inhaling something you’re not supposed to. Another study found that of 1280 kids (ages 6 to 14) treated between 1997 and 2007 for foreign body inhalation in Beijing, 34 had inhaled pen caps.

But the standards help keep kids alive. In that Beijing study, none of the 34 kids died, and the caps were successfully removed by doctors. That wasn’t always the case. In the UK, nine children asphyxiated due to swallowing pen caps between 1970 and 1984. After the UK adopted the international standard for air holes in pen caps, the number of deaths dropped precipitously [PDF]. Unfortunately, it’s not foolproof; in 2007, a 13-year-old in the UK died after accidentally swallowing his pen cap.

Even if you can still breathe through that little air hole, getting a smooth plastic pen cap out of your throat is no easy task for doctors. The graspers they normally use to take foreign bodies out of airways don’t always work, as that 2012 case report found, and hospitals sometimes have to employ different tools to get the stubbornly slippery caps out (in that study, they used a catheter that could work through the hole in the cap, then inflated a small balloon at the end of the catheter to pull the cap out). The procedure doesn’t exactly sound pleasant. So maybe resist the urge to put your pen cap in your mouth.

[h/t Science Alert]

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Big Questions
What Causes Sinkholes?
Mark Ralston/AFP/Getty Images
Mark Ralston/AFP/Getty Images

This week, a sinkhole opened up on the White House lawn—likely the result of excess rainfall on the "legitimate swamp" surrounding the storied building, a geologist told The New York Times. While the event had some suggesting we call for Buffy's help, sinkholes are pretty common. In the past few days alone, cavernous maws in the earth have appeared in Maryland, North Carolina, Tennessee, and of course Florida, home to more sinkholes than any other state.

Sinkholes have gulped down suburban homes, cars, and entire fields in the past. How does the ground just open up like that?

Sinkholes are a simple matter of cause and effect. Urban sinkholes may be directly traced to underground water main breaks or collapsed sewer pipelines, into which city sidewalks crumple in the absence of any structural support. In more rural areas, such catastrophes might be attributed to abandoned mine shafts or salt caverns that can't take the weight anymore. These types of sinkholes are heavily influenced by human action, but most sinkholes are unpredictable, inevitable natural occurrences.

Florida is so prone to sinkholes because it has the misfortune of being built upon a foundation of limestone—solid rock, but the kind that is easily dissolved by acidic rain or groundwater. The karst process, in which the mildly acidic water wears away at fractures in the limestone, leaves empty space where there used to be stone, and even the residue is washed away. Any loose soil, grass, or—for example—luxury condominiums perched atop the hole in the ground aren't left with much support. Just as a house built on a weak foundation is more likely to collapse, the same is true of the ground itself. Gravity eventually takes its toll, aided by natural erosion, and so the hole begins to sink.

About 10 percent of the world's landscape is composed of karst regions. Despite being common, sinkholes' unforeseeable nature serves as proof that the ground beneath our feet may not be as solid as we think.

A version of this story originally ran in 2014.

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