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How Many Germs Are in a Kiss?

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Your mouth is home to 700 different kinds of bacteria, and you may have wondered just how many germs you’re getting—or giving!—when you swap spit with someone else. A new study, just published in the journal Microbiome, provides the answer (germaphobes, you might want to look away now): In a 10 second kiss, an average of 80 million bacteria are transferred.

Researchers from the Amsterdam-based Micropia Museum and TNO Microbiology and Systems Biology in the Netherlands focused on intimate kissing, “involving full tongue contact and saliva exchange … unique to humankind and common in over 90 percent of known cultures.” The scientists asked 21 couples, aged 17 to 45, who visited the Artis Royal Zoo in Amsterdam to fill out questionnaires—which included queries on the last time they ate, time passed since their last kiss, and how often they engaged in intimate kissing—then had them spit into a tube and swabbed tongues with cotton to analyze what bacteria were already on their tongues and in their saliva. They found that couples had similar bacteria in their saliva and on their tongues, possibly due to shared habits (like smoking), diets, and even toothpaste.

To figure out just how many bacteria make the jump during a kiss, they asked one person from each couple to drink a probiotic liquid that contained specific varieties of Lactobacillus and Bifidobacteria which, according to the researchers, make up 0.15 percent of the bacteria in saliva and 0.01 percent of the bacteria on the tongue on average. After the couple made out, they repeated the spit-and-swab routine; when the researchers analyzed the samples, they found that the quantity of the probiotic bacteria was .54 percent in the receiver’s saliva and .49 percent on the tongue. (Additionally, Remco Kort, lead researcher and microbiologist at the Netherlands Organisation for Applied Scientific Research in Amsterdam, told CBS that “significant difference in height between French-kissing partners can result in a greater exchange of saliva—downward—to the shorter participant.”)

The researchers also found that couples who shared at least nine intimate kisses a day were also more likely to have similar microbes in their saliva—but that they weren’t likely to stick around in the absence of French kissing. “Our findings suggest that the shared microbiota among partners is able to proliferate in the oral cavity,” they write in the study, “but the collective bacteria in the saliva are only transiently present and eventually washed out, while those on the tongue’s surface found a true niche, allowing long-term colonization.”

A steamy tongue kiss might transfer 80 million bacteria, but according to a “Kiss-O-Meter” installed at the Micropia Museum, only 1000 bacteria are transferred by a quick smooch. Pucker up!

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Do 'Close Door' Buttons in Elevators Actually Do Anything?
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When you’re running late for work, one small comfort is finding an empty elevator waiting for you at your office building. You scurry inside, and since no one else is waiting to enter, you jab the 'close door' button. The doors comply, the elevator starts moving, and you breathe a sigh of relief.

This is a familiar scenario for many, but it’s also a big fat lie. That’s because most of the door-close buttons in U.S. elevators don’t actually work. In fact, they’re programmed that way.

But before you get ready to send off a strongly worded email to your office building’s elevator manufacturer, you may want to hear why this is the case. When the Americans With Disabilities Act was first passed in 1990, certain requirements for elevators were outlined, such as the installation of raised buttons, braille signs, and audible signals.

The act ensured that someone with a disability would have enough time to get inside, stipulating that elevator doors must remain fully open for at least three seconds and thereby preventing the button from cutting that time short. Some elevator manufacturers took it one step further by deactivating the button entirely.

Since the life span of an elevator is about 25 years and the Disabilities Act has been around for 28 years, it’s safe to assume that most of the elevators in operation today do not have a functioning 'close door' button, The New York Times reports. Only firefighters are able to close elevator doors manually through the use of a key.

It's important to note that there are exceptions to this rule, though. As the New York Daily News noted, New York City elevators are required by law to have working 'close door' buttons, even though some operate on a long delay (so long, in fact, that it calls the button's usefulness into question).

However, you’re in luck if you’re taking a lift (which, of course, is British for “elevator”). 'Close door' buttons are fully functional in most elevators in the UK, according to The Telegraph. A spokesman for the Lift and Escalator Industry Association told the newspaper that not all elevators have the button, but when they’re present, they do work. Again, the time it takes for the doors to shut after pressing the button varies from lift to lift.

While U.S. elevator manufacturers have a seemingly good reason for disabling the 'close door' button, some may question the point of propagating the myth and installing a button that serves no purpose in the first place. In response, some would argue that placebo buttons serve an important psychological function in society.

"Perceived control is very important," Harvard psychologist Ellen J. Langer told The New York Times. "It diminishes stress and promotes well-being."

That’s right: By believing that you’re in control of your fate—or at least how quickly you can make it up to the sixth floor—you’re better off. It doesn’t end with elevators, either. Buttons placed at city crosswalks are often disabled, and the thermostats in many office buildings are rigged so that the temperature can’t be altered (even if the numbers appear to change).

Some might swear up and down that elevator 'close door' buttons work, but this, too, could be your brain deceiving you. As author David McRaney wrote in an essay: “If you happen to find yourself pressing a nonfunctional close-door button, and later the doors close, you’ll probably never notice because a little spurt of happiness will cascade through your brain once you see what you believe is a response to your action. Your behavior was just reinforced. You will keep pressing the button in the future.”

According to The New Yorker, these buttons are designed to alleviate some of the subconscious anxiety that comes from stepping inside a tiny box that's hoisted up some 20 or 40 or 80 floors by a cable: “Elevator design is rooted in deception—to disguise not only the bare fact of the box hanging by ropes but also the tethering of tenants to a system over which they have no command."

So now you know: Next time you’re running late to work, take comfort in the fact that those few extra seconds you would’ve saved by pressing a functioning 'close door' button aren’t worth all that much in the long run.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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What’s the Difference Between Prison and Jail?
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Many people use the terms jail and prison interchangeably, and while both terms refer to areas where people are held, there's a substantial difference between the two methods of incarceration. Where a person who is accused of a crime is held, and for how long, is a factor in determining the difference between the two—and whether a person is held in a jail or a prison is largely determined by the severity of the crime they have committed.

A jail (or, for our British friends, a gaol) refers to a small, temporary holding facility—run by local governments and supervised by county sheriff departments—that is designed to detain recently arrested people who have committed a minor offense or misdemeanor. A person can also be held in jail for an extended period of time if the sentence for their offense is less than a year. There are currently 3163 local jail facilities in the United States.

A jail is different from the similarly temporary “lockup”—sort of like “pre-jail”—which is located in local police departments and holds offenders unable to post bail, people arrested for public drunkenness who are kept until they are sober, or, most importantly, offenders waiting to be processed into the jail system.

A prison, on the other hand, is usually a large state- or federal-run facility meant to house people convicted of a serious crime or felony, and whose sentences for those crimes surpass 365 days. A prison could also be called a “penitentiary,” among other names.

To be put in a state prison, a person must be convicted of breaking a state law. To be put in a federal prison, a person must be convicted of breaking federal law. Basic amenities in a prison are more extensive than in a jail because, obviously, an inmate is likely to spend more than a year of his or her life confined inside a prison. As of 2012, there were 4575 operating prisons in the U.S.—the most in the world. The country with the second highest number of operating prisons is Russia, which has just 1029 facilities.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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