The Volunteers in This Extreme 1965 Isolation Study Lost Track of Entire Weeks

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In 1965, scientists wanted to study the psychological and physiological effects of isolation on humans, so they found two volunteers—a midwife named Josie Laures and a furniture maker named Antoine Senni—and left them alone in two separate caves in the French Alps for several months.

When Laures finally emerged from isolation 88 days later, after setting a world record, she thought it was February 25. It was March 12.

When Senni emerged after his record-setting 126 days, he thought it was February 4. It was April 5. 

After months in complete isolation, and without any sunlight to indicate time of day, both cave dwellers had lost track of entire weeks. Though scientists reported that both volunteers were physically and mentally healthy, their sleep patterns, and perceptions of time, were altered drastically during their time in the caves. 

In their recent story on the cave dwellers, The Atlantic explains, “Absent any cues from sunlight or even from clocks, Laures’s and Senni’s sleep schedules got wacky—sometimes without them realizing it.” Senna, for instance, would sometimes fall asleep for 30 hours at a time, and wake up thinking he’d just had a short nap. Scientists later discovered that, isolated from temporal cues, humans tend to slip into 48-hour sleep cycles—making it even harder to keep track of time.

Though both volunteers survived their ordeal, they admitted it wasn’t a particularly fun time. After emerging from her cave, Laures told the Associated Press

I am so happy to have lasted it out, that I have forgotten everything. I can tell you though that it became very difficult toward the end and I felt terribly worn out … At the start of my stay I read, and then I lost the desire. I didn't suffer from the cold. I was well heated in my little tent. My tape recorder refused to work the first few days, but later I managed to repair it and I listened to music. Outside of that I knitted, and knitted some more, and looked forward to the time when I would finally see the sun.

Check out the full story at The Atlantic to learn more about Laures and Senni's surreal experience.

[h/t: The Atlantic]

England Is Being Invaded By a Swarm of Flying Ants That Can Be Seen From Space

Digoarpi/iStock via Getty Images
Digoarpi/iStock via Getty Images

Last week, the UK's weather service registered what seemed like a system of rain showers moving along the nation’s southern coast. But it wasn’t rain—it was a swarm of flying ants.

Though it sounds like something out of a horror film or the Old Testament, it’s actually a completely normal phenomenon that occurs in the UK every summer when a bout of hot, humid weather follows a period of rainfall, The Guardian reports. Flying ants decide it’s a good time to mate, and the queen takes to the sky, emitting pheromones that attract males.

From there, it’s survival of the fittest. The queen will out-fly most of her suitors, leaving only the strongest males to catch up and mate with her, which ensures the strength of her offspring. The others either lose their wings and fall to the ground, or become bird food. (The ants produce formic acid in their bodies as a defense mechanism, which may make gulls that eat them seem loopy.)

According to Smithsonian.com, the queen will chew off her wings after mating and fall to the ground to start a new colony, and the sperm she collected from that one flight will fertilize her eggs for the rest of her life (which could be up to 15 years in the wild).

The official, rather-romantic term for the annual aerial antics is “nuptial flight,” but locals often refer to it simply as “flying ant day.” It sometimes lasts for weeks, during which billions of the harmless insects can be seen in the skies.

A representative from the Met Office explained that its weather satellites mistook the ants for rain clouds because the radar detects the ants in the same way it sees raindrops. Dr. Adam Hart, an entomologist at the University of Gloucestershire, told The Guardian that he thinks the reason the radar registered the ants this year was a result of better satellite technology rather than an increase in the flying ant population.

[h/t Smithsonian.com]

Why Does Humidity Make Us Feel Hotter?

Tomwang112/iStock via Getty Images
Tomwang112/iStock via Getty Images

With temperatures spiking around the country, we thought it might be a good time to answer some questions about the heat index—and why humidity makes us feel hotter.

Why does humidity make us feel hotter?

To answer that question, we need to talk about getting sweaty.

As you probably remember from your high school biology class, one of the ways our bodies cool themselves is by sweating. The sweat then evaporates from our skin, and it carries heat away from the body as it leaves.

Humidity throws a wrench in that system of evaporative cooling, though. As relative humidity increases, the evaporation of sweat from our skin slows down. Instead, the sweat just drips off of us, which leaves us with all of the stinkiness and none of the cooling effect. Thus, when the humidity spikes, our bodies effectively lose a key tool that could normally be used to cool us down.

What's relative about relative humidity?

We all know that humidity refers to the amount of water contained in the air. However, as the air’s temperature changes, so does the amount of water the air can hold. (Air can hold more water vapor as the temperature heats up.) Relative humidity compares the actual humidity to the maximum amount of water vapor the air can hold at any given temperature.

Whose idea was the heat index?

While the notion of humidity making days feel warmer is painfully apparent to anyone who has ever been outside on a soupy day, our current system owes a big debt to Robert G. Steadman, an academic textile researcher. In a 1979 research paper called, “An Assessment of Sultriness, Parts I and II,” Steadman laid out the basic factors that would affect how hot a person felt under a given set of conditions, and meteorologists soon used his work to derive a simplified formula for calculating heat index.

The formula is long and cumbersome, but luckily it can be transformed into easy-to-read charts. Today your local meteorologist just needs to know the air temperature and the relative humidity, and the chart will tell him or her the rest.

Is the heat index calculation the same for everyone?

Not quite, but it’s close. Steadman’s original research was founded on the idea of a “typical” person who was outdoors under a very precise set of conditions. Specifically, Steadman’s everyman was 5’7” tall, weighed 147 pounds, wore long pants and a short-sleeved shirt, and was walking at just over three miles per hour into a slight breeze in the shade. Any deviations from these conditions will affect how the heat/humidity combo feels to a certain person.

What difference does being in the shade make?

Quite a big one. All of the National Weather Service’s charts for calculating the heat index make the reasonable assumption that folks will look for shade when it’s oppressively hot and muggy out. Direct sunlight can add up to 15 degrees to the calculated heat index.

How does wind affect how dangerous the heat is?

Normally, when we think of wind on a hot day, we think of a nice, cooling breeze. That’s the normal state of affairs, but when the weather is really, really hot—think high-90s hot—a dry wind actually heats us up. When it’s that hot out, wind actually draws sweat away from our bodies before it can evaporate to help cool us down. Thanks to this effect, what might have been a cool breeze acts more like a convection oven.

When should I start worrying about high heat index readings?

The National Weather Service has a handy four-tiered system to tell you how dire the heat situation is. At the most severe level, when the heat index is over 130, that's classified as "Extreme Danger" and the risk of heat stroke is highly likely with continued exposure. Things get less scary as you move down the ladder, but even on "Danger" days, when the heat index ranges from 105 to 130, you probably don’t want to be outside. According to the service, that’s when prolonged exposure and/or physical activity make sunstroke, heat cramps, and heat exhaustion likely, while heat stroke is possible.

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

This article has been updated for 2019.

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