The Great Smoky Mountains' Incredible Firefly Light Show

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Today, the rare Smoky Mountain fireflies are a tourist attraction. Twenty years ago, science didn’t believe they existed.  

At exactly 9:27 P.M., when dusk slips into darkness in the Great Smoky Mountains National Park, the “light show” begins. It’s June, and for two weeks in Elkmont, Tennessee, the fireflies pool their efforts. Instead of scattershot blips of light in the summer sky, the fireflies—thousands of them—pulse this way for hours, together in eerie, quiet harmony. It’s as if the trees were strung up with Christmas lights: bright for three seconds, dark for six, and then bright again, over and over. It continues this way for hours.

As a child, Lynn Faust would huddle with her family on the cabin porch to watch the spectacle. They’d sit, mesmerized by the “drumbeat with no sound.” And though they’d appreciated the show for generations, Faust never thought the event was newsworthy. “I’d assumed there was only one kind of firefly and thought they did a nice show in the Smokies,” she says.

The natural world has long enchanted Faust. In college, she majored in forensic anthropology and minored in forestry. In her twenties, she circumnavigated the globe for three years, visiting islands you could only get to by boat, learning about cultures before they disappeared, pursuing underwater photography. Today, at 60, she’s a naturalist who writes scientific papers and field guides about fireflies. But she wasn’t always obsessed with the insect. In fact, her academic interest began only in the ’90s, when she read an article by Steven Strogatz, a Cornell mathematician, in which he marveled at a species of Southeast Asian firefly that synchronized its flashes. Highlighting how rare this phenomenon was, Strogatz noted that there were no synchronous fireflies in the Western Hemisphere.

This struck Faust as odd. It contradicted the light shows she had seen growing up. As she dug deeper, Faust found that while there had been more than 100 years of colloquial accounts of North American fireflies flashing in sync, scientists discounted those reports, attributing them to lore or optical illusion. Faust knew the truth: that her Tennessse fireflies were every bit as special as the species in Asia. But how could she prove it?

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Fireflies—or lightning bugs—may be the closest thing nature has to a magic trick: lighting the world from the inside out. Technically, they are bioluminescent beetles. Their glow comes from an internal chemical reaction that combines oxygen and calcium with a series of enzymes, including a key light-producing one called luciferin. The bugs flash for lots of reasons: to communicate, to attract mates, to scare off predators. But for creatures so striking, they’re also common. There are roughly 2,000 species worldwide and 125 or more in North America alone, where catching them is a childhood rite of passage.

More than 20 years ago, Faust wrote a letter to Strogatz after reading his article. He connected her with Jonathan Copeland, a biologist and professor at Georgia Southern University who was studying firefly behavior in Malaysia and Indonesia. Copeland was skeptical of Faust’s tale. Reports of synchrony had crossed his desk before but had never panned out. “The dogma said they do not synchronize in North America,” he says.

Still, he indulged Faust, asking her to describe what she’d witnessed by drawing a “musical score.” As a child, Copeland, a tuba player, dreamed of playing with the Boston Symphony. Ever since, music dominated his approach to the natural world. In grad school, he’d studied and documented the rhythmic lunge and strike patterns of praying mantises. He took a similar slant on firefly behavior and found that if people charted the synchronic rhythms they were witnessing, he could separate a bogus account from a real one. Putting pencil to paper, Faust was nervous. “To look at it scientifically is very different from sitting in your rocking chair with a blanket and enjoying it,” she says. “I didn’t want to sound like a complete idiot.”

When her note arrived, “it looked like synchrony on paper,” says Copeland. In June 1993, he was intrigued enough to make the eight-hour drive to Elkmont. He pulled into the cabin’s driveway as dusk fell, no trace of the insects to be seen, and promptly fell asleep—only to wake up to flashes of light all around him. “It was completely obvious—no doubt about it!” he remembers. He rushed to find a pay phone to call his colleague Andy Moiseff. “It must have been about midnight,” he says. “I said, ‘Andy, Andy, you’ve got to see this, they’re flashing synchronously!’ Andy laughed and said, ‘Prove it,’ like any good scientist.” The following summer, that’s exactly what Copeland, Faust, and Moiseff, a professor of physiology at the University of Connecticut, set out to do. It was an unlikely partnership, but the trio made a formidable team. Copeland is a neuroethologist—he studies the neural basis for animal behavior. Faust, an unflappable outdoorswoman and keen observer, knows the area and its wildlife like home. And Moiseff is a computer whiz, with a proclivity for dreaming up theories and building devices to test them.

The three hauled lab equipment, microscopes, video cameras, computers, and insect specimens to sites throughout the Smokies. They started in Elkmont but quickly branched out to determine how widespread the phenomenon was. They hauled bugs back to the lab to do frame-by-frame analyses of the flashes. In the wild, “they were obviously in sync,” Copeland says. But when they repeated the test with individual fireflies in one-gallon freezer bags, the behavior changed. If an insect couldn’t see another, they no longer flashed synchronously. By 1995, the team had the data they needed.

“This was red-hot news in the firefly community,” says Copeland. There are four synchronous species of firefly known in Asia, and they are smaller than the team’s species, Photinus carolinus. “Their flash is wimpy in intensity, but what they lack in flash intensity, they make up in numbers,” Copeland says. They usually remain stationary in trees along the river, unlike carolinus, which fly around in the woods. “Ours are more complicated,” says Faust.

Proving synchrony existed in fireflies in the Western Hemisphere was exciting, but it raised questions about why they flashed this way. And how was that different from what their cohorts did in Asia or, for that matter, from the way their asynchronous relatives behaved in North America and even elsewhere in the park? For the next two decades, Copeland and Moiseff would study the fireflies with Faust each summer, determined to understand these magical creatures. But just as they were getting close, everything in Elkmont changed.

In the beginning, the team had the woods to themselves. “In the old days, there would be the three of us and the odd stranger who was fishing,” says Moiseff. In fact, when Faust first informed park officials about the light show, they didn’t believe her. In 1992, her family had to give up its cabin when the government took control of the resort community’s leases. By then, Faust had noticed that the firefly behavior seemed to be localized: The light show didn’t appear to be taking place even half a mile away from this settled location. She hypothesized that the synchronous behavior could be linked to the unusual conditions near the homes. But when she pointed it out, parks officials assumed her claims were a trumped-up attempt to keep her cabin.

Finally, in 1996, park administrators sent a ranger to the researchers’ campsite to investigate. “It was a funny night,” Faust recalls. “We had this ancient computer set up on the porch and Christmas lights strung across the hill to see if we could control the rhythm of the firefly flashes with the lights going off and on. He was like, ‘Where are they?’ And suddenly, there they were. The guy goes, ‘Oh, my God.’ He said that about six times,” says Faust. The next night they had 20 rangers watching.

By the early 2000s, word had spread. According to one of the park’s supervisory rangers, Kent Cave, “There were fender benders, road rage, crowds of people.” The Smoky Mountain fireflies had become a bona fide tourist attraction. In 2006, the park instituted a trolley service from a parking lot to the viewing area for peak nights, closing access to individual cars. “People were driving up. They might have driven five hours from Alabama or down from Lexington and couldn’t get in,” says Cave.

Today, tourists reserve parking spots in advance online. After the year’s peak firefly emergence has been predicted, reservations for the June viewings go live in late April. The spaces go in minutes. The light show has become the biggest of the park’s special events, with as many as 12,000 attendees in recent years. But as Cave puts it, “Our biggest headache is predicting when these little buggers are gonna flash.” There’s a system for that too. “The pressure of me telling people when to come see the fireflies began 20 years ago,” Faust says. “Like anything in nature, it’s not entirely predictable, but I’ve developed a mathematical way of figuring it out.”

Today, park entomologist Becky Nichols relies on Faust’s degree-day model to determine when the fireflies will emerge. The equation is specific to Photinus carolinus and relies on temperature data Faust and Nichols begin collecting in early March. “You take the high and the low temperatures and plug them into a formula to figure out the larvae’s accumulation of growth,” explains Nichols. “The issue in the past was that we didn’t have good temperature data.” Tiny temperature loggers fixed to trees for air temperature and to the ground for soil temperature have remedied that problem. Faust has her own data logger down the road as well, and the two women compare results as the numbers climb, hoping to come up with the same prediction independently.

Though they’re gratified that the public appreciates the light show, its popularity is bittersweet. The event is too crowded for the scientists to continue studying at the site, so they’ve decamped to other areas in the Appalachian Mountains. As Copeland says ruefully, “We can’t work there anymore because it’s a tourist attraction, and we’re largely responsible for that.”

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So why do Photinus carolinus flash together? No one has quite figured it out, Faust says. But there are theories. In a 2010 paper published in Science, Moiseff and Copeland suggest that synchrony keeps the female firefly from getting confused when searching for a mate. In an experiment using an electronic simulator with light-emitting diodes, they found that uncoordinated stimuli—too many lights coming from too many places at different times—inhibited the female firefly’s response. When flashes were coordinated, the females could clearly send their messages back to the males. Faust agree that synchrony in carolinus is related to mating.

Moiseff, who’s most interested in the firefly’s brain and nerve cells, wonders what it is about the insect’s eyes that helps it process information. Some data has shown that under the right circumstances, a firefly can determine where a flash is coming from. What this could suggest, he says, is that the insect’s brain might break information into different pathways for processing—something that primates and people do, but we don’t think of bugs doing. It’s a problem he’s still studying: “How does a simple nervous system accommodate that? What’s the mechanism?”

Moiseff also points out that Photinus’s synchrony is important not because the phenomenon is so rare but because it changes our perspective on the many ways in which living things interact. With just one proven case in the U.S., the gates opened wide for discovering others. In 1998, Copeland and Moiseff showed that a species on the Georgia and South Carolina coast, Photuris frontalis, was also synchronous. Additionally, the species Photinus pyralis, Copeland says, is “weakly synchronic.” Once you find other species doing this, “all of a sudden they’re not a freak of nature. Instead, they have a solution to a specific environmental need,” says Moiseff.

The last few years, Moiseff and Copeland have kept their firefly studies closer to home. “For the first 10 years, my spouse was very supportive,” says Copeland of his work in Tennessee. “Then she started asking questions about the significance.” He retires from his position at Georgia Southern this year, and, joking aside, considers identifying Photinus’s synchrony to be one of the highlights of his life. “I grew up as a suburban kid afraid of the dark, and I found myself [alone] in the woods with fireflies,” he says. “Serendipity—and a mind set that gets you away from cable TV—plays a role in science.”

Faust, for her part, is still involved with fireflies. She’s working on a field guide that will include images from her collection of more than 60,000 photos. And her family cabin still stands proudly in the same spot where she first saw the light show. But it isn’t quite the same. The cabin now belongs to the park, and she and her family no longer curl up on that porch under thick blankets, waiting for the pulsing spectacle to begin. One thing hasn’t changed, though: No matter how many times Faust has seen the show, Photinus carolinus’s return each summer is still a thrill. “The biggest kick is trying to predict the first night,” she says. “To see that first one and think, ‘Wow, that happened again.’”

This story originally appeared in an issue of mental_floss magazine. Subscribe here.

Chimpanzees Bond by Watching Movies Together, Too

Windzepher/iStock via Getty Images
Windzepher/iStock via Getty Images

Scientists at the Wolfgang Kohler Primate Research Center in Germany recently discovered that, like humans, chimpanzees bond when they watch movies together, the BBC reports.

In the study, published in Proceedings of the Royal Society B, researchers stationed pairs of chimpanzees in front of screens that showed a video of a family of chimps playing with a young chimp. They found that afterward, the chimps would spend more time grooming and interacting with each other—or simply being in the same part of the room—than they would without having watched the video.

They gave the chimps fruit juice to keep them calm and occupied while they viewed the video, and they chose a subject that chimps have previously proven to be most interested in: other chimps. They also used eye trackers to ensure the chimps were actually watching the video. If you’ve ever watched a movie with friends, you might notice similarities between the chimps’ experience and your own. Drinks (and snacks) also keep us calm and occupied while we watch, and we like to watch movies about other humans. Since this study only showed that chimps bond over programs about their own species, we don’t know if it would work the same way if they watched something completely unrelated to them, like humans do—say, The Lion King.

Bonding through shared experiences was thought to be one of the traits that make us uniquely human, and some researchers have argued that other species don’t have the psychological mechanisms to realize that they’re even sharing an experience with another. This study suggests that social activities for apes don’t just serve utilitarian purposes like traveling together for safety, and that they’re capable of a more human-like social closeness.

The part that is uniquely human about this study is the fact that they were studying the effect of a screen, as opposed to something less man-made. The chimps in question have participated in other studies, so they may be more accustomed to that technology than wild apes. But the study demonstrates that we’re not the only species capable of social interaction for the sake of social interaction.

[h/t BBC]

10 Facts You Should Know About Mosquitoes

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tskstock/iStock via Getty Images

Between the itching and the welts and the fears of mosquito-borne viruses, it's easy to forget that mosquitoes are a wonder of evolution, and that maybe they don't get a fair shake from us. Of more than 3000 known species, only 80 actually bite people, and at least one eats other mosquitoes for us. They grow from egg to adult in just five days, begin mating within minutes of hatching, and possess, by way of their stinging mouthparts, some of the coolest appendages in the animal kingdom.

1. Mosquitoes are excellent flyers in bad weather.

The average raindrop is 50 times heavier than the average mosquito, yet they buzz around in the rain with no problems. If a Boeing 747 got whacked with a similarly scaled-up raindrop, there would be 2375 tons of water coming down on it, and things probably wouldn’t turn out as well as they do for the mosquito. How do the insects do it?

A common urban legend said that the bugs were nimble enough to dodge the drops. A few years ago, a team of engineers from the Georgia Institute of Technology watched real mosquitoes and Styrofoam dummy mosquitoes with a high-speed camera during a rainy flight to see if that’s what was really happening. They found that the bugs don’t fly fast enough to dodge the drops, but their slowness is what keeps them from getting knocked out of the sky. A mosquito’s low mass even at slow speed doesn’t provide enough of a target for a raindrop to splash on collision. Instead, the drop just deforms, and doesn’t transfer enough momentum to the mosquito to disrupt its flight.

2. Texas is the mosquito capital of America.

Of the 3000 species of mosquitoes around the world, at least 150 are found in the United States, and 85 of those call Texas home. When people say everything's bigger in Texas, you can also include the biodiversity of the state's biting, disease-carrying insects.

3. Some mosquitoes are truly dangerous to humans ...

The female mosquito, which is the one that stings and sucks blood, is an incredible transmitter of disease and, because of that, the deadliest animal in the world. Each year, the malaria parasites they transmit kill 2 million to 3 million people and infect another 200 million or more. They also spread pathogens that cause yellow fever, dengue fever, Rift Valley fever, Chikungunya and West Nile disease.

4. ... and some mosquitoes are harmless.

Not every species of mosquito sucks blood from people, and among those that do, not every one transmits disease. The blood suckers don’t even need to bite you for every meal. Males live entirely on nectar and other plant fluids, and the females’ diet is primarily plant-based, too. Most of the time, they only go after people when they’re ready to reproduce, because blood contains lipids, proteins, and other nutrients needed for the production of eggs.

5. MosquitoEs actually help the environment.

When you’re rubbing calamine lotion all over yourself, mosquitoes might not seem to serve any purpose but to annoy you, but many species play important ecological roles. The mosquitoes Aedes impiger and Aedes nigripes, which gather in thick clouds in Arctic Russia and Canada, are an important food source for migrating birds. Farther south, birds, insects, spiders, salamanders, lizards, frogs, and fish also eat different mosquito species regularly. Plants need them, too, and some, like the blunt-leaved orchid and endangered monkeyface orchid, rely on mosquitoes as their primary pollinator.

Some mosquito species are also excellent at mosquito control. Species of the genus Toxorhynchites feed on the larvae and immature stages of other mosquitoes and will sometimes even cannibalize members of their own species.

6. Mosquitoes are amazing hunters (as if we needed to tell you that).

Mosquitoes are adept at picking up on the chemicals given off by their human hosts. They can detect the carbon dioxide in our breath, the 1-octen-3-ol in our breath and sweat, and other organic substances we produce with the 70-plus types of odor and chemical receptors in their antennae. These receptors can pick up traces of chemicals from hundreds of feet away, and once the mosquito closes in, it tracks its meal chemically and also visually—and they’re fond of people wearing dark colors.

7. Mosquitoes can be picky.

If it seems like you’re always covered head to toe by bites while people who were sitting right next to you only have one or two, it’s not just paranoia; the skeeters actually are out to get you. Some people happen to give off more of the odors and compounds that mosquitoes find simply irresistible, while others emit less of those and more of the compounds that make them unattractive to mosquitoes—either by acting as repellents or by masking the compounds that mosquitoes would find attractive.

8. A female mosquito's mouth is primed for sucking blood.

A mosquito doesn’t simply sink its proboscis into your skin and start sucking. What you see sticking out of a mosquito’s face is the labium, which sheaths the mouthparts that really do all the work. The labium bends back when a mosquito bites, allowing these other parts to pass through its tip and do their thing. The sharp, pointed mandibles and maxillae, which both come in pairs, are used to pierce the skin, and the hollow hypopharynx and the labrum are used to deliver saliva and draw blood, respectively.

9. Mosquito saliva prevents blood clotting.

The saliva that gets pumped out from the hypopharynx during a bite is necessary to get around our blood’s tendency to clot. It contains a grab bag of chemicals that suppress vascular constriction, blood clotting and platelet aggregation, keeping our blood from clogging up the mosquitoes' labrum and ruining their meal.

10. Mosquitoes can explode.

Blood pressure makes a mosquito's meal easier by helping to fill its stomach faster, but urban legend says it can also lead to their doom. Story goes, you can flex a muscle close to the bite site or stretch your skin taut so the mosquito can’t pull out its proboscis and your blood pressure will fill the bug until it bursts. The consensus among entomologists seems to be that this is bunk, but there is a more complicated way of blowing the bugs up. To make a blood bomb, you’ve got to sever the mosquito’s ventral nerve cord, which transmits information about satiety. When it's cut, the cord can’t tell the mosquito’s brain that its stomach is full, so it’ll keep feeding until it reaches critical mass. At least one researcher found that mosquitoes clueless about how full they were would keep sucking even after their guts had exploded, sending showers of blood spilling out of their blown-out back end.

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