TIME Research

Scientists Now Know Why People Scream

scream
Hans Neleman / Getty Images

Your brain processes shrieks differently from speech, finds a new study

A baby wails upon an airplane’s liftoff, a person shrieks when he stumbles upon something shocking, a kid throws a tantrum because she wants to get her way—people scream in reaction to all kinds of situations.

But exactly why we scream has remained a mystery. Now, new research published in the journal Current Biology suggests that hearing a scream may activate the brain’s fear circuitry, acting as a cautionary signal.

Scream science is a new area of study, so David Poeppel, a professor of psychology and neural science at New York University, and his co-authors collected an array of screams from YouTube, films and 19 volunteer screamers who screamed in a lab sound booth. (This last collection method, by the way, was a highlight for Poeppel, who said he found listening to and judging screams an amusing break from the monotony of lab work.)

The researchers first measured the sound properties of screams versus normal conversation. They measured the scream’s volume and looked at how volunteers responded behaviorally to screams. They then looked at brain images of people listening to screams and saw something they found fascinating—screams weren’t being interpreted by the brain the way normal sounds were.

Normally, your brain takes a sound you hear and delivers it to a section of your brain dedicated to making sense of these sounds: What is the gender of the speaker? Their age? Their tone?

Screams, however, don’t seem to follow that route. Instead, the team discovered that screams are sent from the ear to the amygdala, the brain’s fear processing warehouse, says Poeppel.

“In brain imaging parts of the experiment, screams activate the fear circuitry of the brain,” he says. “The amygdala is a nucleus in the brain especially sensitive to information about fear.” That means screams are inherently considered not just sound but a trigger for heightened awareness.

From these screams, Poeppel and his team mapped “roughness,” an acoustic description for how fast a sound changes in loudness. While normal speech modulates between 4 and 5 Hz in sound variation, screams spike between 30 and 150 Hz. The higher the sound variation, the more terrifying the scream is perceived.

Poeppel and his team had volunteers listen to different alarm sounds and found people responded to alarms with similar variations: The more the alarms varied at higher rates, the more terrifying they were judged to be.

That huge variation in scream roughness is a clue to how our brains process danger sounds, Poeppel says. Screaming serves not only to convey danger but also to induce fear in the listener and heighten awareness for both screamer and listener to respond to their environment.

TIME Food & Drink

Stop Everything: There’s a New Seaweed That Tastes Like Bacon and Is Better for You Than Kale

Getty Images Dulse seaweed: a new variety, when cooked, reportedly tastes like bacon

The world's most perfect food may have just arrived

Researchers from Oregon State University’s Hatfield Marine Science Center say they’ve created and patented a new type of seaweed that has the potential to be sold commercially as the next big superfood.

The reason? It tastes just like bacon, they claim.

The bizarre but tasty creation is actually a new strain of red marine algae called dulse that is packed full of minerals and protein and looks like red lettuce.

Dulse normally grows in the wild along the Pacific and Atlantic coastlines and is harvested, dried and sold as a cooking ingredient or nutritional supplement.

“Dulse is a superfood, with twice the nutritional value of kale,” said Chuck Toombs, a faculty member in OSU’s College of Business and a member of the team working to develop the product into a foodstuff. “And OSU had developed this variety that can be farmed, with the potential for a new industry for Oregon.”

The team began researching ways of farming the new strain of dulse to feed abalone, but they quickly realized its potential to do well in the human-food market.

“There hasn’t been a lot of interest in using it in a fresh form. But this stuff is pretty amazing,” said chief researcher Chris Langdon. “When you fry it, which I have done, it tastes like bacon, not seaweed. And it’s a pretty strong bacon flavor.”

They’ve received a grant from the Oregon Department of Agriculture to explore dulse as a “special crop” and are working with the university’s Food Innovation Center in Portland and several chefs to find out ways dulse could be used as a main ingredient.

Though there is currently no commercial operation that grows dulse for human consumption in the U.S., the team is confident the seaweed superfood could make it big. If it really does taste like bacon, that would be no surprise at all.

Read next: The New Superfruit You’ve Never Heard of But Need to Try

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TIME space

See NASA’s Latest Images of Pluto’s Icy Mountains

The mountains are relatively young

NASA’s latest images of Pluto show off a gigantic icy mountain range that formed no more than 100 million years ago. The mountains are “mere youngsters” compared to the 4.56-billion-year age of our solar system, the agency said. The photos are the latest from NASA’s New Horizons mission to Pluto.

See the photos in the gallery above.

TIME climate change

How Climate Change Is Making Wildfires Worse

Wildfire
Getty Images

In a vicious cycle, wildfires are also making climate change worse, a study finds

Increasingly hot and dry climates, the result of global climate change, have led to a worsening of wildfires around the world, according to new research. In turn, wildfires are aggravating climate change by killing trees that could absorb carbon in the atmosphere.

The study, published in the journal Nature Communications, finds that fire season has gotten longer for more than quarter of the Earth’s vegetated surface from 1979 to 2013. Overall, across the globe, fire weather season increased by nearly 19%. The trend occurred on all continents where wildfires occur except Australia.

“Wildfires occur at the intersection of dry weather, available fuel and ignition sources,” the study authors write.Weather is the most variable and largest driver of regional burned area.”

Read More: How the California Drought Is Increasing the Potential for Devastating Wildfires

South America has faced one of the most dramatic increases in wildfire numbers and intensity, according to the study. Forests in the region have seen their fire season increase by an average of 33 days. Fires threaten to worsen the deforestation that has already destroyed much of the region’s forest land.

And if the loss of forests wasn’t bad enough, worsening wildfires caused by climate change create a feedback loop, the authors note. Forest fires decrease the number of trees that can absorb the carbon that causes climate change in the first place. “When average fire weather seasons are longer-than-normal or when long seasons impacted more global burnable area, net global terrestrial carbon uptake is reduced,” the authors write.

TIME space

Watch Live: NASA Reveals the Latest Pluto Images

NASA is revealing new images of Pluto and discoveries about the dwarf planet from its New Horizons spacecraft.

Watch it live above.

TIME space

See the First Close-Up Photo of Mars Ever Taken

Each image from NASA's Mariner IV mission was composed of 40,000 dots

Almost exactly 50 years before the New Horizons probe brought us a new view of Pluto, the world got its first close-up glimpse of Mars.

Human beings had been looking at the planet forever—first as a distant reddish light in the sky, later with telescopes that presented a tantalizing view of what seemed like canals, weather and frost. But it wasn’t until July 15, 1965, when NASA’s Mariner IV mission made its first photo transmissions, that mankind got its first zoomed-in view of Mars. Though the mission also relayed important information about Mars’ atmosphere and radiation, it was the photography—from a mission that set a new record for long-distance communication—that got the most attention back on Earth.

The unmanned mission had been plagued by malfunctions early in its months-long journey and even on “encounter day,” July 14, there was a false alarm when it appeared that the recorder capturing the photographs wasn’t working right. Even taking the pictures was a difficult process—but it proved worth the trouble.

After all, these were no simple digital photos, easily snapped and transmitted. Rather, each image was composed of 40,000 dots, the way a dot-matrix image works, as shown in the NASA archival footage above. Each dot was coded to be one of 64 shades between pure white and pure black, and each number—from zero to 63—was represented in binary. It took nearly 9 hours to transmit the code for a single photo out of the 21 total that were taken. Because of the Earth’s rotation during that time, a team of different antennae had to be deployed to pick up different pieces of the Mariner’s transmission. Those pieces were then patched back together so that, by the next day, the first picture could be seen:

First TV Image of Mars 1965
NASA/JPLAn enhanced contrast version of the first Mars photograph released on July 15, 1965

The fact that the photo wasn’t much to look at didn’t make it any less important, as TIME explained:

The picture was grainy and ill-defined, a blur of white curving across a black background. It would take months of painstaking analysis to determine what it really showed. But one quick glance gave the scientists at Caltech’s Jet Propulsion Laboratory the most important message of all: from 135 million miles in space, their spacecraft, Mariner IV, had sent home the first closeup portrait man has ever made of the far-off planet Mars.

While all the world watched and waited, the ambitious timetable of U.S. space exploration had been put to its most demanding test. And the high, undulating whine of JPL’s computers seemed to change subtly into a cry of exaltation. Mariner had made it.

Read the full story from 1965, here in the TIME Vault: Portrait of a Planet

TIME space

Neil deGrasse Tyson Is Totally Over Pluto

"You’re still a Dwarf Planet"

Neil deGrasse Tyson is throwing some shade on Twitter at “only a dwarf” planet, Pluto, which has garnered a lot of attention since the New Horizons probe beamed back images of the far-flung planet to NASA.

Some tweeters are already up in arms over the famed cosmologist’s comments.

TIME space

Pluto the Dog Has Appeared on Pluto the Planet

Appropriately, given that the character was originally named after the heavenly body

Twitter seems to think that one of the biggest discoveries from NASA’s Pluto photos is the presence of Pluto himself — the dog, that is.

A lighter patch on the planet happens to be in the shape of what looks like the ear and the face of the Disney dog—which couldn’t be more appropriate, given that the character was originally named after the dwarf planet.

TIME space

New False Color Photos Set Pluto and Its Moon Apart

Pluto and Charon in False Color Show Compositional Diversity
NASA/APL/SwRI Pluto and Charon in False Color Show Compositional Diversity

The color-filtered images reveal new information about the surfaces of Pluto and Charon.

NASA’s New Horizons Team has released new exaggerated color images from its space probe flyby of Pluto and its moons, highlighting differences between the surface of Pluto and its largest moon, Charon.

The images, which were obtained and color-filtered early Monday morning using “Ralph,” one of the seven science instruments on the NASA New Horizons spacecraft that passed just above 7,000 miles away from Pluto on Tuesday, reveal information about the weather on the dwarf planet and its moon, the age of their craters and the molecular make-up of the ice that appears to be prevalent on both surfaces, NASA reports.

The filtered images also show Pluto’s heart—a newly-discovered geological feature on Pluto’s surface that scientists are particularly excited about—as being made up of two seemingly distinct regions: just a taste of how much scientists still have to learn from the New Horizons data as it trickles in.

Read more at NASA.

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