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Why we love big, blood-curdling screams
Among the variety of human screams, it is screams of terror that stand out most vividly.
Of all the sounds humans produce, nothing captures our attention quite like a good scream.
Screams might seem simple, but they can actually convey a complex set of emotions. The arsenal of human screams has been honed over millions of years of evolution, with subtle nuances in volume, timing and inflection that can signal different things.
Screaming can be traced to the prehistoric ancestors we share with other primates, who use screams as a key component of their social repertoire.
Screams are especially important in monkey societies.
Emory University psychologist Harold Gouzoules is one of the world's leading screaming experts. He's been able to show how monkey screams convey a wealth of information. Different screams at different pitches and volumes can communicate different levels of urgency, such as whether a fight is simply about to take place or whether a predator is in the area.
The grammar of monkey screams can be surprisingly sophisticated.
African vervet monkeys, for example, have three main predators: leopards, snakes and eagles. Each type of predator requires different escape routes. To elude an eagle, the monkey must abandon wide-open spaces and seek shelter in dense shrubbery. But this would be exactly the wrong response if a snake were lurking in bushes.
Vervet monkeys have developed a unique language of screams. (Tim Graham/Getty Images)
For this reason, vervets have evolved a pattern of distinct screams that not only act as a warning but also reveal the type of predator in their midst.
Monkeys can even identify other individual monkeys from their screams.
This is highly adaptive, because it enables the listener to assess the importance of the screamer to the listener, facilitating the protection of children and other relatives.
Why screams of terror stand out
Like monkeys, humans have the ability to identify people they know by the sound of their screams.
Humans produce a range of screams as well: There are screams that reflect more positive emotions, such as surprise and happiness. And then there are screams of anguish, screams of pain and, of course, screams of terror.
Screams can be described according to their place along an acoustic dimension known as "roughness."
Roughness is a quality that reflects the rate at which a scream changes or varies in loudness. The more rapidly the loudness fluctuates, the "rougher" the scream. And the rougher a scream is, the more terrifying it's perceived to be.
Psychologist David Poeppel looked at brain images of people listening to recordings of human screams and found that, unlike other human vocalizations, screams get routed directly to the amygdala, which is the part of the brain that processes fear, anger and other intense emotions.
And among the variety of human screams, it is screams of terror that stand out most vividly. Other unpleasant sounds, such as a baby's cry and fingernails on a chalkboard, share some of the same features that make screams unpleasant and terrifying.
The best screamers survived
It makes good evolutionary sense for screams of terror to be the most attention-grabbing; these are the ones that most clearly warn of an imminent danger.
Humans who couldn't readily distinguish among different types of screams may not have responded with appropriate urgency in life-or-death situations. Over time, this would have diminished the frequency of their genes in the population.
So we're probably the descendants of individuals who were good screamers and were also good at reading the screams of their fellow humans. This may help explain the perverse joy we get by intentionally subjecting ourselves to scream-inducing experiences like horror movies and roller coasters.
How better to celebrate the screaming success of our prehistoric ancestors?
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What would it be like to experience the 4th dimension?
Physicists have understood at least theoretically, that there may be higher dimensions, besides our normal three. The first clue came in 1905 when Einstein developed his theory of special relativity. Of course, by dimensions we’re talking about length, width, and height. Generally speaking, when we talk about a fourth dimension, it’s considered space-time. But here, physicists mean a spatial dimension beyond the normal three, not a parallel universe, as such dimensions are mistaken for in popular sci-fi shows.
Duke University researchers might have solved a half-century old problem.
- Duke University researchers created a hydrogel that appears to be as strong and flexible as human cartilage.
- The blend of three polymers provides enough flexibility and durability to mimic the knee.
- The next step is to test this hydrogel in sheep; human use can take at least three years.
Duke researchers have developed the first gel-based synthetic cartilage with the strength of the real thing. A quarter-sized disc of the material can withstand the weight of a 100-pound kettlebell without tearing or losing its shape.
Photo: Feichen Yang.<p>That's the word from a team in the Department of Chemistry and Department of Mechanical Engineering and Materials Science at Duke University. Their <a href="https://onlinelibrary.wiley.com/doi/abs/10.1002/adfm.202003451" target="_blank">new paper</a>, published in the journal,<em> Advanced Functional Materials</em>, details this exciting evolution of this frustrating joint.<br></p><p>Researchers have sought materials strong and versatile enough to repair a knee since at least the seventies. This new hydrogel, comprised of three polymers, might be it. When two of the polymers are stretched, a third keeps the entire structure intact. When pulled 100,000 times, the cartilage held up as well as materials used in bone implants. The team also rubbed the hydrogel against natural cartilage a million times and found it to be as wear-resistant as the real thing. </p><p>The hydrogel has the appearance of Jell-O and is comprised of 60 percent water. Co-author, Feichen Yang, <a href="https://today.duke.edu/2020/06/lab-first-cartilage-mimicking-gel-strong-enough-knees" target="_blank">says</a> this network of polymers is particularly durable: "Only this combination of all three components is both flexible and stiff and therefore strong." </p><p> As with any new material, a lot of testing must be conducted. They don't foresee this hydrogel being implanted into human bodies for at least three years. The next step is to test it out in sheep. </p><p>Still, this is an exciting step forward in the rehabilitation of one of our trickiest joints. Given the potential reward, the wait is worth it. </p><p><span></span>--</p><p><em>Stay in touch with Derek on <a href="http://www.twitter.com/derekberes" target="_blank">Twitter</a>, <a href="https://www.facebook.com/DerekBeresdotcom" target="_blank">Facebook</a> and <a href="https://derekberes.substack.com/" target="_blank">Substack</a>. His next book is</em> "<em>Hero's Dose: The Case For Psychedelics in Ritual and Therapy."</em></p>
An algorithm may allow doctors to assess PTSD candidates for early intervention after traumatic ER visits.
- 10-15% of people visiting emergency rooms eventually develop symptoms of long-lasting PTSD.
- Early treatment is available but there's been no way to tell who needs it.
- Using clinical data already being collected, machine learning can identify who's at risk.
The psychological scars a traumatic experience can leave behind may have a more profound effect on a person than the original traumatic experience. Long after an acute emergency is resolved, victims of post-traumatic stress disorder (PTSD) continue to suffer its consequences.
In the U.S. some 30 million patients are annually treated in emergency departments (EDs) for a range of traumatic injuries. Add to that urgent admissions to the ED with the onset of COVID-19 symptoms. Health experts predict that some 10 percent to 15 percent of these people will develop long-lasting PTSD within a year of the initial incident. While there are interventions that can help individuals avoid PTSD, there's been no reliable way to identify those most likely to need it.
That may now have changed. A multi-disciplinary team of researchers has developed a method for predicting who is most likely to develop PTSD after a traumatic emergency-room experience. Their study is published in the journal Nature Medicine.
70 data points and machine learning
Image source: Creators Collective/Unsplash
Study lead author Katharina Schultebraucks of Columbia University's Department Vagelos College of Physicians and Surgeons says:
"For many trauma patients, the ED visit is often their sole contact with the health care system. The time immediately after a traumatic injury is a critical window for identifying people at risk for PTSD and arranging appropriate follow-up treatment. The earlier we can treat those at risk, the better the likely outcomes."
The new PTSD test uses machine learning and 70 clinical data points plus a clinical stress-level assessment to develop a PTSD score for an individual that identifies their risk of acquiring the condition.
Among the 70 data points are stress hormone levels, inflammatory signals, high blood pressure, and an anxiety-level assessment. Says Schultebraucks, "We selected measures that are routinely collected in the ED and logged in the electronic medical record, plus answers to a few short questions about the psychological stress response. The idea was to create a tool that would be universally available and would add little burden to ED personnel."
Researchers used data from adult trauma survivors in Atlanta, Georgia (377 individuals) and New York City (221 individuals) to test their system.
Of this cohort, 90 percent of those predicted to be at high risk developed long-lasting PTSD symptoms within a year of the initial traumatic event — just 5 percent of people who never developed PTSD symptoms had been erroneously identified as being at risk.
On the other side of the coin, 29 percent of individuals were 'false negatives," tagged by the algorithm as not being at risk of PTSD, but then developing symptoms.
Image source: Külli Kittus/Unsplash
Schultebraucks looks forward to more testing as the researchers continue to refine their algorithm and to instill confidence in the approach among ED clinicians: "Because previous models for predicting PTSD risk have not been validated in independent samples like our model, they haven't been adopted in clinical practice." She expects that, "Testing and validation of our model in larger samples will be necessary for the algorithm to be ready-to-use in the general population."
"Currently only 7% of level-1 trauma centers routinely screen for PTSD," notes Schultebraucks. "We hope that the algorithm will provide ED clinicians with a rapid, automatic readout that they could use for discharge planning and the prevention of PTSD." She envisions the algorithm being implemented in the future as a feature of electronic medical records.
The researchers also plan to test their algorithm at predicting PTSD in people whose traumatic experiences come in the form of health events such as heart attacks and strokes, as opposed to visits to the emergency department.