by David Braun
TRUTH:
DOLPHINS CAN HEAR SOUNDS UNDERWATER FROM 15 MILES AWAY.
Under certain circumstances, humans can also hear frequencies outside of this normal range. For instance, divers underwater can detect sounds of up to 100 kHz, according to Qin’s recent experiments. It’s unclear why divers have enhanced hearing underwater, but it may be because the sounds travel directly through the bones to the brain, he said.
Mechanics of Hearing
In normal hearing, sound waves traveling through the air or water enter our ear canals and strike our eardrums, causing them to vibrate. Our eardrums are connected to three tiny, connected bones called the malleus, incus, and stapes—popularly known as the hammer, anvil, and stirrup, due to their shapes.
As the stapes bone rocks back and forth, it pushes against a fluid-filled structure in the inner ear called the cochlea. Resembling a tiny snail, the cochlea contains tiny hairlike structures that translate the pressure waves in the jostling fluid into nerve signals that are sent to the brain and interpreted as sounds.
Hearing Loss Is Widespread
The deaf and hard of hearing account for the single largest group of disabled people in the United States. Of the more than 49 million disabled, at least 28 million have a significant hearing impairment that interferes with communication. That adds up to more than all those with heart disease, cancer, multiple sclerosis, blindness, tuberculosis, venereal disease, and kidney disease combined.
Skipping Steps
“If you think of the hearing system as one long chain of events, there are multiple places in which bone conduction or underwater hearing can bypass that chain,” he said. For example, bone conduction occurs when very high-frequency sounds directly stimulate the ear bones, sending signals to the brain without activating the eardrums. This is how some species of whales hear underwater.
“The core of our work is trying to understand underwater hearing and bone-conduction hearing, and to determine if they share the same underlying mechanism,” he said. Alternatively, certain ultrasonic frequencies might stimulate the fluid in the cochlea. “It could be like hitting a wrench against a water tank,” Qin explained. “The fluid itself could go into oscillation.”
Coming Soon to an Ear Near You?
Qin and his team are now exploring which bones are most likely to be most sensitive to ultrasonic vibrations. He said, “That’s the great thing about basic science, right? It lets you know how things work, and you can bend it to many applications.”
Could their research lead to devices that give us superhuman hearing or improved hearing aids? Qin is silent, for now.
THE SMELL OF LOVE
Women Can Sniff Out Men
Without Knowing—and Vice Versa
When it comes time to sort out the men from the women, our noses are giving us information that we don’t consciously know about.
Women and men can sniff out the opposite sex via odorless pheromones, a new study suggests. The discovery adds another piece to the growing body of evidence that humans, much like the rest of the animal kingdom, know more from their noses than previously thought.
Scent of a Woman
Pheromones—chemicals that can communicate sexual information—are widespread in the animal world, and some research suggests humans use them unconsciously as well. “We know that for animals, chemosignals are actually the most used signals to communicate, whereas with humans, we think chemosensation is not really used,” said study leader Wen Zhou, a psychologist at the Chinese Academy of Sciences in Beijing. “But based on our experiences, [people] are still influenced by these cues, even if they don’t explicitly know it.”
TRUTH:
SCENTS SMELL BETTER THROUGH YOUR RIGHT NOSTRIL THAN YOUR LEFT.
In a recent experiment, subjects who smelled possible pheromones from the opposite sex were more likely to interpret ambiguous human figures as that sex—even when the participants didn’t know they were smelling anything.
Zhou and colleagues used videos of points of light moving in a way that fools the eye into seeing human motion. The videos were made by filming real people in motion-capture suits with LEDs at each joint—similar to the suits used to create Hollywood special effects. Then the scientists mathematically manipulated the dots until the “figures” had neither a typically male nor typically female gait.
Pheromones Pioneer
Martha McClintock conducted the most prominent study on human pheromones. In 1971 she asserted that pheromones caused women living together to menstruate at the same time, which was a revolutionary idea at the time, because biological processes were not thought to be affected by social factors. McClintock’s work has led the way to further research on understanding various human pheromones and the effect of social and psychological contexts on biology.
The Very Smell of You
Twenty men and 20 women watched the video animations of these ambiguous figures, as well as ones that were more obviously male or female. While watching the videos, the subjects sniffed clove oil infused with the male steroid androstadienone, the female steroid estratetraenol, or a plain oil used as a base for many cosmetics.
Men who smelled the female pheromone were more likely to identify the androgynous walker as a woman, and were even more likely to identify more clearly male figures as female than those who just smelled clove oil. The same results applied when women sniffed the male compound: They more frequently saw the ambiguous figures as male than the women who smelled the plain oil. Estratetraenol had no effect on women, and androstadienone didn’t affect men.
This perception difference seems to be completely unrelated to what their noses told them: A blindfolded test subject couldn’t tell the difference between steroid-infused clove oil and plain oil. “It’s completely below their awareness,” Zhou said. “They didn’t know what they were smelling, but their behavior showed these different patterns.”
CAUTION: NEURONS AT REST
Is Your Brain Asleep
While You’re Awake?
If you think you can function on minimal sleep, here’s a wake-up call: Parts of your brain may doze off even if you’re totally awake.
Sleep deprivation can do strange things to a brain-including putting it on autopilot without your knowledge. In a recent study, scientists observed the electrical activity of brains in rats forced to stay up longer than usual. Problem-solving brain regions fell into a kind of “local sleep”—a condition likely in sleep-deprived humans too, the study authors say.
Surprisingly, when sections of the rats’ brains entered these sleeplike states, “you couldn’t tell that [the rats were] in any way in a different state of wakefulness,” said study co-author Giulio Tononi, a neuroscientist at the University of Wisconsin, Madison.
TRUTH:
THE MAIN SYMPTOM OF FATAL FAMILIAL INSOMNIA (FFI) IS THE INABILITY TO SLEEP, WHICH RESULTS IN EVENTUAL DEATH. ONLY 40 FAMILIES IN THE WORLD ARE KNOWN TO CARRY THE GENE FOR THE DISEASE.
Despite these periods of local sleep, overall brain activity—and the rats’ behaviors—suggested the animals were fully awake. This phenomenon of local sleep is “not just an interesting observation of unknown significance,” Tononi said. It “actually affects behavior—you make a mistake.” For example, when the scientists had the rats perform a challenging task—using their paws to reach sugar pellets—the sleep-deprived animals had trouble completing it.
Sleep Allows Neurons to Reset?
Tononi and his colleagues recorded the electrical activity of lab rats via electroencephalogram (EEG) sensors connected to the rodents’ heads.
As predicted, when the rats were awake, their neurons—nerve cells that collect and transmit signals in the brain—fired frequently and irregularly.
When the animals slept, their neurons fired less often, usually in a regular up-and-down pattern that manifests on the EEG as a “slow wave.” Called non-rapid eye movement, this sleep stage accounts for about 80 percent of all sleep in both rats and people.
; The researchers used toys to distract the rats into staying awake for a few hours—normally “rats take lots of siestas,” Tononi noted. The team discovered that neurons in two sections of these overtired rats’ cerebral cortexes entered a slow-wave stage that is essentially sleep.
“What good does it do to try to educate … so early in the morning? You can be giving the most … interesting lectures to sleep-deprived kids early in the morning or right after lunch … and the overwhelming drive to sleep replaces any chance of alertness, cognition, memory, or understanding.”
James B. Maas, Ph.D.
sleep expert
Why Do We Sleep?
It’s unknown why parts of an awake brain nod off, though it may have something to do with why mammals sleep—still an open question, said Tononi, whose study appeared in the journal Nature.
According to one leading theory, since neurons are constantly “recording” new information, at some point the neurons need to “turn off” in order to reset themselves and prepare to learn again.
“If this hypothesis is correct, that means that at some point [if you’re putting off sleep] you’re beginning to overwhelm your neurons—you are reaching the limit of how much input they can get.” So the neurons “take the rest, even if they shouldn’t”—and there’s a price to pay in terms of making “stupid” errors, he said.
Even “Alert” People Make Mistakes
Sleep deprivation may have dangerous consequences, Tononi said—and those mistakes may become more common. For one, many people are getting fewer Zs. In 2008, about 29 percent of U.S. adults reported sleeping fewer than seven hours per night, and 50 to 70 million had chronic sleep and wakefulness disorders, according to the U.S. Centers for Disease Control and Prevention. Adults generally need about seven to nine hours of sleep a day, according to the National Sleep Foundation.
What’s more, you don’t need to feel sleepy to screw up, Tononi emphasized. “Even if you may feel that you’re fit and fine and are holding up well,” he said, “some parts of your brain may not [be] … and those are the ones that make judgments and decisions.”
TRUTH:
STAYING AWAKE FOR 24 HOURS IMPAIRS HAND-TO-EYE COORDINATION AS MUCH AS HAVING A BLOOD ALCOHOL CONTENT OF 0.1%.
ANCIENT ARTERIES
Oldest Known Heart Disease
Found in Egyptian Mummy
Heart disease is not a recent development-people’s arteries have been clogging up since the days of ancient Egypt.
An ancient Egyptian princess might have been able to postpone her mummification if she had cut the calories and exercised more, medical experts say. Known as Ahmose Meryet Amon, the princess lived some 3,500 years ago and died in her 40s. She was entombed at the Deir el-Bahri royal mortuary temple on the west bank of the Nile, opposite the city of Luxor. The princess’s mummified body is among those now housed at the Egyptian Museum in Cairo.
Heart Trouble
Recent scans of 52 of the museums mummies revealed almost half of the dead have clogged arteries—including the princess. In fact, she is now the earliest known sufferer of coronary atherosclerosis, a condition caused by a buildup of arterial plaque, which can lead to heart attack or stroke.
Ahmose Meryet Amon—“Child of the Moon, Beloved of Amun”—had blockages in five major arteries, including those that supply blood to the brain and heart, said study co-leader Gregory Thomas, a professor of cardiology at the University of California, Irvine.
(Photo Credit 2.2)
“If the princess was in a time machine and I was to see her now, I would tell her to lay off the fat, take plenty of exercise, then schedule her for heart surgery,” Thomas said. “She would require a double bypass.”
Ancient Heart Attacks
Although the mummies’ actual hearts had been removed before entombment, the CT scans uncovered calcium deposits elsewhere in the bodies that are indicative of artery damage. But the study team could not confirm that any of the mummies died of heart disease because most of the mummies’ organs were either disintegrated or missing.
However, a medical text dating back to the time the princess lived—between 1550 and 1580 B.C.—describes the pain in the arm and chest that precedes a potentially fatal heart attack.
In general, blocked arteries and heart attacks are health risks we associate with today’s lifestyle and diet, not those of the ancient Egyptians, noted study co-author Michael Miyamoto of the University of California, San Diego’s School of Medicine.
Fit for a King
The ancient Egyptians ate a variety of different food, much of which is still consumed today. Some of these foods include hummus, dates, grapes, pomegranates, peaches, watermelon, pork, beef, lamb, goat, duck, and bread. As for beverages, beer was quite commonly served at meals, while the wealthy imbibed wine.
“They lacked a lot of the risk factors that we consider to be important in the development of atherosclerosis in modern populations—namely smoking, high rates of diabetes and obesity, and foods rich in trans fats,” Miyamoto said.
Too Much of a Good Thing
But as a daughter of the Pharaoh Seqenenre Tao II, the princess—like the other examined mummies—was a member of the elite. That means she was possibly more prone to heart disease than the rest of the population.
“Since they were the elite, they presumably led more pampered lifestyles, were more sedentary, and also—maybe importantly—had access to foods which were dense in calories, particularly meats,” Miyamoto said.
(Photo Credit 2.3)
Adel Allam, study co-author and professor of cardiology at Egypt’s Al Azhar University, added that the princess lived during a prosperous period of Egyptian history. “Even the very poor people would eat a lot of pork, and the bread became mixed with honey,” he said. “If ordinary people at this time did get a lot of carbohydrates and fat in their diets, then of course the elite would have got even more unhealthy food,” he said.
Running in the Family
Perhaps backing up diet as a contributing factor, researchers had previously found some evidence among ancient Egyptians for diabetes, a condition often associated with obesity, Allam added. Also, Egyptian papyrus documents by ancient physicians refer to diabetes symptoms.
However, although body fat is not preserved on ancient mummies, the signs are that Ahmose Meryet Amon was probably petite, Allam said. In fact, the team suspects some factor other than diet and lifestyle may have contributed to her vascular disease.
For instance, “in her family there were a couple of other queens and princesses that had atherosclerosis, so a genetic element cannot be excluded,” Allam said. The new study suggests that genetics may be even more important than previously thought in causing atherosclerosis, and the mummies might hold clues to which genetic factors are involved.
TRUTH:
IN THE UNITED STATES TODAY, HEART DISEASE IS THE LEADING CAUSE OF DEATH FOR PEOPLE OF MOST ETHNICITIES.
Inflammatory Evidence
Another possibility is that atherosclerosis can be brought on by chronic inflammation caused by a person’s immune system responding to infection, which in turn can lead to inflammation of the blood vessel walls. “The princess was known to have arthritis and inflammation of the joints,” Allam noted. “Also, she had severe dental disease, which is another inflammation.”
The U.S.–Egyptian research team will conduct further studies on a total of 72 mummies to investigate the individuals’ genetic links to heart issues, as well as evidence of other health issues including arthritis and cancer, and whether their bones can reveal how active they were.
LOVE HURTS
Rejection Really Hurts
Brain Scans Show
Science is showing what we’ve always known: a broken heart hurts. Brains of the jilted reveal that rejection actually causes physical pain.
Do words ever hurt you as much as sticks and stones? Romantic rejection, at least, causes physical pain, according to a new study of brain activity.
Don’t Go B
reakin’ My Heart
Past studies have shown that simulated social rejection may be connected to a network of brain regions that processes the meaning of pain but not the sensory experience itself. MRI brain scans of people jilted in real life show “activation in brain areas that are actually tied to the feeling of pain,” said study co-author Edward Smith, a psychologist at Columbia University in New York City.
Being jilted activates regions of the brain that manage pain. (Photo Credit 2.4)
Smith and colleagues recruited 40 participants via flyers posted around Manhattan and through Facebook and Craigslist advertisements. All the volunteers reported going through an “unwanted romantic relationship breakup” within the past six months.
While in an MRI machine, the subjects were asked to look at photographs of their ex-partners and think about being rejected. When they did so, the parts of their brains that manage physical pain—the secondary somatosensory cortex and the dorsal posterior insula, to be exact—lighted up, according to the study.
