2 . For hundreds of years, scientists learned about the brain by observing people recovering from injuries. Many with an injury on the left side of the brain had problems understanding or using words. From this, doctors reasoned that the left brain must manage speech and language. They didn’t know, though, if speech and language centers were on this side in everyone. The finding of a new study may be able to tell the answer.

In the new study, researchers used fMRI (功能性磁共振成像) to watch brains in action as 39 children and 14 adults tried to understand sentences. Each fMRI scan (扫描) produced many pictures of the brain. Patches of color in each image highlighted which parts of the brain were getting the most blood. This is a sign that they were turned on and active.

To the researchers’ surprise, the left side of the brain was not the only part that was turned on in the children. Both sides became active when they tried to understand a sentence. That activity in the right brain started to fall in children who were older. By age 19, no activity showed up on the right. All speech-and-language processing now was taking place only on the left. The move from two-sided to one-sided language processing takes place gradually. It starts around the time we learn to talk.

Elissa Newport, who led the study, finds it exciting that children have speech centers on both sides of their brains. “If both sides of their brains can pitch in, this may also explain why left-brain injuries often are not as damaging in young children as in adults,” said she.

Children process language like “mental switch-hitters”. So, the next time you think your parents or older siblings (兄弟姐妹) don’t understand you, give them a break. They could be using just a smaller part of their brains.

4 . Hearing loss is unavoidable, but listening to loud music when you’re younger can make it worse. To reduce your risk of hearing loss via loud music, learn why and how it can cause hearing loss, and just how loud is too loud.

Hearing loss occurs in four ways: conductive hearing loss, sensorineural hearing loss, mixed hearing loss and auditory neuropathy spectrum disorder. Noise-induced (噪音诱发的) hearing loss is a type of sensorineural hearing loss.

Sensorineural hearing loss occurs when your inner ear becomes damaged. In the case of noise- induced hearing loss, most of the damage affects the cells of tiny sensory hairs in your inner ear.

When those cells get damaged or die, the electrical signal that your auditory nerve sends to your brain changes.

Noise-induced hearing loss can be acute or severe, and it can be temporary or permanent. You might be familiar with acute temporary noise-induced hearing loss, even if you didn’t realize what was happening at the time.

Acute temporary noise-induced hearing loss can occur from attending a loud concert or sporting event, going to a gun range without earmuffs or being near an explosion. It can make noises sound “stuffy” or far away, especially when talking on the phone or in a crowded room. Repeated exposure to those loud situations can eventually lead to permanent hearing loss.

Noise levels from earbuds and headphones can get as loud as 139 decibels, according to the journal Noise &Health, far greater than the recommended range of everyday sound exposure, which is 60 to 85 decibels. And the average level of noise from headphones, with the volume turned all the way up, is 94 to 110 decibels. For context, 60 decibels is about the volume of an average conversation, and 130 decibels is about the noise level of a rock concert. 85 decibels is considered the maximum volume at which you can listen to sound for eight hours without damaging your hearing. So if you were to listen to music from your headphones for eight hours a day, listening at a volume louder than 85 decibels can cause permanent damage to your ears.

Unfortunately, the relationship between decibels and time isn’t linear (线性的). For every three decibels, safe exposure time gets cut in half, according to the CDC. At 88 decibels, you can only safely listen for four hours; at 91 decibels, just two hours.

6 . Much information can be conveyed, purely through our eyes, so the expression “eyes also talk” is often heard.

Can you recall any experience that further proves this statement? On a bus you may quickly glance at a stranger, but not make eye contact. If he senses that he is being stared at, he may feel uncomfortable.

It is the same in daily life. If you are stared at for more than necessary, you will look at yourself up and down to see if there is anything wrong with you. If nothing goes wrong, you will feel angry about other's staring at you that way. Eyes do convey information, right？

Looking too long at someone may seem to be rude and aggressive. But things are different when it comes to staring at the opposite sex. If a man looks at a woman for more than 10 seconds and refuses to turn away his gaze, his intentions are obvious. That is, he wishes to attract her attention, to make her understand that he is showing affection for her.

However, the normal eye contact for two people engaged in conversation is that the speaker will only look at the listener from time to time, in order to make sure that the listener does pay attention to what the former is speaking, to tell him that he is attentive.

If a speaker looks at you continuously when speaking, as if he tries to control you, you will feel uneasy. A poor liar usually exposes himself by looking too long at the victim, since he believes the false idea that to look straight in the eye is a sign of honest communication.

In fact, continuous eye contact happens between lovers only, who will enjoy looking at each other tenderly for a long time, to show love that words cannot express.

Evidently, eye contact should be done according to the relationship between two people and the specific situation.

7 . Crossing your legs is an extremely common habit; most people don't even notice that they're doing it when they sit down. While you may find it comfortable to sit with one knee crossed over the other, it might be causing health problems that you are not aware of.

A study published in Blood Pressure Monitoring stated that sitting with your legs crossed can increase your blood pressure. The reason for this is that the blood in your legs has to work against gravity to be pumped back to your heart and that crossing one leg over the other increases resistance, making it even harder for the blood to circulate. This causes your body to increase your blood pressure to push the blood back to the heart. You won't feel any immediate effects, but repeated, drawn-out increases in blood pressure can cause long-term health issues. So, planning to sit for a long period of time? Don't keep your legs crossed.

Crossing your legs at the knee can also cause pressure on the major nerve in your leg that passes just below your knee and along the outside of your leg, explains Richard Graves, a medical expert. This pressure can cause numbness and temporary paralysis (麻痹) of some of the muscles in your foot and leg, preventing you from being able to raise your ankle—what we know as that “pins and needles” sensation. While the feeling of discomfort may only last a minute or two, repeatedly crossing your legs until they feel numb can cause permanent nerve damage.

So next time you sit down, try to get yourself in the habit of sitting with both of your feet on the floor. Not only will it help your posture and stability, but it will also save your health in the long run.

8 . Mark Bertram, 46, lost the tips of two fingers at work in 2018 when his hand became trapped in a fan belt. “It's life-changing but it's not life-ending,” he says. “Doing work is harder now. Everything is just a little different.”

After two surgeries and occupational therapy, Bertram decided to make light of his condition by asking Eric Catalano, a tattoo (纹身) artist, to create fingernail tattoos. The idea made everyone in the studio laugh—until they saw the final result. “The mood changed,” Catalano recalls from his Eternal Ink Tattoo Studio. “Everything turned from funny to wow.”

When Catalano posted a photo of the tattoos, a pair of fingernails that looked so real that no one could believe their eyes, he had no idea the image would eventually be viewed by millions of people around the world.

The viral photo pushed Catalano, 40, further into the world of paramedical (辅助医疗的) tattooing. Now people with life-altering scars come from as far away as Ireland to visit his shop. They enter Eternal Ink looking for the artistic healing they saw online. Using flesh-toned (肉色的) inks and a needle, Catalano transforms his clients' view of themselves.

Leslie Pollan, 32, a dog breeder in Oxford, was bitten on the face by a puppy in 2014. She underwent countless surgeries to correct a scar on her lip.

“Plastic surgery gave me no hope,” she says. “So I looked for other options.” She ultimately traveled six hours to meet with Catalano. He hid Pollan's lip scar, giving her back a piece of her confidence.“ You don't understand until you've been through it,” Pollan says. “It made me have a different look on life.”

Catalano performs up to eight reconstructive tattoos. While he charges $100 per regular tattoo, he doesn't charge for paramedical tattoos. “Financially, it doesn't make sense,” Catalano says. “But every time I see that emotion from my customers, I'm 100 percent sure this is something that I can't stop doing.”

9 . When we see well, we do not think about our eyes very often. It is only when we cannot see perfectly that we realize how important our eyes are.

People who are near-sighted can only see things that are very close to their eyes. Everything else seems blurry(=unclear). Many people who do a lot of work, such as writing, reading and sewing become near—sighted.

People who are far-sighted suffer from just the opposite problem. They can see things that are far away, but they have difficulty in reading a book unless they hold it at arm’s length. If they want to do much reading ,they must get glasses, too.

Other people do not see clearly because their eyes are not exactly the right shape. They have what is called astigmatism (散光). This, too, can be corrected by glasses. Some people’s eyes become cloudy because of cataracts (白内障). Long ago these people often became blind. Now, however, it is possible to operate on the cataracts and remove them.

Having two good eyes is important for judging distances. Each eye sees things from a slightly different angle. To prove this to yourself, look at an object our of one eye; then look at the same object out of your other eye. You will find the object’s relation to the background and other things around it has changed. The difference between these two different eye views helps us to judge how far away an object is. People who have only one eye cannot judge distance as people with two eyes.