【推荐2】Media multitasking, such as scrolling through social media while watching a movie, may be linked to more brief failures in attention and difficulty remembering things.

“Our data support the idea that we should be aware of how we engage with media,” says Kevin Paul Madore at Stanford University in California. He and his team compared people’s self-reported levels of media multitasking with their performances in a memory task, as part of a study including 80 participants aged 18 to 26.

The researchers specifically tested episodic memory, which helps us recall events, by presenting the participants with images of objects on a computer and then later asking them to recall whether they had seen the objects earlier or not. At the same time, the team used EEG and eye tracking to monitor people’s attentiveness.

Madore and his colleagues also asked participants to complete a questionnaire to determine how often they engage in various forms of media multitasking, such as texting while watching TV or reading while listening to music. They found that people who reported more frequent media multitasking had more brief failures in attention during the memory task, which was associated with increased difficulties with remembering.

“I think conscious awareness of attentiveness and limiting potential distractions can go a long way in memory preparedness and reducing mind wandering or mind blanking,” says Madore. “Resisting media multitasking during school lectures or work zones, or limiting media multitasking to set times, could be valuable.”

“Media multitasking is becoming more prominent. We don’t actually know anything about the effects yet,” says Amy Orben at the University of Cambridge. It will be important to investigate whether media multitasking causes brief attentional failure and memory failure or whether there is another factor, such as how generally distractible a person is, that could explain the association. “This could be investigated through studies that monitor people over time and this is a really interesting area that we should explore,” she says.

【推荐3】Human speech contains more than 2,000 different sounds, from the common “m” and “a” to the rare clicks of some southern African languages. But why are certain sounds more common than others? A ground-breaking, five-year study shows that diet-related changes in human bite led to new speech sounds that are now found in half the world’s languages.

More than 30 years ago, the scholar Charles Hockett noted that speech sounds called labiodentals, such as “f” and “v”, were more common in the languages of societies that ate softer foods. Now a team of researchers led by Damián Blasi at the University of Zurich, Switzerland, has found how and why this trend arose.

They discovered that the upper and lower front teeth of ancient human adults were aligned (对齐), making it hard to produce labiodentals, which are formed by touching the lower lip to the upper teeth. Later, our jaws changed to an overbite structure (结构), making it easier to produce such sounds.

The team showed that this change in bite was connected with the development of agriculture in the Neolithic period. Food became easier to chew at this point. The jawbone didn’t have to do as much work and so didn’t grow to be so large.

Analyses of a language database also confirmed that there was a global change in the sound of world languages after the Neolithic age, with the use of “f” and “v” increasing remarkably during the last few thousand years. These sounds are still not found in the languages of many hunter-gatherer people today.

This research overturns the popular view that all human speech sounds were present when human beings evolved around 300,000 years ago. “The set of speech sounds we use has not necessarily remained stable since the appearance of human beings, but rather the huge variety of speech sounds that we find today is the product of a complex interplay of things like biological change and cultural evolution,” said Steven Moran, a member of the research team.

What is paragraph 5 mainly about?

【推荐1】Just as a hungry brain craves (渴望) food, a lonely brain craves people. A new brain study demonstrates this. After being left alone, it shows people’s brains would be activated at the sight of other people. The action was in the same brain region that speeds up when a hungry person sees food.

Livia Tomova, a neuroscientist, who studies how the brain produces mental activities, and her colleagues began this study. They recruited (招募) 40 people. On one day, the participants had to fast—not eat anything at all—for 10 hours. On another day, the same people were placed in a room for 10 hours. They couldn’t see anyone. No friends, no family and no social media. They weren’t even allowed to check their email. After both days, Tomova and her colleagues put the people in a MRI machine. It shows activity in the brain by tracking how much blood is flowing to each region.

At the end of each day, the participants showed high activity in a brain area called the midbrain. The scientists were interested in two, small areas within it. Both areas produce dopamine, a chemical that is important in craving and rewards. The two areas activated when hungry participants saw pictures of tasty pizza or juicy hamburgers. After the volunteers had been isolated, those brain areas became active when they saw social activities they missed. It might be playing sports or chatting with friends.

The midbrain plays an important part in people’s motivation to seek food or friends. In fact, it responds to food and social signals even when people aren’t hungry or lonely. But hunger and loneliness increased the reactions and made people’s responses specific to the thing they were missing. And the more hunger or isolation the volunteers said they were experiencing, the stronger the activity in this part of the brain. Tomova and her colleagues published their results November 23 in Nature Neuroscience.

【推荐2】Grizzly bears, which may grow to about 2.5 m long and weigh over 400 kg, occupy a conflicted corner of the American psyche — we revere (敬畏) them even as they give us frightening dreams. Ask the tourists from around the world that flood into Yellowstone National Park what they most hope to see, and their answer is often the same: a grizzly bear.

“Grizzly bears are re-occupying large areas of their former range,” says bear biologist Chris Servheen. As grizzly bears expand their range into places where they haven’t been seen in a century or more, they’re increasingly being sighted by humans.

The western half of the US was full of grizzlies when Europeans came, with a rough number of 50,000 or more living alongside Native Americans. By the early 1970s, after centuries of cruel and continuous hunting by settlers, 600 to 800 grizzlies remained on a mere 2 percent of their former range in the Northern Rockies. In 1975, grizzlies were listed under the Endangered Species Act.

Today, there are about 2,000 or more grizzly bears in the US. Their recovery has been so successful that the US Fish and Wildlife Service has twice attempted to delist grizzlies, which would loosen legal protections and allow them to be hunted. Both efforts were overturned due to lawsuits from conservation groups. For now, grizzlies remain listed.

Obviously, if precautions (预防) aren’t taken, grizzlies can become troublesome, sometimes killing farm animals or walking through yards in search of food. If people remove food and attractants from their yards and campsites, grizzlies will typically pass by without trouble. Putting electric fencing around chicken houses and other farm animal quarters is also highly effective at getting grizzlies away. “Our hope is to have a clean, attractant-free place where bears can pass through without learning bad habits,” says James Jonkel, longtime biologist who manages bears in and around Missoula.

How do Americans look at grizzlies?

【推荐3】You may not pay much attention to your daily elevator ride. Many of us use a lift several times during the day without really thinking about it. But Lee Gray, PhD, of the University of North Carolina, US, has made it his business to examine this overlooked form of public transport. He is known as the “Elevator Guy”.

“The lift becomes this interesting social space where etiquette (礼仪) is sort of odd (奇怪的),” Gray told the BBC. “They (elevators) are socially very interesting but often very awkward places.”

We walk in and usually turn around to face the door. If someone else comes in, we may have to move. And here, according to Gray, lift users unthinkingly go through a set pattern of movements. He told the BBC what he had observed.

He explained that when you are the only one inside a lift, you can do whatever you want – it’s your own little box.If there are two of you, you go into different corners, standing diagonally (对角线地) across from each other to create distance.When a third person enters, you will unconsciously form a triangle. And when there is a fourth person it becomes a square, with someone in every corner. A fifth person is probably going to have to stand in the middle.

New entrants to the lift will need to size up the situation when the doors slide open and then act decisively. Once in, for most people the rule is simple – look down, or look at your phone.

Why are we so awkward in lifts?

“You don’t have enough space,” Professor Babette Renneberg, a clinical psychologist at the Free University of Berlin, told the BBC. “Usually when we meet other people we have about an arm’s length of distance between us. And that’s not possible in most elevators.”

In such a small, enclosed space it becomes very important to act in a way that cannot be construed (理解) as threatening or odd. “The easiest way to do this is to avoid eye contact,” she said.

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【推荐3】Sitting in the garden for my friend’s birthday. I felt a buzz (振动) in my pocket. My heart raced when I saw the email sender’s name. The email started off: “Dear Mr Green, thank you for your interest” and “the review process took longer than expected.” It ended with “We are sorry to inform you…” and my vision blurred (模糊). The position—measuring soil quality in the Sahara Desert as part of an undergraduate research programme — had felt like the answer I had spent years looking for.

I had put so much time and emotional energy into applying, and I thought the rejection meant the end of the road for my science career.

So I was shocked when, not long after the email, Professor Mary Devon, who was running the programme, invited me to observe the work being done in her lab. I jumped at the chance, and a few weeks later I was equally shocked—and overjoyed—when she invited me to talk with her about potential projects I could pursue in her lab. What she proposed didn’t seem as exciting as the original project I had applied to, but I was going to give it my all.

I found myself working with a robotics professor on techniques for collecting data from the desert remotely. That project, which I could complete from my sofa instead of in the burning heat of the desert, not only survived the lockdown but worked where traditional methods didn’t. In the end, I had a new scientific interest to pursue.

When I applied to graduate school, I found three programmes promising to allow me to follow my desired research direction. And I applied with the same anxious excitement as before. When I was rejected from one that had seemed like a perfect fit, it was undoubtedly difficult. But this time I had the perspective (视角) to keep it from sending me into panic. It helped that in the end I was accepted into one of the other programmes I was also excited about.

Rather than setting plans in stone, I’ve learned that sometimes I need to take the opportunities that are offered, even if they don’t sound perfect at the time, and make the most of them.