【推荐2】It may sound a bit ^“Dr. Doolittle,” but it turns out kangaroos can communicate with humans. Researchers found that kangaroos communicated with humans “on purpose”--a behavior that was thought to only belong to domesticated(驯养的)animals, like dogs, horses or goats.

Experts from London's University of Roehampton and the University of Sydney set up a task. This task was known as “the unsolvable problem task”・ During the task, they presented kangaroos with food trapped inside a plastic container.

After trying, and failing, to open the boxes, the kangaroos turned their gaze(注视)on a nearby human - and sometimes even pushed or scratched(抓) them to ask for help, researchers said.

“Their gaze was pretty powerful, co-author Alexandra Green said. "We've previously thought only domesticated animals try to ask for help with a problem. But kangaroos do it too. If they can't open the box, they look at the human and back to the container. Some of them use their nose to push the human and some get close to the human and start scratching at him asking for assistance.^,,

Based on these new findings, the team believe kangaroos - considered social animals, like dogs and goats --may be able to change their behavior to interact with humans.

“Through this study, we are able to see that communication between animals can be learnt and that the behaviour of gazing at humans to get food is not related to domestication lead author Alan McElligott said.

^“Indeed, kangaroos showed a very similar pattern of behaviour we have seen in dogs, horses and even goats when put to the same test,“ McElligott added.

【推荐3】Honey is not only a good source of natural sugar; it is also delicious. Most people and many animals like eating it. Unless people build beehives, however, the only way for them to get honey is to find a wild bees’ nest and take the honey from it. Often, these nests are high up in trees, and it is difficult to find them. In parts of Africa, though, people and animals looking for honey have a strange and unexpected helper - a little bird called a honey guide.

The honey guide does not actually like honey, but it does like the wax in the bees’ honeycomb. The little bird cannot reach this wax, which is deep inside the bees’ nest. So when it finds a suitable nest, it looks for someone to help it. The honey guide gives a loud cry that attracts the attention of both passing animals and people. Once it has their attention, it flies through the forest, constantly waiting for the curious animal or person as it leads them to the nest. When they finally arrive at the nest, the follower reaches in to get at the delicious honey as the bird patiently waits and watches. Some of the honey and the wax always falls to the ground, and this is when the honey guide takes its share.

Scientists do not know how the honey guide digests the wax, but it is very determined in its efforts to get it. The birds seem to be able to smell wax from a long distance away. They will quickly arrive whenever a local beekeeper is taking honey from his beehives.

If a person follows a honey guide to a nest, the bird is especially sure of getting a good share. Tribesmen in Africa are very grateful to the honey guide for leading them to good sources of honey, but they are also afraid of the little bird. They believe that if they do not open a bees’ nest and leave some honeycomb for the honey guide, the next time the bird cries to them through the forest, it will lead them to a snake in revenge. So they should consider the share of the honey guide seriously.

【推荐2】A Brief History of Eyeglasses

When it comes to inventions that have entirely changed human existence, what comes to mind? Probably it’s the wheel, the printing press, maybe the refrigerator and definitely personal computers.     1    . Like eyeglasses, for example. Imagine a world without glasses—many of us would walk around knocking into things and driving our cars up onto the sidewalk. So who invented glasses, and how were they first made?

    2    . At some point in Italy between 1268 and 1289 someone came up with the idea, but the actual inventor remains mysterious. What we do know is that the earliest lenses were made from quartz(石英) and were usually set into bone, metal, or leather.     3    , they started making lenses out of glass.

Although glasses spread quickly throughout Europe and Asia, there was one major problem: keeping them on the wearer’s face.     4    . Ouch! It took nearly 400 years before opticians(验光师) figured out that accurate sidepieces resting on top of the ears might do the trick.

No history of glasses would be complete without some mention of Benjamin Franklin, who invented bifocals(双光眼镜) in the 1780s. Annoyed at having to constantly change glasses whenever he wanted to read or take in the sights while traveling, Franklin had his reading glasses cut in half and melted with his distance glasses.     5    .

【推荐3】On US TV shows, you may sometimes see rubber balls on people’s desks. These balls are known as “stress relief balls”. People can squeeze them when they feel stressed out. It’s believed that by concentrating on the act of squeezing, they can let go of the negative energy in their bodies.

“We don’t all get the big, sunny corner office, the super ergonomic (人体工程学的) chair, or four weeks of vacation at work. A focused activity helps take your mind off the problems of your day,” wrote Joseph Shrand, a professor at Harvard University, in his book Manage Your Stress.

Indeed, stress is a big problem for many people. Fortunately, we have many ways to deal with it. In fact, the rubber stress relief balls that are so popular today in the US are believed to date back to ancient China. Back in the Han Dynasty (BC 202-AD 220), soldiers used walnuts (核桃)to get rid of stress. By squeezing them during moments of anxiety, soldiers were able to calm themselves down before going into battle. And in the Ming Dynasty (AD 1368-1644), people started rotating (转动) the walnuts in their hands. Ordinary citizens — not just soldiers — developed the habit of rolling two walnuts, or balls made from iron or stone, around in their hands. This helped them relax as well.

And today, we have many gadgets (器具) and toys that are designed to reduce stress in addition to stress relief balls. One example is the popular fidget spinner (指尖陀螺), which keeps your hand busy with an easy task — spinning the gadget around. There’s also the fidget cube, which features different “gimmicks” (机关) on each side of the cube. You can click, spin, pull, push and rotate different parts of the cube.

These gadgets may look like simple toys, but perhaps we should take them more seriously than they are given credit for. “After all, the history of stress balls is a history of modern-day coping (应对),” reporter Nadia Berenstein wrote for Woolly magazine.

【推荐3】Living in a city is a well-known risk factor for developing a mental disorder, while living close to nature is largely beneficial for mental health and the brain. A central brain region, the amygdala (大脑杏仁核)involved in stress processing, has been shown to be less activated during stress in people living in rural areas, compared to those who live in cities, hinting at the potential benefits of nature. “But so far the hen-and-egg problem could not be resolved, namely whether nature actually caused the effects in the brain or whether the particular individuals chose to live in rural or urban regions,” says Sonja Sudimac.

To achieve causal evidence, the researchers from the group examined brain activity in regions involved in stress processing in 63 healthy volunteers before and after a one-hour walk in Grunewald forest or a shopping street with traffic in Berlin. The results revealed that activity in the amygdala decreased after the walk in nature, suggesting that nature elicits beneficial effects on brain regions related to stress.

“The results support the previously assumed positive relationship between nature and brain health, but this is the first study to prove the causal link. Interestingly, the brain activity after the urban walk in these regions remained stable and showed no increases, which argues against a commonly held view that urban exposure causes additional stress,” explains Simone Kühn, head of the group.

The authors show that nature has a positive impact on brain regions involved in stress processing and that it can already be observed after a one-hour walk. This contributes to the understanding of how our physical living environment affects brain and mental health. Even a short exposure to nature decreases amygdala activity, suggesting that a walk in nature could serve as a preventive measure against developing mental health problems and reducing the potentially disadvantageous impact of the city on the brain.

In order to investigate beneficial effects of nature in different populations and age groups, the researchers are currently working on a study examining how a one-hour walk in natural versus urban environments impacts stress in mothers and their babies.