If you need help herding some sheep or retrieving a stick, you can count on your canine companion(伴犬) because dogs always seem to be keen on lending a paw. But only if their partner is a person. When it comes to cooperating with one another, dogs are truly lost－and instead it’s wolves who’ve mastered the art of teamwork. That’s according to a study in the Proceedings of the National Academy of Sciences.

For thousands of years, humans have been breeding (饲养) dogs that can do all sorts of neat tricks. And because dogs aim to please, we’ve come to think that domestication(驯养) has somehow boosted dogs’ powers of cooperation. But researchers in Austria have been wondering whether that idea could be barking up the wrong tree. Because left to their own devices, dogs are bigger loners than wolves.

“So wolves live in closely knit family packs, they cooperate in raising the young, they also cooperate in hunting and in defending their territories. So they really have a strong dependence on cooperation in many aspects of their lives. In contrast, to this free ranging dogs actually forage (觅食) mostly by themselves. It’s only mothers that raise their young. And they do form packs but they tend to be somewhat more fluid(不固定的), if you want.”

That’s Sarah Marshall-Pescini of the Wolf Science Center at the University of Vienna. She and her colleagues decided to test dogs’ and wolves’ relative powers of cooperation. In the setup, a pair of animals—either two dogs or two wolves—is presented with a contraption(装置) that will allow the participants to access a plate of food—but only if both members of the team pull on the two ends of a rope at the same time.

A dozen wolves and 14 dogs took the challenge. And the results? The wolves ran circles around their doggie descendants. In some 400 attempts, the wolf teams scored a snack 100 times. Which may not sound all that impressive…until you compare it with the doggie duos, who, in nearly 500 trials, succeeded only twice.

Now, it’s not that dogs are less avid learners. Or that they turned tail and avoided the apparatus. Marshall-Pescini says the dogs were curious about the device.

“What seemed to be happening was they didn’t want to get into conflict with each other. So they wouldn’t both go and try things on it but rather took it in turns. And this really hindered(阻碍了) their capacity to cooperate.”So rather than step on each others’ toes, the dogs took turns bowing out, giving their teammate a chance at the plate. That show of social grace left the poor dogs with their tummies growling (饥肠辘辘). And no treat to wolf down.

(Source:Scientific American Oct. 25, 2017)

With its incredibly long neck, giraffe looks like no other animal on Earth. But how did this mammal come to get its famously huge neck? Well, scientists have been asking themselves this question for centuries.

The most commonly believed answer is that the massive neck – which measures on average 180 centimeters and weighs about 270 kilograms – evolved to allow the animal to reach the leaves of tall trees. British scientist Charles Darwin was one of the first people to propose this idea in the 1800s.

Yet, there are other theories.

According to a paper published in September in the Journal of Arid Environments, the giraffe’s neck evolved to increase its surface-area-to-volume ratio (表面积—体积比). Because the animal’s neck increases its body’s surface area, it makes it easier for it to keep cool, the paper’s authors wrote.

This phenomenon can be seen everywhere in nature. For example, this is why elephants have such large ears.

Meanwhile, some believe that competition is the answer.

A 1996 study by two South African zoologists argued that the male giraffes with the biggest necks are the ones who “win” access to females to reproduce, as they are better at fighting, meaning that their long necks are passed down through the generations.

So, it seems like there’s still no definite answer to the question.

Special trees that grow faster, fight pollution, produce better wood, and even sense chemical attacks are being planted by scientists in the US.

When 40 percent of Hawaii's US$14 million-a-year papaya (木瓜)industry was destroyed by a virus（病毒）five years ago, work began on creating genetically engineered(转基因的) trees.

Researchers successfully introduced seeds that were designed to resist the virus. Since then, more and more people have been testing genetically engineered trees.Some researchers put special bacteria into trees to help them grow faster and produce better wood. Others are trying to create trees that can clean polluted soil.Meanwhile fruit farmers are looking for trees that are strong enough to resist worms, and paper companies want trees that produce more wood and therefore more paper.

The Pentagon (五角大楼) even gave the researchers US$500,000 this year after they developed a pine tree that changes its colours if it senses a chemical attack..So far,the poplar, eucalyptus (杨树与桉树), apple and coffee trees are among those being engineered. All this can be done today because we have a better understanding of tree genomes(基因组).

However, some people fear that the genetically engineered trees will cause dangerous results. They are worried that the new trees will breed() with natural species and change the balance of the forest environment.

"It could be destructive," said Jim Diamond, an environmentalist. "Trees are what is left of our natural environment and home to many endangered species."

But researchers insist that science could give nature a fighting chance against both natural and man-made dangers.They hope to answer the critics by stopping the new trees from breeding, so their effect on the environment can be controlled.

Multitasking(多任务) affects the brain, research suggests, and it could be damaging your career. A new study found that men and women who frequently used several types of technology at the same time had less grey matter(灰质) in a key part of the brain.

University of Sussex researchers said: “Using mobile phones, laptops and other media devices at the same time could be changing the structure of our brains.” Worryingly, the part of the brain that shrinks is involved in processing emotion. The finding follows research which has linked multitasking with a poor attention, depression, anxiety and lower grades at school.

The researchers began by asking 75 healthy men and women how often they divided their attention between different types of technology. This could mean sending a text message while listening to music and checking emails, or speaking on the phone while watching TV and surfing the web. The volunteers were then given brain scans which showed they had less of grey matter. The study, published in the journal PLOS ONE, is the first to make a link between multitasking and the structure of the brain.

Researcher Kep Kee Loh said: “Media multitasking is becoming more common in our lives today and there is increasing concern about its influences on our cognition(认知) and social-emotional well-being.” He added that more research is needed to prove that multitasking shrinks the brain. This is because it is also possible that people with less grey matter are more drawn to using lots of devices at the same time. Scientists have previously proved brain structure can be changed on long exposure to new environments and experience. Other studies have shown that training---such as learning to juggle or taxi drivers learning the map of London -- can increase grey-matter densities(密度) in certain parts.

Shoppers could soon use their mobile phones to check how ripe fruit and vegetables are with an “X－ray vision” camera.

    The HyperCam, based on hyper spectral (高光谱的)imaging, can assess ripeness with 94 percent accuracy and could also be used to check for rotting produce in the fridge at home. Scientists at the University of Washington in Seattle managed to create a portable hyper spectral imaging camera that would cost $ 800 (£520).

     Hyper spectral imaging uses a broader range of the electromagnetic spectrum(电磁波)than an ordinary camera. The researchers are now working on a version of the technology that shoppers could download on to a mobile phone for about $ 50. The technology is already used in satellite imaging, building safety inspection, but is a highly costly process.

    Professor Shwetak Patel, of the University of Washington, said: “It’s not there yet but you can probably imagine putting it in a mobile phone. With this kind of camera you could go to the grocery store and know what produce to pick by looking underneath the skin and seeing if there’s anything wrong inside. It’s like having a food safety app in your pocket.”

    Neel Joshi, a Microsoft researcher, said: “Existing systems are costly and hard to use so we decided to create an inexpensive hyper spectral camera and explore these uses ourselves. After building the camera we just started pointing it at everyday objects, really anything we could find in our homes and offices, and we were amazed at all the hidden information it revealed.”

    Other potential uses for the technology include analyzing blood vessels and identifying individual people by the unique texture (纹理) of their skin.

Those who claim bananas are fattening argue that bananas cause the body to make lots of insulin(胰岛素), and insulin causes fat growth.

How much insulin we produce is related to how fast food becomes sugar in our bloodstream. How can you know if food makes a lot of sugar quickly? The glycemic index(血糖指数), or GI rating tells us.  Foods with GI scores above 75 are considered high-GI foods, leading to faster sugar development. Bananas have a GI of 62, which is considered low.

Weight loss can be a struggle for anyone, but it is especially hard for diabetics(糖尿病患者). A study looked at how the starch from unripe bananas affected the weight of a group of obese diabetics.  After four weeks of a diet high in bananas, diabetics lost significantly more weight than on a control diet. They also saw improvements in insulin sensitivity from the banana diet.

What’s more, bananas have been shown to cut risks of strokes, diabetes and cancers(Bananas are the most powerful fruit for lowering the risk of kidney cancer.). Bananas are also a rich source of fiber, which has been shown to help weight loss. Bananas that still have some green on the skin are even higher in fiber.

Skins from green bananas can be taken and, after removing the stem and dark tip, cut into small pieces 2－3 inches long and 1/2 inch wide. These pieces can be made into a tea or added to a dish. When you eat the skins, be sure you are eating organic bananas. The flesh of regular bananas is low in pesticides, but the skins are not.

Your house may have an effect on your figure. Experts say the way you design your home could play a role in whether you pack on the pounds or keep them off. You can make your environment work for you instead of against you. Here are some ways to turn your home into part of diet plan.

Open the curtains and turn up the lights. Dark environments are more likely to encourage overeating, for people are often less self-conscious(难为情)when they’re in poorly lit places----and so more likely to eat lots of food. If your home doesn’t have enough window light, get more lamps and flood the place with brightness.

Mind the colors. Research suggests warm colors fuel our appetites. In one study, people who ate meals in a blue room consumed 33 percent less than those in a yellow or red room. Warm colors like yellow make food appear more appetizing, while cold colors make us feel less hungry. So when it’s time to repaint, go blue.

Don’t forget the clock----or the radio. People who eat slowly tend to consume about 70 fewer calories (卡路里) per meal than those who rush through their meals. Begin keeping track of the time, and try to make dinner last at least 30 minutes. And while you’re at it, actually sit down to eat. If you need some help slowing down, turn on relaxing music. It makes you less likely to rush through a meal.

Downsize the dishes. Big serving bowls and plates can easily make us fat. We eat about 22 percent more when using a 12-inch plate instead of a 10-inch plate. When we choose a large spoon over a smaller one ,total intake (摄入) jumps by 14 percent. And we’ll pour about 30 percent more liquid into a short, wide glass than a tall, skinny glass.

     Now satellites are helping to forecast（预报）the weather. They are in space, and they can reach any part of the world. The satellites take pictures of the atmosphere（大气）, because this is where the weather forms（形成）. They send these pictures to the weather stations. So meteorologists（气象学家）can see the weather of any part of the world. From the pictures, the scientists can often say how the weather will change.

       Today, nearly five hundred weather stations in sixty countries receive satellite pictures. When they receive new pictures, the meteorologists compare（比较）them with earlier ones. Perhaps they may find that the clouds have changed during the last few hours. This may mean that the weather on the ground may soon change, too. In their next weather forecast, the meteorologists can say this.

         So the weather satellites are a great help to the meteorologists. Before satellites were invented, the scientists could forecast the weather for about 24 or 48 hours. Now they can make good forecasts for three or five days. Soon, perhaps, they may be able to forecast the weather for a week or more ahead（提前）.