Have you ever considered why you begin yawning too when you see someone yawn? Or how hard it is to be among people laughing and not laugh yourself? Well, apparently it's because we have mirror neurons (神经元）in our brains.

    Put simply, the existence of mirror neurons suggests that every time we see someone else do something, our brains imitate it whether or not we actually perform the same action. This explains a great deal about how, we learn to smile, talk, walk, dance or play sports. But the idea goes further: mirror neurons not only appear to explain physical actions, they also tell us that there is a biological basis for the way we understand other people.

    Mirror neurons can undoubtedly be found all over our brains, but especially in the areas which relate to our ability to use languages, and to understand how other people feel. Researchers have found that mirror neurons relate strongly to language. A group of researchers discovered that if they gave people sentences to listen to ( for example: “The hand took hold of the ball” ) , the same mirror neurons were triggered as when the action was actually performed (in this example, actually taking hold of a ball).

    Any problems with mirror neurons may well result in problems with behavior. Much research suggests that people with social and behavioral problems have mirror neurons which are not fully functioning. However, it is not yet known exactly how these discoveries might help find treatments for social disorders.

    Research into mirror neurons seems to provide us with even more information regarding how humans behave and interact. Indeed, it may turn out to be the equivalent (相等物）for neuroscience of what Einstein's theory of relativity was for physics. And the next time you feel the urge to cough in the cinema when someone else does — well, perhaps you'll understand why.

    After years of heated debate, gray wolves were reintroduced to Yellowstone National Park. Fourteen wolves were caught in Canada and transported to the park. By last year, the Yellowstone wolf population had grown to more than 170 wolves.

    Gray wolves once were seen here and there in the Yellowstone area and much of the continental United States, but they were gradually displaced by human development. By the 1920s, wolves had practically disappeared from the Yellowstone area. They went farther north into the deep forests of Canada, where there were fewer humans around.

    The disappearance of the wolves had many unexpected results. Deer and elk populations — major food sources (来源) for the wolf – grew rapidly. These animals consumed large amounts of vegetation (植被), which reduced plant diversity in the park. In the absence of wolves, coyote populations also grew quickly. The coyotes killed a large percentage of the park's red foxes, and completely drove away the park's beavers.

    As early as 1966, biologists asked the government to consider reintroducing wolves to Yellowstone Park. They hoped that wolves would be able to control the elk and coyote problems. Many farmers opposed the plan because they feared that wolves would kill their farm animals or pets.

    The government spent nearly 30 years coming up with a plan to reintroduce the wolvers. The U.S. Fish and Wildlife Service carefully monitors and manages the wolf packs in Yellowstone. Today, the debate continues over how well the gray wolf is fitting in at Yellowstone .Elk, deer, and coyote populations are down, while beavers and red fores have made a comeback. The Yellowstone wolf project has been a valuable experiment to help biologists decide whether to reintroduce wolves to other parts of the country as well.

    With only about 1,000 pandas left in the world, China is desperately trying to clone (克隆) the animal and save the endangered species (物种). That's a move similar to what a Texas A & M University researchers have been undertaking for the past five years in a project called "Noah's Ark".

    Noah's Ark is aimed at collecting eggs, embryos(胚胎), semen and DNA of endangered animals and storing them in liquid nitrogen. If certain species should become extinct, Dr. Duane Kraemer, a professor in Texas A& M's College of Veterinary Medicine, says there would be enough of the basic building blocks to reintroduce the species in the future.

    It is estimated that as many as 2,000 species of mammals, birds reptiles will become extinct in over 100 years. The panda, native only to China, is in danger of becoming extinct in the next 25 years.

    This week, Chinese scientists said they grew an embryo by introducing cells from a dead female panda into the egg cells of a Japanese white rabbit. They are now trying to implant the embryo into a host animal.

    The entire procedure could take from three to five years to complete.

    "The nuclear transfer (核子移植) of one species to another is not easy, and the lack of available (capable of being used) panda eggs could be a major problem," Kraemer believes. "They will probably have to do several hundred transfers to result in one pregnancy (having a baby). It takes a long time and ifs difficult, but this could be groundbreaking science if it works. They are certainly not putting any live pandas at risk, so it is worth the effort, adds Kraemer, who is one of the leaders of the Project at Texas A& M, the first-ever attempt at cloning a dog.

    "They are trying to do something that's never been done, and this is very similar to our work in Noah's Ark. We're both trying to save animals that face extinction. I certainly appreciate their effort and there's a lot we can learn from what they are attempting to do. It's a research that is very much needed."

    Sports can help you keep fit and get in touch with nature. However, whether you are on the mountains, in the waves, or on the grassland, you should be aware that your sport of choice might have great influence on the environment.

    Some sports are resource-hungry. Golf, as you may know, eats up not only large areas of countryside, but also tons of water. Besides, all sorts of chemicals and huge amounts of energy are used to keep its courses（球场）in good condition. This causes major environmental effects. For example, in the dry regions of Portugal and Spain, golf is often held responsible for serious water shortage in some local areas.

    There are many environment-friendly sports. Power walking is one of them that you could take up today. You don't need any special equipment except a good pair of shoes; and you don't have to worry about resources and your purse. Simple and free, power walking can also keep you fit. If you walk regularly, it will be good for your heart and bones. Experts say that 20 minutes of power walking daily can make you feel less anxious, sleep well and have better weight control.

    Whatever sport you take up, you can make it greener by using environment-friendly equipment and buying products made from recycled materials. But the final goal should be "green gyms". They are better replacements（代替物）for traditional health clubs and modern sports centers. Members of green gyms play sports outdoors, in the countryside or other open spaces. There is no special requirement for you to start your membership. And best of all, it's free.

    Elephants might be the most well-known and well-loved animal in African wildlife. But conservation (保护) of the African elephant still faces special difficulties. While the elephant population is half of what it was 40 years ago, some areas of Africa have more elephants than populated areas can support. That's why AWF scientists are studying elephant behavior, protecting habitats and finding ways for humans to live peacefully with elephants in Africa.

    Years ago, overhunting and the ivory trade were the biggest threats to elephants' survival. Luckily, ivory bans (禁令), hunting rules and protected areas protect elephants from these dangers today.

    The 21st century brings a different challenge to elephant conservation—land-use. Elephants walk across borders and outside parks and other protected areas. So they often destroy crops, causing conflicts (冲突) between local farmers and these big animals.

    Successful conservation strategies must allow elephants to walk freely in their natural habitats while reducing conflicts between elephants and local people.

    AWF researchers are searching for a way to give both elephants and people the space they need. The AWF is collecting information on elephant habitats and behavior. The information they gather will help to develop the widest possible space for elephants.

    The AWF is helping elephants by protecting their habitats. And they also work with local farmers to improve their life in order to encourage them to protect rather than destroy elephants.

    Petrol and diesel cars may still dominate our roads, but their days are numbered. A recent university study found that current electric cars could be used for 87 per cent of daily car journeys in the US. That figure could rise to 98 per cent by 2020.

One hurdle to the widespread adoption of electric cars has been ‘range anxiety'— drivers' concerns about running out of juice on a journey. While petrol stations are conveniently located across national road systems, the necessary network of electric charging stations is still being developed. That said, charging points are becoming increasingly common throughout the USA.

    Attitudes towards electric vehicles have changed quite considerably over the last few years. Not that long ago, electric cars were met with distrust, and their large price tags drove customers away. Thanks to improvements in battery capacity, recharging times, performance and price, the current generation of electric cars are starting to persuade critics. Plug-in cars will soon give internal combustion engine models a run for their money.

    As well as advancements on the road, electric vehicles are taking to the seas and skies. Electric boats are among the oldest methods of electric travel, having enjoyed several decades of popularity from the late 19th to the early 20th century before petrol-powered outboard motors took over. Now, the global drive for renewable energy sources is bringing electric boats back. Steps towards electric air travel are also being made, with Airbus and NASA among the organizations developing and testing battery powered planes. The experiments could soon make commercial electric flight a reality.

    Electric vehicles do not produce any emissions. Were the US to act on the study's findings and replace 87 per cent of its cars with electric vehicles, it would reduce the national demand for petrol by 61 per cent. However, because of the production processes and the generation of electricity required to charge these vehicles, they cannot claim to be completely emission-free. That said, as many countries continue to increase their use of renewable energy sources, electric vehicles will become even cleaner.