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.

    Even if trees cannot walk, they are still on the move.

    In parts of the Arctic, entire forests are moving northward. Across the Arctic, temperatures are rising faster than anywhere else in the world. As that happens, the tree line that marks where forests stop and the treeless tundra(冻土地带) starts has been shifting northward. Trees growing along the tree line must protect themselves from the cold wind. To do this, plants tend to grow horizontal(水平的) branches low to the ground. The energy it takes for trees to grow this way means they don't have enough energy to make seeds.

    But as Earth's climate has been warming, trees no longer have to just grow horizontally. Many can instead grow up toward the sky. This takes less energy. And with all the leftover energy. these trees have started producing more seeds. This happens especially in places where the white spruce(白云杉) grows.

    White spruce, which is a North American tree, is quite able to produce a lot of seeds, which can move long distances in the wind. When wind-blown seeds end up on the tundra beyond the tree line, they eventually can sprout(发芽) new trees. This explains how a forest can move. Of course, the process would work only if the tundra were warm enough. But in recent years, the whole planet has been warming.

    New trees will provide shelters for some snow, keeping the sun's rays from making the white surface disappear. Instead, the trees absorb the sun's heat. This warms the surrounding air. The extra warmth encourages even more trees to produce seeds. That further boosts a forest's ability to expand. In addition, more trees will trap more snow, preventing much of it from being blown away. Snow can trap heat in the soil below, which encourages trees to grow. The recent rise of temperature has helped more trees grow. The recent rise of temperatures has helped more trees grow past the tree line. People worry about impacts on the animals that depend on frozen conditions for food and shelter.

    I've been researching my family tree since 1998 ，and I've long been curious about DNA as a way to learn more about my roots. The technology has come a long way in the last decade, and it's become more affordable too. Finally, I went ahead and ordered a Y-DNA test.

    The results came in my email inbox from the DNA lab! When I logged in to see the results, there are 29 living people today with whom I share a common direct male ancestor in about the last 1,000 years. They live in Ireland, England, Scotland, South Africa, the United States and probably elsewhere.

    I had two close matches, and the rest were more distant. They both live in Ireland! What makes the connection  to these two men so interesting is that most Irish genealogical (族谱的)records were burned in fires in Dublin and don't exist today. Without them, it's hard to trace Irish roots any further back than the 1800s. I've written emails to both of them and hope to hear back!

    I did some more research on my Y-DNA and found my direct male ancestors were Celtics. They seem to have lived in Western Europe at the time of Ancient Rome. Migration patterns show that my DNA group likely originated in Western Asia, living there 20, 000 and 30, 000 years ago. There are relatives with similar DNA going thousands of years back in what is now Iran, India, Syria, Israel and Turkey.

    I was so excited by these results that I decided to trace my motherly line too. My DNA is already at the lab, so now I just have to wait another month or so, and I'm sure to find more interesting things.

    Every year, millions of people head to London's Trafalgar Square to see Nelson's Column, and the four lion statues that “guard” it. And last month, during the London Design Festival, a bright red lion sculpture was added to the collection.

    But this was more than just a statue: It had a large open mouth, with an LED screen inside it. At the same time, passersby could type in random words on a screen close to the lion, which were used to produce an AI-created poem. The most interesting part of the poems lies in their randomness, as the words that people choose to enter include many things, such as the time, the weather and their mood. In the daytime, the finished poem appeared on the LED screen, but at night, it was projected (投射) onto the lion's body and the famous Nelson's Column, in a 1ovely light display.

    Es Devlin, the sculpture's creator, was inspired by the history behind the four historic lion statues. Edwin Landseer, the designer of the lions, wanted them to look much more animated, but Queen Victoria refused his plan. This made Devlin wonder, "What if we could give a lion a poetic voice?" According to Devlin, although England has seen many poems about national identity in recent years, these works have been lacking imagination. "I wanted to make a piece that was poetic and collective" he told BBC News.

    After standing for almost 180 years, the purpose of Trafalgar Square has changed over the years. But thanks to the high-tech lion and its poetry, the square is standing the test of time.

    The light from the campfire brightened the darkness, but it could not prevent the damp cold of Dennis's Swamp (沼泽地) creeping into their bones. It was a strange place. Martin and Tom wished that they had not accepted Jack's dare. They liked camping, but not near this swamp.

    "So," Martin asked as they sat watching the hot coals. "How did this place get its name?"

    "Are you sure you want to hear it? It's a scary story," warned Jack.

    "Of course!" cried out Tom. "If there were anything to be scared of, you wouldn't have chosen this place!"

    "Ok, but don't say I didn't warn you," said Jack, and he began this tale.

    "Way back in time, a man called Dennis tried to start a farm here. He built that cottage over there to live in. In those days, the area looked quite different—it was covered with tall trees and the swamp was a crystal-clear river. After three hard years, Dennis had cleared several fields and planted crops. He was so proud of his success that he refused to listen to advice.

    "'You are clearing too much land,' warned one old man. 'The land is a living thing. It will hit back at you if you abuse it. '"

    "'Silly fool,' said Dennis to himself. 'If I clear more land, I can grow more crops. I'll become wealthier. He's just jealous!'"

    "Dennis continued to chop down trees. Small animals that relied on them for food and shelter were destroyed. He was so eager to expand his farm that he did not notice the river flowing slowly towards his door. He did not notice salt seeping to the surface of the land. He did not notice swamp plants choking all the native plants."

    "What happened?" Martin asked. It was growing colder. He trembled, twisting his body closer to the fire.

    "The land hit back—just as the old man warned," Jack shrugged. "Dennis disappeared. Old folks around here believe that swamp plants moved up from the river and dragged him underwater. His body was never found."

    "What a stupid story," laughed Tom. "Plants can't …" Before he had finished speaking, he screamed and fainted (晕倒). The other two boys jumped up with fright, staring at Tom. Suddenly, they burst out laughing. Some green swamp ivy (常春藤) had covered Tom's face. It was a while before Tom could appreciate the joke.