How do the world's only flying mammals communicate? Researchers have observed young bats adopting new “dialects” simply by hearing them repeatedly, making them one of the few animals known to have a capacity for vocal (声音的) learning. “These bats may help us clarify the evolution of speech acquisition (习得) skills,” says Yosef Prat, a PhD at Tel Aviv University (TAU).

    For one year, researchers raised 14 Egyptian fruit bat pups with their mothers in controlled area, exposing each young bat to two different vocalizations: the natural call of its mother and a separate recording that varied in pitch (音高) or frequency. They found that the pups in each group developed a dialect like the recording. “The general assumption in this field is that most animals develop their born vocalizations regardless of what they hear, and that human vocal learning abilities have developed during evolution,” says Mr Prat. “The finding that bats learn the common dialect in their rest place was unusual.”

    Scientists know little about the origin of spoken language, which is believed to have appeared in humans within the past 500,000 years. Dozens of theories attempt to explain the complexity of this skill, but none have done so conclusively.

    “Studying vocal communication and vocal learning in animal models is a very useful way to approach the problem,” says Olga Feher, an assistant professor at the University of Warwick in England.

    But animal vocalizations and human speech are very different things, says Jamin Pelkey, a professor at Ryerson University. “All species communicate. Unlike other animals, though, human beings are able to use sound patterns for functions that are far stranger—functions that are imaginative, theoretical, and critical. When speech is involved in these stranger functions, that is what we mean by spoken ‘language'.”

    When Johnnie Martin was in the second grade in high school, one day a psychologist of the school called him into his office.

    “Johnnie, I've made a very careful study of you. And I feel sorry to have to tell you… Though you have worked very hard, it has not helped. You're just not fit for it.”

    The boy buried his face in his hands, “This will be hard on my parents,” he said. “Their one idea is for me to be a college man.”

    The psychologist laid his hand on the boy's shoulder and said, “People have different kinds of talents. Some day you will find what your special gift is and when you do, you will make your parents very proud of you.”

    Johnnie never went back to school. Jobs were scarce in town, but he managed to keep busy mowing the lawns of the householders and puttering in their flowerbeds. Before long he discovered he had an eye for color.

    One day while he was downtown, he happened to notice a stretch of unused land behind the city hall. Chance or fate or whatever you may like to call it brought one of the town's aldermen（市政委员会委员）round the corner just at that moment. The boy said, “I can make a garden out of this dump, if you'll let me do it.”

    “The town's got no money for it,” said the alderman.

    “I don't want any money for it,” said the boy. “I just want to do it.”

    The alderman was shocked to find someone who did not want money. He took Johnnie into an office, and when the young man came out he had the authority to clean up the public eyesore. Before long the old dump became a little beautiful park.

    It was also a kind of show window for Johnnie. People saw the result of his skill and knew him as a natural landscape gardener.

    That was twenty-five years ago. Today Johnnie is the head of a successful business in landscape gardening. His aging parents are proud of Johnnie, for he is not only a success, but he has also made his part of the world a lovelier place to live in.

    Green tree ants are important builders in the rainforest. They're like the worker bees of the ant world. The native forest of Thala Beach Nature Reserve is the natural home of these insects.

    They climb all over the tree that contains their nest and protect it from enemies with great fierceness. The ants are often in the fruiting trees of Tropical North Queensland. When an animal tries to help themselves to some tasty fruit, they find themselves attacked by a powerful, frightening army of green tree ants! Their bite is not very painful but many ants attacking at the same time can be extremely uncomfortable.

    The nests are large and constructed by sticking the leaves at the end of branches together to create a home looking roughly like a globe. Most of the nest construction and weaving is conducted at night. A mature colony of green tree ants can hold as many as 100,000 to 500,000 workers and may include as many as 12 trees and contain as any as 150 nests. Green tree ant colonies have one queen and a colony can live up to eight years.

    However, the ants are so busy that they fail to spot a dishonest figure. There is a spider called the Salticid spider, or the jumping spider, as they are sometimes referred to, which has excellent eyesight and is only active during daylight, weaving a protective covering of silk to spend the night in. Interestingly, the Salticid spider does not look like a green tree ant. Instead, it chemically copies green tree ants' smell. Effectively pretending to be an ant, it goes into the green tree ants' nest, enters the nursery and feasts on their babies. Green tree ants don't have good eyesight and smell everything with their antennae (two long thin parts on an ant's head). Therefore, the ants think the spider is another ant and ignore its presence within the nest.

    Next time, as you wander around Thala's native forest, keep an eye out for these busy little creatures. Look up into the trees and you'll likely spot their nests.

    Are you an optimist? Do you look at your glass and see it as half full? Do you believe that every cloud has a silver lining and that generally things turn out for the best? Do you believe that if something is meant to be, it will be? If you reply "yes" to all of these questions, then you are an optimist. You probably are enthusiastic, cheerful and outgoing. You may well be successful at work and in love.

    But you may be misguided because things don't turn out for the best. You may believe that when one door closes another one opens (For example, you may fail to land a new job, but another chance will come around soon). Wrong. When one door closes, another door slams in your face. That's bitter reality.

    Now a book has been published which confirms what we pessimists(悲观者) have suspected all along. It's called The Positive Power of Defensive Pessimism. Its author argues that defensive pessimism can lead to positive results. Defensive pessimism is a strategy used to manage fear, anxiety and worry. Defensive pessimists prepare for things by setting low outcomes for themselves. They carefully consider everything that may go wrong and plan for ways to handle these problems. And this gives them a sense of control. Lawrence Sanno, a psychology professor, says, "What's interesting about defensive pessimists is that they tend to be very successful people, so their low opinion of the situation's outcomes is not realistic. They use it to motivate themselves to perform better."

    So far, so good. This is not rocket science. Defensive pessimists prepare carefully and consider what might go wrong, whether at work, on a date or even in a sports game. It makes sense to have a backup plan. There are many sayings in English urging caution. For example, "Don't put all your eggs in one basket", and "Don't count your chickens until they hatch." To have a confident and optimistic approach to life's problems is good. But listen to what Woody Alien, the American comedian says, "Confidence is what you have before you understand the problem."

    There are pros and cons to being an optimist and a pessimist. Don't feel bad if you see the glass half empty. You are a realist. But lighten up and hook up with someone who sees the same glass half full.

    Many years ago, Norman Cousins was seriously ill. He was given six months to live. His chance for recovery was 1 in 500.

    He could see the worry, depression and anger in his life contributed to his disease. He wondered, "If illness can be caused by negativity (消极性), can health be created by positivity (积极性)?" He decided to make an experiment of himself.

    Laughing was one of the most positive activities he knew. He watched all the funny movies he could find. He read funny stories. He asked his friends to call him whenever they said, heard or did something interesting.

    His pain was so great that he could not sleep. Laughing for 10 solid minutes, he found, relieved the pain for several hours so he could sleep. He fully recovered from his illness and lived another 20 happy and healthy years.

    Laughing is necessary to our health. If we're not well, laughing helps us get well; if we are well, laughing helps us stay that way. So, if you like laughing, do it as often as you can.

    Use whatever makes you laugh­movies, books, jokes or friends. The people around you may think you're strange, but sooner or later they'll join in even if they don't know what you're laughing about.

    It was a normal school day for senior Solymar Solis until an unexpected visitor arrived. Her dad, Sgt. Carlos Solis Melendez, surprised her by coming home early from Kuwait and visiting her unannounced at Spring Valley High School in South Carolina.

    After serving in Kuwait for nine months, Melendez returned home a week earlier than his daughter expected. He held balloons and flowers in a classroom as he sat at a student's desk to blend in with the crowd. "It came across my mind like, ‘How is she going to react?" he recalled the heartwarming moment. "Is she going to be happy and run to me and hug me, or cry? That was all going on through my mind."

    As unsuspecting Solymar entered the classroom, she was soon overcome with emotion, immediately bursting into tears and covering her mouth. She didn't talk. She was just crying. She was overwhelmed with everything. She thought it was a dream.

    Melendez was a single parent so while he was deployed (调动), he got his sister to live with his daughter. When he was coming back and talking to his sister, both of them came to the conclusion that they should do something special for his daughter. Melendez and his sister got in touch with the school, and they planned this whole being-in-the-classroom thing, and it turned out perfect.

    The two are very much looking forward to some good daddy-daughter time now that he's home. "It means everything," Melendez said of being able to surprise his daughter this way. "After all the sacrifices she's made, she deserves all the special arrangements and special occasions and celebrations. I'll do anything for my daughter. I believe I'm doing good parenting."