Have you ever wondered when dogs first became “man's best friend” and the world's favourite pet? If you have then you're not alone. When and where dogs first began living side-side with humans are questions that have stirred hot debate among scientists. There are a few hard facts that all agree on. These include that dogs were once wolves and they were the first animal to be domesticated(驯养) by humans. They came into lives some 15000 years ago, before the dawn of agriculture.

    Beyond that, there is little agreement. The earliest bones found that are unquestionable dogs and not wolves date from 14,000 years ago. However, 30,000-year-old skulls have been discovered in France and Belgium that are not pure wolf and some scientists think could be dogs.

    With such puzzling evidence, many scientists are now turning to DNA to find out when and where dogs were first domesticated. In one research project, tens of thousands of blood samples have been taken from street dogs around the world. The plan is to compare them with those of wolves. It's even possible to analyse DNA from ancient bones. Tiny pieces of the 30,000-year-old skulls mentioned earlier are currently being studied, and another DNA study has already shown that ancient dogs preserved in the Alaskan ice-fields evolved from Asian wolves, not American ones.

    Indeed, the ancient DNA may turn out to be more informative than the DNA of living dogs. Because dogs have accompanied humans around the world for thousands of years, their current distribution may tell us very little of their origins. This is why different groups of scientists believe that dogs variously originated in eastern Asia, Mongolia, Siberia, Europe or Africa.

    But why were the animals domesticated in the first place? The most recent theory is that dogs domesticated themselves, initially living in and around our ancient villages to eat any food thrown out. Today, this is a way of life still shared by three -quarters of a billion unowned dogs worldwide.

    If humans were truly at home under the light of the moon and stars，we would go in darkness happily，the midnight world as visible to us as it is to the vast number of nocturnal(夜间活动的) species on this planet. Instead，we are diurnal creatures, with eyes adapted to living in the sun's light. This is a basic evolutionary fact, even though most of us don't think of ourselves as diurnal beings. Yet it's the only way to explain what we've done to the night: We've engineered it to  receive us by filling it with light.

    The benefits of this kind of engineering come with consequences 一 called light pollution 一 whose effects scientists are only now beginning to study. Light pollution is largely the result of bad  lighting design，which allows artificial light to shine outward and upward into the sky. III-designed lighting washes out the darkness of night and completely changes the light levels 一 and light  rhythms — to which many forms of life, including, ourselves, have adapted. Wherever human light spills into the natural world, some aspect or life is affected .

    In most cities the sky looks as though it has been emptied of stars, leaving behind a vacant haze(霾) that mirrors our fear of the dark. We've grown so used to this orange haze that the original glory of an unlit nigh, - dark enough for the planet Venus to throw shadow on Earth, is wholly beyond our experience, beyond memory almost.

    We^'ve lit up the night as if it were an unoccupied country, when nothing could be further form the truth. Among mammals alone, the number of nocturnal species is astonishing, Light is a powerful biological force, and on many species it acts as a magnet(磁铁). The effect is so powerful that scientists speak of songbirds and seabirds being “captured” by searchlights on land or by the light from gas flares on marine oil platforms. Migrating at night, birds tend to collide with brightly lit tall buildings.

    Frogs living near brightly lit highways suffer nocturnal light levels that are as much as a million times righter than normal, throwing nearly every aspect of their behavior out of joint including most other creatures ,we do need darkness .Darkness is as essential to our biological welfare, to our internal clockwork, as light itself.

    Living in a glare of our making,we have cut ourselves off from our evolutionary and cultural heritage—the light of the stars and the rhythms of day and night .In a very real sense light pollution causes us to lose sight of our true place in the universe, to forget the scale of our being, which is best measured against the dimensions of a deep night with the Milky Way—the edge of our galaxy arching overhead.

    Anki has introduced Cozmo, a little robot powered by an advanced artificial intelligence. Cozmo promises to be for more interactive（互动的）than any toy robot.

Cozmo, which can lie in your hand, has a “brain”—technically its CPU—that can process data amazingly fast. In addition, Cozmo has a playful personality. He's designed to react to emotions and even ask users to play with him.

    Cozmo is not the first interactive toy to reach the market nor is it the first robot toy. What sets Cozmo apart from the other “smart toys” is that it has greater play value than those toys, which can become repetitious all too quickly.

    “Every interaction with Cozmo is different, so you do not put up with repetitive play patterns and responses typically found with other preprogrammed robots,” explained Anki spokesperson Peter Nguyen. Because it has functionality that is similar to that of video games, Cozmo also can receive regular updates, which could extend its playability. Still, Anki has designed this toy to be just that: a toy. It's not an advanced computerized robot. Its software is app-based.

    Cozmo lacks the “traditional” human-like robot form factor（要素）of legs, arms, and a head. But Cozmo does have an OLED screen/face with blue eyes, which in fact were designed to help it connect with its user.

    “I'm glad my kids are already raised,” said Roger L. Kay, analyst at Endpoint Technologies Associates. “Otherwise, they might become more antisocial if their relationship with Cozmo is more satisfying than those with real people,” said Kay. “Cozmo might encourage kids to learn more about technology or even inspire them to try programming and similar studies,” said Charles King, analyst at Pund-IT.

    Yet this technology does promise to be more than a toy. “It's a pretty cool invention and might have further applications, for example in elder care,” suggested Kay.

    These days, I walk down the steps leading toward the south end of the All England Club in Wimbledon, and still look for the Crow's Nest, a small green observation tower with an outer ladder that I used to climb on for a wide view of the grounds, but which has since been knocked down.

    The Crow's Nest was a particularly useful point, because it allowed a tennis writer to keep track of the action on as many as 10 outside courts at a time. At days end, reporters from different nations would share notes on what they had observed all over the grounds.

    Twenty-seven years later, the press room has touch screens that allow us to watch live videos from any court, and even go back to watch key moments in key matches long after they have finished. You could cover Wimbledon without leaving your seat. But that is a bit like spending all your time ordering room service and looking up fun facts on Wikipedia.

    More than at any other tennis tournament, there is also an appetite for stories that deal with the setting, the history and the traditions.

    If they change the price of the fish tacos (鱼肉卷饼) at the United States Open, it's not a story. If they change the price of the strawberries and cream, the signature treat at Wimbledon. It's time to email your editor using capital letters.

    The new retractable (可伸缩的) roof was put in place in 2009. Until then, you always had to have a rainy-day story in your notebook because there were no guarantees any matches would be played. Now tennis is a sure thing on Centre Court, which has made tennis reporters a bit less creative. But at least it guarantees us daily access to the most atmospheric place in the sport.

    So much has changed, but Centre Court remains true to its original spirit: more a theater than a stadium. Catching that feeling is part of covering Wimbledon, too.

    Everyone is welcome to visit our city Los Angeles (LA). I am sure you can do many things in Los Angeles with your kids.

    Fun at the Beach

    Thanks to its almost perfect weather all through the year, a visit to the beach is one of the best things to do when in Los Angeles with your kids. While they enjoy themselves nearby, you can simply lie back and have a good rest in the sun.

    Trip to Disneyland

    A trip to the City of Angels with your little angels is incomplete (不完整的) without a visit to the Magic Kingdom. The joy they'll feel from being around all those Disney characters that they know and love will light up your day, too.

    Visit to the Museum

    If you want to turn your stay in LA into an educational one for your kids, you should visit the museum. Starting with the Natural History Museum of Los Angeles County to the California Science Center, or even the Kidspace Children's Museum in Pasadena, you have many choices. I'm sure a visit to all these places will make your kids smarter.

    Visit to the University Studios Hollywood

    Your kids could get to see interesting things from some of the most popular movies ever. From the theme park of Jurassic Park to Wisteria Lane from the TV play Desperate Housewives, the Universal Studios Hollywood is a place that we all find wonderful.

    Hundreds of children are being treated for sleep problems in Wales every year. In some cases, babies, infants and teenagers have been admitted to hospital while in north Wales alone.

    The Children's Sleep Charity said many children were suffering from lack of sleep mainly because of technology use. Public Health Wales said sleep was as important to a child's health as healthy eating and exercise, and children with poor sleep patterns were more likely to be fat.

    Statistics obtained under the Freedom of Information Act by BBC Wales found at least 408 children have been admitted to hospitals across Wales suffering from sleep disorders since March 2013.

    Children aged between 0 and4 made up the highest number of inpatients (住院病人), with some newborns being treated for sleep-related problems from the day of birth.

    Vicki Dawson, who set up the Children's Sleep Charity (CSC), said sleepless nights were putting both children and parents in anxiety. "Their weight and growth may also be affected as well as their mental health," she said.

    Teachers said children showing signs of sleep shortage and tiredness in class were a concern as they couldn't concentrate for long periods.

    Psychologist Amy McClelland, of Sleep Wales, said a common problem was children being "over excited" and "not having the chance to relax property" before bed and families should get back to basics. "Think 1950s family home. Dinner as a family, read, chat, a film maybe, lights off and then bed." She added.