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    When people first walked across the Bering Land Bridge thousands of years ago, dogs were by their sides, according to a study published in the journal Science.

    Robert Wayne of the University of California, Los Angeles, and Jennifer Leonard of the Smithsonian Institute, used DNA material—some of it unearthed by miners in Alaska—to conclude that today's domestic dog originated in Asia and accompanied the first humans to the New World about 10,000 to 15,000 years ago. Wayne suggests that man's best friend may have enabled the tough journey from Asia into North America. “Dogs may have been the reason people made it across the land bridge,” said Wayne. “They can pull things, carry things, defend you from fierce animals, and they're useful to eat.”

    Researchers have agreed that today's dog is the result of the domestication(驯化) of wolves thousands of years ago. Before this recent study, a common thought about the precise origin of North America's domestic dog was that Natives domesticated local wolves, the descendents(后代) of which now live with people in Alaska, Canada, and the Lower 48.

    Dog remains from a Fairbanks-area gold mine helped the scientists reach their conclusion. Leonard, an evolutionary biologist, collected DNA from 11 bones of ancient dogs that were locked in permafrost(永冻层) until Fairbanks miners uncovered them in the 1920s. The miners donated the preserved bones to the American Museum of Natural History in New York City, where they remained untouched for more than 70 years. After borrowing the bones from the museum, Leonard and her colleagues used radiocarbon techniques to find the age of the Alaska dogs. They found the dogs all lived between the years of 1450 and 1675 A.D., before Vitus Bering and Aleksey Chirikov who were the first known Europeans to view Alaska in 1741. The bones of dogs that wandered the Fairbanks area centuries ago should therefore be the remains of “pure native American dogs,” Leonard said. The DNA of the Fairbanks dogs would also expose whether they were the descendents of wolves from North America.

    Along with the Fairbanks samples, the researchers collected DNA from bones of 37 dog specimens(标本) from Mexico, Peru, and Bolivia that existed before the arrival of Columbus. In the case of both the Alaska dogs and the dogs from Latin America, the researchers found that they shared the most genetic material with gray wolves of Europe and Asia. This supports the idea of domestic dogs entering the New World with the first human explorers who wandered east over the land bridge.

    Leonard and Wayne's study suggests that dogs joined the first humans that made the adventure across the Bering Land Bridge to slowly populate the Americas. Wayne thinks the dogs that made the trip must have provided some excellent service to their human companions or they would not have been brought along. “Dogs must have been useful because they were expensive to keep,” Wayne said. “They didn't feed on mice; they fed on meat, which was a very guarded resource.”

    I climbed Kilimanjaro with Lava Expeditions (探险队) during the rainy season.

    I flew to Nairobi in Kenya and spent several days there. At my hotel in Nairobi I met the rest of the group with whom I would spend the next week. We all travelled on the bus together for a 6-hour journey into Tanzania and then Arusha, a quiet town.

    After we arrived at our hotel in Arusha, we had dinner and a few drinks. Then we were introduced to more members including Taddeus Minja, the main guide, who was very experienced — climbing Kilimanjaro runs through the generations (代) of his family.

    The next day the Lava Expeditions members checked if we had the correct and enough clothing for our expedition on Kilimanjaro. Only one person needed to bring more clothes.

    After that we set off, walking in the rain through the beauty of the rainforest, all the way to the first camp. I was happy the next few days as the view was so wonderful and changed every day. I suffered a little during the trip and I felt so tired. But the members of Lava Expeditions provided me with lots of encouragement, which was one of the best memories. Finally we reached the top of Kilimanjaro in bright blue skies.

I felt excited about climbing Kilimanjaro and the feeling didn't change during my trip. Lava Expeditions looked after me so well that I was deeply thankful for their help.

    Have you ever noticed that the more you have the more you want? Let's face it. Thinking our life is good enough doesn't come naturally to many people. When we have high expectations of everything in life we will run into disappointment. Only when we are aware that needs are different from desires can we live with satisfaction. Here are a few ideas to help you be happier with what you have and who you are.

    Focus on what you are thankful for. Most people want things to be better than they are, or when things are going well, we forget to appreciate what we have. Learn to reflect on how much better things are than they could be. Focus on what you are thankful for. Write down 5 things you are grateful for right now.

    When we hold onto regrets from decisions we have made, it can really poison our well-being. Many people regret something they can no longer change, which ends up holding them back from moving forward in a more positive manner. What happened in the past is done and gone, so work to stay present and be mindful of the current moment to find more joy and fulfillment.

    When we use other people as the measuring stick for our personal success and quality of life we are likely to be less satisfied. Social comparisons can provide useful information when we try to learn from others, but they also hold our perspective in a discontented position. Compare yourself less with others so you can be satisfied more.

    When you are focused on your big ambitions and future goals you might elide the daily pleasures that surround you. Learn to slow down and absorb the wonder and beauty around you. Stay present and focus on the task you're undertaking at the moment. Don't let the life pass you by because you're always on the go and distracted by ambition.

    Practice looking at life through the lens of contentment and it will become more natural.

    Kung fu is one of the most popular topics of discussion among foreigners talking about China. As a discipline of kung fu with the largest number of practitioners in China, Tai Chi is gaining popularity worldwide. Tai Chi is sweeping the world thanks to its deep cultural roots and the health benefits coming from practicing it.

    The philosophy of Tai Chi features the concept of yin and yang, which is typical of Confucianism and Taoism. Tai Chi also takes in ideas from traditional Chinese medicine, including anatomy (解剖学) and physiology (生理学). It is a practice that couples hardness with softness, and it is a perfect example of traditional Chinese culture.

    Through lasting practice, learners begin to feel the positive impact (影响) of Tai Chi on their health. Unlike kung fu practices that focus on attacking and defending against enemies, Tai Chi focuses more on shaping good characters and keeping fit. By practicing Tai Chi, people will feel an improvement in their physical and psychological health by promoting a balance between yin and yang within their bodies. This is similar to Western medicine's improving people's self-healing ability and immune system.

    Tai Chi is playing an important role in presenting Chinese culture to the rest of the world, acting like a bridge between China and other countries. Recent years have seen a lot of international communication on Tai Chi. In provinces like Hebei, Henan, Shanxi and Shaanxi, where Tai Chi teaching and learning are particularly active, local governments and non-governmental institutions often organize activities and competitions for learners and fans to attend and participate in. Large sporting events hosted by China such as the Asian Games and Olympics have featured Tai Chi performances or contests. These activities have opened a window for the outside world to know more about Tai Chi, paving the way for its overseas wide spread.

    Today, Tai Chi not only belongs to China, but also to the whole world and to everyone who loves it.

    Humans' invention of zero was vital for modern mathematics and science, but we're not the only species to consider “nothing” a number. Parrots and monkeys understand the concept of zero, and now bees have joined the club, too.

    Honey bees are known to have some numerical skills such as the ability to count to four, which may come in handy when keeping track of landmarks in their environment. To see whether these abilities extended to understanding zero, researchers trained 10 bees to identify the smaller of two numbers. Across a series of trials, they showed the insects two different pictures displaying a few black shapes on a white background. If the bees flew to the picture with the smaller number of shapes, they were given delicious sugar water, but if they flew toward the larger number, they were punished with bitter-tasting food.

    Once the bees had learned to consistently make the correct choice, the researchers gave them a new choice: a white background containing no shapes at all. Even though the bees had never seen an empty picture before, 64% of the time they chose it rather than a picture containing two or three shapes, the authors report today in Science. This suggests that the insects understood that “zero” is less than two or three. And they weren't just going for the empty picture because it was new and interesting. Another group of bees trained to always choose the larger number tended to pick the nonzero image in this test.

    In further experiments, the researchers showed that bees' understanding of zero was even more complex: for example, they were able to distinguish between one and zero-a challenge even for some other members of the zero club. Advanced numerical abilities like this could give animals an evolutionary advantage, helping them keep track of predators（捕食者）and food sources. And if an insect can display such a thorough grasp of the number zero, write the researchers, then this ability may be more common in the animal kingdom than we think.

It was a typical weekend for Mitch White and his friends. They were out celebrating a bachelor party, sailing the peaceful waters of the Minnesota River. They never expected that this single party would transform from a relaxed canoe trip into a painful rescue mission. With the sun setting, an unexpected bark changed everything.

Led by Mitch White, the soon-to-be-married man, they searched for the source of the sound along the banks of the river. Suddenly, a weak cry for help came from the mud. They were surprised to find that the head of a 13-year-old St. Bernard named Ed was barely visible in the thick mud. Mitch said, "The dog wasn't moving on its own, so we should feed it and give it water. " The dog looked like i had used all its strength.

The men took up their oars（桨） and began digging, their festive mood giving way to a focused rescue mission. It took them more than half an hour to free the trapped dog as it was already breathing very feebly after possibly being trapped for 24 hours. When they got the poor fellow out of the mud, he couldn't walk, so they carried him back to the house. Back home with his owner, George Niskanen, Ed began his slow restoration-a happy ending to a dangerous adventure. George was thankful to the bachelor party heroes.

Now, the people of Carver, Minnesota, have new heroes to cheer for. Indeed, this incredible act of bravery and compassion redefined the meaning of a bachelor party. It became a heroic tale of humanity, friendship, and the instinct（本能）to do what's right.