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.

    You're rushing to work and a man ahead of you falls down on the sidewalk. Do you stop to help? In a study of by-standers, it was found that some people keep on walking.

    "There is a tendency to decide that no action is needed," says a psychologist, "In order to take action, you have to work against them." Here are some common thoughts that stop you from helping.

    ●Why should I be the one? I'm probably not the most able person in this crowd. You might think someone older or with more medical knowledge should offer assistance.

    ●What if he doesn't really need my help? The fear of embarrassment is powerful; no one wants to risk looking foolish in front of others.

    ●No one else looks concerned. We can follow the people around us, but most people tend to hold back their emotions in public.

    "If you spot trouble and find yourself explaining inaction, force yourself to stop and evaluate the situation instead of walking on," says the psychologist. "Then retry to involve other people; you don't have to take on the entire responsibility of being helpful. Sometimes it's just a matter of turning to the person next to you and saying, 'It looks like we should do something.' Or asking someone if an ambulance has been called and, if not, to call for one. Once you take action, most people will follow you."

    Young sunflowers turn and swing every day. New findings add to evidence that the plants are animal-like.

    Harmer, a professor in the University of California at Davis, Department of Plant Biology, carried out a series of experiments on sunflowers in the field, in pots outdoors and in indoor growth chambers.

    By staking plants so that they could not move, Harmer showed that he could destroy their ability to track the sun. He also noticed that sunflowers prevented from moving were not as tough and leafy as those that were free to move. When plants were moved indoor with a settled overhead light, they continued to swing back and forth for a few days.

    The indoor plants did start tracking the “sun” again when the apparent source of lighting was moved across the room. The plants could reliably track the movement and return at night when the artificial day was close to a 24-hour cycle, but not when it was closer to 30 hours.

    When sunflowers track the sun, the east sides of their stems grew more rapidly than the west sides. At night, the west sides grew faster as the stem swung the other way. The team identified a number of genes that were expressed at higher levels on the sunward side of the plant during the day or on the other side at night. A plant growth-regulating hormone (激素), called auxin, appears to be a key driver.

    The “dance” to the sun cycle obviously slows when the sunflower matures (成熟) and its flowers open up. At that point, the plants stop moving during the day and settle down facing the sun in the east.

    “Bees like warm flowers.” Harmer said, adding that the bees are cold-blooded, so landing on a warm flower saves them energy and perhaps feels really good.

    “The morning warmth changes the flowers in a way to make them more appealing to insects, perhaps causing them to release more attractive scents earlier in the day.” he said “We're currently testing this idea.”

    An 18-year-old US girl gained unexpected appreciation and a surprise after she gave “extra help” to an elderly man in the restaurant she was working.

    It's social media that made her seemingly small action go viral and brought her appreciation from hundreds of thousands of strangers and a scholarship to Texas Southern University.

    The heroine Evoni Williams has reportedly been working full-time to earn money for further study in a restaurant in La Marque, Texas，the United States. It was last week when an old man named Adrian Charpentier asked for help to chop his ham for his hands were weak because of illness. On that busy morning when she had loads of work on shoulder, Williams helped the man without hesitation. The moment she was leaning over the counter and cutting the ham was shot by a customer known as Laura Wolf.

    Wolf posted the picture on the Internet and wrote, “I'm thankful to have seen this act of kindness and caring at the start of my day while everything in this world seems so negative. If we could all be like this waitress and take time to offer a helping hand…” According to local reports, Wolf didn't know Williams, neither did Williams know her act was shot and shared on the web. However, the small act of kindness soon accumulated its own power on and outside the Internet.

    Besides praise from netizens and media reports across the United States, a 16000-dollar scholarship to Texas Southern University was recently granted to Williams to support her study plan on business management.

    “We wanted to reward Evoni's act of kindness and let her know that good deeds do not go unnoticed,” said Melinda Spaulding, an administrator at Texas Southern University.

    The Notre Dame fire has been put out, but its spire and a large portion of its wooden roof have been damaged. The terrible destruction causes a sudden sharp pain to people around the world. On Chinese social media network Wechat a common comment on the disaster is: "What a pity that we cannot see the damaged parts of the wonder anymore."

    But the good news is that there is at least one way of seeing them, namely via a video game called Assassin's Creed: Unity. In this game, the player can travel to one city after another and enter the buildings exactly like what they are in reality, and see Notre Dame as it was before the fire. Further, with virtual reality technology, which is already quite mature, one can even look around the undamaged Notre Dame as if it is still there. Maybe digital technology could help to better protect architectural cultural heritage.

    The idea of digitizing ancient buildings, making digital models of them so their data can be saved, dates back to the 1990s and the necessary technology has continued to advance since then. By scanning the ancient buildings with lasers, building 3D models with multiple images, as well as measuring everything precisely, engineers can make a copy as accurate as the real one.

    As computers and smartphones are hugely popular, the digital replica（复制品）has great use value  First, it allows tourists to feel the cultural relics without touching them, which helps protect them. The virtual tour of Dunhuang Grottoes in Gansu Province is a good example of this as tourists can view the paintings without standing near them. Furthermore, it can make the digitized cultural relics more famous by spreading awareness about them via the Internet. In 2000, a virtual tour of the Great Wall became very popular at the Hannover World Expo, which increased the number of foreign tourists visiting the site in the following years. Above all, it preserves all the information of the cultural relics. Even if the original ones are damaged one day, people can still know what they were like and can build a replica if desired.

    Of course, however precise a model is, it is not the original. Time is the biggest threat to a country's architectural heritage, which will always become ruins with the passing of time. Maybe we will have better technologies in the future, but the digital technology offers a practical way to preserve architectural cultural heritage at the moment.

    Some people say summer is the time when teachers should get more pay. But not everyone is grateful to teachers for keeping kids occupied (无空闲的) between August and June: Washington state representative Liz Pike has written a Facebook post, titled "A life in the day of a WA state representative," and responded to teachers' complaints of rising costs of living. The post has received criticism for being anti-teacher. After reading her post, I feel that Liz Pike should rethink her criticism of public school teaching and avoid comparing it to the private school.

    Many of us teachers would certainly like teaching to be more like the private school. We see nothing wrong with fair pay for fair performance. In fact, performance is the name of the game. With standardized testing popular throughout K-12 education, teachers are some of the most analyzed and performance-measured employees in the United States. Liz Pike is very angry that teachers want raises even while test scores are dropping. Well, how are we supposed to have discipline (纪律) in the classroom when our hands are tied and we can hardly do anything with naughty students or fail students who are not prepared to move on to the next grade?

    Teachers would love to be able to turn education around and improve student performance. But we can't, and we should not suffer for it. Unlike private school businesses, public schools cannot turn away "customers". A private school business serves customers who walk through the door of their own free will, while public schools have to educate students who only attend because courts say they must.

    She says those who are "uninspired" by a lack of a cost of living increase should give up teaching. Is this the message that she thinks should be sent to the students whose academic performance she claims (声称) to care so much about? That "if you love it you'll shut up and not stand up for yourself"? I think teachers should stand up for themselves and I also think supporting teachers can make teachers teach children how to stand up for themselves.