Back in the 1860s, a British scientist named Henry Walter Bates noticed something interesting in the animal world: a kind of butterfly, Common Mormon, can change the pattern on its wings so that it looks like another butterfly species, the Common Rose, which is poisonous for birds to eat.

    Bates argued that animals develop this ability to protect themselves from being eaten. This theory had been widely accepted by scientists. But one question remains: how do these animals manage to do that?

    After more than 150 years, scientists are finally able to answer that question-it is all down to a gene(基因) called “doublesex", according to a study published on March 6 in the journal Nature.

    In fact, scientists have long known that genes are responsible for this useful ability. But until the new study, scientists hadn't been able to find out which genes in particular were responsible.

    Scientists at the University of Chicago compared the genetic structures of the Common Mormons that changed their wing patterns with those of ones that did not. And all the results pointed to a single gene, “doublesex”.

    This was much to the scientists' surprise. They used to expect that something as complex as this would be controlled by many different genes. For example, one gene would control the color of the upper part of the wing, one would do so for the lower part.

    However, the “doublesex” gene doesn't quite do everything by itself. Instead, it acts like a switch-it “tells” other genes to change the wing patterns. Isn't that clever?

    Scientists believe that this special ability of the “doublesex” gene on Common Mormon was developed throughout the long history of evolution. “The harmless species gains an advantage by resembling something predators(捕食者) avoid,” Sean Carroll, a scientist told Nature. “it was obvious evidence for natural selection.”

    Dieting to lose weight has become very popular in recent years. People have become more health conscious and try to take better care of their bodies by eating more healthily and exercising more regularly to lose any unnecessary fat that they may have.

    Not only are people being more careful about what they eat, they are also concerned with how they eat and how their meals are prepared. People are taking more time for each meal. Many avoid the so-called "plastic" fast-food hamburgers and choose to eat a salad or a sandwich of more healthful ingredients(营养成分) in a quiet restaurant with a more leisurely atmosphere. At home, they also try to take enough time to eat a relaxed dinner without phone or TV interruptions.

    While dieting may be viewed as beneficial, it has also become a serious problem for Americans, particularly for young women. Dieting for them has actually become a psychological addiction. They eat so little that they can lose as much as fifty percent of their total body weight, and although they look like skeletons, they still insist that they are fat.

    The current wave of exercising, dieting and the problems produced have caused many organizations to begin educating the public. Many schools, hospitals, health organizations, newspapers and magazines, for example, are offering classed, printing booklet articles and so on, to inform the public of the way to exercise and diet, of the dangers of dieting too rapidly, and of the places people can go for medical help if they find themselves on the road to "diet addiction".

    If you've been diagnosed with high blood pressure, you might be worried about taking medication to bring your numbers down. Chronic（慢性的） stress may contribute to high blood pressure. More research is needed to determine the effects of chronic stress on blood pressure. Occasional stress also can contribute to high blood pressure if you react to stress by eating unhealthy food, drinking alcohol or smoking.

    Take some time to think about what causes you to feel stressed, such as work, family, finances or illness. Once you know what's causing your stress, consider how you can rid or reduce stress. If you can't rid all of your stressors, you can at least handle them in a healthier way. Try to:

    Change your expectations. For example, plan your day and focus on your strengths. Avoid trying to do too much and learn to say no. Understand there are some things you can't change or control, but you can focus on how you react to them.

    Focus on issues you can control and make plans to solve them. If you are having an issue at work, try talking to your manager. If you are having a conflict with your kids or spouse, take steps to resolve it.

    Avoid stress triggers（诱因）. Try to avoid triggers when you can. For example, if rush-hour traffic on the way to work causes stress, try leaving earlier in the morning, or take public transportation. Avoid people who cause you stress if possible.

    Make time to relax and to do activities you enjoy. Take time each day to sit quietly and breathe deeply. Make time for enjoyable activities or hobbies in your schedule, such as taking a walk, cooking or volunteering.

    Practice gratitude. Expressing gratitude to others can help reduce your stress.

    If you successfully control your blood pressure with reducing stress, you might avoid, delay or reduce the need for medication.

    I grew up in New York my whole life. I studied in a perfect college that happened only to be an hour away from home. Then, about three weeks before the spring term was over, my parents told me we were moving to Arizona that summer. They asked me if I was going to transfer (转学) to another college. I said no. I was not going to change everything in my life at one time and I loved my college and all the amazing things I was doing there. It was my second home; I would not leave everything I knew at the same time since that was asking for trouble.

    I never imagined it would be this hard but, at the same time, the best thing that could have happened to me.

    When out in Arizona, life was hard. I didn't know anyone other than my family and friends. I couldn't bear the extreme heat. But it has helped me so much. I have started working on my writing. I also have time to work out in the gym. It has helped me realize that no matter where you are or who you know you can always find something that you enjoy.

    When back at school in New York, it was hard as well. Living close to home was my security blanket. If something was wrong I could get in my car and drive home and see my family. After my family moved to another city, I lacked security and was always controlled by anxiety. However, it helped me learn independence and forced me to be brave.

    I' m so thankful that I didn't transfer to a different school, which has given me the opportunity to go back and see best friends in my hometown. A year ago, I officially left my hometown for good. It has helped me grow and I am so thankful that I have had this experience. Now, when I graduate from college, I can go anywhere I want. I am no longer afraid to go out on my own into the world. The world is full of opportunities and pleasure and I can't wait to see where I will be next.

    Life often requires people to join in unpleasant situations. Rather often, these unpleasant situations do not happen on their own, but happen because of other people's actions and words. Fortunately, there are useful ways to deal with conflicts(冲突).

    The best way to solve a conflict is not to let it happen. Nothing useful comes out of a conflict. It is a total waste of time and energy for both sides and thus everyone should try his best to prevent conflict. To do this, you will need to learn the points of view your potential opponents (对手) share and the benefits of understanding people around you.

    If the conflict has already arisen, one of the best methods to settle disagreements is to treat the situation with humor. It does not mean, however, that you must ignore（忽视） your opponent's arguments and make jokes about them; it means that you should be in a friendly atmosphere, saying difficult-to-express things with a bit of humor. Humor will help you reduce anger and re-think problems to make them look easier to settle, and set your opponent's mind to working on a problem with you, not against you. This way, a conflict can become an opportunity for building a greater connection between you and your opponent.

    If the situation turns verbally abusive (恶语中伤), put a stop to it. Firmly but calmly state: "You're very angry right now and you're saying things you don't mean. I'm going to excuse myself. We can talk again after you calm down." Then leave the room or ask them to leave.

    I began cycling in 2004 when I was a poor student. It was dangerous, sure, but cycling is the fastest, cheapest point-to-point form of transport in Melbourne. I own a car now, but that's just for transporting the baby or groceries.

    I hate driving. So it's been quite encouraging watching the growth in cyclist numbers over the past decade. It is said that over 10,000 cyclists enter the CBD (Central Business District) each day, taking pressure off public transport. But as more people take to cycling as a way of transport, the number of cyclists seriously injured or killed keeps increasing. And that is a sign that our infrastructure (基础设施) is still not good enough.

    Melbourne was once a dream for cyclists—flat, long, wide roads, with plenty of paths along rivers. Now, cycling can be deadly, with roads taken up by cars. I have a friend who broke her back and was lucky to escape death and others with broken bones. In my time riding, I've been forced off the road by a truck, cut off by four-wheel drives, and told to get off the road. Drivers are a particularly rude to cyclists. And that's a sign of exactly one thing: inadequate infrastructure.

    We shouldn't need to be taught how to coexist in the same narrow space. Drivers and cyclists should be kept apart. Designing bike paths so riders are channelled between moving cars and parked cars is deadly. All it takes is one daydreaming driver to fling open the door and you are gone. That's what happened to the young university student James.

    This year, there are to be new cycling lanes (车道) built on Glen Road, where James died in 2010. But these lanes are not safe. Cyclists must still pass between two rows of cars.