Can people change their skin color without suffering like pop king Michael Jackson? Perhaps yes. Scientists have found the gene that determines skin color.

    The gene comes in two versions, one of which is found in 99 percent of Europeans. The other is found in 93 to 100 percent of Africans, researchers at Pennsylvania State University report in the latest issue of Science.

    Scientists have changed the color of a dark-striped zebra-fish（斑马鱼） to uniform gold by inserting a version of the pigment (色素) gene into a young fish. As with humans, zebra-fish skin color is determined by pigment cells, which contain melanin (黑色素). The number, size and darkness of melanin per pigment cell determine skin color.

    It appears that, like the golden zebra-fish, light-skinned Europeans also have a mutation (变异) in the gene for melanin production. This results in less pigmented skin.

    However, Keith Cheng, leader of the research team, points out that the mutation is different in human and zebra-fish genes.

    Humans acquired dark skin in Africa about 1.5 million years ago to protect bodies from ultra-violet rays of the sun (太阳光紫外线), which can cause skin cancer.

    But when modern humans leave Africa to live in northern latitudes, they need more sunlight on their skin to produce vitamin D. So the related gene changes, according to Cheng.

    Asians have the same version of the gene as Africans, so they probably acquired their light skin through the action of some other gene that affects skin color, said Cheng.

    The new discovery could lead to medical treatments for skin cancer. It also could lead to research into ways to change skin color without damaging it like chemical treatment did on Michael Jackson.

    Children grow quickly, especially their feet. But many families cannot buy new shoes each time a child needs them. As a result, about 300 million children around the world go barefoot. Those children risk picking up diseases and parasites from the soil.

    Kenton Lee, an American man invented The Shoe That Grows. He explains, “It grows in three places: the front, on the side and on the back. It can last up to five years. The bottom is rubber like tire rubber. The top is just high-quality leather. ”

    Lee says he got the idea for the shoe while working as a volunteer in an orphanage in Kenya. “I just remember a little girl who wore a pair of small shoes. The shoes were so small that she had to cut open the front of her shoes to let her toes stick out. And I just remember thinking, wouldn't it be nice if there were a pair of shoes that could grow with her feet？”

    However, Lee says it was not easy to turn his idea into a reality. Finally, in 2009 Lee founded a non-profit organization called Because International. In the office of Because International, Lee keeps a pair of his own shoes to help him remember his promise.

    A pair of shoes, he says, gives more than protection. It gives a child self-worth and more chances to succeed. “Because it's a small thing that really does make a big difference to keep them healthy and happy and having more chances to succeed.”

    Kenton Lee adds that his goal is to help get The Shoe That Grows to as many children as he can around the world.

    In the famous fairy tale, Snow White eats the Queen's apple and falls victim to a curse(诅咒);in Shakespeare's novel, Romeo drinks the poison and dies; some ancient Chinese emperors took pellets(药丸)that contained mercury(水银), believing that it would make them immortal, but they died afterward.

    Poison(毒药) has long been an important ingredient in literature and history, and it seems to always be associated with evil, danger and death. But how much do you really know about poison?

    An exhibition, The Power of Poison, opened last month at the American Museum of Natural History in New York, intended to give the audience a more vivid understanding of poison.

    The museum tour starts in a rainforest setting, where you can see live examples of some of the most poisonous animals: caterpillars(毛毛虫), frogs and spiders. Golden poison frogs, for instance, aren't much bigger than a coin, but their skin is covered with a poison that can cut off the signaling power of your nerves, and a single frog has enough venom to kill 10 grown humans.

    "Poisons can be bad for some things," Michael Novacek, senior vice president of the museum, told NBC News. "Yet they can also be good for others."

    A poisonous chemical found in the yew tree is effective against cancer, which is what led to the invention of a cancer-fighting drug called Taxol.

    The benefits from natural poisons are not limited to just medicine. Believe it or not, many substances(物质)that we regularly ingest(摄入)-chili, coffee and chocolate-owe their special flavors or stimulating(提神的)effects to chemicals that plants make to poison insects.

    Martha had been working for Miller Laboratories for two years, but she was not happy there. Nothing significant had happened in the way of promotions or salary increases. Martha felt that her supervisor, a younger and less experienced person than she, did not like her. In fact, the supervisor often said unpleasant things to her.

    One day, while talking with her friend Maria, she mentioned how discouraged she was. Maria gave her the name of a cousin of hers who was director of Human Resources Department for a large chemical company. Martha called him the next day and set up an interview on her lunch hour.

    During the interview, Mr. Petri said, "You're just the kind of person we need here. You're being wasted in your other job. Give me a call in a day or two. I'm sure we can find a place for you in our organization." Martha was so happy that she almost danced out of the building.

    That afternoon, Ruth Kenny, her supervisor, saw that Martha had come in ten minutes late from her lunch hour and she said, "Oh, so you finally decided to come back to work today?"

    This was the last straw. She could not take another insult. Besides, Mr. Petri was right: she was being wasted in this job.

    "Look," she said angrily, "if you don't like the way I work, I don't need to stay here. I'll go where I'm appreciated! Goodbye!" She took up her things and stormed out of the office.

    That night she called Maria and told her what had happened and then asked Maria, "What do you think?"

    "Well," said Maria carefully, "are you sure about the other job?"

    "Well, not exactly, but..."

    Maria continued, "Will you be able to get a recommendation from Ms. Kenny if you need one?"

    "A recommendation?…from Ms. Kenny?" hesitated Martha, in a worried tone.

    "Martha, I hope you didn't burn your bridges," Maria said. "I think I would have handled it differently."

    By now you've probably heard about the "you're not special" speech, when English teacher David McCullough told graduating seniors at Wellesley High School: "Do not get the idea you're anything special, because you're not." Mothers and fathers present at the ceremony 一 and a whole lot of other parents across the Internet — took issue with McCullough's ego-puncturing (伤自尊的) words. But lost in the uproar (喧嚣)was something we really should be taking to heart: our young people actually have no idea whether they're particularly talented or accomplished or not. In our eagerness to elevate their self-esteem, we forgot to teach them how to realistically assess their own abilities, a crucial requirement for getting better at anything from math to music to sports. In fact, it's not just privileged high-school students: we all tend to view ourselves as above average.

    Such inflated self-judgments have been found in study after study and it's often exactly when we're least competent at a given task that we rate our performance most generously, in a 2006 study published in the journal Medical Education, for example, medical students who scored the lowest on an essay test were the most charitable in their self evaluations, while high-scoring students judged themselves much more strictly. Poor students, the authors note, "lack insight" into their own inadequacy. Why should this be? Another study, led by Cornell University psychologist David Dunning, offers an enlightening explanation. People who are incompetent, he writes with coauthor Justin Kruger, suffer from a “dual burden": they're not good at what they do, and their very clumsiness prevents them from recognizing how bad they are.

    In Dunning and Kruger's study, subjects scoring at the bottom on tests of logic, grammar and humor -extremely overestimated'' their talents. Although their test scores put them in the 12th percentile (百分位数) they guessed they were in the 62nd. What these individuals lacked (in addition 9 clear logic, proper grammar and a sense of humor) was "meta cognitive skill" the capacity to monitor how well they're performing. In the absence of that capacity, the subjects arrived at an overly hopeful view of their own abilities. There's a paradox here, the authors note: The skills that lead to competence in a particular domain are often the very same skills necessary to evaluate competence in that field? In other words, to get better at judging how well we're doing at an activity, we have to get better at the activity itself.

    There are a couple of ways out of this double bind. First, we can learn to make honest comparisons with others. Train yourself to recognize excellence, even when you yourself don't possess it, and compare what you can do against what truly excellent individuals are able to accomplish. Second, seek out feedback that is frequent, accurate and specific. Find a critic who will tell you not only how poorly you're doing, but just what it is that you're doing wrong. As Dunning and Kruger note, success indicates to us that everything went right, but failure is more ambiguous: any number of things could have gone wrong. Use this external feedback to figure out exactly where and when you screwed up.

    If we adopt these strategies — and most importantly, teach them to our children — they won't need parents, or a commencement (毕业典礼)speaker, to tell them that they're special. They'll already know that they are, or have a plan to get that way.