Earlier this month, two rock climbers achieved what many thought impossible: They climbed up the 3,000-foot-high Dawn Wall in Yosemite NationalPark without specialized equipment. Climbing without this equipment iscalled“free-climbing.”Until now, no one had free-climbed to the top of the rockface, which is a part of the mountain EI Capitan.

    El Capitan, which means“the captain”or“the chief”in Spanish, has always presented a challenge to climbers. But the Dawn Wall, on the mountain's southeast face, is a particularly difficult route to the summit (顶峰). It is a rock formation that is both steep and relatively smooth. This makes free-climbing the rock face seem almost impossible.

    About seven years ago, professional climber Tommy Caldwell spotted a possible route up the wall. It took years of planning and preparation, but this month, Caldwell, 36, and his friend Kevin Jorgeson, 30, finally make the climb.

    Free climbers do use ropes and other basic safety equipment to catch them if they fall — and Caldwell and Jorgeson fell often. Before starting their climb, they broke down their route into 32 sections. Each section was based on a rope length called a“pitch.”The rope was secured into the rock faceto catch the climbers if they fell.

    Caldwell and Jorgeson's goal was to climb the DawnWall without returning to the ground. If they fell, they had to start that pitch all over again. The two men started climbing on December 27. They slept in hanging tents, and a team of friends brought them food each day.

    The men had spent years rehearsing (排练) them ovements it would take to get through each pitch. They made it through the fist half of the climb relatively easily. But halfway up, Jorgeson ran into trouble. In one difficult spot, he fell each time he attempted to climb. After10 days of trying, Jorgeson finally made it to the next pitch.

    Getting through that troublesome pitch gave both climbers renewed energy. They finished the rest of the climb five days later, on January 14.

    Since 1984,Philadelphia has been cleaning up its act.One by one,graffiti（涂鸦）covered walls are being changed into outdoor art.So far,more than 1,800 murals（壁画）have been painted.Philadelphia now has more murals than any other American city.

    The walls that were once ugly with graffiti are now covered with beautiful pictures of historical heroes and modern art, thanks to the Mural Arts Program(MAP).Its work makes schools and public places attractive,and its citizens very proud.The program began as part of Philadelphia's Anti-Graffiti Network.Jane Golden is the MAP's artistic director."When people ask me what our program is about,"she says,"I answer them with one word: hope." Each year, the MAP offers youth art programs and workshops.Some onetime graffiti writers even help paint MAP murals.

    The MAP's work,says Golden,is all about developing a sense of community（社区）.When a neighborhood requests a mural,the MAP works with the people there to develop a message.Some messages have been "Safe Streets,"Love and Care," and "Peace Walk".

    The MAP receives up to 50 requests for murals each week. Last year, the workers painted 140 murals."The making of a mural enters people's collective memory as an extraordinary, pleasant moment in neighborhood history," says Golden, who began as a muralist in Los Angeles.

    Women are friendly．But men are more competitive．Why? Researchers have found it's all down to the hormone oxytocin （荷尔蒙催生素）．Although known as the love hormone, it affects the sexes differently．

"Women tend to be social in their behavior．They often share with others．But men lend to be competitive．They are trying to improve their social status," said Professor Ryan．

    Generally, people believe that the hormone oxytocin is let out in our body in various social situations and our body creates a large amount of it during positive social interactions （互动） such as falling in love or giving birth．

But in a previous experiment Professor Ryan found that the hormone is also let out in our body during negative social interactions such as envy．

    Further researches showed that in men the hormone oxytocin improves the ability to recognize competitive relationships, but in women it raises the ability to recognize friendship．

Professor Ryan's recent experiment used 62 men and women aged 20 to 37．Half of the participants（参与者）received oxytocin．The other half received placebo （安慰剂）．

    After a week, the two groups switched with participants．They went through the same procedure with the other material．

    Following each treatment, they were shown some video pictures with different social interactions．Then they were asked to analyze the relationships by answering some questions．The questions were about telling friendship from competition．And their answers should be based on gestures, body language and facial expressions．

    The results indicated that, after treatment with oxytocin, men's ability to correctly recognize competitive relationships improved, but in women it was the ability to correctly recognize friendship that got better．

    Professor Ryan thus concluded: "Our experiment proves that the hormone oxytocin can raise people's abilities to better distinguish different social interactions．And the behavior differences between men and women are caused by biological factors （因素） that are mainly hormonal．"

    One of the most outspoken supporters that I know of women and girls is actually a man. As co­founder of the ONE Campaign, my friend Bono spends a lot of time speaking out against global poverty (贫困). Together, we're working to get out a simple, powerful message: poverty is sexist.

    Women and girls are more likely to be in poverty, less likely to get an education and more likely to suffer bad health. And when they are born into poverty, it is much more difficult for them to lift themselves and their families out of it.

    Why? One reason is that breaking out of poverty takes time­and that is a resource women around the world are short on. On average, women spend about twice as much time as men in doing the unpaid work that makes life possible for everyone, like cooking, washing, cleaning, shopping and caring. In developing countries, the gap is even much bigger. As a result, women have no time to finish their education, learn new skills, open a business, develop personal relationships or even go to the doctor. They dream of creating a better future for their children, but they can not spare the hours to put those dreams that they have into action.

    The fact that the potential of so many women and girls is going unrealized is a sad thing­but it is also an opportunity for us. We need to recognize, reduce and redistribute the burden of work that is holding them back. Because if women have time to invest (投资) in themselves and their ideas, they could transform the world.

    I travel a lot, and I find out different "styles"(风格）of directions every time I ask "How can I get to the post office?"

    Foreign tourists(游客) are often confused(困惑)in Japan because most streets there don't have names; in Japan, people use landmarks(地标)in their directions instead of street names. For example, the Japanese will say to travelers, "Go straight down to the corner. Turn left at the big hotel and go past a fruit market. The post office is across from the bus stop."

    In the countryside of the American Midwest, there are not usually many landmarks. There are no mountains, so the land is very flat; in many places there are no towns or buildings within miles. Instead of landmarks, people will tell you directions and distances. In Kansas or Iowa, for example, people will say, "Go north two miles. Turn east, and then go another mile."

    People in Los Angeles , California, have no idea of distance on the map; they measure(度量) distance in time, not miles. "How far away is the post office?" you ask. "Oh," they answer, "it' is about five minutes from here." You say, "Yes, but how many miles away is it ?"They don't know.

    It's true that a person doesn't know the answer to your question sometimes. What happens in such a situation? A New Yorker might say, "Sorry, I have no idea." But in Yucatan, Mexico, no one answers "I don't know." People in Yucatan believe that "I don't know" is impolite. They usually give an answer, often a wrong one. A tourist can get very, very lost in Yucatan!

Some people today might be early risers because of DNA they take after Neanderthals tens of thousands of years ago, suggests new research.

When early humans migrated from Africa to Eurasia roughly 70,000 years ago, some of them mated with Neanderthals, who had already adapted to the colder, darker climates of the north. The ripple (涟漪) effects of that intermating still exist today: Modern humans of non- African ancestry (血统) have between 1 and 4 percent Neanderthal DNA. Some of that DNA relates to sleep more specifically, the internal body clock known as the circadian rhythm.

For the new study, researchers compared DNA from today's humans and DNA from Neanderthal fossils (化石). In both groups, they found some of the same genetic variants involved with the circadian rhythm. And they found that modern humans who carry these variants also reported being early risers.

For Neanderthals, being "morning people" might not have been the real benefit of carrying these genes. Instead, scientists suggest, Neanderthals' DNA gave them faster, more flexible internal body clocks, which allowed them to adjust more easily to annual changes in daylight. This connection makes sense in the context of human history. When early humans moved north out of Africa, they would have experienced variable daylight hours--shorter days in the winter and longer days in the summer-for the first time. The Neanderthals' circadian rhythm genes likely helped early humans' offspring (后代) adapt to this new environment.

Notably, the findings do not prove that Neanderthal genes are responsible for the sleep habits of all early risers. Lots of different factors beyond genetics can contribute, including social and environmental influences. The study also only included DNA from a database called the U.K. Biobank-so the findings may not necessarily apply to all modern humans. Next, the research team hopes to study other genetic databases to see if the same link holds true for people of other ancestries. If the findings do apply more broadly, they may one day be useful for improving sleep in the modern world, where circadian rhythms are disturbed by night shifts and glowing smartphones.