Sometimes, you just can't help it. Maybe you're watching a sad movie, or thinking about the friend who moved away. Next thing you know, your eyes are watering, and you havetears running down your cheeks. Why do peoplecry when they are emotional? What are tears? Scientists are working hard to find the answers to these questions.

    Ad Vingerhoets is a professor of psychology at Tilburg University, in the Netherlands. He is one ofthe few scientists in the world who have studied crying. According to Vingerhoets, there are three types of tears. Basal tearsare the first type. Theylubricate(润滑) the eyes andact as a protective barrier between the eye and the rest of the World. Next arereflex tears. They wash youreyes clean when something gets in them. Finally, there are emotional tears. “These are released in response to emotional states, ”explains Vingerhoets. “Especially when we feel helpless.”

    Scientists believe that crying has something to do with how humans developed and learned to depend on each other.“Humans are very complex social creatures,”says Lauren Bylsma, a professor at the University of Pittsburgh, in Pennsylvania.“It seems that tears serve to arouse help and support from others," She says. “Another reason we weep is that humans have the longest developmental period of almost any animal. It takes along time to grow up. ”

    Vingerhoets agrees. “I think that the reason why humans shed tears(流眼泪) has somethingto do with our childhood,”he says. “That's the time when we are stir dependent on adults for love and protection and care. The major advantage of emotional tears is that you can target them at a specific person.”Vingerhoets says this ability to target someone could have come in hand in prehistorictimes, when humans were living among dangerous animals. Crying couldattract predators(捕食者). Tears were asafer way to get attention. In this case, it is better to use a silent signal to ask for help,”he says.

    Vingerhoets and Bylsma do frequent studies to better understand why humans cry. According to Byhma, there is still much more to discover. “It's surprising,”she says,“how much we still don't know.”

    On a recent visit to the Museum of Modem Art with a friend and her daughter, wandering through the museum's exhibits, I was struck by how often my friend's 13-year-old daughter asked us to take photos of her with her smart phone in front of the artwork. Then, she gazed at the photos which she would then post on Instagram, Snapchat and all the rest. She was not the only person who was doing this; it seemed everyone was busy taking photos of themselves "experiencing" the museum.

    This is by no means a criticism of my friend's daughter or anyone else. What was concerning, at least to me, was that in between being photographed and posting, my friend's daughter had no interest in the artwork, a fact which didn't seem to matter or have anything to do with wanting to post herself as someone enjoying the experience.

    When I was her age, I had no interest in going to museums either. Having no interest in art at her age (and any age) is completely normal. But what is disturbing is how much of a young person's energy these days goes into creating an image of the life they're living and the character they "are" in that life. While creating a self-image has always been a big part of growing up and figuring out our identity, social media seems to have changed the rules of the game. Social media has not just increased the pressure and possibility of creating a self-generated(自我创造的) self-image, but also distorted(歪曲) the process through which we become who we are. Young people now seem to be creating an image of who they are in place of becoming who they are, posting their life rather than living it.

    Social media has turned life and its experiences into an exercise in narcissism(自恋，自我陶醉). No matter what the experience is actually about, it becomes about you, the person who is living it. A concert is not about the music, a restaurant not about the food and a sport event not about the sport; it's all about you, the doer, and what the event says about you. As a result the more we use life create an identity, the more distant from life we feel. Instead of being part of it, we feel as if we have to keep generating new life material.

    I hope the next time you post your story, pause for a moment and experience where you are, feel what it feels like to live what you're living without using life for your benefit, or for anything at all. Just live, without the narrative(叙述). While you may feel this practice is a threat to your identity, causing you to miss a chance to prove your value, in fact, the benefit will far outweigh any loss it brings.

    It's carnival season in Europe, a crazy time for parades, mask, music and dance. No one is sure where the tradition exactly comes from. But while its origin remains a mystery, this does not keep people from joining it.

    The Carnival of Binche, the most famous one that is staged in Belgium, has been announced as a masterpiece (杰作) of the Intangible Heritage of Humanity by UNESCO. The event usually takes place during a Sunday, Monday, and Tuesday, with performers known as "Gilles" dressed in clown-like costumes, dancing and marching along the streets. During parade, the Gilles throw oranges to the crowd as an act of well-washing and it is considered rude to throw them back.

    Venice is said to be the birthplace of carnivals. In the city, the annual carnival starts 58 days before Easter. It features various brightly-colored and well-made masks. Every year, thousands of visitors go to the city to be part of the festive event.

    The Germans, always considered serious-minded, also have their carnivals. The Cologne Carnival is one of the largest, with Rose Monday as the best part. On Rose Monday Parade, lots of gifts are prepared for the people who join it. For this year, 300 tons of candies and more than 300,000 souvenirs were thrown out of the various nicely-decorated floats (花车) to the crowd.

    The Nice Carnival in the southern French city of Nice lasts two or three weeks from February to march every year. It features floats, music, dance, performances and entertainment activities. The parade of lights and the final day carnival parade are the most exciting parts of the entire event. Compared to the Rio Carnival in Brazil and the Winter Carnival in Quebec, Canada, the Nice Carnival has a special artistic touch, and it is one of the three major carnivals around the world.

    Carnivals were first organized in the Middle Ages. They were supposed to be a time of eating and drinking before the Easter fast (斋戒). Nowadays, they have turned into winter tourism attractions of many European cities.

A Different Kind of Spring Break

    For many American university students, the week-long spring break holiday means an endless part on a sunny beach in Florida or Mexico. In Panama City Beach, Florida, a city with a permanent population of approximately 36,000, more than half a million university students arrive during the month of March to play and party, making it the number one spring break destination in the United States.

    A week-long drinking binge is not for everyone, however, and a growing number of American university students have found a way to make spring break matter. For them, joining or leading a group of volunteers to travel locally or internationally and work to address problems such as poverty, homelessness, or environmental damage makes spring break a unique learning experience that university students can feel good at.

    During one spring break week, students at James Madison University in Virginia participated in 15 "alternative spring break" trips to nearby states, three others to more distant parts of the United States, and five international trips. One group of JMU students traveled to Bogalusa, Louisiana, to help rebuild homes damaged by Hurricane Katrina. Another group traveled to Mississippi to organize creative activities for children living in a homeless shelter. One group of students did go to Florida, but not to lie on the sand. They performed exhausting physical labor such as maintaining roving invasive plant species that threaten the native Florida ecosystem.

    Students who participate in alternative spring break projects find them very rewarding. While most university students have to get their degrees before they can start helping people, student volunteers are able to help people now. On the other hand, the accommodations are far from glamorous. Students often sleep on the floor of a school or church, or spend the week camping in tents. But students only pay around $250 for meals and transportation, which is much less than some of their peers spend to travel to more traditional spring break hot spot.

    It's common knowledge that the woman in Leonardo da Vinci's most famous painting seems to look back at observers, following them with her eyes no matter where they stand in the room. But this common knowledge turns out wrong.

    A new study finds that the woman in the painting is actually looking out at an angle that's 15.4 degrees off to the observer's right­well outside of the range that people normally believe when they think someone is looking right at them. In other words, said the study author, Horstmann, "She's not looking at you." This is somewhat ironic, because the entire phenomenon of a person's gaze (凝视) in a photograph or painting seeming to follow the viewer is called the "Mona Lisa effect" . That effect is absolutely real, Horstmann said. If a person is illustrated or photographed looking straight ahead, even people viewing the portrait from an angle will feel they are being looked at. As long as the angle of the person's gaze is no more than about 5 degrees off to either side, the Mona Lisa effect occurs.

    This is important for human interaction with on-screen characters. If you want someone off to the right side of a room to feel that a person on-screen is looking at him or her, you don't cut the gaze of the character to that side­surprisingly, doing so would make an observer feel like the character isn't looking at anyone in the room at all. Instead, you keep the gaze straight ahead.

    Horstmann and his co-author were studying this effect for its application in the creation of artificial-intelligence avatars(虚拟头像) when Horstmann took a long look at the "Mona Lisa" and realized she wasn't looking at him.

    To make sure it wasn't just him, the researchers asked 24 people to view images of the "Mona Lisa" on a computer screen. They set a ruler between the viewer and the screen and asked the participants to note which number on the ruler intersected Mona Lisa's gaze. To calculate the angle of Mona Lisa's gaze as she looked at the viewer, they moved the ruler farther from or closer to the screen during the study. Consistently, the researchers found, participants judged that the woman in the "Mona Lisa" portrait was not looking straight at them, but slightly off to their right.

    So why do people repeat the belief that her eyes seem to follow the viewer? Horstmann isn't sure. It's possible, he said, that people have the desire to be looked at, so they think the woman is looking straight at them. Or maybe the people who first coined the term "Mona Lisa effect" just thought it was a cool name.