Almost every machine with moving parts has wheels, yet no one knows exactly when the first wheel was invented or what it was used for. We do know, however, that they existed over 5,500 years ago in ancient Asia.

    The oldest known transport wheel was discovered in 2002 in Slovenia. It is over 5,100 years old. Evidence suggests that wheels for transport didn't become popular for a while, though. This could be because animals did a perfectly good job of carrying farming tools and humans around.

    But it could also be because of a difficult situation. While wheels need to roll on smooth surfaces, roads with smooth surfaces weren't going to be constructed until there was plenty of demand for them. Eventually, road surfaces did become smoother, but this difficult situation appeared again a few centuries later. There had been no important changes in wheel and vehicle design before the arrival of modem road design.

    In the mid-1700s, a Frenchman came up with a new design of road—a base layer (层) of large stones covered with a thin layer of smaller stones. A Scotsman improved on this design in the 1820s and a strong, lasting road surface became a reality. At around the same lime, metal hubs (the central part of a wheel) came into being, followed by the pneumatic tyre(充气轮胎) in 1846. Alloy wheels were invented in 1967, sixty years after the appearance of tarmacked roads (柏油路). As wheel design took off, vehicles got faster and faster.

    While all cultures share the same basic emotions, the body language used throughout different countries of the world varies（变化）greatly. What can mean one thing in one country can often mean something completely different in another.

    For example, in North America and Europe people tend to prefer direct eye contact（接触）. But in some Asian countries longer eye contact is considered rude.

    So when communicating with people, always be aware of different cultural customs that may exist.

    A V sign in the US could mean victory, but in England, it stands for a rude challenge, which has the same meaning as showing the middle finger in the US.

The OK gesture（手势）in America and England is given to mean everything is good or well. But in Latin America is looked on as a rude sign.

    The thumbs（拇指）up sign in America and most of Europe means that something is good or well done, but it is considered rude in many Asian countries.

    Putting your feet on the table is generally not thought to be rude in America and England. However, in Thailand（泰国）it is really rude.

    Telling someone to come to you by curling your index finger（食指）is acceptable in America and England, but this gesture signifies death in Singapore.

    Raising your hand up means stop in America and England. In some Asian countries this gesture is used when asking for permission to speak.

    In most westernized countries it is considered normal for two men to shake hands. In some Asian countries it is quite normal for men to kiss each other, while in most westernized countries men kissing in public would be viewed as homosexual（同性恋）behavior.

    If you would like more information on different cultural gestures all over the world, see this site on non-verbal （口头的）communication.

    Being sociable looks like a good way to add years to your life. Relationships with family, friends, neighbors, even pets, will all help, but the biggest longevity (长寿) seems to come from marriage. The effect was first noticed in 1858 by William Farr, who wrote that widows and widowers (鳏夫) were at a much higher risk of dying than the married people. Studies since then suggest that marriage could add as much as seven years to a man's life and two to a woman's. The effect can be seen in all causes of death, whether illness, accident or self-harm.

    Even if the chances are all against you, marriage can more than compensate you. Linda Waite of the University of Chicago has found that a married older man with heart disease can expect to live nearly four years longer than an unmarried man with a healthy heart. Similarly, a married man who smokes more than a pack a day is likely to live as long as a divorced man who doesn't smoke. There's a flip side, however, as partners are more likely to become ill or die in the couple of years following their husband or wife's death, and caring for your husband or wife with mental disorder can leave you with some of the same severe problems. Even so, the chances favor marriage. In a 30-year study of more than 10,000 people, Nicholas Christakis of Harvard Medical School describes how all kinds of social networks have similar effects.

    So how does it work? The effects are complicated, affected by socio-economic factors, health-service provision, emotional support and other more physiological mechanisms(生理机制). For example, social contact can promote development of the brain and immune system, leading to better health and less chance of depression later in life. People in supportive relationships may handle stress better. Then there are the psychological benefits of a supportive partner.

    A life partner, children and good friends are all recommended if you aim to live to 100. The overall social network is still being mapped out, but Christakis says: "People are inter-connected, so their health is inter-connected."

    It's 5:00 in the morning when the alarm rings in my ears. I roll out of bed and walk blindly through the dark into the bathroom. I turn on the light and put on my glasses. The house is still as I walk downstairs while my husband and three kids sleep peacefully. Usually I go for a long run, but today I choose my favorite exercise DVD. Insanity. Sweat pours down my face and into my eyes. My heart races as I face my body to finish each movement. As I near the end of the exercise, I feel extremely tired, but a smile is on my face. It's not a smile because the DVD is over, but a smile of success from pushing my body to its extreme limit.

    Some people enjoy shopping, smoking, food, work, or even chocolate. But I need exercise to get through each day. Some shake heads when they see me run through the town. Others get hurt when I refuse to try just one bite of their grandmother's chocolate cake. They raise their eyebrows, surprised by my “no thank you,” or by my choice to have a salad. Over the years , I have learned it's okay to just say “no.” I shouldn't feel sorry for refusing food that I don't want to eat.

    So what drives me to roll out of bed at 5:00 a.m.? What gives me the reason to just say no to ice cream? Commitment. A commitment to change my life with a way that reduces daily anxiety, increases self –confidence and energy, extends life and above all improves my body shape. This is the point where a smile appears on my face as I look at myself in the mirror or try on my favorite pair of jeans that now fit just right. It's through commitment and sweat that I can make a difference within myself inside and out.

    Do you know how it is when you see someone yawn and you start yawning too? Or how hard it is to be among people laughing and not laugh yourself? Well, apparently it's because we have mirror neurons (神经元) in our brains.

    Put simply, the existence of mirror neurons suggests that every time we see someone else do something, our brains imitate it, whether or not we actually perform the same action. This explains a great deal about how we learn to smile, talk, walk, dance or play sports. But the idea goes further: mirror neurons not only appear to explain physical actions, they also tell us that there is a biological basis for the way we understand other people.

    Mirror neurons can undoubtedly be found all over our brains, but especially in the area which relate to our ability to use languages, and to understand how other people feel. Researchers have found that mirror neurons relate strongly to language. A group of researchers discovered that if they gave people sentences to listen to (for example: “The hand took hold of the ball”), the same mirror neurons were triggered as when the action was actually performed (in this example, actually taking hold of a ball).

    Any problems with mirror neurons may well result in problems with behavior. Much research suggests that people with social and behavioral problems have mirror neurons which are not fully functioning. However, it is not yet known exactly how these discoveries might help find treatments for social disorders.

    Research into mirror neurons seems to provide us with ever more information concerning how humans behave and interact. Indeed, it may turn out to be the equivalent for neuroscience of what Einstein's theory of relativity was for physics. And the next time you feel the urge to cough in the cinema when someone else does-well, perhaps you'll understand why.

    On average, Americans spend about 10 hours a day in front of a computer or other electronic devices and less than 30 minutes a day outdoors. That is a claim made by David Strayer, a professor of psychology at the University of Utah. In his 2017 TED Talk, Strayer explained that all this time spent with technology is making our brains tired.

    Using an electronic device to answer emails, listen to the news and look at Facebook puts a lot of pressure on the front of the brain, which, Strayer explains , is important for critical (有判断力的)thinking , problem-solving and decision-making.

So, it is important to give the brain a rest. And being in naure, Strayer claims, helps get a tired brain away from too much technology. More than 15,000 campers from around the world attended an international camping festival in September. That is when friends and family take time off and escape to nature for several days. They take walks, climb, explore, swim, sleep, eat and play. Camping may be just what a tired brain needs.

    Take Carl for example .He lives in West Virginia and enjoys camping. He says that staying outdoors makes him feel at ease. It also prepares him for the work he must do. Kate Somers is another example who also lives in West Virginia. She says she enjoys camping with her husband and two children. She calls it a “regenerative” experience.

    At the University of Utah, David Strayer has studied both short-term and long-term exposure to nature. He found that spending short amounts of time in nature without technology does calm the brain and helps it to remember better. However, he found, it is the long-term contact with nature that does the most good. He and his research team found that spending three days in nature without any technology is enough time for the brain to fully relax and reset itself.