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.

    'Kangaroo mothering' helps boost a child's health and intelligence

    “Kangaroo mothering”, the practice of continuous skin-to-skin contact with a newborn baby, results in healthier, more intelligent and successful children, a new study finds.

    A 20-year follow-up research found that those brought up in the kangaroo method scored higher in IQ tests and earned 53% more. They were also found to be less likely to have behavior problems than babies in a control group.

    Followers of the method nest their kids in a “kangaroo” position on their chest as soon as possible after birth. Both mother and baby are supposed to go home as quickly as possible.

    The technique is often used in cases of premature birth (早产). In such cases, the trained mother acts as the child's main source of stimulation (刺激) and food, in the form of breast feeding. Between 1993 and 1996, a group of more than 700 prematurely born babies in Columbia were, on the basis of random selection, placed either away from mother or were raised using the kangaroo method. Two decades later, a follow-up survey funded by the Canadian Government has shown that those who went through the latter method benefited by comparison.

    Published in the journal Paediatrics, the research shows that kangaroo mothering offered significant protection against early death, with a 3.5% death rate compared to a 7.7% rate in the control group. IQ test also showed a small but significant advantage of 3.5% compared to other infants. 

    Lead researcher Dr Nathalie Charpak, of the Kangaroo Foundation in Bogota, said the method has “significant, long-lasting social and behavioral protective effects”. “We firmly believe that this is a powerful, efficient, scientifically based healthcare intervention that can be used in all settings, from those with very restricted to unrestricted access to healthcare.”

    The study also found that, compared with babies in the control group, those raised in the kangaroo method went on to develop bigger brains, with significantly larger volumes of gray matter.

    Have you ever wondered why birds sing? Maybe you thought that they were just happy. After all, you probably sing or whistle when you are happy.

    Some scientists believe that birds do sing some of the time just because they are happy. However, they sing most of the time for a very different reason. Their singing is actually a warning to other birds to stay out of their territory.

    Do you know what a "territory" is? A territory is an area that an animal ,usually the male, claims(声称)as its own .Only he and his family are welcome there. No other families of the same species(物种)are welcome. Your yard and house are your territory where only your family and friends are welcome. If a stranger should enter your territory and threaten you, you might shout. Probably this would be enough to frighten him away.

    If so, you have actually scared the stranger away without having to fight him. A bird does the same thing. But he expects an outsider almost any time ,especially at nesting(筑巢)season. So he is screaming all the time, whether he can see an outsider or not. This screaming is what we call a bird's song, and it is usually enough to keep an outsider away.

    Birds sing loudest in the spring when they are trying to attract a mate and warn others not to enter the territory of theirs.

    You can see that birds have a language of their own. Most of it has to do with attracting mates and setting up territories.

    People from East Asia tend to have more difficulty than those from Europe in distinguishing facial expressions — and a new report published online in Current Biology explains why.

    Rachael Jack from University of Glasgow, said that rather than scanning evenly across a face as Westerners do, Easterners fix their attention on the eyes.

    "We show that Easterners and Westerners look at different face features to read facial expressions," Jack said. "Westerners look at the eyes and the mouth in equal measure, while Easterners favor the eyes and ignore the mouth."

    According to Jack and his colleagues, the discovery shows that communication of human emotions is more complex than previously believed. As a result, facial expressions that had been considered universally recognizable cannot be used reliably to convey emotions in cross­cultural situations.

    The researchers studied cultural differences in the recognition of facial expressions by recording the facial movements of 13 Western people and 13 Eastern people while they observed pictures of expressive faces and put them into categories: happy, sad, surprised, fearful, disgusted, or angry. They compared how accurately participants read those facial expressions using their particular eye movement strategies.

    It turned out that Easterners focused much greater attention on the eyes and made significantly more errors than Westerners did. "The cultural difference in eye movements that they show is probably a reflection of cultural difference in facial expressions," Jack said. "Our data suggests that while Westerners use the whole face to convey emotions, Easterners use the eyes more and the mouth less."

    In short, the data shows that facial expressions are not universal signals of human emotions. From here on, examining how cultural factors have diversified these basic social skills will help our understanding of human emotions. Otherwise, when it comes to communicating emotions across cultures, Easterners and Westerners will find themselves lost in translation.

    There's a song by the great Jamaican singer Bob Marley called So Much Trouble In The World. Marley understood that part of the reason why there are so many problems in the world is the lack of tolerance between people. The UN understands this too—that's why it made Nov 16 "International Day for Tolerance".

    But first of all, what is tolerance? French philosopher Voltaire (1694—1778) can give us some help. According to him, tolerance "is the consequence of humanity. We are all formed of frailty (脆弱) and error; let us pardon each other's folly—that is the first law of nature."

    Nobody's perfect. When we're tempted to criticize another person, we should perhaps remember our own imperfections first.

    Very often, people don't realize that they're intolerant. This is because intolerance has a lot to do with ignorance. For example, the UN's campaign is in part about the treatment of females by males. But often, the behavior of men toward women is intolerant because men don't put themselves in the shoes of women.

    It's worth thinking a little about the words "tolerance" and "intolerance". Are they the best words to describe the evils of which we're speaking here? To agree to be "tolerant" of someone isn't necessarily a very respectful thing. When someone is tolerated, it implies that there's something wrong with them.

    But it seems wrong that people should agree to "tolerate" people with black skin, for example. And should women think they have received the respect they are due when men agree to "tolerate" them?

    Still, what Voltaire said stands: We humans are not perfect and this weakness is something that we all share. That's the reason we should be tolerant.

    It's a little like generosity. We can give things to another person, and we can also give our forgiveness. Bob Marley understood this. In the song mentioned above, he advised: "Write your love on a rock so it stays for eternity; write your hate in the sand so the waves will wash it away."

    Race walking shares many fitness benefits with running, research shows, while most likely contributing to fewer injuries. It does, however, have its own problem.

    Race walkers are conditioned athletes. The longest track and field event at the Summer Olympics is the 50-kilometer race walk, which is about five miles longer than the marathon. But the sport's rules require that a race walker's knees stay straight through most of the leg swing and one foot remain in contact (接触) with the ground at all times. It's this strange form that makes race walking such an attractive activity, however, says Jaclyn Norberg, an assistant professor of exercise science at Salem State University in Salem, Mass.

    Like running, race walking is physically demanding, she says, According to most calculations, race walkers moving at a pace of six miles per hour would burn about 800 calories(卡路里) per hour, which is approximately twice as many as they would burn walking, although fewer than running, which would probably burn about 1,000 or more calories per hour.

    However, race walking does not pound the body as much as running does, Dr. Norberg says. According to her research, runners hit the ground with as much as four times their body weight per step, while race walkers, who do not leave the ground, create only about 1.4 times their body weight with each step.

    As a result, she says, some of the injuries associated with running, such as runner's knee, are uncommon among race walkers. But the sport's strange form does place considerable stress on the ankles and hips, so people with a history of such injuries might want to be cautious in adopting the sport. In fact, anyone wishing to try race walking should probably first consult a coach or experienced racer to learn proper technique, she says. It takes some practice.