In most big cities, it is easier     1     (hire) a taxi at a moment’s notice when the weather is good. But when it’s raining, people have a much harder time finding one. One obvious reason is that many people     2     walk short distances during good weather prefer to take a taxi in the rain. Therefore, taxis tend to be more fully filled on     3     (rain) days. Besides, the supply of available taxis is also smaller because taxi drivers can     4     (easy) reach the target fares and go home early.

2 . As Frans de Waal, a primatologist (灵长动物学家), recognizes, a better way to think about other creatures would be to ask ourselves how different species have developed different kinds of minds to solve different adaptive problems. Surely the important question is not whether animals can do the same things humans can, but how those animals solve the cognitive (认知的) problems they face, like how to imitate the sea floor. Children and some animals are so interesting not because they are smart like us, but because they are smart in ways we haven’t even considered.

Sometimes studying children’s ways of knowing can cast light on adult-human cognition. Children’s pretend play may help us understand our adult taste for fiction. De Waal’s research provides another interesting example. We human beings tend to think that our social relationships are rooted in our perceptions, beliefs, and desires, and our understanding of the perceptions, beliefs, and desires of others — what psychologists call our “theory of mind.” In the 80s and 90s, developmental psychologists showed that pre-schoolers and even infants understand minds apart from their own. But it was hard to show that other animals did the same. “Theory of mind” became a candidate for the special, uniquely human trick.

Yet de Waal’s studies show that chimps (黑猩猩) possess a remarkably developed political intelligence — they are much interested in figuring out social relationships. It turns out, as de Waal describes, that chimps do infer something about what other chimps see. But experimental studies also suggest that this happens only in a competitive political context. The evolutionary anthropologist (人类学家) Brain Hare and his colleagues gave a junior chimp a choice between pieces of food that a dominant chimp had seen hidden and other pieces it had not seen hidden. The junior chimp, who watched all the hiding, stayed away from the food the dominant chimp had seen, but took the food it hadn’t seen.

Anyone who has gone to an academic conference will recognize that we may be in the same situation. We may say that we sign up because we’re eager to find out what other human beings think, but we’re just as interested in who’s on top. Many of the political judgments we make there don’t have much to do with our theory of mind. We may show our respect to a famous professor even if we have no respect for his ideas.

Until recently, however, there wasn’t much research into how humans develop and employ this kind of political knowledge. It may be that we understand the social world in terms of dominance, like chimps, but we’re just not usually as politically motivated as they are. Instead of asking whether we have a better everyday theory of mind, we might wonder whether they have a better everyday theory of politics.

3 . Living in a city is a well-known risk factor for developing a mental disorder, while living close to nature is largely beneficial for mental health and the brain. A central brain region, the amygdala (大脑杏仁核)involved in stress processing, has been shown to be less activated during stress in people living in rural areas, compared to those who live in cities, hinting at the potential benefits of nature. “But so far the hen-and-egg problem could not be resolved, namely whether nature actually caused the effects in the brain or whether the particular individuals chose to live in rural or urban regions,” says Sonja Sudimac.

To achieve causal evidence, the researchers from the group examined brain activity in regions involved in stress processing in 63 healthy volunteers before and after a one-hour walk in Grunewald forest or a shopping street with traffic in Berlin. The results revealed that activity in the amygdala decreased after the walk in nature, suggesting that nature elicits beneficial effects on brain regions related to stress.

“The results support the previously assumed positive relationship between nature and brain health, but this is the first study to prove the causal link. Interestingly, the brain activity after the urban walk in these regions remained stable and showed no increases, which argues against a commonly held view that urban exposure causes additional stress,” explains Simone Kühn, head of the group.

The authors show that nature has a positive impact on brain regions involved in stress processing and that it can already be observed after a one-hour walk. This contributes to the understanding of how our physical living environment affects brain and mental health. Even a short exposure to nature decreases amygdala activity, suggesting that a walk in nature could serve as a preventive measure against developing mental health problems and reducing the potentially disadvantageous impact of the city on the brain.

In order to investigate beneficial effects of nature in different populations and age groups, the researchers are currently working on a study examining how a one-hour walk in natural versus urban environments impacts stress in mothers and their babies.

7 . Is It Worth Buying Organic Food?

Organic food, grown without artificial chemicals, is increasingly popular nowadays. Consumers have been willing to pay up to twice as much for goods with organic labels (标签). However, if you think paying a little more for organic food gets you a more nutritious (有营养的) and safer product, you might want to save your money. A study led by researchers at Stanford University says that organic products aren’t necessarily more nutritious, and they’re no less likely to suffer from disease-causing bacteria, either.

The latest results, published in the Annuals of Internal Medicine, suggest that buyers may be wasting their money. “We did not find strong evidence that organic food is more nutritious or healthier,” says Dr. Crystal Smith-Spangler from Stanford. “So consumers shouldn’t assume that one type of food has a lower risk or is safer.”

For their new study, Smith-Spangler and her colleagues conducted a review of two categories of research, including 17 studies that compared health outcomes between consumers of organic against traditional food products, and 223 studies that analyzed the nutritional content of the foods, including key vitamins, minerals and fats.

While the researchers found little difference in nutritional content, they did find that organic fruit and vegetables were 20% less likely to have chemicals remaining on the surfaces. Neither organic nor traditional foods showed levels of chemicals high enough to go beyond food safety standards. And both organic and traditional meats, such as chicken and pork, were equally likely to be harmed by bacteria at very low rates. The researchers did find that organic milk and chicken contained higher levels of omega-3 fatty acids, a healthy fat also found in fish that can reduce the risk of heart disease. However, these nutritional differences were too small, and the researchers were unwilling to make much of them until further studies confirm the trends.

Organic food is produced with fewer chemicals and more natural-growing practices, but that doesn’t always translate into a more nutritious or healthier product. The U.S. Department of Agriculture (USDA) states that “Whether you buy organic or not, finding the freshest foods available may have the biggest effect on taste.” Fresh food is at least as good as anything marketed as organic.

Wearing masks is widely believed to be a simple but useful method to protect oneself from a variety of harmful things. In fact, masks have been helping mankind for centuries.

In the first century, many people in Roman Empire worked underground in mines. But most of them suffered from and even eventually died of breathing illnesses. To work out this problem, Pliny the Elder, a Roman philosopher (哲学家) and naturalist, recommended the use of animal bladder (膀胱) skins to stop dust from being breathed in. Thus, Pliny the Elder was considered the inventor of the first recorded mask.

Early inventions did not stop with Pliny. Around the 16th century, Italian artist and inventor Leonardo da Vinci suggested using a cloth wetted in water over the face to protect against the poisonous chemicals (化学物质).

The design of the mask took a big step forward in the 19th century. In 1848, American Lewis Hassley became the first person to get the official right to produce a protective mask for miners, which was a milestone in face mask history. Masks at this stage were similar to gas masks. Later, in 1897, Polish-Austrian doctor Johann von Mikuliez-Radecki designed a simple mask made up of one piece of medical gauze (纱布), recommending medical workers to wear it to prevent getting diseases. That was the first recorded use of a medical mask.

In 1910, a terrible disease broke out in Northeast China. Chinese doctor Wu Liande designed a cheap face mask called “Wu’s mask”, which was made of two pieces of medical gauze. This mask was praised by experts around the world, as it was simple and cheap to make.

With the happening of widely spreading diseases and the rise of air pollution, the materials in masks have continued to develop to better protect the wearers in modern times. For example, mask models such as N95 and KN90, which can help prevent smog from being breathed in, have become highly popular.

10 . Essentially, everyone has two ages: a chronological(按时间计算的) age, how old the calendar says you are, and a biological age, basically the age at which your body functions as it compares to average fitness or health levels.

“Chronological age isn’t how old we really are. It’s merely a number,” said Professor David Sinclair at Harvard University. “It is biological age that determines our health and ultimately our lifespan(寿命). We all age biologically at different rates according to our genes, what we eat, how much we exercise, and what environment we live in. Biological age is the number of candles we really should be blowing out. In the future, with advances in our ability to control biological age, we may have even fewer candles on our birthday cake than the previous one.”

To calculate biological age, Professor Levine at Yale University identified nine bio-markers that seemed to be the most influential on lifespan by a simple blood test. The numbers of those markers, such as blood sugar and immune measures, can be put into the computer, and the algorithm(算法) does the rest.

Perhaps what’s most important here is that these measures can be changed. Doctors can take this information and help patients make changes to lifestyle, and hopefully take steps to improve their biological conditions. “I think the most exciting thing about this research is that these things aren’t set in stone,” Levine said. “People can be given the information earlier and take steps to improve their health before it’s too late.”

Levine even entered her own numbers into the algorithm. She was surprised by the results. “I always considered myself a very healthy person. I’m physically active; I eat what I consider a fairly healthy diet. But I did not find my results to be as good as I had hoped they would be. It was a wake-up call,” she said.

Levine is working with a group to provide access to the algorithm online so that anyone can calculate their biological age, identify potential risks and take steps to improve their own health in the long run. “No one wants to live an extremely long life with a lot of chronic diseases,” Levine said. “By delaying the development of mental and physical functioning problems, people can still be engaged in society in their senior years. That is the ideal we should be pursuing.”