The Nazca Lines are a series of large ancient geoglyphs (地画) in the Nazca Desert, in southern Peru. It is ranging from geometric patterns to drawings of different animals and stylized human-like forms. The ancient lines can only be truly taken in from high in the air, leaving generations puzzled as to how these precise works could have been completed long before the documented invention of human flight.

    The Lines were first spotted when commercial airlines began flying across the Peruvian desert in the 1920,s. Who built them and what was their purpose? Are they roads, star pointers，maybe even a gigantic map? If the people who lived here 2,000 years ago had only a simple technology, how did they manage to construct such precise figures? Did they have a plan? These markings are like a vast puzzle.

    The Nazca Lines are the most outstanding group of geoglyphs in the world. There are also huge geoglyphs in Egypt, Malta，United States (Mississippi and California), Chile，Holivia and in other countries. But the Nazca geoglyphs, because of their numbers， characteristics, dimensions and cultural continuity as they were made and remade throughout a certain history period, form the most impressive archeological (考古学的) group.

    The Nazca plain is unique for its ability to preserve the markings upon it, due to the combination of the climate (one of the driest on Earth, with only twenty minutes of rainfall per year) and the flat, stony ground which minimizes the effect of the wind at ground level. With no dust or sand to cover the plain and little rain or wind to erode (腐蚀) it, lines drawn here tend to stay drawn. These factors, combined with the existence of lighter-colored subsoil beneath the desert surface, provide a vast writing pad that is suited to the artist who wants to leave his mark eternal.

    Last year, when our three-year-old great-granddaughter Kylie was taken to see Santa Claus, she made sure to give him her wish list of toys. A week later, she ran into a different Santa in a mall. He stopped to ask what she wanted for Christmas. Kylie was surprised and let him know: “If you can't remember what I told you last week, how are you going to remember on Christmas Eve?”

    Mary Paul, Milwaukee, Wisconsin

    As my son Mike and I drove to the mall, we passed a Salvation Army Santa ringing his bell. “Mike,” I said, “there's Santa!” He shook his head. “That's just some guy in a Santa suit,” he said. It saddened me to think that maybe my son no longer believed in Santa, and we drove the rest of the way in silence. At the mall, we spotted another Santa greeting young believers. Suddenly, Mike took off toward him. Turning back to me, he shouted. “Now, there's the real Santa!”

    Michael E. Fahey, Huntley, Illinois

    We immigrated to America from China when I was six. Because I was shy and didn't speak English, I had few friends. My days were spent at home with my brother. Sometimes we'd help our neighbor Mr. Mueller pull weeds. One Christmas Day, there was a knock at the door. Grandma opened it, and there stood a big fellow in red with a snow-white beard, laughing, “Ho, ho, ho!” He handed out presents and made us laugh. I had so much fun. It was years later when I learned that our special Santa was our neighbor Mr. Mueller.

    Joanne Tang, Litchfield Park, Arizona

    A recent study led by researchers from the National University of Singapore(NUS)has found a clear link between the color of a taxi and its accident rate. An analysis of 36 months of detailed taxi, driver and accident data from two fleets of yellow and blue taxis in Singapore suggested that yellow taxis have fewer accidents than blue taxis. The higher visibility (能见度)of yellow makes it easier for drivers to avoid getting into accidents with yellow taxis, leading to a lower accident rate.

    The study was led by Prof Ho. To test whether there was a causal relationship between the color of a taxi and the number of accidents the taxi had, the research team analysed data collected by the largest taxi company in Singapore. The researchers found that yellow taxis have about 6.1 fewer accidents per 1,000 taxis per month.

    The researchers also studied the economic effect of changing the color of the entire fleet of taxis to yellow. The Singapore taxi company involved in the study owns about 16,700 taxis in a ratio(比例) of one yellow to three blue taxis. If a commercial decision is made to switch from blue to yellow taxis, 76.6 fewer accidents would occur per month or 917 fewer accidents per year. Assuming an average repair cost of $1,000 per car and a downtime of six days, switching the color of all taxis to yellow could produce an annual savings of $2 million.

    “We are eager to continue to validate(证实) the findings of our study by looking at the use of yellow in other types of public transport, such as school buses. For instance, we hope to compare the accident rates of yellow school buses against other colors to find out if yellow is indeed a safer color for school buses. Besides, we are also interested to look at private-hire vehicles and do a comparison of the accident rates of vehicles that are of different colors,” explained Prof Ho.

    For nearly thirty years I did parent programs in all of the fifty states, and regardless of the community, there was always a shortage of fathers attending, usually by a 10:1 (mothers、 fathers) ratio. Maybe they were all tending to business, and they obviously didn't think school was any of their business.

    The world is now flat. How's that for a sea change? As Thomas Friedman described it in his book The World Is Flat twenty-five years ago, the power structure of the world consisted of highs and lows. The countries with the power and knowledge were at the top of the mountains and the rest were down in the valleys. A handful of countries (the United States, Britain, Germany, and Japan) ruled the world's economy because they monopolize (垄断)the information and power.

    Then came the Internet. Suddenly the countries down in the valleys were connected to the information network and the work flow. These included India, Eastern Europe, South Korea, Brazil, and China. Don't believe it? Walk into a supermarket and pick up any ten toys, checking each for where it was made. My last count: China, ten out of ten. The world's workforce became "flattened". No more disconnected valleys.

    Since 2000, U.S. manufacturing has lost six million jobs, one-third of its workforce, most of them males. For the first time in history, women hold the majority of jobs in the U.S.

    The only people who don't understand the sea change in business are the fathers and sons still clinging to the image of the male who doesn't need to play school—just play ball. It's been thirty years since that idea had any wings, but too many males are still trying to make it fly. Once the only thing that mattered for men was what they could get out of the ground with their hands. Now it's what they can get out of their heads that counts. And without classroom success, today's male faces an impossible challenge from both intelligent women on the home front and foreigners willing to do the same job for less while sitting in an office in Bangalore or Singapore.

    Rich countries are racing to dematerialise payments. They need to do more to prepare for the side-effects.

    For the past 3,000 years, when people thought of money they thought of cash. Over the past decade, however, digital payments have taken off— tapping your plastic on a terminal or swiping a smartphone has become normal. Now this revolution is about to turn cash into an endangered species in some rich economies. That will make the economy more efficient—but it also causes new problems that could hold back the transition(转型).

    Countries are removing cash at varying speeds. In Sweden the number of retail cash transaction per person has fallen by 80% in the past ten years. America is perhaps a decade behind. Outside the rich world, cash is still king. But even there its leading role is being challenged. In China digital payments rose from 4% of all payments in 2012 to 34% in 2017.

    Cash is dying out because of two forces. One is demand— younger consumers want payment systems that plug easily into their digital lives. But equally important is that suppliers such as banks and tech firms (in developed markets) and telecoms companies (in emerging ones) are developing fast, easy-to-use payment technologies from which they can pull data and pocket fees. There is a high cost to running the infrastructure behind the cash economy—ATMs, vans carrying notes, tellers who accept coins. Most financial firms are keen to abandon it, or discourage old-fashioned customers with heavy fees.

    In the main, the prospect of a cashless economy is excellent news. Cash is inefficient. When payments dematerialise, people and shops are less open to theft. It also creates a credit history, helping consumers borrow.

    Yet set against these benefits are a couple of worries. Electronic payment systems may risk technical failures, power failure and cyber-attacks. In a cashless economy the poor, the elderly and country folk may be left behind. And a digital system could let governments watch over people's shopping habits and private multinationals exploit their personal data.

Every four or five years, vast quantities of warm water build up along the west coast of South America. This phenomenon, El Nino, creates storms that cause destructive floods. The result is costly.

Modern farmers come to terms with El Nino. They use money saved in good years to rebuild in bad ones. But history suggests it need not be like that. In a paper published recently, Ari Caramanica, an archaeologist at University of the Pacific, in Lima, shows how it used to be done. And the answer seems to be, "better".

Dr Caramanica and her colleagues have been studying the Pampa de Mocan, a coastal desert plain in northern Peru. Pampa de Mocan is not suitable for farming. Its soil contains little organic matter and the annual rainfall in non-Nino years is usually less than two centimeters. Today's farmers therefore depend on canals to carry water from local rivers to their fields.

It had been assumed that ancient farmers had a similar arrangement — and so they did. But Dr Caramanica also found eight canals that could carry water far beyond the range of modern farms. She thinks that they were intended to guide the floodwaters arriving during Nino years. Around a quarter of the ancient agricultural infrastructure of this area seems to have been built only for managing Nino-generated floodwaters.

Evidence from pollen supports this theory, revealing that Pampa de Mocan produced lots of crops in some years, while remaining nearly barren in others. The team also uncovered two cisterns in the area serviced by the extended canals. These, probably, were used to store extra flood-water.

These findings suggest that, rather than resisting El Nino, early farmers in Pampa de Mocan were ready to make use of it when it arrived. Modern farmers might do well to learn from them.