It's generally believed that people act the way they do because of their personalities and attitudes. They recycle their garbage because they care about the environment. They pay $5 for a caramel brulee latte because they like expensive coffee drinks.

    It's undeniable that behavior comes from our inner dispositions（性情）, but in many instances we also draw inferences about who we are, as suggested by the social psychologist Daryl Bern, by observing our own behavior. We can be strangers to ourselves. If we knew our own minds, why should we need to guess what our preferences are from our behavior? If our minds were an open book, we would know exactly how much we care about the environment or like lattes. Actually, we often need to look to our behavior to figure out who we are.

Moreover, we don't just use our behavior to learn about our particular types of character — we infer characters that weren't there before. Our behavior is often shaped by little pressures around us, which we fail to recognize. Maybe we recycle because our wives and neighbors would disapprove if we didn't. Maybe we buy lattes in order to impress the people around us. We should not mistakenly believe that we always behave as a result of some inner disposition.

Whatever pressures there can be or inferences one can make, people become what they do, though it may not be in compliance（符合）with their true desires. Therefore, we should all bear in mind Kurt Vonnegut's advice: “We are what we pretend to be, so we must be careful about what we pretend to be.”

    The single, decisive factor that made it possible for mankind to settle in lasting communities（社区，聚居地）was agriculture. After farming was developed in the Middle East in about 6500 BC, people living in family units did not have to be on the move continually searching for food or hunting their animals. Once people could control the production of food and be assured of a reliable supply of it, their lives changed completely.

    Farming was a revolutionary discovery. It not only made settlements possible and later the building of cities but it also made available a reliable food supply. With more food available, more people could be fed. Population therefore increased. The growing number of people available for more kinds of work led to the development of new social formations. With more and more food, a community could support a variety of workers who were not farmers.

Farming in the world over has always relied upon a dependable water supply. For the earliest societies this meant rivers and streams or regular rainfall. The first great civilizations grew up along rivers. Later communities were able to develop by taking advantage of the rainy seasons.

    All of the ancient civilizations probably developed in much the same way, in spite of a few differences. As villages grew, the production of more numerous goods became possible. Cloth could be woven from wool. Houses made of wood, brick, and stone could be put up.

    The science of mathematics was an early outcome of agriculture. People studied the movements of the moon, the sun, and the planets to work out seasons, By doing so they created the first calendars（日历）. With a calendar it was possible to find out the arrival of each growing season. Measurement of land areas was necessary if field was to be divided accurately. Measurement of amounts, for example, of seeds or grains was also a factor in farming and housekeeping. Later measures of value as money exchange became common.

    All of the major ancient civilizations in Mesopotamia, Egypt, the Indus Valley, and China appeared in the 4th millennium（千年）BC. Historians still argue over which one came into being first. It may well have been the Middle East. This place reaches out from the Nile River in Egypt northward along the coast of former Palestine, then eastward into Asia to include Mesopotamia. In this area people settled along the riverbanks and practiced field agriculture. This kind of farming depended on the reproduction of seed, normally from grain crops.

    As scientists in the Netherlands tried to figure out how to build a super flying robot, they learned from one of nature s flyers: the humble fruit fly(果蝇).And by building this robot, they've gained new insights into how the fly carries out one of its dangerous tasks.

    The robot is called the DelFly Nimble Its wingspan(冀展)is about a foot wide. It has four wings that can beat at 17 times per second, which appear very delicate because they're made of the same material as space blankets.

    In the previous designs, they always had a tail, like a traditional airplane tail, said the robots main designer Matej Karasek. He's based at the Micro Air Vehicle Laboratory at Delft University of Technology in the Netherlands, and he and his colleagues published their findings on Thursday in Science

    “In the previous generations", he said, "flapping wings drove the robot forward while the tail helped to guide and stabilize it. But now the DelFly Nimble is completely controlled by the wings. The challenge then was actually combine the control into the wing movement, and that's what we achieved, Karasek said

    In the latest generation. the wings can each move individually or rotate(旋转)around the body of the robot in order to maximize the machine s agility(灵活 ) The robot can remain in one place in the air for about five minutes on a full battery or fly for more than a kilometer"， Karasek said, "And because the scientists are controlling all the movements, they can use the robot to learn more about how fruit flies actually carry out their dangerous tasks, which has caught the attention of biologists.”

    You can't imagine how terrible I felt at that time. A month before my first marathon, one of my ankles was injured and this meant not running for two weeks, leaving me only two weeks to train. Yet, I was determined to go ahead.

    I remember back to my 7th year in school. In my first P.E. class, the teacher required us to run laps and then hit a softball. I didn't do either well. He later informed me that I was "not athletic".

    The idea that I was "not athletic" stuck with me for years. When I started running in my 30s, I realized running was a battle against myself, not about competition or whether or not I was athletic. It was all about the battle against my own body and mind. A test of wills!

    The night before my marathon, I dreamt that I couldn't even find the finish line. I woke up sweating and nervous, but ready to prove something to myself.

    Shortly after crossing the start line, my shoe laces(鞋带) became untied. So I stopped to readjust. Not the start I wanted!

    At mile 3, I passed a sign: "GO FOR IT, RUNNERS!"

    By mile17, I became out of breath and the once injured ankle hurt badly. Despite the pain, I stayed the course walking a bit and then running again.

    By mile 21, I was starving!

    As I approached mile 23, I could see my wife waving a sign. She is my biggest fan. She never minded the alarm clock sounding at 4 a.m. or questioned my expenses on running.

    I was one of the final runners to finish. But I finished! And I got a medal. In fact, I got the same medal as the one that the guy who came in first place had.

    Determined to be myself, move forward, free of shame and worldly labels(世俗标签), I can now call myself a "marathon winner".

    Visit Nashville, Tennessee, the capital of country music and the home of the Grand Ole Opry. Forty -day bus tour starts from Pittsburgh.

    Departures August 23, September 13, September 27, October 11, October 25.

$185 per person based on double occupancy. Includes private motor coach from Pittsburgh, hotel rooms, reserved tickets for the Grand Ole Opry. Country Festival Friday and Saturday nights, sightseeing tour of Nashville, admissions to places of interest.

    For information, free booklets, and reservations, call 4212 — 6060. Travel and Tours, 2245 Market Street, Pittsburgh, Pennsylvania 15219. 14-day advanced booking required. Visa and Master Card payment welcome.

    Janus, the Roman god, has two faces looking in opposite directions. So does artificial intelligence (AI). On one side are the positive changes, enabling people to achieve more, far more quickly, by using technology to improve their existing skills. Look the other way, though, and there are plenty of potential pitfalls.

    Like Janus, technological change may also cause disruption(混乱), but AI is likely to have a bigger impact than anything since the appearance of computers, and its consequences could be far more disruptive.

    In the years ahead, AI will raise three big questions for bosses and governments. One is the effect on jobs. Although CEOs publicly praise the broad benefits AI will bring, their main interest lies in cutting costs. One European bank asked Infosys to find a way of reducing the staff in its operations department from 50,000 to 500. The McKinsey Global Institute estimates that by 2030 up to 375m people, or 14% of the global workforce, could have their jobs replaced by AI.

    A second important question is how to protect privacy as AI spreads. The internet has already made it possible to track people's digital behavior in minute detail. AI will offer even better tools for businesses to monitor consumers and employees, both online and in the physical world. Consumers are sometimes happy to go along with this if it results in personalised service or promotions. But AI is bound to bring invasion of privacy that is seen as unacceptable. For example, law-enforcement officials around the world will use AI to spot criminals, but may also monitor ordinary citizens.

    The third question is about the effect of AI on competition in business. A technology company that achieves a major breakthrough in artificial intelligence could race ahead of rivals, put others out of business and lessen competition. This is unlikely to happen in the near future, but if it did it would be of great concern.

    It is too early to tell whether the positive changes brought by AI will outweigh the risk. But it will put an end to traditional ways of doing things and start a new era for business and for the world at large.