IELTS Academic Reading Practice Test 98

A parachute is a device that uses the resistance of the air to slow the descent of a person or object falling from height. The word itself combines the French prefix para-, meaning to shield against, with chute, meaning fall. Although the principle seems obvious today, it took centuries for inventors to turn the idea into a reliable piece of equipment. Early designs were little more than stiffened canopies, and even successful demonstrations were treated as curiosities rather than practical safety devices.

The earliest known design appears in a sketch by Leonardo da Vinci from around 1485. It shows a pyramid-shaped canopy made of linen and wood, with a person suspended beneath. Da Vinci noted that a man could throw himself from any great height without injury if he wore such a device. There is no evidence that the design was ever built or tested in his lifetime, and some modern calculations suggest that its stiff frame would have made it heavy and difficult to control, though in 2000 a British skydiver descended safely using a full-sized replica.

The first confirmed parachute jump from a building was made by the French physicist Louis-Sébastien Lenormand in 1783. He used a rigid-framed canopy about four metres in diameter and jumped from the tower of the Montpellier observatory before a crowd of spectators. Lenormand is often credited with coining the word parachute, and his experiment demonstrated that a falling person could be slowed enough to land without serious harm. However, his device was closer to a rigid umbrella than to the flexible parachutes used today, and its size and weight made it impractical for regular use.

A major step forward came in 1797 when André-Jacques Garnerin made the first descent from a balloon using a parachute without a rigid frame. His canopy, made of silk or canvas and held open by the air itself, was released at a height of perhaps 900 metres over Paris. The descent was successful, but the parachute swung violently from side to side, causing Garnerin to land unsteadily. He later added a small vent at the top of the canopy, which reduced the oscillations. His wife Jeanne-Geneviève became the first woman to make a parachute jump, and the pair performed widely across Europe.

Throughout the nineteenth century, parachute descents remained a form of public entertainment. Showmen would ascend in balloons and then cut away, thrilling crowds below. Yet parachutes were almost never carried as safety equipment by balloonists, who generally preferred to remain with their craft in an emergency rather than trust an unproven device. The canopies of this period were already deployed and open above the jumper's head, often suspended from the balloon during the ascent, which made them bulky and awkward. Balloonists experimented with various designs, but none won widespread acceptance.

The arrival of powered flight created a new demand for escape equipment. The earliest aeroplanes were fragile machines, and pilots had no way to leave them in an emergency. During the First World War, observers in tethered observation balloons became the first military personnel to use parachutes as a standard piece of equipment, because they needed a quick exit when enemy aircraft attacked. Pilots of fixed-wing aircraft, however, were often denied parachutes in the early years of the war, partly because commanders feared that a pilot might abandon a valuable aeroplane too readily.

The development of the pack parachute changed this attitude. In the early twentieth century, inventors designed systems in which the canopy and its lines were folded into a container worn on the back or chest. A ripcord allowed the user to release the canopy after falling clear of the aircraft. After further refinement, these packs became small and light enough to be worn routinely by pilots. By the Second World War, parachutes had become standard issue for aircrews, and large numbers of troops were delivered by parachute during airborne assaults.

After the war, surplus parachutes and trained jumpers gave rise to sport parachuting. Early sport parachutes were round canopies that descended almost vertically and offered little directional control. The situation changed in the 1970s with the introduction of the ram-air design, a rectangular canopy made of two layers of fabric that inflated to form a wing. Ram-air parachutes could be steered precisely, and their forward speed allowed jumpers to land gently rather than drop steeply. This innovation transformed parachuting into a skilled recreational activity, with competitions for accuracy, style and formation flying.

The operation of a parachute depends on two main forces: gravity, which pulls the jumper downward, and drag, the resistance created when the canopy pushes against the surrounding air. When the jumper first leaves an aircraft, gravity causes speed to increase rapidly. As the parachute opens, the large canopy catches a great deal of air, creating a drag force that quickly opposes most of the gravitational pull. Within a few seconds the forces come into balance, and the jumper descends at a steady terminal velocity, typically around twenty-five kilometres per hour for a modern training canopy.

Modern parachutes are highly reliable, but no piece of equipment can be guaranteed to work perfectly. For this reason, sport jumpers almost always carry a reserve parachute packed separately. Many also use an automatic activation device, which measures altitude and speed and releases the reserve canopy if the main parachute has not opened by a preset height. These systems have made serious accidents rare, although they still occur, usually as a result of human error during fast, low turns or when a jumper fails to follow proper procedures.

In most societies, living beyond ninety is rare, but certain small regions have unusually high proportions of people who reach extreme old age. Researchers who study these places hope to identify factors that might be copied elsewhere. The term blue zone was introduced by demographers Michel Poulain and Gianni Pes, and later popularised by the writer Dan Buettner, who used it to describe areas with exceptional longevity. Although the exact boundaries of these zones are debated, the regions themselves have provided a rich source of data for scientists interested in ageing.

The first area identified was the mountainous interior of the Italian island of Sardinia. Studies of villages in the Nuoro province found an unusually high number of men living past 100. Shepherds in this region walk long distances daily over steep terrain, and their traditional diet includes wholemeal bread, beans, garden vegetables and moderate amounts of red wine. Researchers have also noted the strong family bonds and the cultural respect given to older people, particularly to men who have worked the land all their lives.

Okinawa, a group of islands in southern Japan, has also attracted attention for its many centenarians. Older Okinawans traditionally eat a mostly plant-based diet, often beginning meals with a Confucian-inspired saying that encourages eating only until the stomach is 80 percent full. Many maintain strong social ties through groups known as moai, which provide both financial and emotional support throughout life. This practice ensures that individuals rarely face hardship alone and that older members remain active participants in the community.

In the United States, the Seventh-day Adventist community in Loma Linda, California, offers a different kind of evidence. Adventists often follow a vegetarian or partly vegetarian diet and avoid alcohol and tobacco, and studies comparing them with the general population have found significantly lower rates of heart disease and some cancers. The community also emphasises Sabbath rest, regular exercise and close family life, which may contribute to the fact that Adventists in this area live several years longer than the average Californian.

The Nicoya Peninsula in Costa Rica is another area where many residents live into their nineties and beyond. Older Nicoyans tend to eat beans and maize tortillas, drink hard water rich in calcium, and remain physically active through agricultural work. They also maintain a strong plan de vida, or reason to live, which researchers believe helps protect against stress. This sense of purpose is seen as a key psychological asset, and it appears to be shared by older people in several other long-lived populations.

The Greek island of Ikaria has one of the world's lowest rates of middle-age mortality and dementia. Its inhabitants eat a Mediterranean diet, drink herbal teas, take regular naps and live at a slow pace. The island's mountainous terrain encourages walking, and social life remains central, with regular festivals and extended family meals. Researchers have also observed that Ikarians tend to go to bed late and wake up late, but they still manage to obtain enough sleep, and their daily routine includes little time pressure.

Across these regions, certain patterns are consistent. Diets are largely plant-based, with legumes, whole grains, nuts and seasonal vegetables, and meat is eaten sparingly. Physical activity is not confined to gyms; it arises naturally from walking, gardening, herding and household tasks. People also tend to sleep enough, avoid tobacco and consume alcohol only in moderation, if at all. None of these groups relies on a single miracle food or supplement; instead, the benefits appear to come from the combination of habits sustained over a lifetime.

Social and psychological factors appear equally important. Long-lived communities typically keep older people integrated into family and community life rather than isolated. A sense of purpose is common, and stress is reduced through daily routines, strong social support and religious or spiritual practice. Researchers caution, however, that diet and lifestyle are not the whole story; genetics also plays a role, and records of birth dates in some regions were historically unreliable. Some critics also point out that people who live to extreme old age may simply have survived hazards that killed others earlier in life.

Nevertheless, the study of long-lived populations has influenced public health advice. Rather than showing that a single food or habit guarantees long life, these communities suggest that a combination of moderate eating, regular natural movement, social connection and purpose can improve the chances of healthy ageing. As health services struggle with the rise of chronic disease, such lessons remain valuable. The challenge is to translate these traditional patterns into policies that work in modern urban societies, where walking less and eating processed food have become the default.

In 1906, the scientist Francis Galton attended a country fair where visitors were guessing the weight of an ox. Galton, who believed that most people were ill-informed, expected the guesses to be wildly wrong. After the contest, he collected nearly 800 tickets and calculated the average. To his surprise, the average guess was remarkably close to the animal's true weight. The median guess, he later reported in the journal Nature, differed from the actual figure by less than one percent. This famous result is often taken as the first modern demonstration of the wisdom of crowds.

The idea that groups can be wiser than their individual members was popularised a century later by the writer James Surowiecki in his 2004 book The Wisdom of Crowds. Surowiecki argued that a wise crowd needs diversity, independence, decentralisation and a way of aggregating judgments. He cited examples from guessing competitions, stock markets and game shows, and proposed four conditions that must be met for a crowd to be wise. According to Surowiecki, when these conditions hold, a diverse collection of independently deciding people is likely to make better judgments and predictions than even the smartest expert.

The first condition is diversity of opinion. Each person should have some private information, even if it is incomplete or eccentric. When many different perspectives are combined, errors tend to cancel out. The second is independence; people's judgments should not be determined by the opinions of those around them. Independence ensures that the crowd's mistakes are not correlated, because if everyone bases an answer on the same wrong fact, the group will be confidently wrong.

The third condition is decentralisation, which means that people are able to draw on local knowledge and make their own choices. The fourth is aggregation, a mechanism for turning many private judgments into a single collective decision. A market price, a voting system or a computer program that averages estimates can all serve this function. Surowiecki acknowledged that these conditions are often violated, and that crowds can be foolish, panicky and dangerous when they are not met.

Later research has supported parts of this argument while complicating others. Psychologists have found that simple averaging of independent estimates consistently performs well, especially when the task has a clear, verifiable answer. In one well-known experiment, students guessing the number of jelly beans in a jar produced a class average that was more accurate than almost every individual guess. However, the value of the crowd depends heavily on the type of problem. For complex, open-ended questions, groups may simply reproduce shared biases.

The wisdom of crowds is not automatic. Researchers have tested these conditions in laboratory experiments. In one study, participants were asked to estimate a value, and some participants could see the estimates of other participants while others could not. The independent groups produced averages that were much closer to the correct value. This shows that independence is a practical requirement for a wise crowd, not merely a theoretical one. Diversity and independence reduce the chance that the crowd will make the same mistake at the same time.

The most serious threat to collective wisdom is social influence. When people see what others have chosen before making a decision, they often change their own answers, and the range of opinions shrinks. This process, known as herding, can create information cascades in which later decisions are based on earlier ones rather than on private knowledge. Laboratory studies have shown that even mild signals about the majority view can reduce the diversity that makes crowds accurate.

Real-world failures are easy to find. Financial bubbles occur when investors copy one another and push asset prices far beyond any reasonable valuation. The housing market collapse that began in 2007 is often cited as an example of a crowd that was not wise because too many participants were following the same flawed information. In such cases, the crowd does not cancel out errors; it amplifies them.

Yet the wisdom of crowds should not be dismissed. In many areas, from weather forecasting to project management, aggregated judgments outperform individual experts. Prediction markets, in which people bet on future events, have produced accurate forecasts of election results, box-office earnings and product success. These tools work because they provide continuous feedback, reward accuracy and draw on dispersed knowledge that no single expert possesses.

Online rating systems are another example of aggregation in action. When thousands of users rate a product, the average of their ratings is often a better guide than any single rating. This is because each user brings a slightly different perspective, and the aggregation process averages out individual errors. The wisdom of crowds also appears in search engines, which use the links made by many independent website creators to rank pages. However, if the crowd is not diverse, or if its members are influenced by what they have already seen, the result can be poor. This is why designers of online systems try to protect the conditions that make crowds wise.

I am therefore cautiously optimistic about collective intelligence. The crowd is not always right, and it can be catastrophically wrong when herding takes over. But when diversity, independence and good aggregation are protected, the group is often wiser than its smartest member. The challenge is to design institutions that encourage independent thought rather than imitation. If we can do that, Galton's ox may continue to teach us something important about human judgment.