IELTS Academic Reading Practice Test 96

People have always needed to enter the water to obtain food and materials, but the human body is poorly suited to staying below the surface. A trained breath-hold diver can remain underwater for only a few minutes before rising for air, and even then the work is exhausting. For centuries, therefore, divers gathered sponges, pearls and shellfish close to the shore while inventors searched for ways to supply air below the waves. Despite this limitation, many coastal communities developed specialised techniques for extending their time below the surface.

The first practical aid was the diving bell, an inverted open-bottomed vessel lowered into the water. Because the air inside cannot escape upwards, it remains trapped and gives the occupant a small pocket in which to breathe. Simple bells were used in European rivers and harbours by the sixteenth century, but their air quickly became stale. In the late seventeenth century the English astronomer Edmond Halley improved the design by sending weighted barrels of fresh air down to replenish the bell, allowing divers to remain below for considerably longer. Even so, the bell confined workers to one spot and could not follow them.

The next major step was to carry the air supply with the diver. Early nineteenth-century inventors experimented with metal helmets fed by hoses from the surface, but the open helmets allowed water to enter too easily. In the late 1830s the German-born engineer Augustus Siebe solved this problem by attaching the helmet to a waterproof suit, producing a closed dress that covered the whole body.

Air was forced down a hose by hand pumps and escaped through a valve in the helmet. For the first time, divers could walk across the seabed and work on wrecks and harbour walls, and Siebe's apparatus became the standard surface-supplied diving equipment for the rest of the century.

Working in deep water, however, brought new dangers. Men building bridge foundations in pressurised caissons often experienced severe joint pain and paralysis when they returned to the surface, a condition that became known as caisson disease, or the bends. In the 1870s the French physiologist Paul Bert investigated these effects and argued that decompression should be carried out slowly, but practical protection came later. In 1908 the Scottish physiologist John Scott Haldane published a system of staged decompression for the British Admiralty, based on experimental studies of how gases are absorbed and released by the body, which greatly reduced the risk.

Haldane's tables were intended for professional divers, but many inventors also dreamed of a portable self-contained apparatus that would free the diver from the surface hose. A major breakthrough came in 1878 when Henry Fleuss, an English engineer, built a closed-circuit device that used a cylinder of pure oxygen and a chemical absorbent to remove carbon dioxide. Because the oxygen was reused, the diver's breath was recycled, and the apparatus could be worn on the back. A diver later used it successfully in a flooded railway tunnel, although pure oxygen becomes toxic under pressure and severely limited the depth at which such rebreathers could be used.

The device that transformed diving was developed during the Second World War. In 1943 the French naval officer Jacques-Yves Cousteau and the engineer Émile Gagnan designed a demand regulator that released compressed air from a cylinder only when the diver inhaled. This simple open-circuit system was far lighter and more reliable than earlier rebreathers, and after the war Cousteau promoted it through films and books. The Aqua-Lung, as it was called, eventually made recreational scuba diving available to the public, and diving clubs multiplied in the 1950s and 1960s. The modern sport of scuba diving grew directly from this wartime technology.

Modern scuba equipment has become increasingly sophisticated. Divers now wear a buoyancy control device, a vest connected to the air supply that can be partially filled to keep the diver neutrally buoyant at any depth. A dive computer on the wrist continuously records depth and time and calculates a personalised decompression schedule, replacing the earlier reliance on printed tables. Many divers also use gas mixtures such as enriched air, which contains a higher proportion of oxygen than ordinary air and can extend the time that may be spent at moderate depths. These devices have made diving safer and easier to plan.

Training organisations developed standardised courses to teach safe use of all this equipment, and certification cards are now required by most operators. Nevertheless, diving remains an activity with real risks, because the underwater environment is unforgiving of error. Equipment failures, poor judgement and ignored decompression limits still cause accidents every year. For this reason, professionals receive extensive instruction in emergency procedures, and underwater work is carefully planned. Nobody goes below the surface, even with the best modern gear, without acknowledging the debt owed to earlier inventors.

From breath-hold fishing to computer-controlled scuba, the history of diving equipment shows a steady extension of human abilities underwater. Each new device solved one problem and often exposed another, whether stale air, faulty seals, decompression sickness or oxygen toxicity. Yet the underlying goal has never changed: to allow people to stay longer, move more freely and work safely in a world that was not designed for them. Modern divers may not think about this history, but every valve, cylinder and computer is a direct descendant of that long search for a safe breath below the waves.

Around ten per cent of people use the left hand for most skilled actions such as writing and throwing, a trait that has been recorded in every human population studied. Throughout much of history left-handers were viewed with suspicion and sometimes forced to switch hands, but the proportion has remained remarkably stable. Scientists now treat left-handedness not as a defect but as a natural variant that raises fundamental questions about how the brain is organised and why humans are mostly right-handed. Measurements from questionnaires and observational studies produce slightly different estimates, but the overall picture is consistent.

Handedness clearly runs in families, but it is not inherited in a simple Mendelian way. If one parent is left-handed, a child is more likely to be left-handed than if both parents are right-handed, yet many left-handers are born to right-handed parents and vice versa. Twin studies have produced an even stronger message: identical twins, who share all their genes, do not always have the same handedness, with concordance only around three-quarters. In other words, genetic inheritance contributes, but chance events during development and environmental influences after birth must also play significant roles. Recent genetic studies have identified several regions associated with handedness, although each has only a small effect.

Handedness is closely linked to brain lateralisation, the tendency for some mental functions to be controlled more by one hemisphere than the other. In about 95 per cent of right-handers, the main areas for speech and language are located in the left hemisphere, whereas left-handers show a more varied pattern. Some left-handers also process language mainly on the left, but a substantial minority use the right hemisphere or distribute the function across both sides. This variation is normal; it does not mean that left-handed brains are simply reversed versions of right-handed brains. This pattern has been confirmed by brain imaging, which shows that the lateralisation of language is one of the most stable asymmetries in the human brain.

If left-handedness were a serious disadvantage, natural selection should have reduced it to a very low frequency long ago. Its persistence therefore suggests that it must carry some benefits. One widely discussed possibility is frequency-dependent selection: because most people are right-handed, opponents in sports and combat are accustomed to facing right-handers, so left-handers may enjoy an element of surprise. Indeed, left-handers are over-represented in some interactive sports such as fencing and boxing, a pattern that supports the idea that rarity itself can be advantageous in direct competition. Similar arguments have been made for other minority traits that persist in a population.

Cultural attitudes have also shaped the way left-handedness is expressed. In many languages the word for left has negative connotations, and in some societies children were once punished for writing with the left hand. Such pressure probably causes some natural left-handers to learn to use their right hands for certain tasks, and may partly explain why reported rates of left-handedness appear lower in some countries, especially among older generations. The underlying preference may be more common than the statistics suggest, because it is often suppressed.

The relationship between left-handedness and mental or physical abilities has been studied intensely, but findings are generally weak and inconsistent. A few large studies have reported small differences in the average performance of left-handers and right-handers on certain cognitive tasks, but the ranges overlap greatly, and no serious scientist would use handedness to predict an individual's talents. Left-handers are also reported to be over-represented among architects and artists, but such claims often depend on small or unrepresentative samples and should be treated with caution. The popular image of the creative left-hander is therefore more stereotype than scientific finding.

The everyday environment is still largely built for the right-handed majority. Scissors, classroom desks, measuring tapes, musical instruments and many power tools are designed to be used most comfortably with the right hand, and left-handers may have to adapt. In industry and manual work, using right-handed equipment with the left hand has been associated with a higher risk of injury. Although inexpensive left-handed versions of common items are now widely available, the default assumption in design often remains right-handed.

One difficulty in research is that handedness is not a simple either-or category. Questionnaires such as the Edinburgh Handedness Inventory ask people to indicate which hand they use for a variety of activities, and answers form a continuous spectrum from strongly left to strongly right. People who use different hands for different tasks are sometimes called mixed-handed or ambidextrous. Recognising this continuum matters, because results can change depending on whether researchers define handedness by one activity, such as writing, or by a broader set.

Left-handedness remains a fascinating example of how genes, development and culture interact. It is not caused by one factor, nor does it confer automatic advantages or disadvantages. As societies have become more tolerant, more people are willing to identify themselves as left-handed, but the fundamental biology is unchanged. Understanding why most humans favour the right hand may ultimately illuminate broader questions about brain asymmetry and the evolution of our species. In the meantime, left-handers continue to adapt to a right-handed world, just as they have always done.

For much of the twentieth century, science communication was treated largely as a problem of translation. Scientists produced knowledge, professional communicators simplified it into plain language, and the public was expected to absorb the result. The assumption behind this model was that ordinary people were essentially empty vessels: if only they received accurate facts, they would come to share the views of experts. From public lectures to museum displays and television documentaries, the task was to fill a supposed deficit in public understanding.

That assumption is now known as the deficit model, a term coined by social scientists who noticed how frequently scientific institutions described the public as ignorant. Its influence can be traced to a 1985 report by the Royal Society on public understanding of science, together with surveys suggesting that many adults could not answer basic scientific questions. In response, governments invested heavily in education campaigns, science festivals and popular science books. The aim was admirable, but the underlying theory was thin. Later research consistently found that simply supplying more facts did not reliably change how people thought about controversial areas of science.

Why should accurate information fail to persuade? One reason is that people do not process facts in a vacuum. They interpret new evidence in the light of their values, social identities and previous beliefs. In some cases, presenting strong counter-arguments may actually reinforce existing views, a phenomenon sometimes called motivated reasoning. Studies of public attitudes to genetically modified crops, nuclear power and childhood vaccination have shown that providing more scientific detail often leaves overall positions unchanged or even hardens them. This does not mean knowledge is irrelevant, but it does mean that knowledge alone is rarely sufficient for acceptance.

These findings encouraged a shift from the deficit model to what is often called the dialogue model or public engagement with science. Instead of treating the public as learners, institutions began to invite citizens to discuss science and even to contribute to decisions about research priorities. Consensus conferences, citizen juries and deliberative workshops ask participants to consider evidence, question experts and express concerns. The goal of such exercises is not necessarily to produce support for a particular technology, but to make discussions more democratic and to reveal values that experts might overlook.

The rise of the internet and social media has transformed the setting for all such communication. Scientists can now reach audiences directly, without journalists as intermediaries, and members of the public can share their own observations and questions instantly. At the same time, the traditional authority of scientific institutions has weakened. Misinformation can spread faster than careful analysis, and platforms tend to sort users into like-minded groups, creating echo chambers in which particular claims are repeated but rarely examined. Science communication is no longer a lecture; it is a crowded, noisy conversation.

Trust has become a central concern, because people are more willing to accept uncertain or complex information from sources they regard as honest and competent. Trust is damaged when institutions overstate the certainty of findings, hide uncertainties or are perceived as serving narrow interests. During public health emergencies, for example, advice must sometimes change as new evidence emerges. If this is not explained clearly, people may see the revision as incompetence or manipulation. Acknowledging uncertainty, far from undermining science, can actually strengthen public confidence by demonstrating honesty.

My own view is that the deficit model should not be abandoned entirely, because there are indeed significant gaps in public knowledge about matters of common concern. However, these gaps cannot be closed by one-way instruction. Effective science communication must combine accurate, accessible information with genuine listening, and it must recognise that different groups may have different questions and priorities. It is not enough to make the facts clear; communicators also have to make the relevance of those facts clear and to engage with the concerns that led people to doubt them in the first place.

Some scientists complain that engaging with the public is a distraction from research, or that it requires skills they have not been taught. Yet communication is no longer an optional extra. Public money funds much research, and citizens are entitled to understand and debate how it is used. Training in communication should therefore be part of scientific education, not an afterthought. The best communicators are not those who shout loudest, but those who explain clearly, admit uncertainty and treat their audience as partners rather than empty vessels.

Science has never been more important to public decisions, from climate policy to medical treatment. The challenge is not simply to inform a deficient public, but to create relationships in which knowledge can be exchanged, challenged and used wisely. That requires humility from experts and curiosity from everyone else.