IELTS Academic Reading Practice Test 458

In April 1947 a small crew of six men set out from the coast of Peru on a raft made of balsa wood. Their leader was Thor Heyerdahl, a Norwegian explorer who had spent years arguing that the islands of Polynesia might have been settled not from Asia but from South America. The prevailing scholarly view held that Polynesian ancestors had moved eastwards across the Pacific from Southeast Asia. Heyerdahl's proposal was widely regarded as improbable, and his decision to test it at sea was treated with scepticism by many experts.

His interest had been aroused during a long stay in the Marquesas Islands, where he noticed that the trade winds and ocean currents of the equatorial Pacific generally flow from east to west. A vessel drifting with them, he reasoned, could travel from Ecuador towards Polynesia without being towed or rowed. He also collected reports of apparent similarities between South American and Polynesian cultures, including stone carvings and the sweet potato, a crop native to the Andes that was grown in parts of Polynesia before Europeans arrived. Linguists and archaeologists were unimpressed, since the structure of Polynesian languages and the evidence of ancient settlements pointed clearly towards Asia.

To test the idea, Heyerdahl travelled to Ecuador and obtained nine large logs of balsa, a very light wood. The raft was assembled without metal: the logs were lashed together with hemp rope, a deck of bamboo was laid on top, and a small open hut and a square sail were added. Several centreboards, lowered through slots between the logs, could be adjusted to help steer. The craft was named Kon-Tiki after a legendary figure in South American tradition. Its crew of six included an engineer, a painter who acted as navigator, two radio operators and a Swedish ethnographer. They left the port of Callao on 28 April 1947.

Life on board settled into a routine. The raft moved with the current and the trade winds, and the men took turns at the long steering oar. Flying fish landed on the deck at night, and the crew caught tuna, dolphin and sharks, using the last for food and for studying their habits. A fine net towed behind the raft collected plankton, which was preserved for later analysis. The two radio operators maintained occasional contact with amateur radio enthusiasts, though the equipment was damaged by salt water and the raft's motion.

During the crossing the crew encountered several storms. On one occasion the raft was struck by a large wave that swept the deck, and the men spent hours repairing the steering gear. They also had to keep watch for whales and sharks, which were attracted by the fish they caught. The most dangerous problem was the chafing of the ropes beneath the logs, which had to be checked constantly; had the ropes parted, the raft would have broken up.

The six men kept a careful record of everything they saw. They measured water temperature, collected samples of plankton and noted the behaviour of fish that gathered beneath the raft. This work was modest in scale, but it gave the voyage a scientific purpose beyond mere adventure and provided material for later publications.

After 101 days at sea, the raft reached the reef of Raroia, an atoll in the Tuamotu Archipelago, on 7 August 1947. It had covered nearly 7,000 kilometres. The crew survived the impact, salvaged their equipment and eventually crossed to an inhabited island. The voyage demonstrated that a balsa raft, carried by winds and currents, could cross the Pacific. It did not show that Polynesians had actually made the journey, and Heyerdahl was careful to present the crossing as a test of possibility rather than proof.

Heyerdahl's account of the expedition, published in 1948, became an international bestseller, and a documentary film compiled from footage shot on board won an Academy Award in 1951. The adventure made him one of the best-known explorers of the postwar period. He went on to organise further voyages, most famously across the Atlantic in reed boats named Ra, in order to examine contacts between ancient Egypt and the Americas. Those expeditions were also widely publicised, though their scientific conclusions were disputed.

Among specialists, the Kon-Tiki experiment was admired as a feat of seamanship but rejected as evidence for Heyerdahl's migration theory. Studies of Polynesian languages group them with the Austronesian family, whose speakers spread from Taiwan through the Philippines and Indonesia. Genetic research has also found that most Polynesian ancestry derives from East Asian populations. At the same time, the picture is not entirely one-sided. The sweet potato was cultivated in Polynesia before European contact, and it originated in South America. Some genetic studies have identified traces of South American ancestry in eastern Polynesia, suggesting that contact did occur, though perhaps through a few voyages rather than a mass migration.

The raft itself has been preserved and is displayed in a museum in Oslo. The expedition also helped to establish experimental archaeology, in which full-size replicas of ancient vessels are built and sailed in order to test ideas about technology and navigation. Subsequent projects have used the same approach to study Roman ships, Viking longships and Polynesian canoes. For many visitors, the raft remains a symbol of curiosity and courage rather than a proof of any theory.

When a friend says 'I'm fine' in a flat, clipped voice, most listeners suspect that something is wrong. The words carry one message; the way they are spoken carries another. This second channel is known as prosody, and it includes changes in pitch, loudness, tempo and voice quality. Our ability to interpret these cues is remarkably quick, often operating before we have consciously analysed what was said. It also matters socially: misreading a colleague's tone can damage a working relationship, while a doctor who misses anxiety in a patient's voice may fail to offer the help that is needed.

Much research has focused on a small set of emotions that appear to be expressed and recognised across many societies: anger, fear, sadness, happiness, disgust and surprise. In a typical experiment, volunteers listen to recordings and choose a label for each one. Accuracy is usually well above chance. Anger and fear are among the easiest to identify. They tend to be associated with a higher pitch and a faster rate of speech. Sadness, by contrast, is often marked by a lower pitch, softer volume and slower delivery. These patterns are tendencies, not fixed rules. A speaker's age, sex and physical build affect the voice, so listeners must calibrate their judgements to the individual.

Not all emotional information is carried by words at all. Laughter, screams, sighs and cries are produced without language, yet they are highly effective signals. Studies comparing listeners from different countries have found broad agreement on the meaning of laughter and screams, which suggests that some vocal expressions have deep evolutionary roots. Subtler states, such as embarrassment or pride, are recognised less consistently. One reason is that such feelings are often conveyed through combinations of cues, including a hesitation, a sharp intake of breath or a particular rhythm of speech, rather than a single distinctive sound.

Culture shapes both how emotions are expressed and how they are heard. Every society has display rules that determine when it is acceptable to sound angry, enthusiastic or upset, and these rules can alter the pitch and intensity of speech. Listeners also use their knowledge of a language. In tonal languages, changes in pitch distinguish words, so a rising tone may be part of the word itself rather than a sign of surprise. Experiments generally show an in-group advantage: people identify emotions more accurately in speakers from their own community, though they still perform above chance with outsiders. The surrounding context is equally important. The same sharp tone may indicate irritation or urgency.

Brain imaging has begun to reveal a network of regions involved. Areas in the auditory cortex respond to the acoustic features of a voice, while regions in the superior temporal sulcus appear to integrate those features into a meaningful emotional signal. The amygdala is a structure long linked with threat detection. It is particularly important for fear. Patients with damage to the amygdala may fail to recognise fear in a speaker's voice. For many years it was claimed that the right hemisphere specialised in prosody and the left in language, but modern studies show a more bilateral and distributed system. Frontal regions help to combine the sound of speech with its meaning.

Individual differences are considerable. Some people are unusually accurate, while others consistently misread tones; personality, musical training and social experience may all play a part. Certain clinical conditions affect the production or perception of vocal emotion. Parkinson's disease, for example, can reduce the range of vocal expression, so that a person sounds flat or uninterested even when they are not. Some autistic people report difficulty interpreting prosody, although this is far from universal and may depend on the demands of a particular situation. Such findings are a reminder that a voice is not a simple window onto another person's mind.

Automatic systems that claim to detect emotion from speech are now marketed for call centres and health monitoring. Their accuracy is limited. They are trained on recordings that may not represent the full range of ages, accents and cultures, and this can introduce bias. Emotional expressions are also context-dependent: a customer who sounds angry may be frustrated by a faulty product. Ethical questions arise when such systems are used to judge people without their knowledge. Researchers therefore urge caution, and many argue that machines should assist human judgement rather than replace it.

The deepest disagreement concerns the nature of emotion itself. The traditional view treats emotions as distinct categories, each with its own signature pattern of sound. Some psychologists dispute this. They argue that emotions are constructed from more basic ingredients, and that vocal signals vary continuously rather than falling into neat boxes. If they are right, then attempts to match a voice to a single label will always be approximate. What seems clear is that listeners use many sources at once: the voice, the face, the body, the words and the situation.

Practical lessons follow. Doctors and nurses can be trained to listen for signs of distress that patients do not put into words, and telephone services can encourage staff to check their interpretations rather than rely on first impressions. For the rest of us, the useful reminder is that reading emotion from a voice is an inference, not a form of mind-reading. Asking a simple question is often more reliable than guessing from a tone.

Few food technologies have attracted as much attention as meat grown from animal cells in a laboratory. Supporters call the product cultivated meat; critics prefer the term lab-grown meat. The promise is substantial. Livestock farming uses a large share of the world's farmland, uses large quantities of water and produces significant greenhouse-gas emissions, including methane from cattle. It is also a major user of antibiotics. If meat could be produced in factories instead, the argument goes, these pressures would fall. Technology companies and venture funds have put money into the sector, and several companies have built small production plants. Governments have also begun to fund research, because they see an opportunity to combine food security with industrial growth. Yet the environmental case is less settled than early publicity suggested, and some scientists warn that the benefits depend on how the process is powered and scaled.

Making cultivated meat begins with a small sample of muscle cells taken from a living animal. The cells are put in a nutrient solution and kept in containers called bioreactors, where the temperature, the oxygen and the acidity are carefully controlled. To form something like a piece of meat, the cells must be encouraged to multiply and then to develop into muscle fibres, often on a support that gives the meat its shape. The first experiments used fetal bovine serum, a substance taken from the blood of unborn calves, which was expensive and meant that the product was not free of animal material. Synthetic alternatives have since been developed. Even so, the obstacles are formidable: keeping the cells free of contamination, persuading the cells to grow densely, and designing bioreactors large enough to make production economical. The equipment uses a lot of energy, and production remains far from the scale of a modern meat plant.

Environmental assessments have produced sharply different results. Some studies conclude that cultivated meat would use much less land and water than beef and would produce fewer greenhouse gases. Others find that the energy needed to run the bioreactors and to clean the nutrients is so great that, unless electricity comes from low-carbon sources, emissions could be higher than those of chicken or pork. The disagreement arises partly from different ideas about future technology and partly from the choice of comparison. Beef has an unusually large footprint, so almost any alternative looks good next to beef; comparison with beans or grains is far less favourable. Several researchers have called for common standards and independent checks, arguing that companies should not be allowed to make environmental claims based on their own optimistic models. The industry replies that the early assessments used old data.

Animal welfare is often presented as the strongest reason to support the technology. If meat can be grown from a few cells, the number of animals raised and killed for food could fall dramatically. Yet cultivated meat is not automatically free of animals. Cells must originally be taken from a living creature, and although the procedure can be done with a small sample, it still involves an animal. Some companies are developing cell lines that can divide indefinitely, which reduces the need for repeated sampling, but the welfare of the animals that provide the cells has received little public attention. If cultivated meat captures only the expensive end of the market, intensive livestock farming may continue largely unchanged, while consumers feel that they have made an ethical choice. Welfare groups are therefore cautious: they welcome any reduction in suffering but warn against treating a new product as a complete solution.

Health and regulation raise further questions. Because the cells are grown in sterile conditions, the routine use of antibiotics can be avoided, and the risk of food-borne infections from animal waste is reduced. The nutritional composition can also be adjusted: producers may change the mix of fats or add vitamins. But 'can be' is not 'is'. A cultivated burger is not automatically healthier than a conventional burger, and some products may need additives to achieve the taste and texture that consumers expect. Regulators face the task of assessing a technology that does not fit existing categories. A few countries have approved specific products for sale, usually after long reviews, while other countries are still writing their rules. Labels must be clear, and surveys suggest that many shoppers remain uncertain about the technology, with concerns about naturalness, price and unfamiliar ingredients. Trust, as much as science, will decide whether the sector succeeds.

Economics may prove the decisive obstacle. Production costs remain far above those of conventional meat, and although costs are falling, the factories needed for mass production are extremely expensive. Much of the knowledge is held by a few companies in wealthy countries, which raises questions about who will benefit if the technology succeeds. In low-income countries, millions of people depend on livestock for income and for food, and a rapid move away from animal farming could damage those livelihoods unless support is provided. Food security specialists also note that the cheapest way to feed a growing population is usually to eat plants directly rather than to turn them into meat. My own view is that cultivated meat deserves continued research and fair regulation. It may in time supply a useful share of the market. But it is unlikely to replace livestock farming, and presenting it as a silver bullet risks distracting attention from proven measures: eating less meat, cutting waste and helping farmers to farm better.