IELTS Academic Reading Practice Test 428

Few fruits look less like a fruit than the avocado. Beneath its leathery green skin lies a pale, buttery flesh that is rich in oil rather than sugar, and at its centre sits a single enormous seed. Botanically the avocado is a berry, and it belongs to the laurel family, which also includes cinnamon, camphor and bay. Its wild ancestors grew in the damp highland forests of southern Mexico and Central America, where trees can still be found on forested slopes and where the fruit is thought to have been eaten for thousands of years.

Much of what is known about early avocado use comes from dry caves in the Tehuacán Valley, in the Mexican state of Puebla. The stable, arid conditions preserved plant remains that would elsewhere have rotted. Archaeologists have also found signs that people were managing the trees rather than merely gathering from them: the fruits in the deposits are larger than those of wild trees, suggesting that selection for bigger, fleshier fruit had begun long before any written record.

The name most of the world uses for the fruit comes from Nahuatl, the language of the Aztecs. Āhuacatl was the word for the fruit, and ahuacamolli, a sauce of mashed avocado, has come down to us almost unchanged as guacamole. Spanish colonisers adopted the word in the sixteenth century, writing it as aguacate, and English speakers later modified that to avocado. For a long time, however, English cooks used another name: alligator pear, from the rough, dark-green skin and the shape of some varieties.

From Mexico the tree travelled with Spanish and Portuguese traders to the Caribbean, to the northern coasts of South America and eventually to Europe. It was being grown in southern Spain by the seventeenth century, in a climate mild enough to suit it, and from there it spread to other Mediterranean regions. Wherever it went it remained a local curiosity for centuries, because the fruit is easily damaged and does not travel well once it has softened.

Commercial growing in the United States began in California, where the first trees were planted in the 1870s from Mexican stock. The industry's early success rested on a single variety, the Fuerte, which was brought in 1911 from a Mexican orchard. Its name means 'strong', and was chosen after the original tree survived a severe frost that killed the trees around it. Fuerte remained the standard for decades, but it had weaknesses: it ripened unevenly, and its thin skin made it vulnerable to knocks during packing and transport.

The variety that now fills supermarket shelves began with an accident. In the mid-1920s a mail carrier named Rudolph Hass bought some avocado seedlings from a grower in Whittier, near Los Angeles, and planted them in his small orchard. Most produced ordinary fruit, but one tree bore dark, pebbled, thick-skinned avocados that kept well and tasted rich. Hass patented the tree in 1935 and sold cuttings to other growers; every Hass avocado eaten today descends from that one seedling. The original tree lived for many decades, long outliving the man who found it.

The avocado's biology explains much about how it is farmed. A mature tree carries thousands of small yellowish flowers, each of which opens twice: first as female, then as male the following day, so that a single tree pollinates itself poorly. Bees and other insects carry pollen between them. The fruit, however, can hang on the tree for many months without softening, which gives growers a degree of flexibility, since the crop can be left in place and picked when prices or labour make it worthwhile.

Once picked, an avocado is still hard, and it softens only after harvest. The change is triggered by ethylene, a gas to which the fruit both responds and contributes. In the orchard the process is gradual, but exporters speed it up. Fruit for distant markets is picked mature but firm, cooled, and carried in refrigerated containers; at its destination it is placed in sealed rooms, where ethylene and warmth bring on ripening within a few days.

Nutritionally the avocado is an oddity among fruit. Most fruit supplies energy in the form of sugar, but the avocado's flesh is about fifteen per cent fat, most of it monounsaturated, the kind also found in olive oil. It is a source of potassium, along with fibre and several vitamins. Its soft texture has made it useful in dishes from salads to sandwich fillings, and in parts of Latin America it has long been a staple rather than a luxury.

Today the fruit is traded internationally. Mexico is by far the largest producer, and the orchards of Michoacán supply a large share of the crop. Because consumers expect avocados all year round, supply is drawn from both hemispheres in turn. The boom has brought criticism as well as income. In several producing regions, orchards have spread onto land cleared from forest, and in dry areas the water the trees need has become a source of conflict. Growers reply that yields per hectare are high compared with those of many other crops.

The avocado's journey from a forest tree to a global commodity took thousands of years, and it is not finished. Breeding programmes are now seeking trees that resist disease, tolerate drought and ripen predictably, while the old seedling trees, with their slow and uncertain yields, are steadily replaced.

Most people have a rough sense of which dangers are serious and which are not, and that sense is often badly wrong. Ask a group of adults whether it is more dangerous to travel by aeroplane or by car, and many will name the aeroplane, although measured by distance travelled, air travel is far the safer of the two. Asked to name the causes of death that worry them, people tend to choose the dramatic ones — murder, fire, drowning — and to overlook the ordinary ones, such as heart disease, that kill far more. The study of such judgements has become a field in its own right.

The first explanation offered for these patterns was what psychologists call the availability heuristic, a term introduced by Amos Tversky and Daniel Kahneman in the early 1970s. When people have to estimate how likely something is, they do not calculate; they recall examples, and they judge likelihood by the ease with which those examples come to mind. Anything that makes an event easier to picture or to remember — recent coverage on the news, a personal experience — inflates the estimate. Because an air accident kills many people at once and is reported for days, it lodges in memory far more firmly than the many separate car accidents that cause more deaths in total.

In the 1970s and 1980s the psychologist Paul Slovic and his colleagues asked people to rate different hazards on a series of scales: how well they understood the risk, how much control they had over it, and how dreadful the consequences would be. When the ratings were analysed, two broad dimensions emerged. One, often labelled 'dread', was high for hazards seen as catastrophic, uncontrollable, involuntary or unfair, and low for those seen as familiar and under personal control. The other, sometimes called 'unknown', was high for hazards whose effects are invisible, delayed or poorly understood. Nuclear power scored high on both.

Two further qualities make a large difference. The first is whether a risk is taken voluntarily. People accept far higher levels of danger from activities they choose, such as skiing or driving, than from hazards imposed on them, such as pollution from a nearby factory. The second is whether a hazard appears natural or manufactured. Surveys have repeatedly found that a substance produced by industry is judged more dangerous than a similar substance found in nature, and that radiation from granite worries people much less than radiation from a power station.

A further distortion comes from the way people think about themselves. When asked about their own chances of divorce, illness or accident, most people rate them lower than those of the average person of their age — a statistical impossibility, since not everyone can be below average. This optimism is not simply vanity. Believing that harm is unlikely helps people to stay calm, and it may be one reason why warnings that emphasise danger so often fail.

How a risk is described matters as much as how large it is. A medicine that reduces the chance of a stroke from two cases in a thousand to one halves the risk; described as the avoidance of a single case, it sounds negligible, though the two statements are identical. Conversely, a rise in survival from 95 to 97 per cent sounds modest, whereas the same result described as a 40 per cent fall in mortality sounds impressive. People also attend to the number of cases and ignore the size of the population in which they occur, so that a cluster of cases in a small village frightens residents far more than the thousands expected in a city.

More recent work has stressed the role of feeling. The 'affect heuristic' is the name given to the tendency for a quick emotional reaction to stand in for analysis. If a technology feels benevolent, its benefits seem larger and its risks smaller; if it feels threatening, the reverse happens. Images matter for the same reason. A hazard that can be photographed, such as a fire or a damaged reactor, holds public attention in a way that an odourless gas seeping into basements cannot, however many people it harms.

For those whose job is to warn the public, the practical lessons are uncomfortable. Simply presenting the figures rarely changes minds, because figures are interpreted through feelings and prior beliefs. Comparisons drawn from everyday life — the risk of a car journey — communicate better than abstract probabilities, but they can mislead if they are chosen to make a danger appear smaller than it is. What appears to work best is absolute rather than relative numbers, a consistent format, and an acknowledgement of what remains uncertain. Trust matters more than arithmetic: the same message is believed or dismissed according to its source.

Not everyone agrees that these habits of mind should be called errors. Some researchers argue that the shortcuts people use are well suited to the world in which they were formed, where a vivid memory of a previous disaster was a reasonable guide to the next. The problem, on this account, lies less in the public's reasoning than in the way experts present numbers, which are often too complex to be understood.

Others reply that some distortions, such as the persistent gap between the risks people fear and the risks that kill them, cause real harm and should be corrected. The disagreement is unresolved, and it determines whether risk communication is a question of clearer arithmetic or of understanding how people feel.

Few public entertainments have fallen from favour as quickly as the travelling circus that exhibits wild animals. A century ago a procession of camels or elephants through a town was a familiar sight; today only a handful of circuses still tour with animals, and in several countries they are no longer allowed to do so. In England, legislation passed in 2019 made it an offence to use wild animals in a travelling circus, and Wales and Scotland adopted comparable measures. Elsewhere the picture is mixed: some countries control the practice through licensing and inspection, and a few have banned animal circuses altogether.

The case for prohibition rests on welfare. Travelling circuses are, by their nature, mobile: animals are loaded into vehicles, driven between sites, and kept in temporary accommodation that may be a fraction of the space a wild animal would occupy. Critics argue that such conditions cannot meet the needs of wild animals, although a review commissioned by the British government in 2007 found the scientific evidence on circus welfare too limited to settle the matter. Critics add that training for performance relies on methods that inspectors cannot observe, and that the repertoire itself — lions jumping through hoops, elephants balancing on small platforms — displays behaviour with no counterpart in the wild.

Supporters of the practice dispute this account. They point out that the animals in question are usually captive-bred, that many have never lived in the wild, and that a well-run circus provides food, veterinary care and shelter. On this view the choice is not between a circus and a savannah but between a circus and a zoo, an institution that keeps animals in enclosures for public display yet attracts far less criticism. Circuses also argue that they bring animals to towns where no zoo exists, and that the decline of the travelling menagerie has reduced, not increased, the number of people who see a large animal at close quarters.

The numbers involved are small, and both sides interpret this fact to their advantage. When the British legislation was debated, fewer than twenty wild animals remained in travelling circuses in the country, a figure that supporters of the industry regarded as proof that the issue was being exaggerated and campaigners regarded as irrelevant, since a wrong does not become acceptable by being rare. Where the population of performing animals is tiny, a ban costs few livelihoods; where it is larger, as in parts of Eastern Europe and Latin America, the economic argument carries more weight.

A more fundamental disagreement concerns the basis of the claim. Some campaigners argue from the inherent wrongness of using wild animals for entertainment: an animal cannot consent to perform, and to make it do so is to treat a living creature as a prop. Others, including some animal welfare scientists, prefer to argue from evidence, holding that the case should rest on measurable suffering rather than on moral discomfort. The two positions point to different policies. The first implies that no enclosure, however spacious, can make a performance acceptable; the second implies that a circus meeting high standards might be tolerated.

The evidence itself is thinner than the confidence of either side suggests. Compared with research on farm animals and laboratory animals, the scientific literature on circus animals is sparse, and much of what exists comes from inspections and from the testimony of former trainers rather than from controlled studies. It is genuinely difficult to measure the welfare of an elephant in a tent. There is little agreement, too, about how the findings should be interpreted: a behaviour that looks like boredom to one observer may be recorded as normal resting behaviour by another. The argument therefore turns, to an unusual degree, on what counts as evidence.

A further complication is that the ban addresses a small part of a much larger question. Wild animals are kept for entertainment in zoos and on television, and the welfare problems associated with those settings have not disappeared because a few circuses have stopped touring. Critics of the legislation therefore describe it as symbolic: cheap to pass, because so few animals and businesses are affected, and liable to create the impression that the wider trade has been dealt with. Campaigners reply that symbols matter, and that the principle established by a ban outlasts its immediate effect.

There is also a practical question that the debate rarely addresses: whether a ban is the most effective instrument. Several countries have chosen licensing instead, setting minimum space requirements and requiring independent inspection, on the argument that a regulated circus is better for the animals than no oversight at all. Prohibition is simpler to enforce, but it removes the animals from view rather than from captivity.

My own view is that the ban is justified, but not for the reason most often given. The decisive objection to the travelling circus is not that wild animals are kept in captivity — a position that would condemn every zoo — but that performance and constant travel combine two demands that are difficult to reconcile with welfare: the animal must be moved repeatedly, and must also learn routines that serve no purpose except display. A settled collection with space, expert staff and public education may be defensible; a tent that is dismantled every week is far harder to defend. The value of the ban lies less in the small number of animals it rescues than in the line it draws between keeping animals and making them perform.