IELTS Academic Reading Practice Test 441

Of the many sharks that inhabit the world's oceans, few are as poorly understood as Somniosus microcephalus, the Greenland shark. The species lives in the cold waters of the North Atlantic and the Arctic Ocean, often at depths of several hundred metres, where temperatures stay close to freezing all year. Its scientific name means 'small-headed', a reference to a snout that looks unusually blunt for a shark. Because it is rarely seen and hard to keep alive in captivity, much of what scientists know has been pieced together from dead specimens, from fishermen's reports and, more recently, from electronic tags.

The Greenland shark is a heavy, cylindrical animal with grey or brownish skin that is sometimes marked with darker patches or pale spots. Most adults measure between three and five metres, and a few exceptional individuals have been reported at more than six metres, which makes the species one of the largest sharks in the world.

Greenland sharks are among the slowest swimming fish known. Studies using acoustic tags have recorded cruising speeds of little more than a kilometre an hour, and short bursts of activity are not much faster. The animal's small tail cannot produce the powerful thrust with which a great white shark launches itself at prey, so the Greenland shark appears to travel by gliding and gentle undulation rather than by chasing. This sluggishness is probably an adaptation to cold water, in which the metabolic rate of fish is low.

Almost every adult Greenland shark carries a parasite in its eyes. The culprit is a small copepod, Ommatokoita elongata, which attaches itself to the surface of the cornea and feeds on the tissue there. The damage it causes leaves the eye cloudy and, in many individuals, useless. Researchers once assumed that the parasite must be a serious handicap, yet the sharks appear to manage perfectly well, and some have suggested that the copepod may itself attract prey by glowing faintly in the dark. The shark relies on senses other than sight: on smell, and on a line of pressure-sensitive organs running along its body that detects the movement of water.

The species is an opportunist rather than a fast hunter. Its stomach has been found to contain a remarkable variety of animals: fish of many kinds, squid, crustaceans, seals and, in sharks caught in the Arctic, the remains of reindeer and polar bears. Such items cannot have been caught alive, and they confirm that the Greenland shark is a scavenger as well as a predator, willing to feed on carcasses that sink to the sea floor. The teeth of the upper jaw, which are narrow and pointed, grip the prey, while those of the lower jaw, which are broad and saw-like, cut pieces from it.

The most surprising discovery about the species concerns its age. In 2016 an international team led by Julius Nielsen published a study in the journal Science in which they estimated the ages of 28 female sharks. The method relied on radiocarbon dating of proteins in the nucleus of the eye lens, a structure that forms before birth and grows throughout life. The results suggested that the oldest animal in the sample was around 392 years old, give or take 120 years, and that the sharks do not reach sexual maturity until about the age of 150. Growth of about one centimetre a year supports this picture. The estimates carry a wide margin of uncertainty, but the conclusion that the species lives for several centuries commands wide acceptance.

Reproduction remains largely mysterious. Females are not ready to breed until they are about four metres long, which, at such a slow rate of growth, may take a century and a half. The species gives birth to live young rather than laying eggs, and litters appear to number around ten pups, though records are few. Where the sharks give birth, and how often, is still unknown, and nobody has ever watched a Greenland shark mate. Even the fate of the pups, which are less than a metre long at birth, has never been followed in the wild.

Its flesh is poisonous unless it is treated. The tissues contain high concentrations of urea and of trimethylamine oxide, a compound that helps the animal regulate its internal chemistry in deep, cold water. Eaten fresh, the flesh releases substances in the digestive system that cause vomiting and convulsions. In Iceland the traditional solution is to bury the carcass in gravel for several weeks and then hang the meat to dry for months; the resulting dish, hákarl, has a powerful smell and a devoted following. Earlier generations hunted Greenland sharks mainly for their livers, which yielded a valuable oil for lamps.

A fish that matures late, breeds slowly and lives for centuries cannot recover quickly from heavy losses. For a long time the species was killed in large numbers by a Norwegian fishery, and today it is taken accidentally by longlines set for halibut and by trawlers. Its populations are thought to be declining, and in 2020 it was reassessed as Vulnerable on the IUCN Red List. Slow though it is, the Greenland shark has proved capable of long journeys: sharks tagged off Greenland have later been recorded thousands of kilometres away.

Anyone who has watched two small children divide a plate of biscuits will have heard the word 'fair'. What interests psychologists is not that children want the biscuits but that they appeal to a rule, and that the rule they appeal to changes as they grow. Researchers describe this as the study of other-regarding preferences: the principles people apply when their own interests conflict with someone else's. Two broad answers to the question of origins compete. One holds that a rudimentary sense of fairness is present from infancy, part of the equipment a child brings to social life. The other holds that fairness is learned, assembled slowly from adult instruction, from experience with siblings and peers, and from a growing understanding of what other people feel and know. The evidence fits neither answer in its pure form.

The earliest claim for an innate moral sense came from experiments with infants. In 2007 a team led by J. Kiley Hamlin, then at Yale, showed babies of six to ten months a short animation in which one shape helped another climb a hill while a third blocked its path. When the babies were afterwards offered both characters, most reached for the helpful one. The result was widely reported as evidence that moral evaluation is present before language. Later attempts to repeat the experiment have produced mixed results, and many researchers now regard the finding as weaker than it first appeared.

A different method has been used with toddlers. In one experiment, children of nineteen to twenty-one months watched an adult divide a small number of crackers between two other people, sometimes equally and sometimes not. The children looked longer at the unequal outcome, a reaction that researchers interpret as surprise. The inference is cautious: the toddlers may expect equal treatment without holding any general principle of fairness, and the effect depends on details of the situation that are still being explored. The method rests on the assumption that a baby looks longer at something unexpected, an assumption widely used but hard to verify.

The most influential study of older children was published in Nature in 2008 by a team led by Ernst Fehr, an economist at the University of Zurich. Children of three and four, and of seven and eight, were asked to choose between allocations of sweets that gave themselves and another child different amounts. The youngest children behaved in a strikingly egalitarian way, preferring equal shares even when an unequal share would have given them more. By seven and eight the picture was more complicated: children still valued equality, but they also compared their share with the other child's and favoured children from their own group.

Other tasks reveal a clear developmental pattern. When children are given sweets or stickers and invited either to keep them all or to give some away, the average amount given rises steadily between the ages of about six and twelve. Around the age of eight a new concern appears: children begin to dislike receiving more than a partner, and will give away a sweet to avoid an outcome in which they come out ahead. Before that age most children are untroubled by such an advantage, though even quite young children complain when they are the one who receives less.

How much of this is universal has been tested directly. In a study published in 2015, a large team compared children between the ages of four and fifteen in seven societies, among them the United States, Canada, Mexico, Peru, Senegal, Uganda and India. Children everywhere rejected a distribution that left them worse off than another child, and did so from about the age of four. The dislike of being better off, by contrast, appeared later and varied enormously. In some of the societies studied it was strong by middle childhood; in others it was barely detectable even in adolescence. A preference for equal treatment, the researchers concluded, is widespread, whereas the willingness to surrender an advantage of one's own depends heavily on the surrounding culture.

Several explanations for these changes have been proposed. One is that children's ideas about what fairness means are transformed as they grow. For a four-year-old, fairness generally means sameness: an equal number of biscuits, whatever the circumstances. Between six and eight, children begin to take account of effort, need and intention, and to judge a child who has worked harder as deserving more. Another explanation points to the social world. Parents and teachers talk about fairness, resolve disputes and reward generosity, while children spend increasing time with peers, who enforce their own rules and ostracise those who break them.

A third line of research shows that children do not merely prefer fairness but will pay to enforce it. By the age of about six, children in experiments will give up some of their own rewards to reduce the payment of someone who has behaved selfishly, even when they are not the victim. What remains genuinely unclear is how far such laboratory measures predict behaviour in the classroom or the home. Almost all the studies are small, and most have been carried out in a handful of wealthy countries. A picture drawn from one generation of children may not hold for the next.

Cities have regulated outdoor advertising for more than a century, limiting the size of hoardings and the districts in which they may stand. What is new is the ambition of the rules. In 2006 São Paulo, a Brazilian city of more than ten million people, began to remove almost every advertisement from its streets, treating them as visual pollution rather than as a source of revenue. Other authorities have attacked particular categories instead of the medium itself: London's transport network stopped accepting advertisements for foods high in fat, sugar or salt, and a number of European municipalities have moved against campaigns promoting fossil fuels or meat.

Supporters of sweeping restrictions start from the nature of the medium. A poster on a wall is not a message that anyone has asked to receive. It occupies shared space, it is difficult to ignore, and it reaches people who have no way of switching it off. On this view the city is entitled to decide what may be said in the common spaces it owns, in the same way that it decides where traffic may flow. Advertising is, on this argument, a use of property rather than a form of speech, and the owner of a wall may set conditions for it. The removal of advertising in São Paulo was said to have made the streets calmer and easier to read, though the evidence for such claims is largely anecdotal.

The objection is that adults are capable of ignoring a poster and of judging a claim, so that a ban protects nobody who needs protecting. To forbid commercial messages altogether, critics argue, treats citizens as children and silences a form of expression that, however commercial, is still expression. The distinction matters: a government that may restrict what is said about a product is not the same as one that may forbid the product's name to appear at all. The law in most countries takes a middle position. In the United States commercial speech enjoys some constitutional protection, though less than political speech; in Europe courts have generally accepted restrictions on advertising where they serve public health or protect the appearance of a town.

The strongest evidence for restriction concerns what is advertised rather than where. When London's transport authority stopped taking advertisements for unhealthy food, researchers compared the shopping of households in the capital with that of households elsewhere and found that the former bought somewhat less of the relevant products. The estimated effect was modest, a few per cent at most, but it applied across a very large population. Defenders of advertising point out that such studies cannot prove that the advertisements caused the change, and that a ban on a product category punishes the medium for a decision that belongs to public health policy.

There are economic arguments on both sides. A billboard is a cheap way for a small firm to reach local customers, yet a ban removes that channel without reducing the total volume of advertising, which migrates to screens and to the internet. There it is targeted, personalised and far harder for a city to see. Transport operators depend on advertising income: a network that gives up a substantial part of its revenue must either raise fares or cut services. A ban may therefore move the problem somewhere less visible, leaving a quieter streetscape but the same quantity of persuasion.

Digital displays have complicated the debate. A screen is brighter than any painted board and changes several times a minute. It can also be programmed to alter its message according to the time of day. Several cities now restrict the brightness of screens after dark. Others limit the proportion of a screen's time that may be sold to advertisers. Screens also raise a question that painted hoardings never did, since a device that can recognise a passing phone can in principle select the message for the person carrying it.

Where does this leave the case for a total ban? In my view, the simplicity of prohibition is its chief attraction and also its weakness. A city that removes every advertisement is spared the difficulty of deciding which products are harmful enough to exclude, but it also gives up the ability to make distinctions that matter. The argument for removing advertisements for cigarettes, for gambling, or for foods that damage children's health rests on evidence of harm and on the cost that the city already bears in treating it. That argument cannot be stretched to cover a poster for a local bookshop or a concert.

Public space is a scarce asset, and the sensible response is to license its use rather than to abolish it. Municipalities should charge advertisers properly for the space they occupy, should refuse categories of advertisement that promote demonstrably harmful products, and should limit the size, brightness and animation of illuminated screens. None of this requires a city to declare war on advertising as such. The direction of travel should be towards fewer posters for harmful goods and quieter streets at night, and not towards the removal of an entire medium from the urban landscape. A rule that can be explained in a sentence and applied by inspectors is also more likely to survive a legal challenge than a long schedule of exceptions.