IELTS Academic Reading Practice Test 474

The platypus, Ornithorhynchus anatinus, is among the strangest animals on Earth, and for decades after its discovery Europeans refused to accept that it was real. It is a mammal, yet it lays eggs. It has a bill like a duck's, a tail like a beaver's and webbed feet like an otter's, and it lives in the rivers of eastern Australia, from Queensland to Victoria, as well as in Tasmania. With the echidnas, or spiny anteaters, it belongs to an ancient group of egg-laying mammals known as the monotremes, of which only a handful of species survive.

The first scientific description was published in 1799 by George Shaw, an English naturalist, who worked from a preserved skin sent from the colony of New South Wales. Shaw was suspicious from the start. European collectors had recently been shown objects assembled by taxidermists to deceive them, and the animal looked like a convenient combination of parts.

He examined the edge of the bill for stitches. Another anatomist, Robert Knox, is said to have taken a pair of scissors to the specimen in search of the thread that he was convinced must hold it together. Neither found anything. The name Platypus, which Shaw had used, was already occupied by a genus of beetles, so the animal was renamed Ornithorhynchus, meaning 'bird-snout'.

Almost every feature of the platypus suits a life spent largely underwater. Its fur is dense, with a layer that traps air and keeps the skin dry and warm; its front feet are webbed for paddling, while the hind feet act as rudders; and its broad tail stores fat and helps it to steer. It has no visible ears, only small openings behind the eyes, and when it dives the eyes, ears and nostrils are all closed. A hunting platypus is therefore blind, deaf and unable to smell, yet it locates food with remarkable accuracy.

The explanation emerged only in the 1980s, when researchers showed that the animal's leathery bill carries tens of thousands of nerve endings. Most of them respond to touch, but around 40,000 are electroreceptors, able to detect the faint electrical fields generated by the muscles of small invertebrates. Shrimps, insect larvae and worms all produce such fields. A hunting platypus sweeps its bill from side to side, comparing the signals reaching each side of its head in order to judge where a meal is hiding. In laboratory experiments, platypuses have even attacked small artificial sources of current in preference to real food.

Prey is not eaten underwater. Instead it is stored in pouches inside the cheeks and chewed later, either at the surface or in the burrow. The mouth itself is unusual. Young platypuses have teeth, but these are shed early and replaced by horny pads, so an adult possesses nothing that resembles a normal set of mammalian teeth. Food is crushed rather than cut, and hard parts such as the shells of crayfish are ground down between the pads before being swallowed.

Breeding is as unusual as everything else. A female digs a nesting burrow, which may be many metres long, and seals the entrance behind her with a plug of soil and vegetation. Inside, she lays one to three eggs, usually two, which are soft and leathery rather than hard-shelled. She incubates them by curling her body around them, and they hatch after about ten days. The young are tiny, blind and hairless, and they feed by licking milk from the skin of the mother's abdomen, for the platypus, like the echidna, has no nipples. They stay in the burrow for three or four months.

Males are larger than females and carry a weapon found in no other mammal. On the inside of each hind leg, at the ankle, is a hollow spur connected by a duct to a venom gland in the thigh. The gland is inactive for much of the year but swells during the breeding season, when males fight over territory and mates. The venom is not normally life-threatening to people and no human death has been reliably recorded, but the pain is severe and may last for days, while swelling and stiffness can persist for weeks.

The platypus also breaks several rules of mammalian physiology. Its body temperature is about 32°C, well below the figure of roughly 37°C typical of placental mammals, and it controls that temperature less precisely. In 2008 its genome was sequenced, and the results surprised biologists: the animal combines features associated with reptiles, birds and mammals. It also has ten sex chromosomes, arranged as five pairs, where most mammals, human beings included, have two. Fossils found in Patagonia show that close relatives of the platypus lived in South America about 60 million years ago, so the group was once far more widespread than it is today.

Platypuses are hard to study and hard to keep alive in captivity, and there are signs that they are becoming scarcer. Drought and the extraction of water for agriculture shrink the pools and streams on which they depend, land clearing silts up the rivers, and animals drown in nets and in traps set for freshwater crayfish. The International Union for Conservation of Nature classifies the species as Near Threatened, and some biologists have argued that it should be listed as Vulnerable. Its future will depend on how carefully Australia manages the rivers it occupies.

Arriving in an unfamiliar city is a humbling experience. The traveller steps out of a station, turns the wrong way, and within minutes has lost all sense of direction. Yet within a day or two the same streets begin to make sense, and after a week the visitor can take shortcuts and give directions. What changes is not the city but the map of it that has been built in the visitor's head. Understanding how that map is made has occupied psychologists, neuroscientists and urban planners for more than half a century.

The starting point for much of this work is a short book published in 1960 by the American planner Kevin Lynch. Lynch interviewed residents of three American cities and asked them to draw sketch maps of their surroundings. He found that people did not remember a city as a photograph. They reduced it to a small number of elements, and the same kinds of element appeared again and again in different cities. Lynch argued that a city whose elements are clear and easy to recognise has what he called legibility, and that legible cities are more pleasant to move through.

Paths come first: the streets, footways and canals along which people move, which Lynch regarded as the most powerful element in the image of a city. Then there are edges, the boundaries that divide one area from another, whether a river, a wall or a line of railway. Districts are sections of the city with a recognisable identity, such as a university quarter. Nodes are focal points where routes meet and activity is concentrated, such as a busy junction or a market square. Landmarks, finally, are distinctive objects — a tower, a dome or a statue — that can be seen from a distance and used as reference points.

Work in the second half of the twentieth century made clear that such maps are not merely a figure of speech. In the 1970s researchers recorded the activity of single nerve cells in rats and found cells that fired only when an animal was in a particular place. Later work identified cells that fire in a regular grid as an animal crosses a space. These place cells and grid cells, found in the hippocampus and neighbouring regions of the brain, are thought to provide the biological machinery from which a mental map is built.

The best-known evidence for a link between navigation and the brain comes from London. In 2000 a team led by Eleanor Maguire scanned the brains of licensed taxi drivers, who must memorise thousands of streets, and compared them with those of other people. The posterior hippocampus, a structure associated with spatial memory, was larger in the drivers, and larger still in those who had worked longest. The obvious interpretation is that the job had reshaped the structure. The authors stressed, however, that the study was correlational. Later work has suggested that the relationship may be more complicated, since people who choose the job may already differ from those who do not.

Psychologists describe three kinds of spatial knowledge, which normally appear in sequence. The first is landmark knowledge: a child remembers the clock tower but not the way to it. The second is route knowledge, a string of turns and landmarks that allows a familiar journey to be repeated, though not altered. The third is survey knowledge, an overview in which routes are seen in relation to one another, like a map viewed from above. Survey knowledge is what allows a person to invent a shortcut, and it is the last to develop.

Even survey knowledge is far from accurate. Distances along familiar streets are underestimated, distances on unfamiliar routes overestimated, and gentle bends remembered as sharp corners. People also exaggerate the alignment of roads that run roughly parallel. Such distortions are not random errors but the expected result of a system that compresses information so that it can be used quickly. Whether there are reliable differences between groups of people is disputed, and many reported effects are small or hard to replicate.

Satellite navigation has changed the way many people travel. Step-by-step instructions remove the need to build a map at all. Several experiments have found that people who followed spoken directions finished with a poorer mental picture of the area than those who had used a paper map. It would be wrong to conclude that technology is making us worse at navigating in general. The results may reflect how attention is used rather than any loss of ability, and no study has yet shown that the effect is permanent.

Cities, meanwhile, have begun to take legibility seriously. In the late 2000s transport officials in London began installing a network of signs, known as Legible London, which show three-dimensional maps drawn from the pedestrian's point of view. Similar schemes exist elsewhere, though the evidence that such signs encourage walking is thin and few schemes have been evaluated properly. Some general principles, however, do seem robust. Long, straight streets that offer a view to a distant object are easier to learn than the winding alleys of a medieval town, and signs are most valuable at junctions, where mistakes are most likely. A housing estate in which every street looks the same deprives the traveller of the landmarks that memory depends on.

Few questions in employment policy divide opinion as sharply as the length of the working week. Almost every wealthy country imposes some limit on hours, but the limits differ widely in level, in the period over which they are averaged and in how easily they can be avoided. The European Union's Working Time Directive, adopted in 1993, sets an average of 48 hours a week, including overtime, over a reference period of several months. Individual workers in some member states may opt out of it. The United States, by contrast, has no general federal ceiling on the hours an adult may work; long hours there are controlled mainly through the obligation to pay a premium for overtime. The question is whether such rules protect people or merely restrict them.

Demands for shorter hours are not new. In the nineteenth century, campaigns for a ten-hour day were among the first successes of organised labour, and the eight-hour day became a central demand of unions in Europe and North America. Henry Ford's decision in 1926 to run his factories on a five-day, forty-hour week was widely reported as evidence that shorter hours did not reduce output. Much of what is now taken for granted about weekends and holidays was won in that period, often against fierce resistance.

Opponents of a legal maximum make three arguments. The first is economic: a statutory ceiling raises the cost of employing people at busy times and reduces the flexibility that firms need. The second concerns choice. Some economists maintain that a worker who wants to earn more should be free to sell more of their time. A cap, they say, removes that option, particularly from people who value cash more than leisure. The third is practical. Where the law is strict, they argue, work does not disappear; it moves into unrecorded arrangements where nobody is protected at all.

Those who favour a limit reply that the freedom to refuse long hours is largely imaginary. A worker whose manager expects an answer by midnight, or whose pay is set so low that overtime is the only way to cover the rent, is not making a free choice. They also point to a growing body of medical evidence. A joint estimate by the World Health Organization and the International Labour Organization, published in 2021, attributed some 745,000 deaths in 2016 to strokes and heart disease. In both cases the risk was linked to working 55 hours a week or more. Other studies associate very long hours with depression, sleep loss and higher rates of injury.

Such figures are less decisive than they appear. Most of the underlying studies are observational, following people who already differ in countless ways. It is difficult to separate long hours from everything that accompanies them: shift work, physical strain, low pay, job insecurity, poor housing. There is also a reverse effect to consider, since people in poor health may work fewer hours rather than more. Not every study finds harm at moderate levels of overtime, and the point at which risk begins to rise steeply is still debated.

Enforcement is the difficulty that neither side discusses often enough. A rule that is not monitored is little more than a statement of good intentions. In many countries labour inspectorates are small, penalties are modest and hours are recorded poorly or not at all. Employers may classify staff as self-employed to remove them from the scope of the law, and remote work across borders makes it harder still to decide which rules apply. The result can be a cap that looks impressive in legislation and changes nothing in practice.

Other approaches deserve more attention than they receive. Collective agreements in some European industries set limits well below the statutory level, and because they are negotiated by the workers concerned, they are more likely to be observed. Rules on rest are also important. A limit on the length of a shift, or on the number of consecutive days worked, may do more for health than a weekly ceiling. After all, a weekly ceiling can be met by cramming the same hours into fewer days. Averaging over a longer period allows seasonal flexibility while capping the total.

The distribution of harm matters too. A flat ceiling is often said to penalise the ambitious professional, but in practice professionals frequently work long unpaid hours and are rarely covered by hourly rules. Meanwhile the workers most exposed to excessive hours are those with the least power to refuse them: agency staff, delivery drivers, carers and hospital staff on consecutive shifts. A cap without a higher floor under wages may simply cut the earnings of the poorest, which is the strongest argument for treating the two policies together.

On balance, the case for a legal maximum seems to me strong, but for a different reason from the one usually given. It is not that long hours are always harmful, still less that adults cannot manage their own lives, but that the labour market does not distribute the freedom to say no evenly. A limit expresses a collective judgement that some hours are not for sale in a decent society. The exact number, whether 48 or 50, matters less than three things. The limit must cover everyone, including the self-employed; it must be enforced by inspection; and it must be accompanied by decent minimum pay and adequate rest.