IELTS Academic Reading Practice Test 438

Of all the world's mammals, only one group is covered from head to tail in hard, overlapping scales. The pangolin looks like a walking pine cone, with a small pointed snout, a long tail and short, powerful legs. Eight species are recognised: four live in Asia, from Pakistan eastwards to the Philippines, and four in Africa south of the Sahara. All belong to the order Pholidota, a group with no close living relatives. Their scales are made of keratin, the same protein that forms human fingernails and hair. They continue to grow throughout the animal's life, so an individual that survives to old age carries a thick, battered coat of them.

Each scale is roughly triangular and overlaps its neighbour like a tile on a roof. The arrangement allows the animal to bend and twist when it is active and to form a tight, almost seamless shell when it is not. It is this armour, rather than any weapon, that has allowed a slow-moving, toothless animal to persist for so long. The edges of the scales are sharp, and an animal that tries to bite through them may cut its mouth.

The name comes from the Malay word pengguling, meaning 'something that rolls up', an accurate description of the animal's defence. Pangolins have no teeth and feed almost entirely on ants and termites. Their eyesight is poor, so they rely heavily on smell to find food and to recognise one another. What sets them apart is the apparatus of feeding. The tongue can be almost as long as the body, and it is anchored not in the mouth but on a specialised structure near the pelvis, from which it can be extended far beyond the snout.

A pangolin begins a meal by locating an ant or termite nest, largely by smell. It then breaks open the hard outer casing with the curved claws on its front feet and pushes the sticky tongue into the tunnels. Insects adhere to the saliva and are drawn back into the mouth, and the tongue can be withdrawn and extended several times a minute. Small stones and sand are swallowed with the food and are thought to help grind it in the stomach, replacing the teeth the animal lacks.

The claws are so long that a pangolin cannot walk on the soles of its front feet. Instead it curls them underneath and moves on its wrists, which gives it an awkward, waddling gait. When threatened, it tucks its head beneath its body and wraps itself around its limbs and tail, presenting a tough, sharp-edged ball that can inflict painful cuts on a predator. Some species also release a foul-smelling fluid from glands near the tail. Rolling up defeats most predators but is useless against a human being, who simply picks the animal up.

Pangolins are shy, solitary and mostly nocturnal, and they are rarely seen even where they are relatively common. The Asian species inhabit forests and grasslands, and they can swim, entering streams and rivers to cross them. Among the African pangolins, the tree-dwelling species spend much of their lives in the forest canopy. They grip branches with a bare, sensitive patch at the tip of a prehensile tail, while the ground-dwelling species dig burrows that are later occupied by other animals. Females usually produce a single pup, born with soft scales, which rides on its mother's tail for the first weeks of life.

The greatest threat to pangolins is trade. Their meat is considered a delicacy in parts of Asia and Africa, and their scales are used in traditional medicine, although there is no scientific evidence that keratin has any medicinal effect. Because the animals are difficult to keep alive in captivity and breed rarely in zoos, almost all trade depends on animals taken from the wild. In 2016 all eight species were moved to Appendix I of the Convention on International Trade in Endangered Species, which prohibits commercial international trade in them. Enforcement, however, is another matter.

Seizures of smuggled scales and meat continue on a large scale, and confiscated consignments are counted in tonnes. Demand has not disappeared, and the profits are high enough to justify the risk. Conservationists argue that no single measure will be sufficient: reducing demand, improving detection at borders, strengthening penalties and giving local communities a reason to protect the animals all have a part to play. Some add that protecting pangolins means protecting the forests and grasslands where they live, since an animal hunted out of a remnant patch of woodland rarely returns.

Pangolins are also significant within their ecosystems. A single animal removes enormous numbers of ants and termites, and its abandoned burrows provide shelter for insects, reptiles and small mammals. Yet their habits remain poorly studied. They are hard to find, difficult to follow and almost impossible to maintain in captivity, and much of what scientists know comes from animals rescued from traders or from camera traps set in forests at night. Even basic questions, such as how far an individual travels in a year, remain largely unanswered.

The pangolin's lineage is an ancient one: fossils of animals resembling modern pangolins have been found in deposits tens of millions of years old. Whether the species survives the next century is another question. To a poacher, a pangolin is worth far more dead than alive, and conservation will succeed only if that calculation can be changed.

Desertification is one of the most misunderstood terms in environmental science. It does not mean that deserts are marching across the landscape and swallowing farmland, although that is the image the word conjures. It refers instead to the degradation of drylands — the arid, semi-arid and dry sub-humid regions that together cover roughly two-fifths of the Earth's land surface and are home to well over a billion people. These regions include the Mediterranean basin, the Sahel, the steppes of Central Asia and large parts of Australia. Land in them is losing its fertility and vegetation, usually gradually and in ways that are hard to see from a distance.

The immediate causes are mostly agricultural. Too many animals grazing a fragile pasture remove the vegetation that holds the soil in place. Repeated cultivation without fallow periods exhausts nutrients, and trees and shrubs are cut for fuel and for land. Irrigation, if it is badly managed, can do more harm than drought. Behind these practices lie social and economic pressures: growing populations, insecure land tenure and the need to export cash crops.

Once vegetation is lost, the process accelerates. Plant roots bind soil particles together and channel rainwater into the ground; without them, rain runs off the surface, carrying the finest and most fertile particles with it. Wind then removes what is left, and the exposed subsoil sets hard when it dries, forming a crust that sheds water almost as efficiently as a roof. The land can no longer absorb the rain that falls on it, so springs and shallow wells fail even in years of average rainfall. Degradation can therefore spread outwards from a single well or waterhole where animals congregate.

Irrigation brings its own problems. Where water is applied to fields without adequate drainage, the water table rises until it reaches the root zone. Water then evaporates and leaves its dissolved salts behind, and after a few seasons the topsoil may be too salty for crops. Civilisations have suffered from this for millennia: salt accumulation is one explanation offered for the decline of agriculture in ancient Mesopotamia, and salinised land is still abandoned today in the irrigated plains of Pakistan and Iraq.

A second mechanism operates at a larger scale. Bare, pale ground reflects more sunlight back to space than dark vegetation does, so the air above it warms less, and the rising motion that produces clouds and rain may weaken. In the 1970s, when the Sahel was suffering a catastrophic drought, some climate scientists suggested that overgrazing might itself have reduced rainfall. They argued that the change in reflectivity could create a feedback loop in which dry land produced drier air.

Dust is the visible evidence of degradation. Storms lift the fine fraction of degraded soil and carry it far: Saharan dust crosses the Atlantic in enormous quantities, and satellites track the plume from Africa to the Caribbean. The dust is not simply a loss. It carries phosphorus and other nutrients that fertilise the soils of the Amazon basin and the surface waters of the Atlantic, where iron encourages the growth of plankton. In the towns it passes over, however, the same particles thicken the air and add to the burden on people with breathing difficulties.

Drought and degradation are not the same thing, though they are often confused. A drought is a temporary shortage of rain; degradation is a lasting loss of the land's capacity to support plants and people. Rainfall across the Sahel recovered substantially from the mid-1980s onwards, and satellite images showed vegetation returning over large areas. Some researchers interpreted this as proof that earlier predictions of irreversible decline had been wrong. Others cautioned that a greener image can reflect a single wet year rather than a lasting improvement.

Measuring degradation is genuinely difficult. Satellite instruments record the colour and brightness of the land surface, from which vegetation cover is inferred, but a green flush after rain looks much like recovery. Ground surveys are more reliable but expensive and local. What is not disputed is that degradation is real, that it is concentrated in poor rural regions, and that it is difficult to reverse once the soil itself has been lost.

Prevention is far cheaper than cure, and much of the successful work has been done by farmers rather than governments. In parts of Niger, farmers began protecting the seedlings that sprout naturally in their fields instead of clearing them, and within two decades many villages had regained a cover of trees. Elsewhere in the Sahel, low stone walls along the contour of a slope slow runoff and trap soil, and planting pits dug into hardened ground collect rainwater around a single seedling. These techniques are labour-intensive but cheap, and they work with the land rather than against it.

Large-scale programmes have tried to build on such experience. The Great Green Wall, launched by the African Union in 2007, was originally envisaged as a continuous belt of trees from Senegal to Djibouti; it has since been redefined as a mosaic of restoration projects across the Sahel, with an ambition to restore a hundred million hectares of degraded land by 2030. Whether deserts 'advance' is less important than whether the people who live at their edges can keep their soil. On that question the evidence is cautiously encouraging: land can be restored, but only where those who use it have a reason to invest in it.

Chief executives of large companies are paid differently from almost everyone else who works for them. In the United States, the ratio between the pay of a typical chief executive and that of a typical employee has risen from roughly twenty to one in the 1960s to several hundred to one today. The change is not explained by a general rise in wages, which have stagnated for many workers in real terms. Defenders of present arrangements point out that modern companies are enormous and that running one is a complicated task, but few of them would claim that the difficulty of the job has increased twentyfold. Something has happened to the way senior pay is set, and it is that process, rather than the size of the resulting figure, that deserves attention.

Those who favour a legal maximum make two arguments. The first is about fairness. A gap of several hundred to one strikes many people as indefensible, particularly when the lowest-paid employees of the same organisation depend on state benefits. The second is about incentives. A director rewarded chiefly for the share price has a strong reason to cut costs, buy back shares and postpone investment, since all three tend to lift the price in the short term. Critics contend that this produces a style of management that looks impressive in quarterly reports and leaves the company weaker a decade later; a cap, they suggest, would blunt that temptation.

Opponents of caps reply that the policy would be both ineffective and damaging. A statutory ceiling, they maintain, would simply be avoided: companies would award shares, pension contributions or consultancy fees instead, or move their headquarters abroad. The ablest candidates, it is said, would join firms that are not covered, leaving public companies in the hands of the second rate. Some economists add that shareholders own the company and are the natural people to decide what a director is worth. On this view the problem is not the level of pay but the weakness of the owners' control over it.

Research on how pay is actually determined lends some support to both sides. Several studies have found that a substantial part of a chief executive's remuneration can be attributed to movements that have nothing to do with personal effort — the price of oil, interest rates, exchange rates, or the performance of the whole stock market. In a good year for the industry, almost every chief executive is judged to have performed well. Economists call this pay for luck, and its persistence is hard to reconcile with the claim that pay measures talent. Yet the same studies show that pay does respond to performance, just less strongly than the theory of the market would predict.

Attention has therefore turned to the machinery by which pay is set. Remuneration committees, made up of non-executive directors, are supposed to represent shareholders in negotiations with the chief executive, but critics point out that committee members are often chief executives of other companies, with an interest in a general upward drift. Pay consultants hired by the committee routinely compare their client with a group of similar firms; since almost every firm aims to be at or above the middle of its peer group, the comparison produces a ratchet. One response has been to give shareholders a vote. The United Kingdom introduced an advisory vote in 2002, and the United States legislated for one in 2010; Switzerland went further in 2013, when a referendum approved binding votes and a ban on certain exit payments.

Have such votes made a difference? The evidence is modest. Studies of say-on-pay in several countries have found small reductions in the growth of pay and a greater sensitivity of pay to poor performance, but no dramatic change in its level. Votes against remuneration reports are rare, and where they occur they are usually followed by consultation and a revised scheme rather than by a reduction. Shareholders, especially large fund managers, have little appetite for a public fight over boardroom pay.

Other proposals aim at the structure of pay rather than its amount. Requiring that shares awarded to a chief executive be held for several years prevents a director from selling at the top of a short-lived boom. Clawback provisions, which allow a company to recover bonuses paid on the basis of figures later shown to be wrong, are now common in several countries. Some argue for a simple multiple: a company might be permitted to pay its chief executive no more than, say, thirty times the wage of its lowest-paid employee, with the multiple chosen by shareholders rather than fixed by law.

My own view is that a legal cap on the absolute level of pay is a blunt instrument, easily evaded and likely to drive the most ambitious managers elsewhere. The case for restricting the ratio between the highest and lowest pay in a company is stronger, because a ratio is transparent, hard to disguise with share options, and easy for outside observers to check. Publishing that ratio within each firm, as a few countries now require, would let employees and investors judge it for themselves. But the most useful reforms are procedural: binding votes, independent remuneration committees, longer holding periods, and honest disclosure of what comparable firms pay. Executive pay is high partly because the process that sets it is weak. Fix the process and the level will look after itself, or at least it will stop rising quite so fast.