IELTS Academic Reading Practice Test 12

Long before anyone could view the Earth from above, people were drawing pictures of the land around them. One of the earliest known attempts to portray the whole world is a small clay tablet from Babylon, made around the sixth century BCE. It shows Babylon near the centre of a flat disc, encircled by a ring of water labelled the 'bitter river'. The tablet was never meant to guide travellers; it expressed a view of the cosmos in which Babylon occupied the most important place.

The scholars of ancient Greece approached the problem more mathematically. In the third century BCE Eratosthenes estimated the circumference of the Earth by comparing the angle of the Sun's shadow at Alexandria with that at Syene, a town further south. His result was remarkably close to modern measurements, although historians still debate the exact length of the units he used.

Four centuries later, Claudius Ptolemy compiled his Geography, a work listing around 8,000 places together with their positions expressed as latitude and longitude. Ptolemy also explained how a curved surface could be represented on a flat sheet. No maps drawn in his own time have survived, but his text was preserved by Byzantine scholars and translated into Latin at the beginning of the fifteenth century, when it had an enormous influence on European cartography.

In medieval Europe, by contrast, many of the most impressive maps were not designed for finding one's way at all. The Hereford Mappa Mundi, drawn on a single sheet of animal skin around 1300, is the largest medieval world map still in existence. It places Jerusalem at its centre and puts east, rather than north, at the top, and it combines real places with scenes from the Bible, classical legends and drawings of strange creatures believed to live at the edges of the world. Meanwhile, at the court of Roger II, the Norman king of Sicily, the Arab geographer al-Idrisi completed a great world map in 1154 which drew on the reports of merchants and travellers. Following the convention of many Islamic maps of the period, it was oriented with south at the top.

A more practical tradition developed among Mediterranean sailors. From the late thirteenth century, navigators used portolan charts which recorded coastlines, harbours and headlands with surprising precision. Across each chart ran a web of straight lines radiating from compass roses, which allowed a pilot to choose a compass direction from one port to another. Inland areas on these charts were usually left almost empty, since the information that mattered to sailors was the shape of the shore.

The most famous single innovation in the history of maps came in 1569, when the Flemish cartographer Gerardus Mercator published a world map based on a new projection. On Mercator's map, any line of constant compass bearing appears as a straight line, so a navigator could plan a course simply by drawing a line with a ruler. The price of this convenience was distortion: to keep directions correct, Mercator had to stretch the map increasingly towards the poles. As a result, Greenland appears roughly as large as Africa, even though Africa is about fourteen times bigger. Mercator's projection remains useful for navigation and is the basis of many online street maps. Mercator was also the first to use the word 'atlas' for a collection of maps, in a volume published shortly after his death.

Accurate maps of whole countries required a different technique, known as triangulation. Surveyors began by measuring a straight baseline on flat ground with great care. From each end of this line they then measured the angles to a distant landmark such as a church tower or hilltop. Because one side and two angles of the triangle were known, the lengths of the other two sides could be calculated using trigonometry, and each of these sides could then serve as the base of a new triangle.

In this way a chain of triangles could be extended across an entire territory with relatively few distances measured directly on the ground, although additional baselines were measured at intervals to check for accumulated errors. The method was described by the Dutch mathematician Willebrord Snellius in the early seventeenth century, and it was later used on a national scale in France, where four generations of the Cassini family worked on a survey of the kingdom. Their map, at a scale of 1:86,400, was almost finished by the time of the French Revolution.

The most ambitious triangulation project of all was the Great Trigonometrical Survey of India, begun in 1802 under the direction of William Lambton. Its instruments included a theodolite that weighed about half a tonne and needed a team of men to carry it. Lambton's successor, George Everest, extended the work northward towards the Himalayas, and in the 1850s the survey's calculations showed that a summit then known as Peak XV was the highest in the world. In 1865 it was named Mount Everest in his honour.

In the twentieth century, photographs taken from aircraft made it possible to map large areas far more quickly, and from the 1970s satellites began to record the Earth's surface systematically. Today the Global Positioning System, which became fully operational in 1995, allows anyone with a smartphone to find their position within a few metres. Every map still involves choices about what to include, what to omit and how to represent a round planet on a flat screen, and those choices continue to shape the way people understand the world.

Each autumn, billions of birds leave their breeding grounds and set off for wintering areas that may lie thousands of kilometres away. In 2022 a young bar-tailed godwit fitted with a satellite tag flew without stopping from Alaska to Tasmania, a distance of at least 13,560 kilometres, in just eleven days. How birds manage such feats of navigation has puzzled naturalists for centuries, and although a great deal has been learned in the past seventy years, important parts of the answer remain uncertain.

One way to study navigation is to remove birds from home and see whether they can find their way back. In one celebrated case in 1952, a Manx shearwater was taken from its nesting burrow on Skokholm, an island off the coast of Wales, and flown across the Atlantic to Boston in the United States. Released there, it was back in its burrow about twelve and a half days later, having crossed roughly 5,000 kilometres of ocean that it had almost certainly never seen before. Such results suggest that birds possess not only a 'compass', which tells them which direction they are facing, but also something like a 'map', which tells them where they are in relation to home.

The compass part of the puzzle was the first to be solved. In the early 1950s the German ornithologist Gustav Kramer kept starlings in circular cages and noticed that, during the migration season, they hopped restlessly in the direction in which they would normally have flown. When he used mirrors to change the apparent position of the Sun, the birds shifted their direction accordingly, showing that they were using the Sun as a guide. Because the Sun moves across the sky during the day, this also implied that the birds could compensate for the time of day by means of an internal clock. Night-flying migrants, which include most songbirds, face a different problem. In the 1960s the American biologist Stephen Emlen placed indigo buntings in a planetarium and found that they oriented themselves according to the pattern of stars projected on the ceiling. Rather than relying on any particular star, young birds learn to identify the point around which the night sky appears to rotate, which in the Northern Hemisphere lies close to the Pole Star.

Birds can also detect the Earth's magnetic field. In experiments with European robins during the 1960s and early 1970s, the German researchers Wolfgang and Roswitha Wiltschko showed that the birds changed direction when the magnetic field around their cages was altered. Their results contained a surprise: the robins' compass did not respond to the polarity of the field, as the needle of a hiker's compass does, but to the angle at which the field lines are inclined relative to the Earth's surface. This 'inclination compass' tells a bird whether it is heading towards the pole or towards the equator rather than distinguishing north from south. How the field is sensed is still debated. An earlier idea that iron-containing cells in the beak act as tiny magnets has lost support, and many researchers now favour a mechanism in the eye involving light-sensitive proteins called cryptochromes, in which the magnetic field may influence chemical reactions triggered by light.

Evidence that the magnetic sense is delicate came from an unexpected discovery in Germany. Researchers at the University of Oldenburg found that robins kept in wooden huts on the university campus were unable to orient themselves using the magnetic field. When the huts were screened with aluminium, the birds' ability returned, and it disappeared again when the screening was disconnected from the earth. The cause turned out to be weak electromagnetic noise produced by electronic equipment. The study, published in 2014, raised the possibility that birds in and near cities may sometimes be deprived of one of their navigational tools.

The 'map' remains far more mysterious than the compass. A classic experiment carried out in the Netherlands in the 1950s indicated that it develops with experience. The Dutch biologist Albert Perdeck caught thousands of starlings migrating through the country in autumn and transported them to Switzerland before releasing them. Adult birds, which had made the journey before, corrected for the displacement and headed for their normal wintering grounds in north-western Europe, while young birds continued in their original direction and ended up in France and Spain. Inexperienced birds, it seemed, were following an inherited compass direction, whereas adults had learned to determine their position. What the adults' map consists of is unclear. Some researchers, following work begun in Italy in the 1970s, argue that pigeons build an olfactory map from the smells carried by the wind, and pigeons deprived of their sense of smell often fail to return from unfamiliar sites. Others propose that birds detect regional variations in the strength and inclination of the magnetic field, which could in principle serve as a kind of grid.

Most scientists now believe that birds do not depend on any single system but combine several sources of information, using one to calibrate another. Some migrating songbirds appear, for instance, to check their magnetic compass against the position of the setting Sun. Such redundancy may explain how birds cope when clouds hide the sky or when the magnetic field is disturbed. Understanding these mechanisms is not merely of academic interest. Many migratory species are in decline, and knowing how they find their way could help conservationists to assess the effects of artificial light, electromagnetic noise and the loss of the stopover sites on which birds depend during their long journeys.

For most of the twentieth century, economists judged the success of a nation largely by one number: gross domestic product, the total value of the goods and services it produces. GDP was never intended as a measure of welfare. Simon Kuznets, the economist who developed the first official national income accounts for the United States in the 1930s, warned that national income revealed very little about how well a population was actually living. Yet as economies grew after the Second World War, rising output came to be treated as a convenient shorthand for rising well-being, and governments were praised or punished according to its growth rate.

In 1974 the economist Richard Easterlin published a paper that challenged this assumption. Drawing on surveys in which people were simply asked how happy they were, he found that within any one country richer people did tend to report greater happiness than poorer people. Over time, however, average happiness in the United States had not risen, even though income per person had increased substantially since the 1940s. This apparent contradiction became known as the Easterlin paradox. One explanation is that people judge their circumstances relative to others: if everyone becomes richer together, nobody feels better off. Another is adaptation: a pay rise or a new car brings pleasure at first, but people quickly become accustomed to it, and their expectations rise accordingly.

The paradox has been fiercely contested. In 2008 the economists Betsey Stevenson and Justin Wolfers analysed a much larger body of international data and argued that richer countries do have more satisfied populations on average, and that economic growth is associated with rising life satisfaction. Easterlin and his supporters replied that such relationships often reflect short-term fluctuations, such as recessions, rather than long-term trends. The disagreement has never been fully settled, partly because the answer depends on which countries, periods and survey questions are examined.

A related debate concerns whether happiness stops rising beyond a certain income. In 2010 Daniel Kahneman and Angus Deaton, both of whom have received the Nobel prize in economics, reported that Americans' evaluations of their lives continued to improve as income rose, but that their day-to-day emotional experience levelled off at an annual income of around 75,000 dollars. In 2021, however, the psychologist Matthew Killingsworth, using data collected by smartphone from tens of thousands of people, found no such plateau. Rather than continue the argument in print, Kahneman and Killingsworth then worked together, with Barbara Mellers acting as an arbiter, to reanalyse the evidence. Their joint paper, published in 2023, concluded that a plateau did exist, but only for the least happy fifth or so of the population; for most people, emotional well-being kept rising with income.

Whatever the precise relationship between money and happiness, such findings have encouraged a movement to measure well-being directly. The Himalayan kingdom of Bhutan has promoted the idea of Gross National Happiness since the 1970s. In 2009 a commission led by Joseph Stiglitz, Amartya Sen and Jean-Paul Fitoussi, set up at the request of the French president, recommended that official statistics should shift their emphasis from measuring economic production to measuring people's well-being. Two years later the United Kingdom's Office for National Statistics began asking large samples of the population how satisfied they were with their lives, and since 2012 the World Happiness Report has ranked countries according to their citizens' own ratings of their lives on a scale from zero to ten. New Zealand went further in 2019, presenting what its government described as a well-being budget.

There is much to welcome in this shift. GDP counts the sale of cigarettes and the cost of cleaning up after a disaster as gains, while ignoring unpaid care, leisure and the quality of personal relationships. Asking people directly how their lives are going places their own judgements, rather than those of experts, at the centre of policy, which seems to me a genuine democratic advance. Survey data have also highlighted problems that income figures miss. Unemployment, for example, reduces life satisfaction far more than the loss of earnings alone would predict, suggesting that work provides status, routine and social contact as well as money.

Nevertheless, I believe that the enthusiasm for happiness as the goal of policy should be tempered. Self-reported happiness is sensitive to apparently trivial factors, such as the weather on the day of the survey or the questions asked immediately beforehand, and people in different cultures may interpret rating scales in different ways. A more fundamental difficulty is that a government which set out to maximise reported happiness might be tempted to change expectations rather than circumstances. If people adapt to hardship, low aspirations could be mistaken for success. Amartya Sen himself has long warned that deprived people may learn to be content with very little, and that their contentment should not be used to justify neglect.

The most sensible conclusion is that well-being data should complement, not replace, conventional economic statistics. Income still matters, particularly for the poor, for whom additional money brings clear improvements in both life satisfaction and daily experience. But measures of happiness can reveal where growth is failing to deliver better lives, and draw attention to things such as health, security and friendship that no price can fully capture. Used in this way, the economics of happiness is not a rival to traditional economics but a valuable corrective to its narrowest assumptions.