IELTS Academic Reading Practice Test 448

The marathon is unusual among Olympic events in that its origins lie in a legend rather than in any record of an actual race. According to the story, in 490 BC an Athenian army defeated a far larger Persian force on the plain of Marathon, about forty kilometres from Athens. A messenger was then sent to carry news of the victory back to the city. Arriving in the market place, he is said to have gasped out a single word, 'Rejoice', before collapsing and dying. The tale has been retold for centuries and gave the modern race its name.

The historian Herodotus, writing within a few decades of the battle, makes no mention of any run to Athens. What he describes is a professional courier named Pheidippides being dispatched to Sparta to request military help, a journey of some 240 kilometres that he supposedly completed in two days. It was later Greek and Roman authors who placed the fatal run on the road from Marathon to the city. Most historians therefore treat the episode as a patriotic invention rather than as a record of an event.

When the first modern Olympic Games were held in Athens in 1896, a French scholar, Michel Bréal, proposed that a long-distance race from Marathon to the city should be added to the programme. The idea appealed to the organisers, and the race was duly included. On 10 April about seventeen runners set off from a bridge near the village. The course was roughly forty kilometres long and the rules were rudimentary: competitors were forbidden to ride, but nothing prevented them from stopping for refreshment. The race was won by Spyridon Louis, a Greek water carrier, in just under three hours.

The next two Olympic marathons were chaotic. The race in Paris in 1900 was run over a maze of city streets in stifling summer heat. In St Louis in 1904 the course was laid out over dusty roads, and one competitor, Fred Lorz, was carried part of the way in a car after dropping out. He later rejoined the race on foot and entered the stadium first, to applause, before the deception was exposed and he was disqualified. The eventual winner, Thomas Hicks, was given doses of strychnine, a stimulant, and brandy by his handlers as he struggled through the closing miles.

For more than two decades the length of the race was not fixed. Courses were measured to suit the host city, ranging from about forty kilometres to more than forty-two, so that winning times could not usefully be compared. The best-known of these routes was laid out for the London Games of 1908. The race began beneath the windows of Windsor Castle and finished in front of the royal box in the White City Stadium. That course happened to measure 26 miles and 385 yards.

The 1908 race produced one of the most famous incidents in Olympic history. Dorando Pietri, a small Italian confectioner, entered the stadium far ahead of the field but turned the wrong way and then collapsed several times on the track. Officials, uncertain what to do, helped him to his feet and virtually carried him over the line. He was disqualified for receiving assistance, and the gold medal went to the American Johnny Hayes. Pietri was awarded a special cup by Queen Alexandra, and the episode did much to establish the marathon as an event of high drama.

The confusion over distances ended in 1921, when the International Amateur Athletic Federation adopted 42.195 kilometres as the official distance for future Olympic races. By then the marathon had already spread beyond the Games. The Boston Marathon was first run in 1897, a year after the Athens race, and it is the oldest marathon still held every year. Others followed in Europe and North America, and the race became the traditional climax of the Olympic athletics programme.

The event changed greatly after the Second World War. At the 1952 Games in Helsinki the Czechoslovak athlete Emil Zátopek, who had already won the 5,000 and 10,000 metres, decided to enter the marathon for the first time and won it. In Rome in 1960 Abebe Bikila, a member of the Ethiopian imperial guard, ran the entire course barefoot along the Appian Way. Four years later in Tokyo he became the first runner to win the Olympic marathon twice, and his success encouraged a generation of East African distance runners.

Women were excluded from the Olympic marathon until 1984, on the grounds that the distance was too demanding for them. Some ran anyway. In 1967 Kathrine Switzer entered the Boston Marathon using initials rather than her first name; an official tried to pull her off the course, and she finished the race. Women were officially admitted to Boston from 1972. The first Olympic women's marathon, at Los Angeles in 1984, was won by the American Joan Benoit.

Today the marathon is a mass-participation sport as well as an elite one. The largest races, in cities such as New York, London, Berlin and Boston, each attract tens of thousands of entrants, most of whom run for charity or personal satisfaction rather than for prizes. The New York City Marathon was first held in 1970, with a modest field running laps of Central Park, and the London Marathon followed in 1981. What survives of the ancient legend is the appeal of a simple contest over a fixed distance, in which amateur and professional share the same course.

Few animals are as closely associated with a single behaviour as the chameleon is with changing colour. The familiar image is of a lizard that fades into the background, matching a leaf or a branch so precisely that predators pass it by. That image is misleading. Although camouflage is one function of the chameleon's remarkable skin, it is neither the only one nor, in most species, the most important. Careful observation in the wild has shown that colour is used chiefly to send messages to other chameleons and to regulate the animal's temperature.

The chameleon is also remarkable for parts of its body that have nothing to do with colour. Its eyes are mounted in conical turrets and can be moved independently, so that one may look forward while the other looks back; only when both settle on the same object does the animal gain the depth perception it needs to strike. The tongue, which may be longer than the body, is fired out in a fraction of a second by the release of stored elastic energy.

The misunderstanding about colour arose partly because the change is so visible and partly because the animals are difficult to study. Most chameleons live in trees and bushes, and many are found only in remote forests. The family is large: well over two hundred species are recognised, nearly half on Madagascar, and they vary enormously in size and colour. Until recently, almost everything known about the mechanism came from a handful of species kept in captivity.

That changed in 2015, when a team of researchers at the University of Geneva published a detailed study of the panther chameleon, a species from Madagascar whose males display vivid blues, greens and reds. Examining the skin under a microscope, the researchers found that it contains two distinct layers of specialised cells called iridophores. Each layer is packed with tiny crystals of guanine, a substance also found in the reflective scales of fish, arranged in a regular three-dimensional lattice. The space between the crystals determines which wavelengths of light are reflected, and therefore which colour the skin appears to be.

What makes the chameleon unusual is that it can alter this spacing. In a relaxed animal the lattice in the upper layer of iridophores is dense and the gaps between crystals are narrow, so the reflected light is blue or green. When the animal becomes excited, for example on meeting a rival, the crystals move further apart and longer wavelengths, such as yellow and red, are reflected; when it calms down, the lattice contracts and the colour shifts back towards blue. The crystals themselves do not change size, only their arrangement. Nor is the change produced by pigments moving through the skin, as was long assumed. It is a structural effect, the same optical principle that gives a soap bubble or a peacock's feather its colour.

Other animals achieve colour change in quite different ways. Squid, octopus and cuttlefish control small elastic sacs of pigment, called chromatophores, by contracting muscles around them; when the muscles relax, the sacs shrink and the pigment inside is hidden. Fish, frogs and many reptiles move dark granules within cells, spreading them out to darken the skin or gathering them into a cluster to lighten it. These mechanisms are fast but crude compared with the chameleon's.

Temperature control is probably the oldest function of colour change. Like all reptiles, chameleons rely on external heat, and dark skin absorbs solar radiation efficiently. On cool mornings an animal may turn almost black, allowing it to warm up quickly; by the middle of the day, when overheating is the greater danger, it becomes pale and reflective. The deeper of the two iridophore layers, which contains larger and less orderly crystals, appears to be responsible for reflecting infrared radiation. In this respect the skin works as a tunable mirror rather than as a display.

Communication, however, has driven the evolution of the most striking colours. Males of many species defend territories and compete for females, and displays of bright colour signal strength and status to rivals. Females often use colour to indicate whether they are receptive to a mate, and a female that has already mated may adopt a dark, conspicuous pattern that discourages further attention. Because these signals must be seen by other chameleons rather than hidden from predators, the most brilliant species tend to live in open habitats where visibility is good.

There are limits. The change takes seconds or minutes, not the split second achieved by a squid, and a chameleon cannot imitate an arbitrary background; it tends to settle on a pattern that resembles the general texture and light of its surroundings rather than a particular object. The match between an animal and its habitat is therefore usually approximate rather than exact. Nor is colour always voluntary. A sick or frightened animal may darken and stay dark, which is why keepers use skin colour as a rough guide to health.

Many questions remain. The nerves and hormones that trigger the rearrangement of crystals have not been traced in detail, and it is not clear how far an individual can learn or adjust its repertoire during its lifetime. The ultraviolet patterns that are visible to other chameleons but invisible to human eyes are only beginning to be mapped. Recent work has also started to ask whether the shades an animal shows might reveal something about its stress levels. Even in the species studied most closely, the map of colour is far from complete. What is certain is that the animal's reputation for disguise is, at best, half the story.

A generation ago, a referee's mistake was simply bad luck, argued about and then forgotten. Today almost every major professional sport has some form of video review, and the arguments that follow a disputed decision can last for days. Every week seems to bring another controversy, and another committee promising to reform the system that was supposed to end the arguments. The question is no longer whether to use technology, but what to ask it to do, and who should ask. My own answer is that replays can settle questions of fact, but they cannot settle questions of judgement, and the attempt to make them do both has done considerable damage.

The case for review rests on two familiar pressures. A single decision can determine the outcome of a match worth enormous sums to clubs, sponsors and broadcasters, and the institutions that run sport cannot easily ignore those interests. The second is visibility. Television companies now place a dozen cameras at every fixture, and spectators in the stadium watch the same slow-motion pictures on giant screens as the viewers sitting at home. A goal awarded although the ball never crossed the line is no longer a private misfortune. It is a public embarrassment that undermines faith in the result.

Some decisions, moreover, are genuinely factual and can now be measured with remarkable precision. Whether a tennis serve landed inside the line, whether a football crossed the goal line, whether a batsman's foot was behind the crease: these are questions about position and timing, not about intention. Systems that combine high-speed cameras with computer modelling can locate a ball to within a few millimetres, and they have been accepted because they answer a narrow question to which there is a single correct answer. In such cases the technology does not replace the official's knowledge; it supplies a measurement that no human eye could ever provide.

The difficulty begins when the same machinery is applied to judgement. Whether a challenge was reckless, whether a handball was deliberate, whether a defender's contact was sufficient to bring an attacker down: these depend on reading a player's purpose, and no number of camera angles can settle them. Slow motion, far from revealing the truth, often distorts it. Movements that take a fraction of a second appear deliberate when replayed at a quarter of normal speed, and a freeze frame turns a continuous action into a pose that never existed. Football's phrase 'clear and obvious error' sounds precise, but it conceals a judgement of degree that two reasonable people will always make differently.

There is a cost, too, in time and attention. A review interrupts the flow of a match, drains the moment of its excitement and gives players and coaches an incentive to protest in the hope that a monitor will do their arguing for them. Meanwhile spectators in the ground are often left staring at a screen without knowing what is being examined or why, and the atmosphere that a crowd creates begins to evaporate. Officials who know that every decision may be scrutinised become hesitant, and the authority they need in order to control a fast and physical game is gradually eroded. Coaches, meanwhile, learn to treat the review as a tactical resource rather than as an emergency measure.

The most successful systems have recognised these limits. Cricket's review system gives each team a small number of appeals and takes one away when an appeal fails, so that only genuine mistakes are challenged. Tennis works in much the same way. Both retain the on-field decision when the evidence is marginal: in cricket the umpire's original call stands unless the replay shows clearly that it was wrong. This principle, that technology should overturn an official only when it is decisive, protects the referee's authority instead of destroying it, and it gives players a reason to use appeals sparingly. The result is a system that corrects the errors that matter while leaving the rest of the game to the people playing and officiating it.

Some critics would go further and remove the machinery altogether. They argue that uncertainty and human error are part of what makes sport a human activity, and that a game purified by machines loses something essential. I have considerable sympathy with the sentiment, but none at all with the conclusion. No serious observer proposes returning to the days when a linesman who was unsighted could award a goal that everyone in the stadium knew was not one. The players themselves, who have most to lose from a bad decision, are usually the keenest supporters of accuracy.

What, then, should the role of replay be? It should be confined to questions with a single correct answer: did the ball cross the line, was the foot in touch, had the clock run out. It should be subject to a strict time limit, so that a review which cannot be resolved quickly is abandoned and the original decision stands. It should be triggered by a limited number of appeals from captains rather than by officials watching monitors in a distant room. And it should never be asked to decide whether an action was intentional. Used in this way, technology supports the official rather than replacing the judgement that makes sport worth watching. None of this requires new machinery; it requires only the discipline to decide what the machinery is for.