IELTS Academic Reading Practice Test 5

Few machines are as efficient as the bicycle. A cyclist travelling at a moderate pace uses considerably less energy per kilometre than a person walking, and far less than any motor vehicle, yet the device that makes this possible took most of the nineteenth century to reach its familiar form. Its development was not a smooth progression from one improvement to the next, but a series of experiments, several of which turned out to be dead ends, shaped as much by fashion and commercial competition as by engineering logic.

The story usually begins in 1817 in Mannheim, Germany, where a civil servant named Karl Drais demonstrated what he called a 'running machine'. It consisted of a wooden frame with two wheels in line, a padded seat and a handlebar for steering, but it had no pedals: riders propelled themselves by pushing against the ground with their feet. Some historians have suggested that Drais was searching for an alternative to the horse after a series of poor harvests had made animal feed expensive, although this explanation remains speculative. The machine enjoyed a brief period of popularity among wealthy young men in Germany, France and Britain, but it was heavy, uncomfortable on rough roads and soon came to be regarded as a fashionable novelty rather than a practical means of transport.

The next significant step came in France in the 1860s, when pedals were attached directly to the hub of the front wheel. Who deserves the credit for this innovation is still disputed: claims have been made on behalf of the Paris carriage-maker Pierre Michaux and his son, and of a mechanic named Pierre Lallement, who later obtained a patent in the United States. The resulting machine, known in France as the vélocipède and in Britain, rather less flatteringly, as the 'boneshaker', had an iron frame and wooden wheels with iron tyres, and riding it on cobbled streets was an exhausting experience.

Because the pedals turned the front wheel directly, a single rotation of the pedals moved the machine forward by exactly the circumference of that wheel. The only way to travel faster without pedalling more rapidly was therefore to make the front wheel bigger. During the 1870s this logic produced the high-wheeler, later nicknamed the 'penny-farthing' after the contrast between a large British penny and a much smaller farthing coin.

Front wheels grew to well over a metre in diameter, limited only by the length of the rider's legs. The machines were fast and, on a good surface, surprisingly smooth, but they were also dangerous. Because the rider sat high above the front wheel, any sudden stop – caused by a stone or a pothole – could throw him head first over the handlebars.

The solution was a design that its makers advertised, with deliberate emphasis, as the 'safety bicycle'. The most influential version, the Rover, was produced in 1885 by John Kemp Starley in the English city of Coventry. It had two wheels of similar size and transmitted power from the pedals to the rear wheel by means of a chain and gears, so that a modest wheel could be made to turn several times for each rotation of the pedals. The rider sat lower and further back, making falls far less likely. Within a few years the safety bicycle had acquired the diamond-shaped frame of steel tubes that is still standard today, and the high-wheeler had become obsolete.

One problem remained: comfort. Solid rubber tyres transmitted every bump in the road to the rider. In 1888 John Boyd Dunlop, a veterinary surgeon living in Belfast, fitted air-filled tyres to his son's tricycle, and the idea was rapidly adopted by bicycle manufacturers. Dunlop was not, in fact, the first to have the idea – a Scottish engineer, Robert William Thomson, had patented a pneumatic tyre more than forty years earlier – but Thomson's invention had never been commercially successful, and it was Dunlop's version that transformed the industry.

The result was a boom in cycling during the 1890s, particularly in Europe and North America. For the first time, large numbers of people could travel independently over considerable distances at little cost. The bicycle had a particularly strong impact on the lives of women, many of whom gained a new degree of personal freedom; it also contributed to changes in women's clothing, as long, heavy skirts were replaced by more practical garments. Campaigners for women's rights frequently cited cycling as a symbol of independence.

Later engineering advances, such as gears contained within the rear hub and, eventually, lightweight frames of aluminium and carbon fibre, refined the machine without changing its basic principles. Although the arrival of the motor car reduced the bicycle's importance in many wealthy countries during the twentieth century, it remains the most common form of mechanical transport in much of the world, and many cities are now investing in dedicated cycle lanes in an effort to reduce traffic congestion and air pollution.

When scientists discuss intelligence in animals, they usually turn first to creatures that are closely related to humans, such as chimpanzees, or to animals with large brains and long lives, such as dolphins, elephants and crows. The octopus fits none of these patterns. It is a mollusc, more closely related to snails and clams than to any vertebrate, and the last ancestor it shared with humans – a simple, worm-like animal – lived more than 500 million years ago. Yet octopuses can solve problems, use objects as tools and recognise individual people. Their abilities therefore suggest that complex intelligence has evolved independently at least twice on Earth, along entirely separate lines. This possibility makes the octopus particularly valuable to scientists who wish to understand which features of intelligence are universal and which are peculiar to the vertebrate line.

The anatomy of an octopus is unusual in almost every respect. It has three hearts and blue blood, which contains a copper-based molecule rather than the iron-based haemoglobin found in vertebrates. Its nervous system is equally remarkable. A common octopus has around 500 million neurons, a number comparable to that of a dog, but roughly two-thirds of them are located not in its central brain but in its eight arms. Each arm can respond to touch and taste, and can perform some movements without instructions from the brain; experiments have shown that an arm that has been separated from the body will still reach for food and attempt to pass it towards where the mouth would be.

Octopuses are also masters of disguise. Their skin contains thousands of specialised cells called chromatophores, each holding a sac of pigment that can be expanded or contracted by tiny muscles, allowing the animal to change its colour and pattern in a fraction of a second. Some species can also alter the texture of their skin to resemble rock or seaweed. Remarkably, most octopuses appear to be colour-blind, possessing only one type of light-sensitive cell in their eyes. How they match the colours of their surroundings so precisely remains uncertain; one hypothesis is that light-sensitive molecules in the skin itself may detect the colour of nearby surfaces.

Stories of octopuses escaping from aquariums are common, and some are well documented. In 2016 an octopus named Inky escaped from his tank at the National Aquarium of New Zealand in Napier, crossed the floor and slipped into a drainpipe that led to the sea. Accounts of octopuses unscrewing the lids of jars from the inside, or squeezing through gaps scarcely larger than their eyes, are familiar to aquarium staff, since the only rigid part of an octopus's body is its beak. In the wild, researchers working in Indonesia in the late 2000s observed veined octopuses collecting the discarded halves of coconut shells, carrying them across the sea floor and later assembling them into a shelter. Because the animals transported the shells for future use rather than for any immediate benefit, the researchers argued that this behaviour qualified as tool use – the first such case reported in an invertebrate.

In the laboratory, octopuses have learned to open jars, navigate simple mazes and distinguish between shapes. They also show individual differences that resemble personality: some animals are consistently bold and others shy, and keepers frequently report that particular octopuses respond differently to particular people, occasionally squirting water at staff they appear to dislike. In one widely reported experiment, octopuses distinguished between a person who regularly fed them and a person who touched them with a bristly stick, even when both wore identical uniforms. Such observations are difficult to quantify, but they have encouraged researchers to study octopus behaviour more systematically.

What makes this intelligence especially puzzling is the octopus's short life. Most species live for only one or two years, and many die soon after breeding, so they have little opportunity to learn from their parents or to pass knowledge on to their offspring. Biologists have traditionally linked intelligence to long lifespans and complex social lives, in which individuals benefit from learning from one another. The octopus, a largely solitary and short-lived animal, appears to contradict this theory. Some researchers suggest that its intelligence instead evolved as a result of losing the protective shell of its ancestors: a soft-bodied animal that must find food while avoiding predators may need exceptional flexibility of behaviour simply to survive.

These findings have had practical consequences. In 2021 a review commissioned by the British government concluded that there was strong scientific evidence that octopuses and their relatives, together with crabs and lobsters, are sentient – that is, capable of experiencing feelings such as pain. As a result, these animals were included in the United Kingdom's Animal Welfare (Sentience) Act of 2022. The growing recognition of octopus intelligence has also intensified debate about proposals to farm octopuses for food, which critics argue would cause considerable suffering to animals that are naturally curious, solitary and easily stressed.

Every new drug must prove that it works better than nothing – or, more precisely, better than a placebo, an inactive substance such as a sugar pill that is made to look identical to the real medicine. In a typical clinical trial, patients are randomly divided into two groups, one receiving the drug and the other the placebo, and neither the patients nor the doctors treating them know who has received which. If the drug group improves significantly more than the placebo group, the drug is judged effective. This method, now regarded as the gold standard of medical research, rests on an assumption that has itself become the subject of intensive study: that people who receive a placebo will often improve too.

The modern interest in this 'placebo effect' is often traced to an article published in 1955 by the American anaesthetist Henry Beecher, entitled 'The Powerful Placebo'. Reviewing a number of earlier studies, Beecher concluded that around a third of patients experienced significant relief from a placebo alone. The figure was widely quoted for decades. Beecher's interest had been stimulated during the Second World War, when he observed that badly wounded soldiers often seemed to require less pain relief than civilians with comparable injuries. Later analysts, however, pointed out serious weaknesses in his reasoning. Many patients improve without any treatment at all, because illnesses often get better naturally or because symptoms that are unusually severe when a patient seeks help tend to return towards their normal level. Beecher had not separated these effects from any genuine response to the placebo.

When researchers did attempt to make that separation, the results were more modest. In 2001 two Danish researchers, Asbjørn Hróbjartsson and Peter Gøtzsche, analysed trials that had included both a placebo group and a group that received no treatment whatsoever. They found little evidence that placebos had powerful clinical effects in general, although there appeared to be a small benefit for conditions such as pain, in which outcomes depend largely on what patients themselves report. Their study did not show that the placebo effect is imaginary; rather, it suggested that it is narrower and less dramatic than had been claimed.

Within those limits, however, the effect can be surprisingly sensitive to context. Experiments have shown that the colour, size and number of pills, the way a treatment is delivered and even its price can influence how patients respond. In one study published in 2008, volunteers who received mild electric shocks reported greater pain relief from a pill described as expensive than from an identical pill described as heavily discounted. Injections tend to produce stronger placebo responses than tablets, and a warm, attentive manner on the part of a doctor appears to increase the benefit further. Brain-imaging studies have shown that, in the case of pain, the expectation of relief can trigger the release of the body's own natural painkillers.

The same power of expectation has a darker side, known as the nocebo effect. Patients who are warned about possible side effects of a drug are more likely to report experiencing them, even when they have in fact been given a placebo. The phenomenon may also help to explain why some people who believe themselves to be sensitive to particular foods or technologies report symptoms in blind tests, even when they have not actually been exposed to the supposed cause. In clinical trials, a substantial proportion of patients in placebo groups abandon the treatment because of side effects that cannot have been caused by the inactive pill. Doctors therefore face a genuine dilemma: they are obliged to inform patients of possible risks, yet the information itself may contribute to the problem.

Perhaps the most unexpected finding concerns placebos given openly. In 2010 a team led by Ted Kaptchuk of Harvard Medical School gave patients with irritable bowel syndrome pills that they were explicitly told contained no active ingredient. Compared with a group that received no treatment, these patients reported significantly greater improvement in their symptoms. Similar 'open-label' studies have since produced encouraging results for some other conditions, although the effects are generally small and not every trial has confirmed them. If such findings hold, they would remove one of the main ethical objections to the use of placebos – namely, that they depend on deceiving the patient.

None of this means that doctors should begin prescribing sugar pills in place of effective treatments. Placebos cannot shrink tumours, cure infections or repair broken bones, and claims that they can are not supported by the evidence. Yet the research has changed how many clinicians think about their work. It suggests that the setting in which treatment takes place – the explanation a patient is given, the confidence of the practitioner and the time spent listening – is not a trivial addition to medicine but part of its effect. Making better use of these factors, in combination with treatments that are effective in their own right, may be the most valuable lesson the placebo has to teach.