IELTS Academic Reading Practice Test 484

The Galápagos Islands lie on the equator, some 1,000 kilometres west of the coast of Ecuador, and they are home to the largest tortoises in the world. A fully grown animal may weigh more than 200 kilograms and live for a century or more. Their dark shells and slow, deliberate movements are among the most familiar images of island wildlife. When Spanish sailors first reached the archipelago in the sixteenth century, the tortoises were so numerous that a ship could take on dozens at a time, and the islands' name comes from an old Spanish word for the shape of their shells.

Naturalists recognise two main types of shell. Saddleback tortoises have a carapace that rises sharply at the front, leaving an opening through which a remarkably long neck can stretch upwards; domed tortoises carry a heavy, rounded shell that sits low over the body. The difference is usually explained by habitat. On dry, low-lying islands, where food is sparse, a saddleback shape allows an animal to browse on cactus and shrubs well above the ground. On the humid highlands of the larger islands, where grass and herbs grow close to the soil, there is no advantage in a long reach, and a domed shell may offer better protection from the sun.

Charles Darwin spent about five weeks in the archipelago in 1835, during the voyage of HMS Beagle. He rode on the animals' backs, ate their meat and recorded how slowly they moved. According to his account, the vice-governor, an Englishman named Nicholas Lawson, told him that he could identify which island any tortoise had come from simply by looking at its shell. Darwin noted the remark but made little of it at the time; the significance of such local variation became clear to him only after he had returned to England.

By then the tortoises had already suffered a long assault. From the late eighteenth century, whaling and sealing ships called at the islands and took animals on board, where they could be kept alive for months without food or water, supplying fresh meat long after other provisions had run out. Sailors also killed them for their oil. Historians estimate that many tens of thousands were removed during the nineteenth century, and on some islands the animals disappeared altogether.

Introduced animals did further damage. Goats had arrived with early settlers and passing ships, and without predators they multiplied into herds of thousands, stripping the vegetation on which young tortoises depend. Rats and pigs ate eggs and hatchlings, while donkeys trampled nesting sites. Goats were eventually hunted from the air, with the help of helicopters and satellite positioning, in a campaign that ended in 2006 with several large islands cleared of the animals. Vegetation on the cleared islands has slowly begun to return, though in some places the ground was so bare that soil itself had washed away.

In 1959 the Galápagos National Park was created, covering almost the whole land area of the archipelago, and before long a breeding centre opened on Santa Cruz. Its first task was to rescue the tortoises of Española, the oldest and flattest of the main islands, where only a handful of animals survived. These were brought into captivity, their eggs were collected and incubated, and the young were reared in pens until they were large enough to be released without being eaten. The programme has since produced more than a thousand young tortoises for that island.

The best-known individual lived on Pinta. The last tortoise known to belong to that island's own form was found in 1971 and taken to Santa Cruz, where he was kept for decades in the hope that a female might be discovered. None was, and the animal, known as Lonesome George, died in June 2012. A later survey of the remote slopes of Wolf Volcano on Isabela found a few tortoises carrying genetic traces of the Pinta animals, which offers a faint hope that the line has not been entirely lost.

Giant tortoises are reptiles and cannot generate their own body heat. Much of the day is therefore spent basking in the sun, with the animals extending their necks and legs to expose as much skin as possible, and at night they may gather in groups or wallow in mud to keep warm. They feed on grass, leaves and cactus, spines included, and can go for long periods without drinking, storing water in the bladder and reabsorbing it when needed. Their metabolism is slow, which is one reason for their exceptional longevity.

Tortoises shape the islands in ways that are easily overlooked. They eat a wide range of fruit, and the seeds inside pass through the gut, sometimes germinating more readily than seeds that simply fall to the ground. Some researchers describe the animals as gardeners of the archipelago, because an individual may walk several kilometres in a week and carry seeds far from the parent plant. Their heavy feet also scrape bare patches and churn muddy wallows, where other plants can establish themselves.

Perhaps 20,000 to 30,000 giant tortoises survive today, a small fraction of the number that existed before humans arrived. Their future depends on the continued control of introduced mammals, on strict rules for tourism and on the breeding centres, which remain a lifeline for the rarest forms. Rats are a particular problem, since they eat eggs and newly hatched tortoises, and feral cats take the young as well. The islands now attract roughly a quarter of a million visitors a year, and the income they bring pays for the unglamorous work of eradicating species that do not belong there.

Most of us make dozens of moral judgements in a day. We decide that a colleague has behaved unfairly, that a stranger deserves help or that a public figure should resign, and we do so in a fraction of a second and with complete confidence. Only afterwards, if at all, do we produce reasons. This everyday experience poses an awkward question for anyone who assumes that human beings reach moral conclusions the way a mathematician solves a problem.

For much of the twentieth century the dominant account in psychology was rationalist. Its most influential figure was Lawrence Kohlberg, who from the 1950s onwards presented children and adults with moral dilemmas and asked them to explain what should be done. One of his best-known cases concerned a man whose wife was dying of cancer and who considered stealing an unaffordable drug from a pharmacist. From the answers he collected, Kohlberg concluded that moral understanding develops through a series of stages, each resting on more sophisticated reasoning than the last.

Philosophers had their own puzzle. In 1967 Philippa Foot described a runaway tram heading towards five people who cannot move; a bystander can throw a switch to send it down a side track, where it will kill one person instead. Most people say the switch should be thrown. In the 1980s Judith Jarvis Thomson modified the case so that the only way to stop the tram is to push a heavy stranger off a footbridge into its path. Most people refuse, even though the arithmetic of lives saved is identical, and explaining why has occupied philosophers ever since.

Psychologists began to suspect that the explanation lies in the speed of moral reactions. The most prominent critic of the rationalist tradition has been Jonathan Haidt, whose social intuitionist model reverses the traditional order. A situation produces an immediate intuitive reaction of liking or distaste; a judgement follows at once, before any deliberate thought; and reasoning arrives afterwards, functioning less like a judge than like a lawyer paid to defend a verdict already reached. In experiments on what Haidt called moral dumbfounding, participants were given a scenario designed to be offensive but harmless, such as a brother and sister who commit a single act of incest and use contraception. Many said the act was wrong, yet could not produce a reason that survived their own interrogation.

Other researchers approached the question with brain imaging. From about 2001, Joshua Greene and his colleagues scanned the brains of volunteers as they considered the tram dilemmas. Personal dilemmas of the footbridge kind, which require the direct infliction of harm, produced greater activity in regions associated with emotion, while impersonal dilemmas that could be resolved by throwing a switch recruited regions associated with working memory. Greene argued for a dual-process account, in which rapid emotional responses and slower deliberate reasoning compete, and in which the emotional response often prevails.

Developmental research added a further complication. In experiments first published in 2007, Kiley Hamlin and her colleagues showed infants of six and ten months a puppet climbing a hill; the puppet was then either helped by a second puppet or pushed back down. Given a choice, the babies preferred the helper. Such findings have been taken as evidence that a preference for helpful behaviour is present before a child can speak, though critics point out that the effect is small and that reading the gaze or reach of a baby is not straightforward.

Haidt's later work with Craig Joseph and Jesse Graham developed moral foundations theory, which holds that human beings possess several distinct moral systems rather than one. In their account, care and fairness sit alongside loyalty, respect for authority and concern for purity, and different individuals and cultures weight these foundations differently. The theory has been influential well beyond psychology, not least because it appears to explain why people of different political persuasions talk past one another, but it has also been criticised: the foundations are difficult to define precisely, and it is not clear what evidence would count against the theory.

Anthropologists and economists have supplied another kind of challenge. In ultimatum game experiments, one person is given a sum of money and must offer part of it to a second person, who may accept or reject the offer; a rejection leaves both with nothing. Students in wealthy countries typically offer about half. When the anthropologist Joseph Henrich and his colleagues played the game with small-scale societies around the world from the late 1990s, the results varied enormously: in some groups an offer of a quarter was considered generous, while in others a near-equal split was rejected as insulting. The researchers concluded that the sense of what is fair is not a universal constant but is learned in a particular economy and society.

What remains uncertain is how the parts fit together. Brain imaging studies typically involve a few dozen volunteers and hypothetical dilemmas that bear little resemblance to the decisions people actually face. Some of the most-cited findings have not always been replicated, and the interpretation of the images is contested. Nor does the intuitive model explain everything: people can and do revise their moral views after reflection or argument, which suggests that reasoning is not merely decorative. A growing number of researchers therefore prefer to study the small judgements of daily life rather than the elaborate dilemmas of the laboratory.

None of this has produced a settled theory. What has changed is the assumption with which the field began. Moral judgement now looks less like a calculation performed by a detached intellect and more like a rapid response, reached in ignorance of its causes and defended afterwards by whatever means are available.

Few proposals for feeding the world attract quite as much enthusiasm as insect farming. Its advocates point out that insects are already eaten in many parts of the world; a widely cited report from the Food and Agriculture Organization of the United Nations, published in 2013, noted that more than two billion people were said to eat insects regularly. Farming them, the argument goes, would provide animal protein without the land, water and greenhouse gases associated with cattle, sheep and pigs. The claim is attractive and has been repeated in countless newspaper articles and company brochures, but the evidence behind it deserves a closer look.

The strongest part of the case is feed conversion. Insects are cold-blooded, so a far smaller share of what they eat is spent on maintaining body temperature. Crickets raised for food are usually reported to convert roughly two kilograms of feed into one kilogram of body mass, while cattle require several times that amount and use much of it to build bones and other parts that people do not eat. Insects can also be reared on organic waste such as vegetable peelings and brewery residues, material that would otherwise be composted or dumped, and they need a fraction of the land and water that mammals do. In tropical countries, where the animals thrive without artificial heat, a small farm can be set up at modest cost.

Nutritionally, farmed insects are comparable to conventional meat. Crickets and mealworms contain a high proportion of protein, together with fats, several minerals and vitamin B12, and some species supply amino acids that are limited in cereal diets. Processing matters too: drying, grinding and extrusion all consume energy and alter the digestibility of the protein. Two caveats are commonly raised. Some insect proteins are closely related to those found in shellfish, and cases of allergic reaction have been reported, so products may need to carry warnings. The nutrient content also depends heavily on what the insects have been fed: a diet of clean waste produces a very different animal from one enriched with grain.

A more recent concern is animal welfare. Farmed insects are invertebrates, and whether they experience pain is not settled. They have receptors that respond to damage and behave differently after injury, and some researchers regard this as reason for caution, while others argue that the evidence falls far short of what would be needed to conclude that insects suffer. Either way, insect farms deal in numbers that are hard to grasp: a single facility may produce billions of individuals in a year. To describe such a method of rearing animals as humane, critics say, is to use the word without justification.

The environmental case depends on where the farm is. Because insects grow quickly only in warmth, producers in northern Europe and North America must heat their facilities through the winter, and several life-cycle assessments have found that the energy used in heating and drying can cancel out the savings gained from feed. Results vary widely between studies, partly because no standard method has been agreed. Nor is it always sensible to compare insect meal with soya as though the two were interchangeable: soya is already produced in enormous quantities at low cost, and its yield per hectare in warm climates is difficult to beat.

Regulation has also shaped the industry. In the European Union, insects intended for human consumption were initially treated as a novel food, requiring an authorisation that took years to obtain. Insect protein was approved for use in fish feed in 2017, a decision that created a market for producers almost overnight, since fish farming requires large quantities of protein. Retail sales of insect-based snacks have grown, but they remain a small niche in most European countries, and surveys consistently find that many consumers are unwilling to try them.

Sceptics question the food-security argument in particular. The people who most need protein, they observe, are generally poor, and the products of insect farming are usually sold as premium goods — protein bars, pet food and speciality flour — rather than as cheap food for low-income households. Reared properly, insects are not free to produce. On this view the technology is a useful addition to the range of feeds and foods available, and it may raise the incomes of smallholders who farm insects for local markets, but it is no remedy for hunger, which is more often caused by poverty and conflict than by a shortage of protein.

My own view is that insect farming is worth developing, but that it has been oversold. Judgements about it should be made species by species and system by system, in the light of measured data rather than of the word 'sustainable' on a packet. The welfare question is not an inconvenience to be set aside; if billions of animals are being reared, the least we can do is establish what they experience. And the claim that this new industry will feed the world should be treated with suspicion, because reducing waste and changing what prosperous people eat still matter far more.