IELTS Academic Reading Practice Test 14

Salt is so cheap and plentiful today that it is hard to imagine it as a source of wealth, conflict and political power. Yet for most of human history it was among the most valuable of all commodities. The human body needs sodium to regulate fluids and transmit nerve signals, and people who ate mainly meat could obtain enough from their diet.

When farming societies began to depend on cereals, however, they needed additional salt, and so did their domestic animals. Just as importantly, salt was the principal means of preserving food. Meat and fish packed in salt or soaked in brine could be stored for months, allowing communities to survive long winters and sailors to undertake long voyages. Salted cod from the North Atlantic, for example, became a staple food in much of southern Europe.

There have traditionally been three main ways of obtaining salt. The simplest, practised wherever the climate is warm and dry, is solar evaporation. Seawater is let into a series of shallow ponds, known as salt pans, where the sun and wind gradually remove the water until crystals form and can be raked up by hand. In cooler regions, people boiled seawater or water from salt springs in large, shallow vessels over a fire, a method that required great quantities of fuel. The third method is to mine rock salt, the remains of ancient seas that dried out millions of years ago and were buried beneath later layers of rock.

Some salt mines are extraordinarily old. At Hallstatt, in the Austrian Alps, salt has been extracted for at least three thousand years, and the mine has preserved remarkable evidence of prehistoric life, including wooden tools, leather bags and even the remains of meals, because salt prevents organic materials from decaying. The site is so important that it has given its name to the Hallstatt culture, an early Iron Age culture of central Europe. At Wieliczka, near Kraków in Poland, mining began in the thirteenth century and continued commercially until 1996. Over the centuries the miners carved chapels, statues and even chandeliers out of the rock salt itself, and in 1978 the mine was among the first places to be added to UNESCO's World Heritage List.

In China, salt production drove remarkable technical innovation. In the province of Sichuan, where salt lay in underground brine rather than in the sea, engineers developed methods of drilling deep wells using bamboo cables and heavy iron bits that were repeatedly raised and dropped by teams of workers. Natural gas encountered during drilling was piped through bamboo tubes and burned to boil the brine. By 1835 a well at Zigong known as the Shenhai well had reached a depth of about 1,001 metres, and it is often described as the first well in the world to pass the thousand-metre mark.

Because everyone needed salt, and because its sources were limited to particular places, governments found it an ideal thing to tax or control. In China, the Han dynasty established a state monopoly over salt and iron in the second century BCE, and in 81 BCE officials and scholars held a famous debate at court over whether such monopolies were justified. In France, a salt tax known as the gabelle was imposed for centuries. It varied greatly from one region to another, which encouraged widespread smuggling, and it was among the most hated taxes of the period before the French Revolution.

In British India, too, salt became a symbol of resistance. The colonial government held a monopoly on salt and taxed it, so that even the poorest Indians, who could easily have collected salt along the coast, were forbidden to do so. In March 1930 Mohandas Gandhi set out with a group of followers on a march of about 385 kilometres from his ashram near Ahmedabad to the coastal village of Dandi. On reaching the sea in April, he picked up a lump of natural salt from the shore, deliberately breaking the law. The journey had taken twenty-four days. The march attracted worldwide attention, and tens of thousands of Indians were arrested in the campaign of civil disobedience that followed.

Salt has also left its mark on language. The English word 'salary' comes from the Latin salarium, and it is often claimed that Roman soldiers were paid in salt. Historians point out, however, that no ancient source actually says this; the word may have referred to an allowance for buying salt, or its origin may be different altogether. The Via Salaria, one of the oldest roads leading to Rome, does appear to take its name from the salt that was carried along it from the coast.

Today salt is produced on an enormous scale, with world output estimated at around 270 million tonnes a year, and China is the largest producer. Only a relatively small proportion is eaten. Most is used by the chemical industry, particularly to make chlorine and sodium hydroxide, or spread on roads to melt ice in winter. Much modern salt is obtained by solution mining, in which water is pumped down into underground deposits and the resulting brine is brought to the surface and evaporated. Refrigeration and canning have long since replaced salt as the main methods of preserving food, and health authorities now warn that most people consume far more salt than they need.

Of all the animals that humans have domesticated, the dog was the first, and it is the only one that was domesticated by hunter-gatherers rather than by farmers. Every one of the world's hundreds of millions of dogs, from the Chihuahua to the Great Dane, is descended from wolves. Yet despite decades of research, scientists still disagree about when, where and how this transformation took place, and new evidence continues to overturn earlier conclusions. Domestication, in this sense, means far more than taming individual animals: it involves inherited changes, accumulated over many generations, that adapt a species to life with people.

Archaeology provides some of the most striking clues. In 1914 quarry workers at Oberkassel, near Bonn in Germany, discovered a grave containing the skeletons of two people together with the remains of a dog. When the bones were re-examined a century later, a team led by the veterinary researcher Luc Janssens found that the dog had died at around seven months old. It had suffered from canine distemper, a viral disease that is usually fatal without care. To have survived for several weeks, the young animal must have been kept warm, fed and cleaned by people, even though it can have been of little practical use to them. The burial, about 14,000 years old, suggests that humans had formed emotional bonds with dogs by that time. Older skulls that some researchers interpret as early dogs have been found at sites in Belgium, Russia and the Czech Republic, but their status remains disputed, because it is difficult to distinguish an early dog from a wolf on the basis of bones alone.

Genetics was expected to settle these questions, but at first it added to the confusion. One difficulty is that dogs and wolves have continued to interbreed since domestication, blurring the genetic signal. Another is that the population of wolves from which dogs descend appears to have died out, so modern wolves are not their direct ancestors but their distant cousins. In 2020 an international team led by Anders Bergström analysed the genomes of 27 ancient dogs and concluded that by 11,000 years ago, at the end of the last Ice Age, there were already at least five distinct lineages of dog in different parts of the world. A later study by many of the same researchers, which compared dogs with the genomes of ancient wolves, found that dogs are more closely related to ancient wolves from eastern Eurasia than to those from the west.

How the process began is equally debated. One long-standing idea is that humans deliberately captured wolf pups and raised them. Many researchers find this unlikely as the sole explanation, because adult wolves are dangerous and difficult to control, and a few tame individuals would probably have bred with wild wolves. An alternative view, sometimes called the self-domestication hypothesis, holds that wolves which were less fearful of humans began to scavenge around human camps, eating discarded scraps. Over many generations, natural selection would have favoured tamer animals, and humans may only later have begun to manage their breeding. A further suggestion is that during the coldest part of the last Ice Age, hunters who had more lean meat than they could eat may have shared the surplus with wolves, since people cannot safely live on protein alone.

Some of the most influential evidence about domestication comes not from dogs but from foxes. Beginning in 1959, the Soviet geneticist Dmitry Belyaev and his colleagues in Novosibirsk bred silver foxes, selecting in each generation only those animals that reacted least fearfully or aggressively to people. Within a few decades, the foxes not only sought human company but had also begun to show physical changes, including floppy ears, curly tails and patches of white fur, features that are common in domestic animals of many species. Belyaev concluded that selecting for tameness alone could bring about a whole package of changes. Recent research has complicated this picture, however, since the original foxes came from fur farms and may already have been partly tame, and some of the traits had been recorded in farmed foxes before the experiment began.

Dogs have also changed in ways that make them unusually responsive to humans. Experiments led by the American anthropologist Brian Hare in the early 2000s found that dogs readily follow a human pointing gesture to find hidden food, while chimpanzees, our close relatives, and even wolves raised by humans generally perform less well. In 2015 Japanese researchers led by Miho Nagasawa reported that when dogs and their owners gaze into each other's eyes, levels of oxytocin, a hormone associated with social bonding, rise in both species, a response that was not seen in hand-reared wolves. Such abilities may reflect thousands of years in which dogs that cooperated well with people were more likely to survive and breed.

Dogs' bodies also show the effects of living alongside farmers. In 2013 a team led by Erik Axelsson in Sweden compared the genomes of dogs and wolves and found that dogs carry extra copies of a gene called AMY2B, which produces an enzyme that breaks down starch. This adaptation probably helped dogs to thrive on scraps from early agricultural communities, whose diet was rich in cereals. The number of copies varies between breeds. Dogs from regions where farming arrived late or not at all, such as the Arctic, tend to have fewer, a pattern consistent with the idea that the trait spread after domestication rather than at its very beginning.

Few changes to working life have been introduced with such confidence, or criticised with such passion, as the open-plan office. Today a large share of office employees in many countries work in shared spaces without walls or doors, and the arrangement has become so familiar that it is easy to forget that it was once a radical idea. Its supporters promise lively collaboration and a sense of shared purpose; its critics describe noisy, distracting rooms in which concentration is impossible. Having examined the research, I believe that both camps have overstated their case, but that the critics are considerably closer to the truth.

Open offices are not new. Early twentieth-century offices often placed rows of clerks at identical desks in a single large hall, an arrangement inspired by factory production lines and intended above all to allow supervisors to watch the workforce. Frank Lloyd Wright's Larkin Administration Building, completed in Buffalo, New York, in 1906, was a celebrated example. A very different philosophy emerged in Germany in the late 1950s, when a consulting group called the Quickborner Team proposed Bürolandschaft, or 'office landscape', in which desks were grouped irregularly according to patterns of communication and separated by plants and screens. In the United States, the designer Robert Propst created a flexible system of movable panels in the 1960s that was meant to give workers both privacy and autonomy. To his later dismay, companies used his ideas to pack employees into rows of identical cubicles.

The most recent wave of open-plan design, which gathered pace in the early twenty-first century, combined two motives. The first was financial: removing walls allows more people to be accommodated in a given area, reducing the cost of expensive city-centre property. The second was a belief, popular among technology companies in particular, that innovation depends on chance encounters between colleagues and that walls are barriers to the exchange of ideas. Facebook's headquarters in California, designed by Frank Gehry and opened in 2015, placed thousands of employees in a single enormous room. It is this second claim that deserves the closest scrutiny, since it is the justification that companies usually offer in public.

The most direct test of the collaboration argument was published in 2018 by Ethan Bernstein and Stephen Turban of Harvard Business School. They studied employees at two large companies that were moving from individual workspaces to open-plan offices. Participants wore electronic badges that recorded when they were talking face to face with colleagues, and the researchers also collected data on email and instant messaging. After the move, the amount of face-to-face interaction fell by around 70 per cent, while electronic communication increased. Rather than mixing more freely, employees appeared to protect what privacy they could by withdrawing into their screens, sending messages to colleagues who were sitting only a few metres away. The study had limitations, since the badges recorded that conversations took place but not what was said. Even so, its findings are hard to reconcile with the idea that removing walls brings people together.

Other research points in the same direction. In 2013 Jungsoo Kim and Richard de Dear of the University of Sydney analysed survey responses from more than 40,000 office workers, mostly in the United States, and found that those in enclosed private offices were the most satisfied with their workspace. The supposed benefit of easier interaction in open-plan offices did not compensate for the dissatisfaction caused by noise and a lack of privacy. A Danish study published in 2011 found that employees in open-plan offices shared by more than six people reported 62 per cent more days of sickness absence than those in individual offices, although surveys of this kind cannot show that the office layout itself was responsible.

The central problem appears to be noise, and in particular speech. Psychologists have shown repeatedly that people find it harder to perform tasks such as reading, writing and mental arithmetic when they can hear other people talking nearby. This 'irrelevant speech effect' is difficult to escape, because the human brain seems to process speech automatically, and it does not reliably fade as people become accustomed to their surroundings. One study even suggested that hearing only one side of a telephone call is more distracting than hearing a whole conversation, perhaps because the listener cannot help trying to predict what the unheard speaker is saying.

None of this means that walls are always better. Some kinds of work, such as that carried out in newsrooms or on trading floors, genuinely benefit from people being able to overhear one another, and junior employees may learn a great deal simply by observing more experienced colleagues. Open offices can also make managers more visible and approachable. The difficulty is that most office work involves a mixture of activities, some requiring collaboration and others demanding sustained concentration, and a single large room serves the second kind badly.

A more promising approach is to give people a choice of settings. In so-called activity-based offices, employees have no fixed desk but can move between quiet rooms, open areas for teamwork and small booths for telephone calls according to the task in hand. Such arrangements are not a cure-all: some studies suggest that people tend to stay in one place rather than moving, and that the lack of a personal desk can be unsettling. But they at least acknowledge what the open-plan enthusiasts overlooked: that collaboration cannot be produced merely by removing walls, and that the ability to concentrate is not a luxury but a basic requirement of most office work.