IELTS Academic Reading Practice Test 22

Stonehenge stands on Salisbury Plain in Wiltshire, southern England, and is probably the best-known prehistoric monument in Europe. What visitors see today, however, is only the ruined final version of a structure that was built, altered and rebuilt over roughly fifteen hundred years. In the twelfth century the writer Geoffrey of Monmouth claimed that the wizard Merlin had carried the stones by magic from Ireland, while antiquarians of the seventeenth and eighteenth centuries linked the site with the Druids, the priests of Iron Age Britain. Modern dating methods have shown that both explanations are wrong. The monument was begun more than two thousand years before the Druids are recorded, by farming communities of the Neolithic period, or New Stone Age.

The first Stonehenge, constructed around 3000 BCE, was not a ring of tall stones but an earthwork: a circular ditch roughly 110 metres across, with a bank built from the excavated chalk. The builders dug the ditch using picks made from the antlers of red deer, and many of these tools were deliberately left on its floor. Because antler can be dated by the radiocarbon method, these discarded picks have provided some of the most reliable evidence for when work began. Just inside the bank lay a ring of 56 pits, known as the Aubrey Holes after the antiquarian John Aubrey, who first recorded them. Excavations have recovered cremated human remains from these pits and from the ditch, suggesting that Stonehenge was also an important burial place.

Many archaeologists now think that some of the Aubrey Holes originally held upright stones, so stone may have been part of the design from the start. These were the so-called bluestones, pillars of two to five tonnes each that are remarkable because they are not local. In the 1920s the geologist Herbert Thomas showed that many of them came from the Preseli Hills in south-west Wales, more than 200 kilometres away, and researchers have since found traces of Neolithic quarrying at outcrops there. Exactly how the stones reached Wiltshire is still debated. A minority of geologists have argued that glaciers carried them most of the way during an earlier Ice Age, but most archaeologists are convinced that people moved them, probably on wooden sledges hauled over land.

The most dramatic transformation took place around 2500 BCE, when much larger stones were raised. These are sarsens, blocks of extremely hard sandstone found scattered across the chalk downland of southern England. The builders arranged them in an outer circle of 30 uprights topped by a continuous ring of lintels and, within it, a horseshoe of five trilithons, each consisting of two uprights supporting a single lintel. The largest trilithon stones weigh more than 30 tonnes. The lintels were secured with mortise-and-tenon joints, in which a projection on top of an upright fitted into a hollow on the underside of the stone above, while neighbouring lintels were locked together with tongue-and-groove joints. Both techniques are normally associated with carpentry, which suggests that the builders adapted methods from woodworking.

Where the sarsens came from was long uncertain, although the Marlborough Downs, some 25 kilometres to the north, were the obvious candidate. During restoration work in 1958, engineers drilled a cylinder of rock, or core, out of one of the uprights. A man who had worked for the drilling company kept the core as a souvenir and took it with him when he later moved to the United States. Some sixty years afterwards he returned it to Britain, and a team led by the geographer David Nash analysed its chemistry. Their study, published in 2020, found that 50 of the 52 surviving sarsens share a chemical signature that matches stone at West Woods, on the edge of the Marlborough Downs. The source of the remaining two sarsens has still not been identified.

The Altar Stone, a six-tonne sandstone slab at the centre of the monument, was assumed for decades to have come from Wales. In 2024, however, a study published in the journal Nature showed that tiny mineral grains in the slab match rocks of the Orcadian Basin in north-east Scotland, roughly 700 kilometres away. This is the longest known journey of any stone used in a Neolithic monument, and how it was achieved remains unknown. An overland route would have crossed mountains, rivers and dense forest, so some archaeologists consider a journey by sea at least as plausible.

The purpose of Stonehenge remains a matter of interpretation, but its main axis is aligned with the sunrise on the summer solstice and, in the opposite direction, with the sunset on the winter solstice. At Durrington Walls, a vast earthwork enclosure about three kilometres to the north-east, excavations have uncovered the remains of houses and enormous quantities of pig bones. Analysis of the pigs' teeth indicates that many were slaughtered in winter, suggesting that large numbers of people gathered for feasts around the midwinter solstice. Some archaeologists believe that Durrington Walls housed the workers who built the sarsen phase of Stonehenge.

The monument was long private property, but in 1915 it was put up for auction, and a local barrister, Cecil Chubb, bought it for £6,600; three years later he gave it to the nation. During the twentieth century several fallen or leaning stones were straightened and set in concrete. Today Stonehenge forms part of a UNESCO World Heritage Site, designated in 1986 together with the nearby monument of Avebury, and is cared for by English Heritage.

Elephants are among the most sociable of all mammals. Female African savanna elephants live in close-knit family groups led by an experienced older female, the matriarch, while adult males move between groups and often travel alone. Keeping such a society together across a landscape of open grassland and dense bush requires constant communication. Some of this is visible: elephants touch one another with their trunks, spread their ears and adopt particular postures. Much of it, however, takes place through sound, and a surprising proportion of that sound lies below the range of human hearing. Long-term field studies, such as the research begun in 1972 in Kenya's Amboseli National Park, have gradually revealed how rich and complex this hidden channel is.

The first clue came not from the African plains but from a zoo in Portland, Oregon. In 1984 Katy Payne, a biologist who had spent years studying the songs of humpback whales, was watching the Asian elephants there when she noticed a faint throbbing in the air, a sensation she could feel rather than hear. She suspected that the animals were producing sounds too low for her ears but powerful enough to be felt. When she returned with equipment capable of recording such frequencies, she confirmed that the elephants were calling to one another in infrasound, below about 20 hertz, the lower limit of human hearing. Later playback experiments showed that wild African elephants use the same channel.

Low-frequency sound offers important advantages to an animal whose relatives may be scattered over a wide area. Long sound waves lose less energy as they travel through the air, and they pass around obstacles such as trees and hills rather than being blocked by them. Elephant rumbles, which carry much of their energy at very low frequencies, can therefore be detected by other elephants several kilometres away. Their range also depends strongly on the weather and the time of day. Atmospheric scientists working with elephant researchers found that on clear, calm evenings a layer of cool air often forms close to the ground beneath warmer air above. This temperature inversion traps sound near the surface, and in such conditions the area over which a rumble can be heard may expand several times compared with the middle of the day.

Sound in the air is not the only route. A powerful rumble also sets up vibrations that travel through the ground, and the biologist Caitlin O'Connell-Rodwell and her colleagues set out to discover whether elephants could detect them. At a waterhole in Etosha National Park in Namibia, they converted recorded alarm calls into vibrations and transmitted them through the soil using a device buried in the ground. Elephants visiting the waterhole bunched together and left the area, just as they did when an alarm call was played through loudspeakers. Strikingly, they responded only to calls from herds that were familiar to them, ignoring a similar call recorded from elephants in Kenya. The team proposed that sensitive receptors in the feet and the trunk pick up these signals.

Elephants produce a wide repertoire of calls, including trumpets, roars, barks and many kinds of rumble, and researchers have learned to link several of them to particular situations. Some of the clearest evidence of meaning comes from experiments with alarm calls. When researchers in Kenya played recordings of disturbed African honeybees to resting elephants, the animals moved away, shook their heads and produced a characteristic low rumble. Later work showed that elephants give acoustically different rumbles in response to bees and to the voices of local people, and that playing back the 'bee' rumble alone was enough to make other elephants retreat. These findings have had a practical application: fences hung with beehives are now used in parts of Africa and Asia to protect farmers' crops from raiding elephants.

The most surprising recent discovery concerns the way elephants address one another. In a study published in 2024, a team led by Michael Pardo analysed hundreds of rumbles recorded from wild elephants in Samburu and Amboseli, in Kenya, between 1986 and 2022. A machine-learning model was able to identify the individual being addressed more often than would be expected by chance, although it succeeded in only around 28 per cent of cases. When the researchers played recordings to elephants, the animals responded more energetically, approaching the loudspeaker or calling back, to calls that had originally been addressed to them than to calls addressed to others. Unlike dolphins, which address one another by imitating the other animal's signature whistle, the elephants did not seem to be copying the calls of the individual they were addressing. The researchers have not yet identified which part of a rumble functions as the 'name'.

Such findings suggest a degree of vocal flexibility that is rare among mammals. The ability to learn new sounds by imitation, known as vocal learning, is well documented in humans, some birds, whales and bats, but in few other animals. Elephants appear to belong to this small group. In 2005 researchers described Mlaika, a young African elephant raised in captivity in Kenya, who imitated the noise of lorries on a distant road. In South Korea, an Asian elephant named Koshik learned to reproduce several Korean words by placing his trunk inside his mouth to modify the sound. In the forests of central Africa, meanwhile, networks of recording devices now listen for elephant calls, helping conservationists to estimate population sizes.

Few economic ideas have attracted such an unusual coalition of supporters as the universal basic income. In its purest form, it is a regular cash payment made by the state to every adult, regardless of income, and without any requirement to work or to look for work. Anti-poverty campaigners see it as a guaranteed minimum standard of living. Some free-market thinkers favour it as a simple replacement for a tangle of means-tested benefits, while technology entrepreneurs promote it as a response to automation. This breadth of support is, in my view, partly an illusion: the people who praise basic income often have quite different schemes in mind, with very different costs and consequences.

The idea is older than it appears. In his pamphlet Agrarian Justice, published in 1797, Thomas Paine proposed that every person should receive £15 on reaching the age of 21, and £10 a year from the age of 50, financed by a tax on inheritances. Paine justified the scheme by arguing that the private ownership of land had deprived people of a natural inheritance in the earth, for which they deserved compensation. The only long-running programme that resembles a universal payment today is in Alaska, where since 1982 every resident has received an annual dividend from a state fund built on oil revenues. The amount varies from year to year and has generally been far too small to live on.

Recent pilot projects have produced findings that deserve to be taken seriously. Between 2017 and 2018, Finland paid 2,000 randomly selected unemployed people €560 a month, with no obligation to seek work and no reduction if they found a job. By the end of the trial, recipients had worked only slightly more days than a comparison group, but they reported less stress, better health and greater confidence in their future. In the 1970s, the Canadian town of Dauphin, Manitoba, took part in an experiment called Mincome, under which any family could receive a guaranteed income. When the economist Evelyn Forget later examined health records, she found that hospitalisation rates had fallen in comparison with similar communities, particularly for mental illness and injuries.

The most common objection to basic income is that people who receive money unconditionally will stop working. The evidence so far suggests that this fear is exaggerated, though not entirely groundless. In a large American study published in 2024, 1,000 low-income adults aged between 21 and 40 in Texas and Illinois received $1,000 a month for three years, while a control group of 2,000 people received $50 a month. Recipients worked on average about 1.3 hours a week less than the control group, and their earnings from employment fell slightly, yet they were somewhat more likely to be looking for a job. Such results support neither the most optimistic claims of enthusiasts nor the warnings of critics who foresaw a mass withdrawal from the labour market.

Encouraging as they are, pilot studies cannot answer the questions that matter most. First, they are temporary, and people who know that payments will stop may behave differently from those who can rely on them for life. Second, they are small: a few thousand recipients cannot alter prices or wages, whereas a national scheme might. Most importantly, pilots are funded by governments or donors from existing budgets, so they reveal nothing about the effects of the taxes needed to pay for a permanent programme. The arithmetic is daunting. The United States has roughly 260 million adults, so a payment of $12,000 a year to each of them would cost more than three trillion dollars annually, equivalent to well over half of all the revenue currently collected by the federal government.

Supporters reply that the net cost is far lower than such figures suggest, because much of the money received by better-off people would be recovered through higher taxes, and because a basic income could replace some existing benefits. They also identify a genuine weakness of means-tested systems. When benefits are withdrawn as earnings rise, a low-paid worker who takes on extra hours may keep only a small fraction of the additional income, a situation economists call a poverty trap. Universal payments avoid this problem, and they also avoid the stigma and administrative complexity that discourage many eligible people from claiming support at all. I find these arguments more persuasive than the claim that basic income is necessary because machines will soon take everyone's jobs.

That claim deserves considerable scepticism. Predictions of technological mass unemployment have been made repeatedly since the nineteenth century, and so far new technologies have tended to change the kinds of work people do rather than eliminating work altogether. It is possible that artificial intelligence will prove different, but a policy as expensive as a universal income should not rest on a forecast that may never come true. If basic income is worth having, it should be because it reduces poverty and insecurity in the world as it is, not because of an imagined future.

The honest answer is that the evidence needed for a confident decision does not yet exist. More useful than further small pilots would be experiments that are larger, longer and closer to the real thing. One example is already under way in rural Kenya, where the charity GiveDirectly began in 2017 to pay a modest monthly income to every adult in a group of villages, with payments planned to continue for twelve years. Meanwhile, governments could test many of the same ideas, at a fraction of the cost, by guaranteeing a minimum income to those who need it most.