IELTS Academic Reading Practice Test 2

Humans were collecting honey long before they kept bees. A rock painting in a cave near Valencia in Spain, thought to be around 8,000 years old, shows a figure climbing towards a wild nest with a basket, surrounded by bees. Honey hunting of this kind, which still survives in parts of Asia and Africa, was dangerous and usually destroyed the colony. Keeping bees in containers close to home was therefore a significant step: it offered a more reliable supply of honey and wax, and it allowed the same colony to be harvested year after year.

Some of the earliest evidence for this practice comes from Egypt. Carvings in a temple built around 4,400 years ago show a worker who appears to be blowing smoke into a stack of horizontal hives, while others remove honeycomb and store honey in sealed jars. Honey was valued in Egypt not only as a food but also as a medicine, and it was applied to wounds.

The Egyptians made their hives from mud or clay, a design that helped to keep the colony cool in the desert heat. In 2007, archaeologists working at Tel Rehov in northern Israel uncovered the remains of around thirty clay cylinder hives dating back roughly 3,000 years – the oldest beekeeping site yet discovered by excavation.

In northern Europe, where unfired clay was less suited to wet winters, beekeepers used hollow logs and, later, 'skeps' – dome-shaped baskets woven from straw. Skeps were cheap and easy to make, but they had a serious disadvantage. Because the bees attached their combs directly to the inside of the basket, the only way to reach the honey was to cut the combs out, and the colony was often killed in the process. Beekeepers then relied on swarms from their remaining hives to replace the bees they had lost.

The modern hive owes most to an American clergyman, Lorenzo Langstroth. In 1851, he observed that bees leave a gap of a particular width – slightly less than a centimetre – between their combs and the walls of the hive. If a space is narrower than this, the bees seal it with a resin-like substance called propolis; if it is wider, they fill it with comb. Langstroth realised that if wooden frames were hung inside a box with exactly this 'bee space' around them, the bees would build their combs inside the frames without attaching them to the walls.

The frames could then be lifted out, inspected and returned, and honey could be removed without destroying the colony. He patented his movable-frame hive in 1852, and versions of it are still used by most commercial beekeepers today. Langstroth's design also made other innovations possible. Because combs could now be removed intact, beekeepers began to use centrifugal extractors, introduced in the 1860s, which spin the frames so that the honey is thrown out while the wax comb is left undamaged and can be returned to the hive. Since bees must eat a considerable amount of honey in order to produce wax, reusing combs in this way allowed colonies to devote more of their energy to storing honey.

Scientific understanding of bees advanced as well. In the twentieth century, the Austrian biologist Karl von Frisch showed that honeybees communicate the location of food sources through a 'waggle dance', in which the angle of the dance indicates direction and its duration indicates distance. His research, which earned him a share of the Nobel Prize in 1973, helped to change the way people thought about communication in animals. Von Frisch also demonstrated that bees can see colours, although their range of vision differs from ours: they cannot see red, but they are sensitive to ultraviolet light, which reveals patterns on many flowers that are invisible to the human eye.

Today, beekeeping faces new pressures. The most serious is the varroa mite, a parasite that originally lived on the Asian honeybee but spread to the western honeybee during the twentieth century and is now found almost everywhere bees are kept. The mites feed on bees and spread viruses, and colonies that are not treated often die within a few years. Australia remained free of the mite for longer than any other major beekeeping country, although it was finally detected there in 2022. Pesticides, the loss of flowering plants and a changing climate add to the strain, and in some regions beekeepers regularly lose a large share of their colonies over the winter.

Despite these difficulties, interest in beekeeping has grown, particularly in cities, where rooftop hives have become a familiar sight. Some ecologists have warned, however, that too many managed hives in one area may compete with wild bees for limited food, and that protecting wild pollinators requires more than simply adding honeybees. Nor are honeybees valued only for their honey. They pollinate many crops, from almonds to apples, and in some countries beekeepers earn more by renting their hives to farmers during the flowering season than they do by selling honey.

Although around 70 per cent of the Earth's surface is covered by water, almost all of it is too salty to drink or to use for growing crops. Fresh water accounts for only about 2.5 per cent of the total, and much of that is locked in ice caps and glaciers. In some coastal areas, groundwater has been pumped out so heavily that seawater has begun to seep into underground supplies. As populations grow and droughts become more frequent, a growing number of countries are turning to desalination – the removal of salt from seawater or from salty groundwater – to secure their supplies. Large parts of the world already face severe shortages for at least part of each year, and climate change is expected to make rainfall less predictable in many regions.

The basic idea is ancient. Sailors in the classical world are said to have boiled seawater and collected the steam in sponges, and for centuries ships carried simple stills for emergencies. Large-scale desalination, however, only became practical in the twentieth century. The first major plants used thermal methods, heating seawater until it evaporated and then condensing the vapour as fresh water. Because this requires a great deal of energy, thermal desalination spread fastest in the oil-rich states of the Middle East, where fuel was cheap and fresh water was scarce. Countries such as Kuwait and Saudi Arabia became, and remain, among the world's largest producers of desalinated water. Many of their plants were built along the coasts of the Gulf in the second half of the century.

Today, most new plants use a different technology: reverse osmosis. In natural osmosis, water moves through a membrane from a weaker solution to a more concentrated one. Reverse osmosis forces this process to run backwards. Seawater is first drawn in from the sea through an intake pipe and passed through filters that remove sand, algae and other particles which could damage the equipment. It is then pumped at very high pressure against a semi-permeable membrane – a thin sheet that allows water molecules to pass through but holds back most of the dissolved salt. Minerals are then added to the fresh water that emerges, partly to improve its taste and partly to stop it from corroding pipes, before it enters the supply network. The salt left behind is discharged as a concentrated liquid known as brine. The membranes themselves are usually made from thin layers of plastic material and are packed into spiral-wound cylinders, so that a large surface area fits into a small space. They must be cleaned regularly, because a build-up of microorganisms and minerals – a problem known as fouling – reduces their performance.

Reverse osmosis is far more efficient than older thermal methods, and improvements such as devices that recover energy from the high-pressure brine have reduced its power consumption considerably since the 1970s. As membranes have improved, the cost of the process has also fallen steadily, and in some dry regions it is now competitive with alternatives such as transporting water over long distances. Nevertheless, desalinated water remains more expensive than water from rivers, lakes or underground sources in most places, and the energy it requires is often generated from fossil fuels. Critics argue that, in some regions, the money would be better spent on repairing leaking pipes or encouraging people to use less water. Because electricity accounts for a large part of the running costs of a plant, the price of desalinated water also tends to rise and fall with energy prices.

The brine itself is also a concern. For every litre of fresh water produced, a typical plant discharges more than a litre of brine, which is considerably saltier than seawater and may contain chemicals used to clean the membranes. Because it is denser than seawater, brine tends to sink and spread along the sea floor, where it can harm organisms that cannot tolerate high salt levels. Engineers try to reduce the damage by releasing brine through pipes fitted with diffusers, which mix it rapidly with the surrounding water. Plants can also harm marine life at the other end of the process: fish larvae and other small organisms may be drawn into intake pipes along with the seawater, and many modern plants use slow-moving intakes or fine screens to reduce this.

Some researchers see brine not as waste but as a resource. It contains magnesium, lithium and other valuable elements, and several projects are investigating ways of extracting them economically. Others are developing solar-powered systems for small communities far from electricity grids. Whether desalination becomes a sustainable solution, however, is likely to depend less on any single invention than on how carefully plants are planned, powered and regulated. In Israel, for example, desalination already supplies a large share of the water used in homes, showing what is possible when it is combined with efficient water management.

For much of the early twentieth century, bilingualism was regarded with suspicion. Some studies, often carried out with children from immigrant families who were tested in a language they had not fully mastered, concluded that growing up with two languages led to confusion and lower intelligence. These findings were later recognised to be deeply flawed, since they failed to take account of differences in social background and language ability.

A landmark Canadian study published in 1962 by Elizabeth Peal and Wallace Lambert, which compared bilingual and monolingual children from similar backgrounds, found that the bilingual children actually performed better on a range of tests. By then, however, concerns of this kind had already led some parents and teachers to discourage children from using their home language.

From the 1990s onwards, the idea that bilingualism might bring mental benefits attracted growing attention, much of it inspired by the work of the psychologist Ellen Bialystok at York University in Toronto. Her reasoning was straightforward. A bilingual person, she argued, has both languages active in the mind at all times, even when only one is being used, and so must constantly suppress the language that is not needed. This continual practice in controlling attention, the theory went, might strengthen what psychologists call executive function – the set of mental skills that allow us to plan, switch between tasks and ignore distractions.

Early experiments appeared to confirm this. In tasks that required participants to respond to one feature of an image while ignoring another – for example, pressing a button according to the colour of a shape rather than its position on a screen – bilingual children and adults were often faster than monolinguals. Even more striking was a study of hospital records published by Bialystok and her colleagues in 2007, which suggested that bilingual patients had developed the symptoms of dementia around four years later, on average, than monolingual patients. Such findings were widely reported in the media, and the 'bilingual advantage' became something close to accepted wisdom. Several later studies of dementia produced similar results, although others found no delay at all.

Over the following decade, however, doubts began to grow. Several research teams, including one led by the American psychologist Kenneth Paap, attempted to repeat the original experiments with larger groups of participants and found little or no difference between bilinguals and monolinguals. Paap argued that many of the earlier studies had involved small samples, and that apparent advantages might be explained by other factors, such as differences in education, income or immigrant experience, which are difficult to separate from bilingualism itself.

A further problem concerned which results reach the public at all. In 2015, a team led by Angela de Bruin examined studies on the bilingual advantage that had been presented at scientific conferences and then traced which of them were later published in journals. They found that studies reporting a clear advantage were much more likely to be published than those that found no effect or mixed results. If this was the case, the published research would give a misleadingly positive picture, even if each individual study had been carried out honestly.

The difficulty is not unique to this field. Psychology as a whole has been going through what is often called a 'replication crisis', in which a number of well-known findings have proved hard to reproduce when other researchers repeat the experiments. Many journals now encourage researchers to register their plans before collecting any data, so that a study is judged on the quality of its design rather than on whether its results are exciting.

Supporters of the advantage have responded in several ways. Some suggest that the benefits may depend on how bilingualism is experienced: someone who switches between languages many times a day may be affected differently from someone who learned a second language at school and rarely uses it. Others point out that standard laboratory tasks may be too simple to reveal differences in healthy young adults, whose executive function is already near its peak, and that effects might be more visible in children or older people. There is also some evidence that bilingual experience is associated with differences in brain structure, although what such differences mean for everyday thinking remains unclear.

The debate has become heated at times, but it has also had positive consequences. Researchers on both sides now pay closer attention to sample sizes, to the precise definition of 'bilingual', and to the need to publish negative results. What seems clear is that the strong claim – that learning a second language reliably makes people more intelligent – is not supported by the evidence. That does not, however, weaken the case for learning languages. The practical, social and cultural rewards of speaking more than one language are considerable, and they do not depend on whether bilinguals perform slightly better on a computer task in a psychology laboratory.