IELTS Academic Reading Test 12

Dyes and fabric dyeing

Putting color into clothes

When primitive people began using their hands to be creative, they began to add color to their lives. They used natural materials like ochre to stain animal hides, decorate shells and feathers, and paint on the walls of caves. Ochre is a naturally occurring brownish yellow earth containing iron oxide. Scientists have been able to date the black, white, yellow and reddish pigments made from ochre, used in cave paintings, to over 15,000 BCE. With the development of fixed settlements and agriculture, around 7,000 to 2,000 BCE, people began to produce fabrics, and used natural substances such as ochre to color them.

Natural dyes, or dyes made from substances found in nature, can be broken down into two categories: substantive and adjective. Substantive, or direct dyes, become fixed to fibers to without the aid of any other chemicals or additives. Adjective dyes require a mordant (usually a metal salt) which acts as a fixative and prevents the color from washing out or being bleached by sunlight. Most natural dyes are adjective dyes, and require the application of a mordant solution to the fibers at some point in the dyeing process.

Historically, three natural fibers were used in making fabrics: wool, silk and cotton. Wool fabric remains have been found in Europe dating back to 2,000 BCE. It was a common medieval fabric worn in both dyed and natural colors and was processed by both professional manufacturers and by people in their own homes. Silk was imported from China to Europe, and in the 14th to 16th centuries major silk manufacturing centers were set up in France, Spain and Italy. These silk production centers also became centers of dye technology, as most silk was dyed and required the highest quality dyes available. Cotton was considered a luxury fabric in Europe, as it was imported all the way from India and was dyed before it was shipped. Cotton was also valued because of the brightness and colorfastness of the dyes used to color it.

Dyes that gave fabrics a good bright color and were able to withstand washing and exposure to sunlight without losing their color were highly prized. The names of some of these valued and traded colors are still familiar today. The color known as Tyrian purple, for example, originated in the Mediterranean 2,000 years ago, and cochineal is the name given to the red dye from Latin America. Both of these colors came from animals; the mucus found in certain species of shellfish produced the deep rich Tyrian purple and cochineal was extracted from insects. Two other natural sources of color were saffron and indigo. Saffron, the base of yellow dyes, comes from the flowers of a particular kind of crocus which is thought to have first been cultivated on Crete in the eastern Mediterranean. The leaves of a plant native to India were used to produce indigo, which was the main source of the color blue.

As societies developed over the centuries the demand for dyes and dyed fabric grew, and by the 17th century a world-wide shipping and trading network was in place, allowing dyestuffs from all parts of the world to be brought to Europe. This meant that numerous dyestuffs could be blended to create a variety of colors for the rich and powerful. Fiber dyeing in the lower classes was a bit more restrictive. Without the money to buy exotic imported dyes, clothing in the countryside tended to be black, brown, grey and tan. Country people had some resources they could use to get a wider range of colors. They had always used local plants as food, and many of these plants were also used as medicines and in some cases as sources of dyes. Home dyers used any plants they could find that would give a good color. People who picked blackberries to make jam soon recognized this wild fruit as a source for a blue dye. Washing beehives in preparation for making mead (a popular drink containing honey) yielded a liquid that could be used as a yellow dye. The mosses which grow in many parts of Europe were used to produce green dye.

With the tremendous rise of interest in chemistry in the mid-19th century, several important innovations in dyeing came about. WH Perkin, a student of celebrated European scientist Wilhelm von Hofmann, accidentally discovered the first synthetic dye, later called mauve. The color was so popular that Perkin was able to open a factory of his own and went on to develop more synthetic dye colors. Synthetic dye production grew in Europe, and hardly a year passed until the end of the century without a new synthetic dye being patented.

Eventually, the old natural dyes lost popularity in favor of the newer synthetic ones and now the use of natural dyes on a commercial scale only exists in a few remote areas where people have either little access to synthetic dyes or a vested interest in retaining their ancient dyeing customs.

Questions 1–8

• Ochre was used in paintings before it was used in fabric dyes.
• Natural dyes that need a mordant are rare.
• In medieval times people sometimes wore fabric made of undyed wool.
• Silk has always been more expensive than cotton and wool.
• Cotton imported from India was dyed upon arrival in Europe.
• Perkin became more famous than his teacher, von Hofmann.
• Very few synthetic dyes were produced in Europe in the second half of the 19th century.
• Today the commercial production of natural dyes is limited to a small number of isolated communities.

Questions 9–13

• Highly valued dyes Tyrian purple - mucus from ___ found in the Mediterranean cochineal (a red dye) - made from found in Latin America 17th century Europe dyes made by country people: had two uses - jam - blue dye liquid from cleaning had two uses - making mead - yellow dye 19th century Europe progress in study of led to synthetic dyes

A mechanical friend for children

A The development of robots that interact socially with people and assist them in everyday life has been an elusive goal of modern science. Despite impressive advances in the mechanical aspects of this problem, producing robots that bond and socialize with people for sustained periods of time has proven difficult. The most successful robots so far have been storytellers, but they have only been able to maintain human interest for a limited time and typically rely on the robot telling stories that change over time. In practice, commercially available robots seldom cross the 10-hour barrier (i.e. individual users tend to spend less than a combined total of 10 hours with the robots before losing interest). This observation is in sharp contrast to the long-term interactions and bonding that commonly develop between humans and their pets.

B In a recent study, researchers from the Institute for Neural Computation in California introduced a state-of-the-art social robot into a classroom of 18- to 24-month-olds for five months as a way of studying human/robot interactions. The researchers, including Fumihide Tanaka and Javier R Movellan, introduced a toddler-sized humanoid robot into a classroom at a childhood education center. One of the QRIO series of robots, the 58cm machine, was originally developed by Sony. ‘Children of toddler age were chosen because they have no preconceived notions of robots, according to Tanaka. One of the goals of the study was to establish whether it was possible for social robots to maintain the interest of children beyond the 10-hour barrier.

C The researchers sent instructions to the robot about every two minutes to do things like giggle, dance, sit down, fall down or walk in a certain direction. The 45 sessions were videotaped, and interactions between toddlers and the robot were later analyzed. The results showed that the quality of those interactions improved steadily over 27 sessions. The interactions deteriorated quickly over the next 15 sessions, when the robot was ordered to behave in a more limited, predictable manner. Finally, the human/robot relations improved in the last three sessions, after the robot had been instructed to display its full range of behaviors.

D ‘Initially the children treated the robot very differently from the way they treated each other,’ Tanaka said. ‘Early in the study some children cried when QRIO fell. But a month into the study, the toddlers helped QRIO stand up by pushing its back or pulling its hands.’ The most important aspect of interaction was touch, Tanaka said. At first the toddlers would touch the robot on its face, but later on they would touch it only on its hands and arms, like they would with other humans. Another robot-like toy named Robby, which resembled QRIO but did not move, was used as a control in the study. While hugging of QRIO increased, hugging of Robby decreased throughout the study. Furthermore, when QRIO laid down on the floor as its batteries ran down, a toddler would put a blanket over his silver-colored ‘friend’ and say ‘night-night’. Care-taking behaviors were frequently observed toward QRIO but seldom toward Robby.

E The study concluded that after 45 days of immersion in a childcare center over a period of five months, long-term bonding and socialization occurred between toddlers and a state-of-the-art social robot. Overall, the interaction between children and the robot improved over time and the children progressively treated it more as a peer than a plaything. ‘To my knowledge, this is the first long-term study of this sort,’ said Ronald Arkin, a roboticist at the Georgia Institute of Technology in the US.

F Tanaka and Movellan are now developing autonomous robots for the toddler classroom. ‘It could have great potential in educational settings assisting teachers and enriching the classroom environment,’ Tanaka said. The researchers hope that more advanced versions of robots like QRIO could become personalized tutors to assist teachers in classrooms. A robotic tutor could react on the spot to social cues and approximate social skills like facial expression and eye gaze, they said. ‘It is becoming clear that, to achieve this goal, we are going to [need to] endow machines with something similar to emotion, not just traditional forms of intelligence,’ said Movellan.

G Associate professor David Powers, an expert in artificial intelligence and cognitive science at Flinders University in South Australia, commented, ‘In this study it is clearly demonstrated that a limited range of robot behaviors, however impressive, is nowhere near as important to human/robot interaction as being able to make appropriate responses from a broad repertoire of behaviors. Ronald Arkin was not surprised by the affection demonstrated by the toddlers toward the robot. ‘Humans have a tremendous propensity to bond with artifacts, whether it be a car, a doll, or a robot,’ he said. But he also cautioned that researchers do not yet understand the consequences of increased human/robot interaction. ‘Studying how robots and humans work together can give us insight into whether this is a good thing or a bad thing for society,’ Arkin said. "We need to find out what the consequences are of introducing a robot into a cadre of children. How will that enhance, or potentially interfere with, their social development? Do we really understand the long-term impact of having a robot as a childhood friend?"

Questions 14–18

• a comparison of children’s reactions towards different robots
• a speculation about ways robots may be able to communicate
• a description of changes in the way the children physically handled a robot
• a comparison between people’s connections with animals and their connections with robots
• an account of the way one robot was programmed

Questions 19–23

• In future, robots will not only have to think, but also to show feelings.
• It is uncertain whether more contact between people and robots will be beneficial.
• Very young children have not yet developed ideas about robots.
• Robots need to perform a wide variety of actions for people to relate to them.
• Using robots as an aid in schools may have many benefits.

Questions 24–26

• Until recently, robots that were best at holding people’s attention were those that acted as ___
• The children responded to the QRIO robot as a friend or a ___, rather than as a toy.
• Arkin expected that the children would show ___ towards the QRIO robot.

Animals predicting earthquakes?

Surely it is too much to believe that animals can predict earthquakes when we haven’t worked out how to do it ourselves?

On 26 December 2004, villagers from Bang Koey in Thailand noticed buffalo on the beach lift their heads, look out to sea, then stampede to the top of a nearby hill. Minutes later, the tsunami struck. Could these creatures have been sensing early warning signs of the earthquake that triggered the Asian tsunami? It is a strange assertion but the possibility that animals might hold the answer cannot be ignored, as a warning system could save many lives.

The idea that animals can predict earthquakes has ancient origins. From 373 BC there are stories of rats, dogs and snakes deserting the Greek city of Helice before an earthquake hit. It was the first in a long line of such anecdotes. What has been lacking is any real scientific data linking animal behaviour with earthquakes.

In late 2000, however, Stanley Coren from the University of British Columbia started a study to discover whether dogs suffer from ‘seasonal affective disorder.’ Twice weekly, he emailed 200 dog owners in Vancouver, asking them to rate their pets’ activity and anxiety levels using a nine-point scale. In general there was little daily variability; Coren’s initial analysis of many months’ worth of information strongly refuted his suspicion that dogs become depressed during winter, and he abandoned the project. When he finally went through the figures in detail several years later however, he noticed that on 27 February 2001, nearly 50 per cent were well above their usual baseline for activity and anxiety. The likelihood of such a difference was remote and Coren searched through the newspaper archives for a cause. He found that on 28 February a quake of magnitude 6.8 shook the Pacific north-west, with an epicentre at Nisqually about 240 kilometres south of Vancouver. Coren wondered what the dogs could have sensed. There was little to guide him.

Even the most comprehensive earthquake research project in the world, the Parkfield experiment in California, couldn’t help. Since 1985, researchers from the US Geological Survey (USGS) have monitored a section of the San Andreas fault near the town of Parkfield. They have analysed every tremor, and measured tiny movements of the fault at 10-minute intervals, but to date the project has revealed nothing that would reliably indicate that an earthquake is imminent.

There is still much speculation about animals predicting earthquakes. For example, one idea is that some animals detect changes in the Earth’s electrical field. Another theory is that animals are responding to gas such as radon released from rocks before a quake, despite the fact that few experts accept such gas is produced. Rupert Sheldrake, a British researcher, suggests that ‘people notice unusual animal behaviour before disasters. I think animals are picking up on something that we can’t, perhaps by using a sixth sense.’

Coren, however, had read about rescue dogs hearing avalanche victims under the snow, and suspected the dogs in his study might also be hearing vibrations. So he returned to his data to search for supporting evidence. He discovered that only one of the 14 hearing-impaired dogs in his study had shown any significant increase in anxiety on 27 February, and it was living with a hearing dog that had become anxious. Dogs with floppy ears showed only half the change in activity and one-third the change in anxiety level of dogs with pricked ears. Not only would an ear flap reduce the amount of sound reaching the inner ear; Coren also realised that it would weaken high frequency sounds more than low frequency ones. Further, dogs with smaller heads were significantly more likely to behave strangely than those with larger heads, which was interesting, given that smaller-headed dogs are more sensitive to higher frequencies.

Taken together, Coren’s results present an alluring hypothesis. He suggests that the kind of high frequency sounds that many dogs can hear are emitted before an earthquake, perhaps from rocks scraping underground. Admittedly this is only one study. Even if Coren is right, is it still possible that other animals could predict quakes in different ways? Eric Wikramanayake, a conservation scientist who used radio collars and happened to be studying elephants in Sri Lanka when the tsunami struck, is entirely sceptical. What he found was precisely nothing. One herd was only 100 metres away from the beach when the tsunami arrived and they just took cover behind a large sand dune when the wave came in sight. The other herd was safely located about 5 kilometres inland and did not show any unusual movements.

Even if some quakes are preceded by high-frequency vibrations, is it feasible that dogs in Vancouver could detect sounds emitted near Nisqually? USGS seismologist Andy Michael points out that the epicentre was over 240 kilometres south of Vancouver. ‘It is physically implausible for seismic waves in the kilohertz range to travel that far,’ he says. Although unconvinced by Coren’s ideas, Michael adds a cautionary tale. ‘When Alfred Wegener presented his theory of continental drift, his core ideas about tectonics were right but nobody listened because the mechanisms were wrong.’

So if animals are able to foretell earthquakes, does it matter how? In fact, while western society has been reluctant to use animals as earthquake predictors, China has already embraced the idea. Experts there use a video link to keep a 24-hour watch on snakes in farms nationwide. If they try to escape from their enclosure, observers raise a warning.

Other governments may not be willing to go that far just yet, but Coren believes that a centre that people could call when they see unusual things would be useful. ‘We would be able to collect much more data and give warnings when we get hundreds of calls from a single area,’ he says. It could cost little more than the price of setting up a phone line. Put that way, what have we got to lose?

* tsunami: large, destructive wave caused by earthquakes

** seasonal affective disorder, emotional and psychological changes created by changes in the amount of daylight in winter

Questions 27–30

• There is historical scientific evidence to support stories of animals predicting earthquakes.
• Coren’s decision to investigate the possibility that dogs can anticipate an earthquake was based on some archive information.
• Dogs may be more sensitive to changes in the Earth’s electrical field than other animals.
• Coren’s findings from his original study of dogs clearly prove they can hear high frequencies which signal earthquakes.

Questions 31–35

• What is the writer’s main point in paragraph 4?
• When Coren re-analysed his data for 27 February he found that on that day
• Seismologist Andy Michael refers to Alfred Wegener in order to
• What is the writer doing in the penultimate paragraph?
• What point is the writer making by using the phrase ‘what have we got to lose’ in the final paragraph?

Questions 36–40

• The belief in the ability of animals to predict earthquakes
• Experts think it is unlikely that gas
• Sheldrake says that an animal’s ability to predict disasters
• Coren speculated that a dog’s ability to predict earthquakes
• The behaviour of the elephant herds in Wikramanayake’s study