Table of Contents
Passage
Many animals seem able to treat their illnesses themselves. Humans way have a thing or two to learn from them.
A For the past decade Dr Engel, a lecturer m environmental sciences at Britain’s Open University, has been collating examples of self-medicating behavior in wild animals. She recently published a book on the subject. In a talk at the Edinburgh Science Festival earlier this month, she explained that the idea that animals can treat themselves has been regarded with some skepticism by her colleagues in the past. But a growing number of animal behaviourists now think that wild animals can and do deal with their own medical needs.
B One example of self-medication was discovered in 1987. Michael Huffman and Mohamedi Seifu, working in the Mahale Mountains National Park in Tanzania, noticed that local chimpanzees suffering from intestinal worms would dose themselves with the pith of a plant called Veronia. This plant produces poisonous chemicals called terpenes. Its pith contains a strong enough concentration to kill gut parasites, but not so strong as to kill chimps (nor people, for that matter; locals use the pith for the same purpose). Given that the plant is known locally as “goat-killer”, however, it seems that not all animals are as smart as chimps and humans. Some consume it indiscriminately, and succumb.
C Since the Veronia-eating chimps were discovered, more evidence has emerged suggesting that animals often eat things for medical rather than nutritional reasons. Many species, for example, consume dirt-a behaviour known as geophagy ( 食土癖 ). Historically, the preferred explanation was that soil supplies minerals such as salt. But geophagy occurs in areas where the earth is not a useful source of minerals, and also in places where minerals can be more easily obtained from certain plants that are known to be rich in them. Clearly, the animals must be getting something else out of eating earth.
D The current belief is that soil-and particularly the clay in it-helps to detoxify the defensive poisons that some plants produce in an attempt to prevent themselves from being eaten. Evidence for the detoxifying nature of clay came in 1999, from an experiment carried out on macaws by James Gilardi and his colleagues at the University of California, Davis. Macaws eat seeds containing alkaloids, a group of chemicals that has some notoriously toxic members, such as strychnine. In the wild, the birds are frequently seen perched on eroding riverbanks eating clay. Dr Gilardi fed one group of macaws a mixture of a harmless alkaloid and clay, and a second group just the alkaloid. Several hours later, the macaws that had eaten the clay had 60% less alkaloid in their bloodstreams than those that had not, suggesting that the hypothesis is correct.
E Other observations also support the idea that clay is detoxifying. Towards the tropics the amount of toxic compounds in plants increases-and so does the amount of earth eaten by herbivores. Elephants lick clay from mud holes all year round, except in September when they are bingeing on fruit which, because it has evolved to be eaten, is not toxic. And the addition of clay to the diets of domestic cattle increases the amount of nutrients that they can absorb from their food by 10-20%.
F A third instance of animal self-medication is the use of mechanical scours to get rid of gut parasites. In 1972 Richard Wrangham, a researcher at the Gombe Stream Reserve in Tanzania, noticed that chimpanzees were eating the leaves of a tree called Aspilia. The chimps chose the leaves carefully by testing them in their mouths. Having chosen a leaf, a chimp would fold it into a fan and swallow it. Some of the chimps were noticed wrinkling their noses as they swallowed these leaves, suggesting the experience was unpleasant. Later, undigested leaves were found on the forest floor.
G Dr Wrangham rightly guessed that the leaves had a medicinal purposethis was, indeed, one of the earliest interpretations of a behaviour pattern as self-medication. However, he guessed wrong about what the mechanism was. His (and everybody else’s) assumption was that Aspilia contained a drug, and this sparked more than two decades of phytochemical research to try to find out what chemical the chimps were after. But by the 1990s, chimps across Africa had been seen swallowing the leaves of 19 different species that seemed to have few suitable chemicals in common. The drug hypothesis was looking more and more dubious.
H It was Dr Huffman who got to the bottom of the problem. He did so by watching what came out of the chimps, rather than concentrating on what went in. He found that the egested leaves were full of intestinal worms. The factor common to all 19 species of leaves swallowed by the chimps was that they were covered with microscopic hooks. These caught the worms and dragged them from their lodgings.
I Following that observation, Dr Engel is now particularly excited about how knowledge of the way that animals look after themselves could be used to improve the health of livestock. People might also be able to learn a thing or two-and may, indeed, already have done so. Geophagy, for example, is a common behaviour in many parts of the world. The medical stalls in African markets frequently sell tablets made of different sorts of clays, appropriate to different medical conditions.
J Africans brought to the Americas as slaves continued this tradition, which gave their owners one more excuse to affect to despise them. Yet, as Dr Engel points out, Rwandan mountain gorillas eat a type of clay rather similar to kaolinitethe main ingredient of many patent medicines sold over the counter in the West for digestive complaints. Dirt can sometimes be good for you, and to be “as sick as a parrot” may, after all, be a state to be desired.
Questions
Question 1-4 Do the following statements agree with the information given in Reading Passage? In boxes 1-4 on your answer sheet, write
TRUE if the sataement agrees with the information
FALSE if the statement contradicts the information
NOT GIVEN if there is no information on this
1 It is for 10 years that Dr Engel has been working on animal self-medication.
2 In order to find plants for medication, animals usually need to walk a long distance.
3 Birds such as Macaw, are seen eating clay because it is a part of their natural diet.
4 According to Dr Engel., it is exciting that research into animal self-medication can be helpful in the invention of new painkillers.
Question 5-9 Complete the notes below using NO MORE THAN ONE WORD from the passage. Write your answers in boxes 5-9 on your answer sheet
Questions 10-13 Complete the summary below using words from the box. Write your answers, A-H, in boxes 10-13 on your answer sheet.
A mineral
B plants
C unpleasant
D toxic
E clay tablets
F nutritional
G geophagy
H harmless
Animal self-medication has been supported by an increasing amount of evidences. One of them is called 10 …………………. , a soil-consuming behavior commonly found across animals species. Because earth, especially clay, can neutralize the 11 …………………. content of their diet. Similar behavior can also be found among humans in Africa, where patients will buy 12 …………………. at medical stalls to heal them. Another one is related to chimps who eat leaves with 13 …………………. taste probably, but with medicinal value due to their special structure.
Answers
Below are the answers, key words, synonyms and full explanations for the IELTS Reading passage Health in the Wild (Passage 1, Questions 1–13).
Questions 1–4: True / False / Not Given
1. It is for 10 years that Dr Engel has been working on animal self-medication.
Answer: TRUE
Key words: For the past decade Dr Engel … has been collating examples of self-medicating behaviour
Synonyms: 10 years = the past decade = “For the past decade Dr Engel … has been collating examples of self-medicating behaviour in wild animals”
Explanation: Paragraph A: a decade equals ten years of work → TRUE.
2. In order to find plants for medication, animals usually need to walk a long distance.
Answer: NOT GIVEN
Key words: no mention of walking long distances
Synonyms: The passage describes what animals eat, but says nothing about how far they travel to find it.
Explanation: There is no information about animals walking long distances → NOT GIVEN.
3. Birds such as macaws are seen eating clay because it is a part of their natural diet.
Answer: FALSE
Key words: the birds are frequently seen … eating clay … the macaws that had eaten the clay had 60% less alkaloid
Synonyms: not natural diet but detoxification = “soil … helps to detoxify the defensive poisons … macaws that had eaten the clay had 60% less alkaloid in their bloodstreams”
Explanation: Paragraph D: macaws eat clay to detoxify poisons, not as ordinary food → FALSE.
4. According to Dr Engel, it is exciting that research into animal self-medication can be helpful in the invention of new painkillers.
Answer: FALSE
Key words: excited about how knowledge … could be used to improve the health of livestock
Synonyms: not painkillers but livestock health = “Dr Engel is now particularly excited about how knowledge of the way that animals look after themselves could be used to improve the health of livestock”
Explanation: Paragraph I: she is excited about improving livestock health, not inventing painkillers → FALSE.
Questions 5–9: Note Completion (NO MORE THAN ONE WORD)
5. (1987, Huffman & Seifu, Chimpanzee) — Food: the ______ of Veronia.
Answer: pith
Key words: would dose themselves with the pith of a plant called Veronia
Synonyms: = “chimpanzees suffering from intestinal worms would dose themselves with the pith of a plant called Veronia”
Explanation: Paragraph B: the chimps ate the pith of Veronia → pith.
6. Mechanism: it contained chemicals named ______ which can kill parasites.
Answer: terpenes
Key words: This plant produces poisonous chemicals called terpenes … strong enough … to kill gut parasites
Synonyms: = “This plant produces poisonous chemicals called terpenes. Its pith contains a strong enough concentration to kill gut parasites”
Explanation: Paragraph B: terpenes kill the gut parasites → terpenes.
7. (1999, Gilardi, Macaw) — Food: seeds containing ______ and clay.
Answer: alkaloids
Key words: Macaws eat seeds containing alkaloids
Synonyms: = “Macaws eat seeds containing alkaloids, a group of chemicals that has some notoriously toxic members, such as strychnine”
Explanation: Paragraph D: the seeds contain alkaloids → alkaloids.
8. Mechanism: clay can ______ the poisonous contents in the food.
Answer: detoxify
Key words: clay in it—helps to detoxify the defensive poisons
Synonyms: = “soil—and particularly the clay in it—helps to detoxify the defensive poisons that some plants produce”
Explanation: Paragraph D: the clay detoxifies the poisons → detoxify.
9. (1972, Wrangham, Chimpanzee) — Food: leaves with tiny ______ on the surface.
Answer: hooks
Key words: covered with microscopic hooks. These caught the worms
Synonyms: tiny = microscopic = “The factor common to all 19 species of leaves … was that they were covered with microscopic hooks. These caught the worms and dragged them”
Explanation: Paragraph H: the leaves have tiny hooks that snag the worms → hooks.
Questions 10–13: Summary from a Box (A–H)
A mineral · B plants · C unpleasant · D toxic · E clay tablets · F nutritional · G geophagy · H harmless
10. One piece of evidence deals with ______, a soil-consuming behaviour found across animal species.
Answer: G (geophagy)
Key words: consume dirt—a behaviour known as geophagy
Synonyms: soil-consuming behaviour = geophagy = “Many species … consume dirt—a behaviour known as geophagy”
Explanation: Paragraph C: eating soil is called geophagy → G.
11. Because the earth, often clay, can neutralize the ______ content of their diet.
Answer: D (toxic)
Key words: clay … helps to detoxify the defensive poisons
Synonyms: neutralize = detoxify; content = poisons = “the clay in it—helps to detoxify the defensive poisons that some plants produce”
Explanation: Paragraph D: clay neutralizes the toxic (poisonous) part of the diet → D.
12. Humans in Africa purchase ______ at market stalls as medication.
Answer: E (clay tablets)
Key words: medical stalls in African markets frequently sell tablets made of different sorts of clays
Synonyms: = “The medical stalls in African markets frequently sell tablets made of different sorts of clays, appropriate to different medical conditions”
Explanation: Paragraph I: people buy clay tablets at market stalls → E.
13. Chimps eat leaves with an often ______ taste but with hidden medicinal value.
Answer: C (unpleasant)
Key words: wrinkling their noses as they swallowed these leaves, suggesting the experience was unpleasant
Synonyms: = “Some of the chimps were noticed wrinkling their noses as they swallowed these leaves, suggesting the experience was unpleasant”
Explanation: Paragraph F: the leaves taste unpleasant but work mechanically → C.
Answer Key (Quick Reference)
| Q | Answer | Q | Answer |
|---|---|---|---|
| 1 | TRUE | 8 | detoxify |
| 2 | NOT GIVEN | 9 | hooks |
| 3 | FALSE | 10 | G |
| 4 | FALSE | 11 | D |
| 5 | pith | 12 | E |
| 6 | terpenes | 13 | C |
| 7 | alkaloids |
