🎯 Master IELTS with Real Computer-Based Practice!
Prepare smarter with ieltsonestopcbt.com — India’s most trusted platform for IELTS Computer-Based Tests.
✅ Practice Reading and Listening in real exam format
✅ Instant results with detailed feedback
✅ Authentic test interface just like the official CBT exam
🚀 Start your free practice now at ieltsonestopcbt.com and experience the real IELTS test environment before your exam day!
Reading Practice
Health in
the Wild
A
For the past decade Dr Engel, a
lecturer in environmental sciences at Britain’s Open University, has been
collating examples of self-medicating behaviour 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 scepticism 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. 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 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 purpose—this 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 kaolinite – the 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 1-4
Do the following statements agree
with the information given in Reading Passage 1?
In
boxes 1-4 on your answer sheet,
write
TRUE if the
statement is true
FALSE if the
statement is false
NOT GIVEN if the
information is not given in the passage
1..................... It is for 10 years that Dr Engel has been
working on animal selfmedication.
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 selfmedication can be helpful in the invention of new
painkillers.
Questions 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.
|
Date |
Name |
Animal |
Food Mechanism |
|
1987 |
Michael Huffman and Mohamedi Seifu |
Chimpanzee |
Contained chemicals 5.....................
o named 6..................... f Veronia which can kill parasites |
|
1999 |
James Gilardi and his colleagues |
Macaw |
Clay Seeds can 8..................... the (contain 7........... poisonous contents in ..........) and clay food |
|
1972 |
Richard WranghamChimpanzee |
Leaves with Such
leaves can catch tiny 9..................
and expel worms from ... on surface intestines |
|
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.
Though often doubted, the self-medicating behaviour of
animals has been supported by an increasing amount of evidence. One piece of
evidence particularly deals
with 10.....................,
a soil-consuming behaviour commonly found across animals species,
because the earth, often clay, can neutralize the 11..................... content of
their diet. Such
behaviour can also be found among humans in Africa, where
people
purchase 12..................... at market stalls as a kind of medication to
their illnesses. Another example of this is found in chimps eating leaves of
often 13..................... taste
but with no apparent medicinal value until its unique structure came into
light.
A mineral B plants C unpleasant
D toxic
E clay tablets F nutritional
G geophagy
H harmless
Solution:
|
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
Password: IELTSONESTOPCBT
No comments:
Post a Comment