Adaptation: The Key to Survival
from Open Content Curriculum
1.
A traveler who gets off a plane at La Paz, Bolivia, is going to have a worrying
experience: breathing the rarefied air of this highest big city in the world. Although his
first few breaths may leave him cheerful, talkative and happily giddy, the pleasant
feeling does not last. Suddenly he may become nauseated and develop a violent
headache and a strange inability to climb even a few stairs. If he reacts as some people
do, he will soon move with difficulty, and his feet will turn icy. He may become irritable
and even irrational, and his mood may swing from one extreme to another. Whatever
his symptoms may be— and they are usually unpleasant — their only cure is time: it
may take several weeks for his body to adapt to the high altitude.
2.
La Paz is 11,900 feet above sea level; at this height, the air is so thin that people
from lowland areas inhale only half as much oxygen as they normally do at lower
elevations. Since they are not breathing more quickly, their tissues feel the need of
oxygen. In addition, because the brain is very sensitive to oxygen deficiency, symptoms
of mental confusion are among the first reactions to appear. Fortunately, the visitor
finally gets used to the new environment : he begins to breathe more deeply and his
body begins to increase its production of red cells so that there are more of them to pick
up the oxygen that is available. At this point, he is able to function almost normally,
though his mental and emotional processes are still a little disturbed.
3.
People who were born and raised at high altitudes suffer no such difficulties. The
Indians of Morococha, a Peruvian mining town - 14,900 feet up in the Andes - regularly
put in long, hard days of physical labor in the mines, and in their spare time play a great
deal of soccer. Comparative studies showed they could run much longer on a treadmill
in their sky-high town than could a group of Peruvian sailors who were tested in the
nation's capital, Lima, at sea level. The Indians ran an average of 59 minutes before,
feeling exhausted while the sailors could run for only 34 minutes.
4.
This impressive difference must be related to the mechanisms of physiological
adaptation that the Indians have developed: they have a larger number of red blood
cells to carry oxygen to the tissue, and they breathe more quickly and more deeply. As
a result, 20 percent more air reaches their lungs than in the case of those people who
live at sea level.
5.
It is clear from these examples that every man is a creature of his environment,
and his physical responses are powerfully influenced by the world he lives in. When he
shifts to a new environment, his body makes a violent effort to adapt to it. In this
respect, a child born at high altitudes and a visitor who has lived in a lower area face the
same problem. Yet, natural selection must also play a role: it encourages the
reproduction of people well fitted genetically to adapt to high altitudes. People born at
low altitudes have smaller rib cages than the Andean Indians. In addition, it has been
frequently noted that people from the lowlands become much less fertile when they
move to high altitudes, while native Indians reproduce normally.
6.
One of the most interesting kinds of genetic adaptations is body shape. In hot, dry
climates there is a big number of tall, thin people, whose body shape doesn’t keep heat
In cold areas, on the other hand, people may tend towards a rounder shape, which
conserves heat.
7.
Skin color provides another example of genetic adaptation. In areas with strong
sunshine and clear skies, dark-skinned people have an advantage: dark pigment helps
to filter out some of the more harmful solar rays. People who live in forests need less
protection from the sun. They have lighter skins. And the lightest skins of all may be
found among people who live in cool and cloudy climates of Northern Europe.
8.
While genetic adaptation becomes obvious after many generations, physiological
adaptation develops quite soon after the individual is exposed to a new environment.
Fishermen, whose hands are frequently exposed to cold water, develop better blood
circulation in their hands. As a result, their local resistance to low temperatures is
greater
9.
A more common example of short-term adaptation has been experienced by most
of the people living in Northern Europe. In midwinter the temperature of 12 degrees
centigrade feels quite warm if it comes immediately after freezing days. In summer,
though it seems very cold. In conclusion, all organisms need to adapt in order to
survive.
Adaptation: The Key to Survival
I. Comprehension questions
1. Why is the experience of “breathing the rarefied air of the largest city in
the world” (L 2) worrying for a traveler?
Complete the following sentence.
First he may feel _____________________________________.
Soon after that, however, he will _________________________
___________________________________________________.
2. Paragraphs 1 – 2
Put a check (V) next to the FOUR symptoms of pre-adaptation to the high
altitude.
-- very strong headaches
-- perfect brain functioning
-- being in a chatting mood
-- pleasant emotions
-- hardly going upstairs
-- extreme changes in the mood
-- not thinking clearly
3. Since the brain is sensitive to the lack of oxygen, symptoms of mental
disorder may appear during the first days in La Paz.
True / False
Support your answer by quoting from the text.
_______________________________________________________
4. Paragraph 3 reports the results of “comparative studies” (L4).
Fill in the missing parts of the chart below.
Country
1.Peru
City
Professional Physical
Duration of
(Town)
Occupation
Activity
Its
of the
Altitude
Participants
Activity
Morococha
running a
14.900 feet
treadmill
2.
sailors
34 minutes
5. Why do Indian miners breathe 20 percent more air?
General reason, NOT specific
Because of their ________________________ (TWO WORDS)
6. Paragraph 5
a. Which “same problem” (L5) does the author refer to?
___________________________________________________
b. Why is natural selection important in physiological adaptation?
____________________________________________________
c. How does moving to highlands affect fertilization?
Circle the correct word in the following sentences.
The reproduction of people born in highlands is normal / lower as
compared to people from lowlands with normal / low reproduction
after moving to high altitudes.
7. Paragraphs 6 and 7 discuss the possible ______________ (ONE WORD)
of genetic adaptation.
8. What causes fishermen’s greater local resistance to low temperatures?
They___________________________________________________
(NO MORE THAN SIX WORDS)
9. What is the main purpose of the article?
a. to give examples of long and short-term adaptations.
b. to describe highland and lowland areas across the globe..
c. to stress the importance of physiological and genetic adjustment.
d to compare between physiological and genetic adaptations
II.
Vocabulary
Study the following words as they appear in each paragraph:
Paragraph 1
Paragraph 5
Inability
creature
Irritable
shift
Irrational
violent
Paragraph 2
face
deficiency
fit
confusion
Paragraph 6
available
tend
Paragraph 3
Paragraph 8
raise
obvious
exhausted
individual
a great deal
expose
Paragraph 4
resistance
impressive
Paragraph 9
survive
Exercise 1
Match the words in Column A with their synonyms or definitions in Column B
Column A
Column B
1. deficiency
a. bring up
2. raise
b. person
3. individual
d. evident
4. exhausted
e. open
5. obvious
h. lack of something
6. expose
g. extremely tired
Exercise 2
Match the words in Column A with their antonyms in Column B
Column A
Column B
1. irrational
a ability to be unaffected
by something
2. resistance
b. a little
3. shift
c. capacity
4. inability
d reasonable, logical
5. great deal
e leave in the same position
Exercise 3
Fill in the blanks in the following sentences with the words from the word bank.
face survive violent available tend irritable
1. The hall is _____________________ on Saturday night.
2. Plants ________________ to die in hot weather.
3. She was in an ____________________________ mood.
4. He didn't _____________________ long after the accident.
5. I'm sure, he is responsible enough to __________________ the reality.
6. There was a _____________________sea storm.