<TED Worksheet (Free)>
71.Why are some people left-handed?
Daniel M. Abrams
 
<4:52> February 2015

 

 

Questions
PDF)(Word

Answers
PDF)(Word

Trascript

<Key Vocabulary>
Write the meaning(s) of each word. Write an example sentence (example sentences) if you need.

(1) proper

(2) archeological

(3) evidence

(4) associated

(5) density

(6) artifacts

(7) fetus

(8) womb

(9) inborn

(10) genetic

(11) proportion

(12) millennia

(13) attempt

(14) competitive

(15) cooperative

(16) combat

(17) encounter

(18) hypothesis

(19) imbalance

(20) phenomenon

(21) persistence

(22) equilibrium

(23) simultaneously

(24) intriguing

 





<Questions> 

  1. Which of the following sentences is not true?
  1. In some countries, it is still common practice to force children to use their right hands.
  2. There is archeological evidence which shows that more than 20 % of the people in the world were left- handed 500,000 years ago.
  3. In some languages, the word for right also means correct or good.
  4. Today, about 10% of the world population is left-handed.

 

  1. Write “T” if the statement is true and “F” if the statement is false. 
  1. Handedness is not a choice.                       
  2. Handedness can be predicted before birth.                       
  3. Most of the time, identical twins have the same dominant hands.                       

 

  1. The chances of being right or left-handed are determined by the handedness of our parents. Fill in the blanks with the correct numbers.
  1. If your father was left-handed but your mother was right-handed
    → you have a                 % chance of being born left-handed.
  2. If your father was right-handed but your mother was right-handed
    → you have a                 % chance of being born left-handed.

 





 

  1. Why does handedness exist in the first place?
    Why are most people right-handed? Fill in the blanks.
    A recent mathematical model suggests that the actual ration reflects a balance between competitive and cooperative pressures on human (1)                         .

[Competitive]

Being left-handed has clear
advantages in activities
involving an (2)                         ,
like combat or competitive sports.
(e.g.) Baseball:
about (3)                 of top hitters
have been left-handed.

<Q: Why does this happen?>

  1. Because lefties are a (4)                        . (Competitors will spend most of their time encountering and practicing against righties.)

*This imbalance in the population results in an advantage for left-handed fighters or athletes. This is an example of (5)                                                                                                (4 words).

[Cooperation]

According to the principles of evolution, groups that have a relative advantage tend to grow until that advantage disappears.
→ But only 10% of the world population is left-handed today. Why?

  1. Because they cooperate with right-handed people.

(e.g.) <Golf>
Only (6)               % of top players are left-handed because it is easier to find a set of right-handed clubs than a set of left-handed clubs.

<Important instruments that have shaped society>
Lefties are worse at (7)                    these tools, and suffer from higher (8)                      rates.

*Left-handed people are less likely to be (9)                          in a purely cooperative world.

 





<Answers>

  1. Which of the following sentences is not true?
  1. In some countries, it is still common practice to force children to use their right hands.
  2. There is archeological evidence which shows that more than 20 % of the people in the world were left- handed 500,000 years ago.
  3. In some languages, the word for right also means correct or good.
  4. Today, about 10% of the world population is left-handed.

 

  1. Write “T” if the statement is true and “F” if the statement is false. 
  1. Handedness is not a choice.      T   
  2. Handedness can be predicted before birth.     T   
  3. Most of the time, identical twins have the same dominant hands.       F   

 

  1. The chances of being right or left-handed are determined by the handedness of our parents. Fill in the blanks with the correct numbers.
  1. If your father was left-handed but your mother was right-handed
    → you have a   17  % chance of being born left-handed.
  2. If your father was right-handed but your mother was right-handed
    → you have a   10  % chance of being born left-handed.

 





 

  1. Why does handedness exist in the first place?
    Why are most people right-handed? Fill in the blanks.
    A recent mathematical model suggests that the actual ration reflects a balance between competitive and cooperative pressures on human (1)   evolution  .

[Competitive]

Being left-handed has clear
advantages in activities
involving an (2)   opponent  ,
like combat or competitive sports.
(e.g.) Baseball:
about (3)  50%  of top hitters
have been left-handed.

<Q: Why does this happen?>

  1. Because lefties are a (4)  minority   . (Competitors will spend most of their time encountering and practicing against righties.)

*This imbalance in the population results in an advantage for left-handed fighters or athletes. This is an example of (5)   negative frequency-dependent selection     (4 words).

[Cooperation]

According to the principles of evolution, groups that have a relative advantage tend to grow until that advantage disappears.
→ But only 10% of the world population is left-handed today. Why?

  1. Because they cooperate with right-handed people.

(e.g.) <Golf>
Only (6)   4  % of top players are left-handed because it is easier to find a set of right-handed clubs than a set of left-handed clubs.

<Important instruments that have shaped society>
Lefties are worse at (7)  using    these tools, and suffer from higher (8)  accident     rates.

*Left-handed people are less likely to be (9)  successful   in a purely cooperative world.

 

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