Teeth to the past (P6)
吉林毓文中学 赵莹

I. Lead in
•    What is the name of the animal?
•    What do you know about it?

II. Read for general information
Read the article quickly to get the main idea.
    Scientists have retrieved the oldest DNA on record within the teeth of ancient mammoths in Siberia, Russia, from over one million years ago. 

III. Read for details 
Read and divide the article into two parts and summarize the main idea. 
 

III. Read for details 
Read part one and answer the following questions. 
1. Where did the previous DNA sequence come from? 
   Previously, the oldest DNA sequence was from a horse in Canadian Yukon territory about 700,000 years ago.

2. What is the importance of retrieving the DNA from these mammoths according to Tom van der Valk? 
   He said, “Breaking this somewhat magical barrier of more than one million years old opens a new time window, so to say, and evolutionary perspective.”

3. How did scientists previously study prehistoric creatures? 
 By studying fossils.

4. What do the three DNA samples show? 
•    The Krestovka mammoth was found to have diverged from the ancestors that led to the famous woolly mammoth more than two million years ago. The DNA also shows that woolly mammoths’ adaptations to the cold weather were already present in earlier mammoth populations. 

5. What do the last two paragraphs tell us?
The significance of the study. 

IV. Language study 
•    记录在案           on record
•    解锁遗传因物质     unlock the genetic material
•    打开新窗口              open a new window
•    开创新局面          break new ground
•    一些特征          a handful of characteristics
•    数以万计         tens of thousands of 

2. Although the samples (样本) from the mammoths – ancestors of elephants and one of the largest Ice Age mammals – were found in the 1970s, new scientific methods were required to unlock the genetic material. 
What does this sentence tell us?
把本句拆分成简单句，学习本句如何把短句写成长难句的技巧

1)    The samples are from the mammoths. 
2)     The mammoths are ancestors of elephants and one of the largest Ice Age mammals.  
3)     The samples were found in the 1970s. 
4)     Scientists had to find new scientific methods to unlock the genetic material. 
释义：虽然从猛犸象——大象的祖先和冰河时代最大的哺乳动物之一——身上提取的样本是在 20 世纪 70 年代被发现的，但需要新的科学方法来解开这些遗传物质的谜团。