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None of our early ancestors could digest milk as adults because their bodies never had to-milk drinking simply wasn't an option.As people began to extract milk from animals,though,some people developed the
ability to keep drinking it throughout their lives.
Scientists now know of a milkrelated mutation (变异) in our genes-the chemical instructions for life that we carry in almost every cell in our bodies.People who have a mutated form of one particular gene can
drink milk just fine.People without the mutation tend to get sick from milk.
To figure out where,and possibly why,milk drinking started,some scientists have been looking at who
has the milkdigesting mutation today.Patterns are striking.
Most adults in Northern and Central Europe are able to digest milk-and they do.Cheese,butter and
other dairy products are popular in countries such as Sweden,Denmark,Germany and England.Because
European settlers dominated North America,most people here can handle milk just fine,as well.That may
explain why ice cream is such a popular dessert in the United States.
In much of Africa,Asia and South America,on the other hand,people tend to avoid dairy products
because they lead to diarrhea (腹泻) and other stomach problems.(That's why you won't typically find
cheese on the menu at a Chinese,Japanese or Ethiopian restaurant.) Native Americans are also unable to
digest milk.
Based on these genetic patterns,scientists have long thought that milk drinking started in Northern
Europe,where dairy is an institution and the milkdigesting mutation is everywhere.
A recent study painted a different picture.With a computer model,Thomas and colleagues looked at the spread of the milkdrinking mutation,farming and other related factors.Working backward,the scientists
concluded that the first milkdrinkers lived in Central Europe around what's now Hungary about 7,500
years ago.The practice didn't start farther north,as scientists had thought before.
1. Which of the following is the proper order of events according to the passage?
a. Their children were able to digest milk as adults.
b. They got sick from the milk.
c. Some people got a mutation in their genes.
d. Some people tried drinking milk from animals.
e. Some people started to drink milk from animals on a regular basis.
A. c→d→b→e→a
B. d→e→b→c→a
C. d→b→e→c→a
D. e→b→d→c→a
2. Most people in the USA can digest milk because________.
A. they have strong stomachs
B. their ancestors were Europeans
C. that's where milk drinking started
D. farmers raise a lot of cows there
3. Which of the following is LEAST likely to appear on the menu in a Japanese restaurant?
A. Butter.
B. Vinegar.
C. Fish.
D. Beef.
4. Which of the following is the author most likely to agree with?
A. Milk drinking first started in Northern Europe.
B. Milk drinking first started in Central Europe.
C. North American Indians were able to digest milk.
D. Dairy products are very popular in North Korea.
5. The main focus of the scientists'research was________.
A. mutation of human genes
B. development of the human stomach
C. why milk drinking started
D. where milk drinking first started

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