题目内容：

Heat might explain why we lost our fur and now strike an upright and slim pose(姿势).

If our ancestors lived somewhere really hot, the theory goes, it would have made sense for us to lose body hair, start sweating more, become slender(修长的) and even walk upright—to create distance between our bodies and the hot ground.

A new study supports the theory that heat helped drive human evolution(进化), by showing that a key source of human evolution in East Africa has indeed been really hot for at least four million years.

“It’s something that’s been hard to get at,” said Ben Passey, a geochemist(地球化学家) at Johns Hopkins University in Baltimore. “It’s nice to say that these body features would be advantageous to live in hot and open environments. But was it actually hot and open?”

To find out, Passey and his colleagues analyzed dated soil examples from the Turkana Basin, a well-studied region in Kenya and Ethiopia that contains lots of fossils(化石) from our human and pre-human ancestors. In particular, they looked at weighted carbon and oxygen atoms, called isotopes(同位素).

Their results, published in the Proceedings of the National Academy of Sciences, showed that dirt in the Turkana Basin has remained above about 85 degrees Fahrenheit with spikes(尖状物) above 95 degrees Fahrenheit over the past four million years. Since soil absorbs heat from the air, it means that the region has been really hot for a really long time.

“There is no question that the results are fascinating,” said Harvard anthropologist(人类学家), Daniel Lieberman, who studies how and why the human body looks the way it does.

For one thing, at some point we developed a unique ability to control our body temperature while running, which might have helped people catch prey(猎物) in hot and dry conditions. “The hotter it is, the more humans have an advantage over other mammals, especially when running.”

“No one knows for sure when we lost our fur,” he added. “But this paper provides strong evidence that the right climatic conditions were present for a long time.”

1.What is the main idea of the text?

A. Heat made humans lose their fur.    B. Heat caused humans to walk upright.

C. Heat helped the evolution of humans.    D. Heat affected the height of our ancestors.

2.The main aim of Passey’s study is to find out__________.

A. why Africa is suitable for humans to live in

B. how many types of fossils there are in the Turkana Basin

C. what the climatic conditions were like four million years ago

D. whether East Africa is the key source of human evolution

3.According to Daniel Lieberman, ___________.

A. the result of Passey’s study is not satisfactory

B. controlling the body temperature helped catch prey

C. a hot climate was not helpful for human evolution

D. humans ran faster than other animals in winter

4.Which of the following statements about East Africa is TRUE?

A. The high temperature in this area has been stable for a long time.

B. It was one of the toughest places for human ancestors to bear.

C. Few people studied the Tukana Basin before Passey.

D. The soil has remained over 95 degrees F for a long time.