She is one of mankind’s oldest ancestors and is more than three million years old. New analysis of the arm bones of Lucy, an early hominid, suggests she was a tree climber. Lucy’s remains were uncovered in Ethiopia in the 1970s, with the 3.18 million-year-old skeleton(骨骼)being the most complete of any upright, walking human ancestor. Since she was discovered, researchers have debated whether she spent her life in the trees or spent time walking on the plains as well.

The new evidence from scans of her arm bones proves she spent time climbing and used her arms to pull herself up. The scans were compared with cross sections of humans and chimpanzees, which spend a mixture of time in trees and walking on all fours on the ground. They found that the arm bones were more heavily built, similar to those of chimps, while her lower limbs(下肢)would have meant she walked less efficiently than modern humans. Professor John Kappelman, at University of Texas, believes the advantage of his study was that it focused on characteristics that reflect actual behavior during life, suggesting that even when Lucy walked upright, she may have done so less efficiently than modern humans, limiting her ability to walk long distances on the ground.

Previous studies suggested that Lucy was just 4 feet tall and weighed just 65 pounds. Combining the new data paints a picture of an ancestor who may have spent a great amount of her time in trees. It also expands on evidence from earlier this year which claimed that Lucy may have died from a fall, most likely from a tree. The evidence suggests Lucy may have spent time on the ground, returning to the safety of the trees for food and to sleep, to avoid her enemies.

【小题1】What did the researchers argue about after Lucy was discovered?

A．Where she lived.	B．How long she lived.
C．What she ate.	D．How she worked.

【小题2】How could people tell Lucy spent time climbing?

A．By her walking style.	B．By her heavily built arm bones.
C．By her strong lower limbs.	D．By her large cross sections.

【小题3】When Lucy walked, she may________.

A．have walked with bigger steps	B．have walked at a faster speed
C．have walked more efficiently than us	D．have walked a shorter distance than us

【小题4】What is the main idea of the last paragraph?

A．Guesses about Lucy’s characteristics.	B．Some evidence of Lucy’s health.
C．The safety of Lucy.	D．The ancestor of Lucy.