B Artificial Intelligence Programs.
C Todays Robots and How They Function.
D Modern-Day Sensors.
第三篇
Why Humans Walk on Two Legs
A team of scientists that studied chimpanzees(黑猩猩)trained to use treadmills(跑步机)has gathered new evidence suggesting that our earliest apelike ancestors started walking on two legs because it required less energy than getting around on all fours。
Michael Sockol, researcher of UC Davis, worked for two years to find an animal trainer willing to coax(劝诱)adult chimps to walk on two legs and to walk on all fours.
The five chimps also wore face masks used to help the researchers measure oxygen consumption. While the chimps worked out. the scientists collected data that allowed them to calculate which method of locomotion(移动)used less energy and why. The team gathered the same information for four adult humans walking on a treadmill.
The researchers found that human walking used about 75 percent less energy and burned 75 percent fewer calories than quadrupedal and bipedal walking in chimpanzees. They also found that for some but not all of the chimps, walking on two legs was no more costly than on all fours.
We were prepared to find that all of the chimps used more energy walking on two legs-but that finding wouldnt have been as interesting. Sockol said. What we found was much more telling. For three chimps,bipedalism was more expensive,but for the other two chimps, this wasnt the case, one spent about the same energy walking on two legs as On all fours. The other used less energy walking upright. These two chimps had different gaits(步法)and anatomy(解剖)than their quadrupedal peers.
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