2014职称英语理工阅读理解课件s592-1-33-2014-36735049--芒果.doc.doc

第八篇
Researchers Discover Why Humans Began Walking Upright
Most of us walk and carry items in our hands every day. These are seemingly simple activities that the majority of us don’t question. But an international team of researchers, including Dr. Richmond from GW’s Columbian College of Arts and Sciences1, have discovered that human walking upright, may have originated millions of years ago as an adaptation to carrying scarce, high-quality resources. The team of researchers from the ., England, Japan and Portugal investigated the behavior of modern-day chimpanzees as peted for food resources, in an effort to understand what ecological settings2 would lead a large ape — one that resembles the 6 million-year old ancestor we shared mon with living chimpanzees — to walk on two legs.
“These chimpanzees provide a model of the ecological conditions under which our earliest ancestors might have begun walking on two legs,” said Dr. Richmond.
The research findings suggest that chimpanzees switch to moving on two limbs instead of four in situations where they need to monopolize a resource. Standing on two legs allows them to carry much more at one time because it frees up their hands. Over time, intense bursts of bipedal activity3 may have led to anatomical changes4 that in turn became the subject of natural selection petition for food or other resources was strong.
Two studies we