Most of us walk and carry items in our hands every day. These are seemingly simple activities that the majority of us dont question. But an international team of researchers, including Dr. Richmond from GWs 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 U. S., England, Japan and Portugal investigated the behavior of modern-day chimpanzees as they competed 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 in common with living chimpanzees---to walk on two legs.
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 where competition for food or other resources was strong.
When the rare coula nuts were available only in small numbers, the chimpanzees transported more at one time. Similarly, when coula nuts were the majority resource, he chimpanzees ignored the oil palm nuts altogether. The chimpanzees regarded the coula nuts as a more highly---prized resource and competed for them more intensely.
The second study, by Kimberley Hockings of Oxford Brookes University10, was a 14-month study of Bossou chimpanzees crop-raiding, a situation in which they have to compete for rare and unpredictable resources. Here, 35 percent of the chimpanzees activity involved some sort of bipedal movement, and once again, this behavior appeared to be linked to a clear attempt to carry as much as possible at one time.
chimpanzee n.黑猩猩
ape n.无尾猿;类人猿
注释：
1.GWs Columbian College of Arts and Sciences：乔治华盛顿大学哥伦比亚艺术与科学学院。乔治华盛顿大学(George Washington University)的英文简称为GW，是美国顶尖的私立大学之一，于1821年建校，位于美国首都华盛顿。
3.bipedal activity：双足活动
5.Kyoto University：京都大学，是继东京大学之后成立的日本第二所国立大学，于1897年建校。京都大学主要校区位于日本历史名城京都市。
7.oil palm nut：油棕榈坚果