进化之于人类肩膀的负担-凯发k8官网

进化之于人类肩膀的负担
文章来源:未知 文章作者:enread 发布时间:2015-09-09 07:08 字体: [ ] 
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as early humans increasingly left forests and 1 tools, they took an 2 step away from apes. but what this last common ancestor with apes looked like has remained unclear. a new study led by researchers at uc san francisco shows that important clues lie in the shoulder. humans split from our closest african ape relatives in the genus pan - including chimpanzees and bonobos - 6 to 7 million years ago. yet certain human traits resemble the more distantly related orangutan or even monkeys. this combination of characteristics calls into question whether the last common ancestor of modern humans and african apes looked more like modern day 4 and 6 or an ancient ape unlike any living group. 

 

"humans are unique in many ways. we have features that clearly link us with african apes, but we also have features that appear more 7, leading to 8 about what our common ancestor looked like," said nathan young, phd, assistant professor at uc san francisco school of medicine and lead author of the study. "our study suggests that the simplest explanation, that the ancestor looked a lot like a 3 or 5, is the right one, at least in the shoulder." 

 

it appears, he said, that shoulder shape tracks changes in early human behavior such as reduced climbing and increased tool use. the paper, titled fossil hominin shoulders support an african ape-like last common ancestor of chimpanzees and humans, published online sept. 6, in the journal pnas. 

 

the shoulders of african apes consist of a trowel-shaped blade and a handle-like 9 that points the 10 with the arm up toward the 11, giving an advantage to the arms when climbing or swinging through the branches. in contrast, the scapular spine of monkeys is 12 more 13. in humans this trait is even more pronounced, indicating behaviors such as stone tool making and high-speed throwing. the 14 question was whether humans evolved this 15 from a more primitive ape, or from a modern african ape-like creature, but later 16 back to the downward angle.



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1 a24badb66c4d7870fd211f2511461fff     
v.利用,使用( utilize的过去式和过去分词 )
参考例句:
  • in the19th century waterpower was widely utilized to generate electricity. 在19世纪人们大规模使用水力来发电。 来自《简明英汉词典》
  • the empty building can be utilized for city storage. 可以利用那栋空建筑物作城市的仓库。 来自《简明英汉词典》
2 ctqz7m     
adj.进化的;演化的,演变的;[生]进化论的
参考例句:
  • life has its own evolutionary process.生命有其自身的进化过程。
  • these are fascinating questions to be resolved by the evolutionary studies of plants.这些十分吸引人的问题将在研究植物进化过程中得以解决。
3 wxgza     
n.黑猩猩
参考例句:
  • in fact,the color of gorilla and chimp are light-color.其实大猩猩和黑猩猩的肤色是较为浅的。
  • the chimp is the champ.猩猩是冠军。
4 2a09048610e52de775e2fe426c063f06     
(非洲)黑猩猩( chimp的名词复数 )
参考例句:
  • chimps are too scarce, and too nearly human, to be routinely slaughtered for spare parts. 黑猩猩又太少,也太接近于人类,不可以作为人器官备用件说杀就杀。 来自英汉非文学 - 生命科学 - 医学的第四次革命
  • and as nonprimates, they provoke fewer ethical and safety-related concerns than chimps or baboons. 而且作为非灵长类,就不会产生像用黑猩猩或狒狒那样的伦理和安全方面的顾虑。 来自英汉非文学 - 生命科学 - 医学的第四次革命
5 0ylyx     
n.大猩猩,暴徒,打手
参考例句:
  • i was awed by the huge gorilla.那只大猩猩使我惊惧。
  • a gorilla is just a speechless animal.猩猩只不过是一种不会说话的动物。
6 a04bd21e2b9b42b0d71bbb65c0c6d365     
n.大猩猩( gorilla的名词复数 );暴徒,打手
参考例句:
  • the similitude between humans and gorillas 人类和大猩猩的相像
  • each family of gorillas is led by a great silverbacked patriarch. 每个大星星家族都由一个魁梧的、长着银色被毛的族长带领着。 来自《简明英汉词典》
7 vswz0     
adj.原始的;简单的;n.原(始)人,原始事物
参考例句:
  • it is a primitive instinct to flee a place of danger.逃离危险的地方是一种原始本能。
  • his book describes the march of the civilization of a primitive society.他的著作描述了一个原始社会的开化过程。
8 nlfwk     
n.易变,靠不住,不确知,不确定的事物
参考例句:
  • her comments will add to the uncertainty of the situation.她的批评将会使局势更加不稳定。
  • after six weeks of uncertainty,the strain was beginning to take its toll.6个星期的忐忑不安后,压力开始产生影响了。
9 lfqzt     
n.脊柱,脊椎;(动植物的)刺;书脊
参考例句:
  • he broke his spine in a fall from a horse.他从马上跌下摔断了脊梁骨。
  • his spine developed a slight curve.他的脊柱有点弯曲。
10 m3lx4     
adj.联合的,共同的;n.关节,接合处;v.连接,贴合
参考例句:
  • i had a bad fall,which put my shoulder out of joint.我重重地摔了一跤,肩膀脫臼了。
  • we wrote a letter in joint names.我们联名写了封信。
11 cetyo     
n.头骨;颅骨
参考例句:
  • the skull bones fuse between the ages of fifteen and twenty-five.头骨在15至25岁之间长合。
  • he fell out of the window and cracked his skull.他从窗子摔了出去,跌裂了颅骨。
12 il8zb4     
adj.尖的,直截了当的
参考例句:
  • he gave me a very sharp pointed pencil.他给我一支削得非常尖的铅笔。
  • she wished to show mrs.john dashwood by this pointed invitation to her brother.她想通过对达茨伍德夫人提出直截了当的邀请向她的哥哥表示出来。
13 msdxu     
adj./adv.向下的(地),下行的(地)
参考例句:
  • he lay face downwards on his bed.他脸向下伏在床上。
  • as the river flows downwards,it widens.这条河愈到下游愈宽。
14 e1ozf     
adj.盛行的;占优势的;主要的
参考例句:
  • she wears a fashionable hair style prevailing in the city.她的发型是这个城市流行的款式。
  • this reflects attitudes and values prevailing in society.这反映了社会上盛行的态度和价值观。
15 nypyb     
n.结构,布局,形态,(计算机)配置
参考例句:
  • geographers study the configuration of the mountains.地理学家研究山脉的地形轮廓。
  • prices range from $119 to $199,depending on the particular configuration.价格因具体配置而异,从119美元至199美元不等。
16 5ac73b57fcce627aea1bfd3f5d01d36c     
恢复( revert的过去式和过去分词 ); 重提; 回到…上; 归还
参考例句:
  • after the settlers left, the area reverted to desert. 早期移民离开之后,这个地区又变成了一片沙漠。
  • after his death the house reverted to its original owner. 他死后房子归还给了原先的主人。
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