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SSS 2010-07-29

时间:2010-08-05 08:02来源:互联网 提供网友:konicaqq   字体: [ ]
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    (单词翻译:双击或拖选)

This is Scientific American’s 60-Second Science. I’m Karen Hopkin. This will take just a minute.

What’s in a neck? Well, it’s a good place to hang a pendant or a tie. Or to rest your head. Now scientists say that by separating our heads from our bodies, the neck gave our brains a leg up in evolution. Their findings appear in the online journal Nature Communications.

Not all animals have necks. A fish's head is pretty much continuous with its body. And a fish gets around just fine. Nerves based in the fish’s brain instruct its fins1 to move, and off it goes.

But something happened when our aquatic2 ancestors first slithered onto the land. The source of the nerve cells that power the animals’ forelimbs shifted, from the brain down to the spinal3 cord. That move allowed the body to grow more distant from the head, taking the arms with it. And so the neck was born.

That neck, say the scientists, was more than just a way to keep the head off the shoulders. The anatomical relocation improved dexterity4 by leaving the arms free to move in new ways. And the resulting flexibility5 helped shape the evolution of our heads and our hands, and how we can use them together to do all sorts of nifty things—like tie a perfect Windsor knot.

Thanks for the minute for Scientific American’s 60-Second Science. I’m Karen Hopkin


点击收听单词发音收听单词发音  

1 fins 6a19adaf8b48d5db4b49aef2b7e46ade     
[医]散热片;鱼鳍;飞边;鸭掌
参考例句:
  • The level of TNF-α positively correlated with BMI,FPG,HbA1C,TG,FINS and IRI,but not with SBP and DBP. TNF-α水平与BMI、FPG、HbA1C、TG、FINS和IRI呈显著正相关,与SBP、DBP无相关。 来自互联网
  • Fins are a feature specific to fish. 鱼鳍是鱼类特有的特征。 来自辞典例句
2 aquatic mvXzk     
adj.水生的,水栖的
参考例句:
  • Aquatic sports include swimming and rowing.水上运动包括游泳和划船。
  • We visited an aquatic city in Italy.我们在意大利访问过一个水上城市。
3 spinal KFczS     
adj.针的,尖刺的,尖刺状突起的;adj.脊骨的,脊髓的
参考例句:
  • After three days in Japan,the spinal column becomes extraordinarily flexible.在日本三天,就已经使脊椎骨变得富有弹性了。
  • Your spinal column is made up of 24 movable vertebrae.你的脊柱由24个活动的脊椎骨构成。
4 dexterity hlXzs     
n.(手的)灵巧,灵活
参考例句:
  • You need manual dexterity to be good at video games.玩好电子游戏手要灵巧。
  • I'm your inferior in manual dexterity.论手巧,我不如你。
5 flexibility vjPxb     
n.柔韧性,弹性,(光的)折射性,灵活性
参考例句:
  • Her great strength lies in her flexibility.她的优势在于她灵活变通。
  • The flexibility of a man's muscles will lessen as he becomes old.人老了肌肉的柔韧性将降低。
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