TED演讲：拥有大脑的真正原因(1)

 　　I'm a neuroscientist. And in neuroscience, we have to deal with many difficult questions about the brain.  我是个神经生物学家。在神经生物学研究里，我们需要处理很多关于大脑的难题。

　　But I want to start with the easiest question and the question you really should have all asked yourselves at some point in your life,  不过我今天要从这个最简单的问题开始，这个问题是大家应该在以前问过自己的，

　　because it's a fundamental question if we want to understand brain function.  因为如果大家想了解大脑功能的话。

　　And that is, why do we and other animals have brains?  这个问题是很基本的，那就是，为什么我们和其他动物都有大脑呢？

　　Not all species on our planet have brains, so if we want to know what the brain is for, let's think about why we evolved one.  地球上不是所有物种都有大脑，所以要搞清大脑有什么用，那我们应该先考虑为什么我们进化出了大脑。

　　Now you may reason that we have one to perceive the world or to think, and that's completely wrong.  大家也许觉得我们有大脑是为了感知世界或者思考，其实是完全错误的。

　　If you think about this question for any length of time, it's blindingly obvious why we have a brain.  如果再好好思考一段时间的话，其实我们有大脑的原因很明显。

　　We have a brain for one reason and one reason only, and that's to produce adaptable¹ and complex movements.  大脑的存在，有且仅有一个原因就是为了生成有适应性的、复杂的动作。

　　There is no other reason to have a brain.  没有其他原因了。

　　Think about it. Movement is the only way you have of affecting the world around you.  想想看。动作是你唯一对世界产生影响的方法。

　　That's not quite true. There's one other way, and that's through sweating.  当然也不尽然，另一个办法是通过排汗。

　　But apart from that, everything else goes through contractions² of muscles. 不过除了那个以外，所有事情都是由肌肉的收缩来办到的。

　　So think about communication -- speech, gestures, writing, sign language -- they're all mediated³ through contractions of your muscles.  想想我们的沟通方式--语言、手势、写作、手语--都是由肌肉的收缩来完成的。

　　So it's really important to remember that sensory⁴, memory and cognitive⁵ processes are all important,  所以重要的一点就是感知、记忆，认知过程也很关键，

　　but they're only important to either drive or suppress future movements.  但是它们的重要性都只是在于它们能够促使或者抑制动作的发生。

　　There can be no evolutionary⁶ advantage to laying down memories of childhood or perceiving the color of a rose if it doesn't affect the way you're going to move later in life. 如果不是能够影响到大家未来生活中的动作的话，能够记住小时候的回忆或者感知到玫瑰花的颜色，在进化这一点上没有任何特别的优势。

　　Now for those who don't believe this argument, we have trees and grass on our planet without the brain,  如果有谁不相信这个说法，我可以举例说不会运动的树和草都没有大脑，

　　but the clinching⁷ evidence is this animal here -- the humble⁸ sea squirt.  不过有一种动物提供了确凿的证据--不起眼的海鞘。

　　Rudimentary animal, has a nervous system, swims around in the ocean in its juvenile⁹ life.  海鞘是一种初等生物，有神经系统，生命初期在海中游动。

　　And at some point of its life, it implants¹⁰ on a rock.  然后在某一时刻海鞘会把自己移植到岩石上再也不移动。

　　And the first thing it does in implanting on that rock, which it never leaves, is to digest its own brain and nervous system for food.  海鞘在岩石上固定后的第一件事就是把自己的大脑和神经系统作为食物消化掉。

　　So once you don't need to move, you don't need the luxury of that brain.  也就是说，一旦不用再移动也就不需要大脑这样的奢侈品了。

　　And this animal is often taken as an analogy to what happens at universities when professors get tenure¹¹, but that's a different subject. 并且，这种动物常常被类比到大学里面，教授获得终身职位之后的情况，不过那是另一个话题了。

1 adaptable   

adj.能适应的，适应性强的，可改编的

参考例句：

• He is an adaptable man and will soon learn the new work.他是个适应性很强的人，很快就将学会这种工作。
• The soil is adaptable to the growth of peanuts.这土壤适宜于花生的生长。

2 contractions   

n.收缩( contraction的名词复数 )；缩减；缩略词；（分娩时）子宫收缩

参考例句：

• Contractions are much more common in speech than in writing. 缩略词在口语里比在书写中常见得多。 来自《简明英汉词典》
• Muscle contractions are powered by the chemical adenosine triphosphate(ATP ). 肌肉收缩是由化学物质三磷酸腺苷(ATP)提供动力的。 来自辞典例句

3 mediated   

调停，调解，斡旋( mediate的过去式和过去分词 )； 居间促成； 影响…的发生； 使…可能发生

参考例句：

• He mediated in the quarrel between the two boys. 他调解两个孩子之间的争吵。
• The government mediated between the workers and the employers. 政府在工人与雇主间搞调和。

4 sensory   

adj.知觉的，感觉的，知觉器官的

参考例句：

• Human powers of sensory discrimination are limited.人类感官分辨能力有限。
• The sensory system may undergo long-term adaptation in alien environments.感觉系统对陌生的环境可能经过长时期才能适应。

5 cognitive   

adj.认知的，认识的，有感知的

参考例句：

• As children grow older,their cognitive processes become sharper.孩子们越长越大，他们的认知过程变得更为敏锐。
• The cognitive psychologist is like the tinker who wants to know how a clock works.认知心理学者倒很像一个需要通晓钟表如何运转的钟表修理匠。

6 evolutionary   

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。

7 clinching   

v.（尤指两人）互相紧紧抱[扭]住( clinch的现在分词 )；解决（争端、交易），达成（协议）

参考例句：

• Joe gets clinching evidence of the brains role when he dreams. 乔做梦时得到了大脑发生作用的决定性依据。 来自辞典例句
• Clinching, wrestling, pushing, or seizing, without attempting a throw or other technique. 抱，扭摔，推或抓而没有摔或其它的技术。 来自互联网

8 humble   

adj.谦卑的，恭顺的；地位低下的；v.降低，贬低

参考例句：

• In my humble opinion,he will win the election.依我拙见，他将在选举中获胜。
• Defeat and failure make people humble.挫折与失败会使人谦卑。

9 juvenile   

n.青少年，少年读物；adj.青少年的，幼稚的

参考例句：

• For a grown man he acted in a very juvenile manner.身为成年人，他的行为举止显得十分幼稚。
• Juvenile crime is increasing at a terrifying rate.青少年犯罪正在以惊人的速度增长。

10 implants   

n.（植入身体中的）移植物( implant的名词复数 )

参考例句：

• Hormone implants are used as growth boosters. 激素植入物被用作生长辅助剂。 来自《简明英汉词典》
• Perhaps the most far-reaching project is an initiative called Living Implants From Engineering (LIFE). 也许最具深远意义的项目，是刚刚启动的建造活体移植工程 (LIFE)。 来自英汉非文学 - 生命科学 - 医学的第四次革命

11 tenure   

n.终身职位；任期；(土地)保有权，保有期

参考例句：

• He remained popular throughout his tenure of the office of mayor.他在担任市长的整个任期内都深得民心。
• Land tenure is a leading political issue in many parts of the world.土地的保有权在世界很多地区是主要的政治问题。