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人类也有“外星生物”吗? – 译学馆
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人类也有“外星生物”吗?

Will Alien Life Resemble Life on Earth? Harvard Biologist Jonathan Losos Explains

关于进化的必然性问题以及世界上哪些事情
So this question about the inevitability of evolution, the extent to which the outcomes
注定会发生 都有很多种解释
we see in the world today were destined to occur, has a number of implications.
我的意思是总的来说 它告诉我们命中注定的进化将如何发生
I mean just most generally it tells us whether how fated evolution was to occur, how the
今天的世界又是如何注定的
outcome today was destined in a way.
但也有一些其它的含义 人类一直推测的问题
But it has other implications as well that people have long speculated about, and that
那就是 进化后的生命在其它星球上会是怎样的?
is: what would life be like on other planets if it is evolved?
它们会和地球上的生物一样还是完全不同?
Would it be like the world today here on Earth or would it be completely different?
这个问题日渐紧急 至少近年来人类对它很有兴趣
And this question has taken on some increased urgency or at least interest in recent years
因为我们如今意识到还有很多像地球一样的星球
because we now realize that there are many planets out there that are like Earth.
我们以前也许认为地球是特别的 所以众所周知生命也是特殊的
We used to think that Earth was perhaps unique and so perhaps life as we know it is unique,
因为我们是生物进化的唯一载体
because we’re the only place that it could evolve.
但是与之相反的是我们已经发现了很多
But quite the contrary we’ve now discovered that there are lots of what are called “habitable
“可居住行星”据估计仅在银河系 就有数百万甚至数十亿存在
exoplanets”, Some people estimate millions, even billions just in our own Milky Way galaxy.
所以这样的话 是否存在很多类地行星 也就是像地球一样
So if that’s the case, if there are that many Earth-like planets – and by Earth-like
我是说在大小 温度 大气等上和地球相似 也许有流动的水源
I mean about the same size, temperature, atmosphere somewhat similar, running water – roughly
这些相似的环境
similar conditions.
如果真的存在很多类地行星 很多人认为很有可能
If there are really that many Earth-like planets many people think that it’s very likely
生命也在这些行星上进化
that life has evolved on them.
那么问题是 这些生命会是什么样子的?
And so the question is what will that life look like?
有些人认为从趋同进化论出发
Well there are those who argue that from the argument of convergent evolution they argue
在地球上面临同样条件的物种 会通过自然选择
that species facing the same conditions here on Earth evolved the same solutions by natural
进化出相同的物种
selection.
他们推断说如果其它星球的条件和地球相似 那么我们会看到
They extrapolate to say if conditions on other planets are similar to here then we would
非常相似的生命形式 无论你到哪个星球你都会发现
see very similar lifeforms, that you arrive on whatever planet you’ll see animal and
看起来非常熟悉的动物和植物类生物
plant-like organisms that look very familiar.
有些人甚至认为 事实上人形生物甚至人类
Some people have gone so far as to say that, in fact, human type organisms, humanoids will
也会出现在其它星球上
occur on other planets.
所以会有外星智慧生物的存在 当我们见到他们时能识别出来
So there will be intelligent beings that if we saw them they would be recognizable which,
当然 这是好莱坞告诉我们的
of course, is what Hollywood tells us.
如果你看过任何的科幻电视节目或电影就会发现
If you watch almost any science fiction TV show or movie the intelligent lifeform is
有智生物是两足动物 几只胳膊 一张嘴
bipedal, a couple of arms, a mouth.
也许他们只有三根手指和尖尖的耳朵甚至是绿色的
Maybe they only have three fingers and pointy ears and they’re green, but they’re pretty
但是他们都和人类非常相似
humanoid.
所以有人说 事实上人类很有可能是地球上
And so some people say yes, that’s actually very likely that humans are a very successful
非常成功的一种生命形式 因为我们对环境有极高的适应性
lifeform here on Earth that we are extremely well adapted to our environment which ancestrally
虽然这种适应性也曾出现在非洲平原上
was occurring on the plains of Africa.
但我们惊人的适应环境能力使我们主宰了这个世界
But we have adapted so exquisitely that we now dominate the world.
如果这种良好适应性存在于地球 同样也可以存在于其它星球
And so if this is such a good adaptation here on Earth it would similarly be a good adaptation
进化可能也会经历同样的演变过程
on another planet and evolution would be likely to take the similar course.
这个论点在一些方面得到论证
That is the argument that is being made in some quarters.
不是每个人都相信这个进化的说法
Not everyone is convinced by this argument that evolution is deterministic.
趋同进化的发生 远比我们已知的要多
We recognize that convergent evolution does occur more than we used to realize but still
但是仍有人认为 我赞同这个观点 这是不可避免的
it is argued and I agree with this viewpoint, it’s not inevitable.
理由是有很多不同的方式来适应相同的环境
And the reason is that there are often multiple ways to adapt to the same environmental circumstance.
所以即使物种面临相同的环境 它们也有可能
And so even though species are faced with the same conditions they may find different
以不同的方式去适应环境
ways to adapt to them.
关于这个 我最喜欢的例子是众所周知的一种鸟-啄木鸟
And my favorite example of that has to do with a bird that everyone knows – the woodpecker.
相信每个人都在车库旁 或者其它的什么地方
And everyone’s heard the tat-tat-tat of a woodpecker on a tree or on your garage siding
听过树上的啄木鸟“嗒嗒嗒”的声音
or whatever.
事实上人们并不知道啄木鸟在做什么
People don’t actually know what the woodpecker is doing.
其实啄木鸟是在 用它的喙去敲打死木
This is what the woodpecker is doing: It is using its beak to pound on dead wood, listening
倾听空洞的声音 从回声可以判断出树中的空洞中
for a hollow space, the echo indicating there’s a hollow space in the wood which is where
是否有蛆虫 幼甲虫或者其它的昆虫在吃死木
a grub, a larval beetle or some other insect is eating the dead wood.
所以啄木鸟倾听空心物体的回声
And so it listens for the sound of a hollow space.
当它们听见时 就开始发出“嗒嗒嗒嗒”的声音
When it hears it, it then starts tapping very hard – tat-tat-tat-tat-tat-tat – using
它的喙像手提钻一样深入 或者说凿入木头深处
its beak as a jackhammer to dig into the, to chisel or to dig into the deep wood to
从而到达空穴
get to the tunnel.
如此一来 啄木鸟就有了一个相当长的舌头
Once it’s there—the woodpecker has an extremely long tongue.
如此长以至于甚至包裹住了它的大脑
So long, in fact, that it wraps around its brain case.
啄木鸟伸出长长的有小刺舌头
But it sticks out this long tongue that has little prickles on it, and the tongue goes
深入木头 迅速挂住看起来像粉虱的害虫 再把害虫
in and it snags the grub which looks like a mealworm or a – snags the grub and pulls
钩出来再吃掉
it out and eats it.
它们就是这样捕获所需的食物
And that is how they capture the food that they eat.
啄木鸟遍布世界 随处可见
Well woodpeckers are found on almost every continent in the world.
它们是非常成功的 但它们在水面上的飞行能力较弱
They’re very successful, but they don’t fly very well across water.
它们不喜欢飞过水面
They don’t like to fly across water.
所以说孤岛往往没有啄木鸟
And so isolated islands tend not to have woodpeckers.
其它的物种已经通过进化填补了它们留下的空缺
And in their absence other species have evolved to fill the same niche.
用不同的方法做相同的事 最极端的例子是一种
And the most extreme example of a different way of doing the same thing is an animal on
马达加斯加岛上的被称为“艾艾”的动物
the island of Madagascar called an aye-aye.
现在它是一种狐猴
Now an aye-aye is a type of lemur.
今天的人们从电视节目得知狐猴 也许已经见过它们
Now people know lemurs from the TV show Zooboomafoo and maybe they’ve seen them, the ring-tailed
摇着尾巴的狐猴
lemur.
它们跳来跳去 非常可爱
They hop around, very cute, and so on.
但是艾艾并不十分可爱
The aye-aye is not very cute.
它的大小和家猫差不多 有着恶魔般的外表
It’s about the size maybe of a small housecat and it’s kind of demonic looking.
它有着大大的皮革似的耳朵和亮黄色的眼睛
It has these big leathery ears and these bright yellow eyes and a face that only a mother
还有一张丑陋的脸
can love.
马达加斯加的原住民有着各种各样关于它们的传说
And the native people of Madagascar had all kinds of taboos and myths about them because
因为它可怕的外表 而且他们只在夜晚出现
they look – and they only come out at night.
但它们最大的特点 我认为真的可以吓到人的
But their most extreme feature that I think really kind of freaks people out is that their
是它们的第三根手指又长又细
third finger is long and extremely thin.
看起来像骨头 而且能旋转到任何方向
It looks skeletal, and it can rotate in any direction.
那是一种能到处摆动的手指
It’s this kind of finger that can wiggle around.
总之 它们和啄木鸟有着相同的生活方式
Anyway, they live the same lifestyle as a woodpecker.
它们也在死木中寻找害虫
They’re looking for the same grubs in dead wood.
但是它们却有一个完全不同的方式
But they do it in a completely different way.
它们用手指而不是喙敲打死木
Instead of tapping with their peak they tap with their finger.
它们来到死木旁开始敲打 大大的耳朵正向旋转
They go around the wood going tap-tap-tap and their big ears are rotated forward listening
倾听着传来的回声
for the sound of an echo.
当它们听到从空木中传来的回声时 它们用它们的牙齿
And when they hear the echo of an empty tunnel they have these teeth that are – these teeth
就像这样伸出来 这些凿牙相当有力
are kind of sticking out like this, these chiseling incisors that are very strong.
它们以特有的方式啃咬进死木 直到抵达空穴
And they bite their way through the wood and bite into the wood until they get the tunnel.
然后这时它们再次使用手指
And then once they get there they then use their finger again.
它们将手指深入木中 抓住害虫再扯出来
They stick it in there and they snag the larvae and pull it out.
所以说 它们在做和啄木鸟完全相同的事情
And so they’re doing exactly the same thing that the woodpecker is doing but they’ve
但是它们却进化出了一种完全不同的版本
evolved a completely different set of adaptations.
这仅仅是一个 关于物种怎样用不同的方式来适应相同的环境
And so that’s just one example of how species can adapt to do the same thing in very different
的例子
ways.
在世界上还有很多例子
And we see many examples of that in the world.
反之 我们也同样发现了很多无关联进化的例子
Conversely we also see many examples of species that have no evolutionary parallel.
我们把它叫做进化的单例模式
What we call an evolutionary singleton.
也就是说一个物种非常适应它的生活环境 但没有其它的物种
That is a species that is very well adapted to where it lives but no other species has
能做相同的事
done the same thing.
我最喜欢的关于这个的例子是鸭嘴兽 这种澳大利亚的神奇动物
And my favorite example of that is the duck-billed platypus, this extraordinary animal in Australia.
现在的人们喜欢取笑鸭嘴兽 但它们并不知道
Now people like to make fun of the platypus but they don’t realize that the platypus
鸭嘴兽非常适应居住在澳大利亚东部的河域
is exquisitely adapted to living in the streams in eastern Australia.
它们浓密的皮毛使它们能几乎能在冰冻的水里游泳
And so it has very lush fur that allows it to swim in water that’s basically almost
它们拥有有力的尾巴 拥有带蹼的脚掌来划水
at freezing; It has a powerful tail; It’s got webbed feet for swimming; And then most
最神奇的要算它们的鸭嘴
extraordinarily it has this duck bill.
虽然如今它已经不再 它只是看起来像鸭子的嘴
Now it’s not actually – it kind of looks like a duck’s bill, but it’s not hard
但它没有鸭嘴坚硬 它实际上是一种皮革
like a duck’s bill.It’s actually leathery.
但更重要的是 它覆盖着成千上万的感官 这些感官
But more importantly it’s covered with thousands of little receptors and these receptors there’s
有两种
two types of them.
一种能够察觉水波的变化
One of them can detect slight variation in ripples of water.
所以如果有东西在水中靠近它们 它们能通过水波察觉
And so if something goes swimming by they can detect it in the water But in addition
除此之外 它们有电子感官
they have electro receptors.
它们可以检测到非常轻微的放电现象
They can detect very slight electrical discharges.
所以当有动物肌肉运动时 会有轻微的电流活动
And so when an animal moves its muscles there’s a little bit of electrical activity, and the
鸭嘴兽能够检测到它们
platypus can detect that.
所以当鸭嘴兽在水下游泳时 它闭上了它的眼睛耳朵和嘴巴
And so when it’s swimming under water it closes its eyes, its ears and its mouth, but
但借助这些在鸭嘴上的感官器 它能够找辨别方向
based on the receptors on its bill it can find its way around and it can locate its
准确定位——这是为了捕食龙虾等其它猎物所形成的卓越的适应性
prey—Remarkable adaptation to eating crayfish and other food items like that.
所以说 鸭嘴兽生活的这些毫无异常的河流
Well so, the platypus lives in these streams that are in no way remarkable.
就像在圣路易斯 我成长所居住的那座房子背后的河流一样
There are streams like that behind the house I grew up in in St. Louis and they occur around
它们存在于全世界
the world.
然而其它地方并没有鸭嘴兽进化
Yet nowhere else has a duck-billed platypus evolved.
为什么它只在澳大利亚而不在其它地方进化呢?
Why is it that it evolved in Australia and nowhere else?
有很多关于物种有很高的环境适应性却不同化的例子
Well there are many examples of species extremely well-adapted but no parallel.
比如说变色龙 大象 长颈鹿和很多种植物
Things like the chameleon, elephants, giraffes, many types of plants.
很多进化的单例模式
Many evolutionary singletons.
事实上 人类也是一种进化单例
In fact, humans are an evolutionary singleton.
如果我们已经如此适应我们的生存环境了 为什么没有其它类人的生物
If we are so well adapted to our environment, why didn’t something like us evolve anywhere
进化出现在这个世界上呢?
else in the world?
为什么它们没有在马达加斯加或者南美地区
Why didn’t they evolve on Madagascar or in South America where monkeys colonized 40
这些猿猴4000万年前曾居住过的地方进化呢?
million years ago?
这类似于进化决定论和进化趋同论
And so this is the counterpart to the argument of evolutionary determinism and convergence.
我们也许可以列一个并未趋同化的物种的清单
We could probably make a list just as long of species that have not converged.
这样一来对很多物种来说 进化好像并不是确定性的
And so in many cases species – in many cases evolution seemed not to be deterministic.
由环境所导致的一些问题也许会引起不同的进化选择
That problems posed by environment may elicit different evolutionary solutions.

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人类会进化出“外星生物”吗?哈佛生物学家Jonathan Losos为您解释

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