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

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
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?
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
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,
because we’re the only place that it could evolve.
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
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
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?
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
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
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
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.
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.
Maybe they only have three fingers and pointy ears and they’re green, but they’re pretty
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
was occurring on the plains of Africa.
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
on another planet and evolution would be likely to take the similar course.
That is the argument that is being made in some quarters.
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.
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
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
or whatever.
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.
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
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.
So long, in fact, that it wraps around its brain case.
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
it out and eats it.
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.
They don’t like to fly across water.
And so isolated islands tend not to have woodpeckers.
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
the island of Madagascar called an aye-aye.
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
它们跳来跳去 非常可爱
They hop around, very cute, and so on.
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.
It has these big leathery ears and these bright yellow eyes and a face that only a mother
can love.
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
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.
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.
They’re looking for the same grubs in dead wood.
But they do it in a completely different way.
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
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.
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
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
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.
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
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
is exquisitely adapted to living in the streams in eastern Australia.
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
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
two types of them.
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.
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
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
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
the world.
Yet nowhere else has a duck-billed platypus evolved.
Why is it that it evolved in Australia and nowhere else?
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.
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
else in the world?
Why didn’t they evolve on Madagascar or in South America where monkeys colonized 40
million years ago?
And so this is the counterpart to the argument of evolutionary determinism and convergence.
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.
That problems posed by environment may elicit different evolutionary solutions.



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