生命的奇迹（2013）

the vibrations are passed into the inner ear
传进内耳
with much greater force.
那就会产生戏剧性的效果
And that has a dramatic effect.
与99.9%的声能被反射相反
Rather than 99.9% of the sound energy being reflected away,
事实证明这样的组合
it turns out that with this arrangement,
能让60%的声能
60% of the sound energy is passed
从鼓膜传进内耳
from the eardrum into the inner ear.
这个组合复杂而高效
Now, this setup is so intricate and so efficient,
以至于这些骨头看起来
it almost looks as if those bones could only ever
专门为这个目的诞生
have been for this purpose,
但其实 如果回顾我们
but in fact, you can see their origin
的进化史 你就能发现它们的由来
if you look way back in our evolutionary history.
为了了解我们耳内的这些小骨头
In order to understand where that collection of small bones
从何而来
in our ears came from,
你得追溯回到
you have to go back in our evolutionary family tree
远早于当今鱼类的时期
way beyond the fish that we see today.
事实上 在大约5.3亿年前
In fact, back around 530 million years
海洋中遍布着无颚鱼
to when the oceans were populated with jawless fish,
属于无颚类
called agnathans.
它们相似于现在的八目鳗
They're similar to the modern lamprey.
它们没有颌骨
Now, they didn't have a jaw,
但它们有鳃弓支撑着的鳃
but they had gills supported by gill arches.
经过大约五千万年
Now, over a period of 50 million years,
这些鳃弓的最前端
the most forward of those gill arches
移♥动♥到了头部的前方
migrated forward in the head
形成了颌骨
to form jaws.
在4.6亿年前的化石中
And you see fish like these,
你可以看到最早
the first jawed fish in the fossil record,
有颌骨的鱼类
around 460 million years ago.
在颌骨后面
And, there, at the back of the jaw,
有块骨头 叫舌颚骨
there is that bone, the hyomandibular,
支撑着颌骨的后方
supporting the rear of the jaw.
大约4亿年前
Then, around 400 million years ago,
最早的脊椎动物从海洋走上陆地
the first vertebrates made the journey from the sea to the land.
它们的鳍变成了腿
Their fins became legs,
但在它们的颅骨和喉咙内
but in their skull and throat,
其他变化悄然发生
other changes were happening.
它们不再需要鳃
The gills were no longer needed
来呼吸大气中的空气
to breathe the oxygen in the atmosphere,
所以鳃渐渐退化
and so they faded away
演变成了颅骨和喉咙中不同的结构
and became different structures in the head and throat,
而那块舌颚骨
and that bone, the hyomandibular,
变得越来越小
became smaller and smaller,
直到功能也改变了
until its function changed.
它现在负责接收颌骨中的震动
It now was responsible for picking up vibrations in the jaw
然后传递到爬行动物的内耳中
and transmitting them to the inner ear of the reptiles.
直到现在 这依然适用于那边的朋友
And that is still true today of our friends over there...
鳄鱼先生
The crocodiles.
又是短吻鳄
Once more with alligator.
即使那样 演变还在继续
But even then, the process continued.
大约2.1亿年前
Around 210 million years ago,
第一种哺乳动物诞生
the first mammals evolved,
不像我们的朋友 这种爬行动物
and unlike our friends, the reptiles here,
哺乳动物的颌骨仅有一块骨头
mammals have a jaw that's made of only one bone.
爬行动物的颌骨是由几块骨头组成的
A reptile's jaw is made of several bones fused together,
所以就多出了两块骨头
so that freed up two bones,
它们移♥动♥ 并缩小
which moved, and shrank,
最终变成了锤骨 砧骨和镫骨
and eventually became the malleus, the incus and stapes.
对哺乳类动物听觉至关重要的
So this is the origin of those three tiny bones
三块小骨头就是由此而来
that are so important to mammalian hearing.
它真是个大块头 对吧
He's quite big, isn't he?
我觉得鱼腮中的骨头
I think this is a most wonderful example of the blind,
转化成我耳中的复杂结构
undirected ingenuity of evolution,
使其能高效地把声音从空气传入流体
that it's taken the bones in gills of fish and converted them
这个绝妙的例子完美展现出
into the intricate structures inside my ears
盲目无向的进化多么巧妙
that efficiently allow sound to be transmitted from air into fluid.
这个想法非常奇特
It's a remarkable thought that to fully understand
为了了解我耳朵的结构和功能
the form and function of my ears,
你必须追溯回到原始海洋
you have to understand my distant evolutionary past
去了解我的进化史
in the oceans of ancient earth.
我们在找皮皮虾
We're hunting for the mantis shrimp.
所有感官的进化都是为了一个简单的功能
All sensing has evolved to fulfil one simple function
那就是为我们提供生存所必需的信息
to provide us with the specific information we need to survive.
在那呢
There he is!
我可以试着去抓它
I might try and grab him.
而没有比视觉信息更清晰的了
And nowhere is that clearer than in the sense of vision.
太狡猾了 不好抓
He's quite tricky to catch!
几乎所有动物都看得见
Almost all animals can see.
96%的动物拥有眼睛
96% of animal species have eyes.
但眼睛所看到的东西却有着天壤之别
But what those eyes can see varies enormously.
你会好奇 是什么样的生活方式
So with an animal like the mantis shrimp,
让皮皮虾这种动物
you have to ask what it is about its way of life
需要如此复杂的视觉系统
that demands such a complex visual system.
拿这个手要稳 速度要快
Got to be very quick and very careful with this.
放它出来
Let him out.
皮皮虾复杂的眼睛
The complex structure of the mantis shrimp's eyes
使它能极其精确地确定深度
give it incredibly precise depth perception.
我们拥有双眼视觉
We have binocular vision.
距离 大约21厘米
我们用双眼从略微不同的角度观察事物
We look with two eyes from slightly different angles,
通过比较图像的差别
and judge distance by comparing the differences
判断距离
between the two images.
皮皮虾的每只眼睛都拥有三目视觉
Each of the mantis shrimp's eyes has trinocular vision.
同一个物体在每一只眼中成三个像
Each eye takes three separate images of the same object.
距离 21.4厘米
通过比较三个图像
Comparing all three
它们能极其精确地测距定位
gives them exceptionally precise range-finding,
并且利用此信息捕食猎物
and they need that information to hunt their prey.
撇开表象不说
Despite appearances,
这是种危险的动物
it is a dangerous animal.
它能发起自然界中最猛烈的攻击之一
He has one of the hardest punches in nature.
它身前这些黄色的附肢
Those yellow appendages you can see on the front of his body
叫做攻击附肢
are called raptoral appendages.
它们由腿部高度进化而来
They're actually highly evolved from legs,
攻击时力量惊人
and they can punch with tremendous force.
皮皮虾的攻击
The mantis shrimp's punch
是动物界中最快的动作之一
is one of the fastest movements in the animal world.
放慢至少一千倍
Slowed down by over a thousand times,
我们能看出其惊人的力量
we can clearly see its power.
它弹腿的力量堪比子弹
It can release its legs with the force of a bullet.
加速度 1♥0♥0♥0♥0♥g
在野外
In the wild,
它们利用这种猛击来击碎猎物的硬壳
they use that punch to break through the shells of their prey.
冲击力 体重的2500倍
但也能轻易地打断我的手指
But it could easily break my finger.
精确地部署利用这一强大武器
The need to precisely deploy this formidable weapon
才使得皮皮虾进化出
is one of the reasons the mantis shrimp has developed
精确测距的能力
its complex range-finding ability.
这种猛击
And that punch
还能解释它们复杂的色觉
can also help explain their sophisticated colour vision.
前肢
用来威慑对手
它们身体上的彩斑
Because the coloured flashes on their body
能够警告同类 自己将要发动攻击
warn other mantis shrimp that they may be about to attack.
尾部彩斑
用来吸引配偶
而其他彩色信♥号♥♥则另有含义
While other colour signals have a quite different meaning.
不过要在大海里读取这些信♥号♥♥
Yet reading these signals in the ocean
是异常困难的
can be surprisingly difficult.
在深海中 随着光线
In the deep ocean, colours shift from minute to minute,
和海里情况的改变
from hour to hour, with changing lighting conditions,
色彩也在时时刻刻发生改变
changing conditions in the ocean,
但人们认为
but it's thought that
即使光质变化异常剧烈
even though the light quality can change tremendously,
皮皮虾仍然可以