你体内的鱼（2014）

that flowed pretty much throughout the year.
很久以前，这里的景观看起来有着惊人的不同
Long ago, this landscape looked dramatically different.
它是有水的、潮湿的…
It was wet, humid,
有着巨大、笨重的动物…聚集在河岸边
with huge, lumbering animals crowding the river banks.
而这些和德国牧羊犬差不多大小的食肉动物，丽齿兽，
And these large, Alsatian-sized carnivores, the Gorgonopsids,
猎食着它们
which fed upon them.
所以，它们非常繁盛
So, they were flourishing.
在将近两千万年之中，丽齿兽…蚕食鲸吞了这整片大♥陆♥
For nearly 20 million years,the Gorgonopsids sliced and diced their way across the planet.
但是它们的恐布统治即将结束
But their reign of terror was about to end.
两亿五千两百万年前，气候开始有了戏剧性的变化
252 million years ago, the climate began to change dramatically.
这个大巨变…让许多的生物灭绝
This cataclysm wiped out most animal species...
包含了…丽齿兽
..including the Gorgonopsids.
当我们上来到这里，可以开始见到岩石的变化，
As we go up here, we start to see the change in the rocks from these
从有水的泛滥平原到这干旱地
wet flood plains to the drying out.
平原死去，土壤被冲走
Plants died, soils washed away.
卡鲁成为了死寂之地
The Karoo became a dead zone.
这是二叠纪末期的大灭绝，大死亡
This is the great end Permian mass extinction, the Great Dying.
大规模灭绝之母，像他们所说的？
The mother of all mass extinctions,as they say?
没有错，大规模灭绝之母
That's right,the mother of all mass extinctions.
你知道，当你思考关于地球上生命的历史…
You know, when you think about the history of life on Earth,
如果你摆出我们至今发现的所有化石，
if you lay out every fossil we've ever discovered,
必然会出现一个时期，许多的生物都消失了，
there's certain periods of time where many creatures just disappear, never
永远不会再见到，我们把这称作…你知道的…大灭绝
to be seen again and we call these,you know, the mass extinctions.
而这些大灭绝是极度的重要…
Well, these mass extinctions are hugely important
…对了解我们这个今日的世界
for understanding our world today.
了解我们的身体，它们是如何存在
Understanding our bodies,how they came into being.
因为这些大灭绝…不只是移除了生物，
Because these mass extinctions don't only just remove creatures
它们也为幸存者创造了机会，
but they create new opportunities for the survivors.
不是我们所有的远亲都在二叠纪大灭绝中罹难
Not all our distant relatives were wiped out by the Permian extinction.
化石证据告诉我们，其中有一些在地表上存活下来
The fossil evidence tells us that some survived on the surface,
而其他的…则躲在地底
and others burrowed underground.
尼尔，来看看这个…我们挖堀出一个地底洞穴
Neil, have a look at this. We're excavating an underground burrow.
这本来是在远古泛滥平原中的一个地洞
This was originally a hole down into the ancient flood plain,
由这些动物之一所挖堀出来
dug by one of these animals.
这洞穴被沙子给填满，而沙子现在已经硬化
And has been filled with sand and the sand is solidified now.
我们把这称作…"洞穴铸型"
And it's what we call a burrow cast.
这太酷了
This is so cool.
当你看着这个，它有点像是一个S型的曲线
When you look at this thing,it's sort of an S-shaped curve.
但是那里还有分支，那些分支是干什么用的？
But there's a branch going off of it.What's going on with the other shape?
那个是主室的入口，
Well, that's the entrance chamber
根据我们对一些现代洞穴动物的研究，
and we know from some of our modern burrowing animals
这些侧室是被当作厕所，或是放垃圾的地方
that these side chambers are used as latrines,or places to store their waste.
非常注重卫生，真叫人刮目相看
Very sanitary of them. I'm impressed.
罗杰认为，生活在地底，也许帮助了我们的祖先，
Roger thinks that living underground may have helped our ancestors
在极端的气候之中存活了下来
survive in a world of extreme temperatures.
而在这些洞穴之中，新的身体特征也许开始出现
And it's within burrows like this that a new body feature may have emerged.
一个对现今哺乳动物至关重要的特征
One that is important to all mammals today...
毛发
hair.
毛发化石很罕见，但是罗杰…
在这些远古洞穴中看到的有趣证据，
Hair rarely fossilises but Roger sees tantalising evidence in these ancient burrowers
也许可以解释它们是如何…及为何演化出来的
that may explain how and why it first evolved.
哇，这太美了，两副化石？
Oh, that is beautiful. Yeah.Two specimens?
这是两只三尖叉齿兽，两只幼三尖叉齿兽
That's two Thrinaxodon,two juvenile Thrinaxodon.
哇！这简直是美的无话可说
Wow! That is just absolutely beautiful.
你知道你有多幸运可以找到这些东西吗？这真是太棒了
Do you know how lucky you are to find things like this? This is great.
找到的时候真的很感动
It was quite a sensation to find that.
它们躺着的姿势，这只身体很漂亮的卷曲起来
The way they're lying,this body beautifully curled around,
这一只是直躺着
this one lying straight.
这看起来很像是他们的洞穴倒塌了
It really looks like the burrow has collapsed on these
它们可能是在睡觉或是冬眠，然后被保存了起来
and just preserved them as they were sleeping or hibernating.
你对这动物的生物学特征有什么了解？
So, what do you know about the biology of these creatures
从我们在这里看到的东西，骨骼结构…
just from what we're seeing here,the skeletons?
很清楚的可以知道，它是靠食虫为生
Its teeth clearly show that it had an insectivorous diet,
甲虫，蟑螂…类似的东西
beetles, cockroaches that sort of thing.
它有双大眼睛
It has large eyes,
所以它可能是夜行动物，或至少是在拂晓或黄昏出没…
so it appears to have been nocturnal, or at least in the dawn and dusk,
那时它们会从洞里出来捕食昆虫
where they would come out of their burrows to hunt insects.
毛？那是值千金的问题…三尖叉齿兽有毛吗？
Hair? That's the million dollar question. Does Thrinaxodon have hair?
我们不主张三尖叉齿兽全身都覆盖着皮毛
We prefer not to reconstruct Thrinaxodon with full body hair.
但是，我们确实找到两颊有胡须的证据
But, we do have evidence around the cheeks of whiskers,
在它们的下颚周围也有，还有上颌骨附近，在这里，
around the lower jaw as well as on their maxilla, around here,
主要被用来当作感觉器官，而不是温度调节
so more as a sensory organ than a thermoregulation.
这些头盖骨上的小凹洞，显示了三尖叉齿兽有胡须
These pits on the skull suggest that Thrinaxodon had whiskers,
就像今日的猫和狗一样
just like a cat or a dog today.
虽然我们不能完全的肯定
And, although we can't be completely certain,
但是没有证据显示，它身上其他部位是有毛的
there's no evidence that it had hair anywhere else.
所以…无毛的家伙留着胡须？
So, a hairless guy with whiskers at the front.
没有错，标准的混合构造动物
That's right, yeah.Very much a half and half animal.
如果我们能够回到过去，并深入到地底
If we could go back in time,and venture deep underground,
我们会看到毛发…也许是被当做感觉器官第一次被进化出来
we'd see that hair may have first evolved as a sensory organ.
胡须…可以为三尖叉齿兽在这地洞中…
Whiskers would have helped Thrinaxodon to navigate
为它们导航
inside its burrow.
而当它们出现在夜色中，
And when it emerged at dusk,
它们会用胡须在黑暗中找到道路
they were used to find its way in the dark.
研究认为，数百万年后，我们的远亲，
It's thought that, over millions of years, our distant relatives
变得愈来愈多毛，
got hairier and hairier.
最后，在三尖叉齿兽的五千万年后，
And, by 50 million years after Thrinaxodon,
它们开始将毛赋予了一个新的功能…保暖
they had started using hair for a new purpose, to keep warm.
所以，毛发可以回溯到拥有胡须的生物，
So, hair dates back to a whiskered creature
生活在大灭绝的冲击之后，
that lived in the aftermath of a great extinction.
复杂的牙齿，则可连结到掠食者在这片陆地上…
Complex teeth are linked to predators that battled
长远的生存战役
in long lost lands.
而防水的皮肤，则要回到当我们的祖先登陆那一刻
And a waterproof skin to a time when our ancestors moved onto land.
每一个这些身体特征，都连结到新的篇章，
Each of these body features is linked to a new chapter
在生命的历史之中
in the history of life.
但是毛发、牙齿和皮肤甚至有着更深的关连
But hair, teeth and skin share an even deeper connection.
其中之一，就在我们体内的爬行动物深处
One that lies at the heart of our inner reptile.
有一位在伦敦的科学家，名叫艾比盖儿.塔克
There's a scientist in London,named Abigail Tucker,
解释了这段远古历史
who's deciphering this ancient history.
这位是海绵宝宝，它是一只松狮蜥
This is SpongeBob,the bearded dragon.
尽管我们看起来…和我们的爬行朋友非常不同
And even though we look so different from our reptile friends here,
但其实我们在皮肤上…共享了许多同样的特征
we actually share lots of common features in our skin.
皮肤不只是外部的覆盖物
Skin is not just an outer covering.
在它上面，又发展出了不同的身体部份，像是头发、牙齿…
Out of it grow body parts as different as hair, teeth,
爪子…和鳞片
claws and scales.
艾比盖儿对调查这个谜团充满了热情，
Abigail's passion lies in probing the mystery of how
就是这些"皮肤器官"是如何形成的
these so-called skin organs form.
举例来说，拿一颗牙齿，
As an example, take the tooth.
从老鼠的胚胎中，
From a mouse embryo,
她从下颚处剪下了一小部份的皮肤组织，
she cuts out an area of skin tissue from the lower jaw,
而这些组织最终会转变成为牙齿
which will eventually transform into a tooth.
这样的工作需要非常稳定的双手
You need really steady hands for this kind of work.
在这里我使用的是钨针，
Here I'm using a tungsten needle,
但如果要处理非常小的组织，我们将睫毛黏合在玻璃棒上，
but for very small tissue,we glue an eyelash to a glass stick
然后把它当作一支很小的手术刀
and use that as a really fine little knife.
现在要开始了，好了
It's starting to go now.There we go.
这里我们看到的是芽胞阶段的牙齿，
So, here we're looking at a tooth at the bud stage.
它还不具有真正牙齿的形状，它本来是一片薄膜
It hasn't really sort of got a tooth shape yet, so it was a flat sheet
然后被不断推挤，形成现在这个芽胞的形状
and now it's pushed its way in,forming this little bud shape.
在将芽胞放置到培养器之后，艾比盖儿现在可以观察…
After placing the tooth bud in an incubator, Abigail can observe
它如何生长
how it grows.
而她所观察到的非常惊人
And what she sees is remarkable.
皮肤自已进行了折叠
The skin folds in upon itself,
就好像在看折纸一样
very much like watching origami.
现在你可以清楚的看到，那里形成了牙齿
And now you really can see that that's formed a tooth
而且不是任何的一颗牙齿
and it's not just any old tooth.
这是臼齿，拥有这些发展中的漂亮牙尖
It's a molar tooth, with all these nice cusps developing here.
而牙齿，才正要开始
And the tooth is just the beginning.
所有我们的皮肤器官，从头发…
All our skin organs, from hairs...
…到汗腺，都形成于类似的过程
..to glands, are formed in a similar way.
从皮肤组织…简单的折叠开始
From simple folds in skin tissue.