达尔文和生命之树（2009）

弗朗西斯·克里克和詹姆斯·沃森正在建立这样的模型
Francis Crick and James Watson,
were building models like this.
这是他们思考和研究一种复杂分子结构的方式
It was their way of thinking about
and investigating the structure
这种复杂分子存在于所有动物的基因中 – DNA。
of a complex molecule that’s found in the genes
of all animals – DNA.
至关重要的一点是这些链
The crucial bit are these chains,
这些链围绕着杆 –
which encircle the rod –
这是第二个 – 缠绕在一起
and here is a second – and entwine.
这是双螺旋结构
This is a double helix.
DNA分子的工作原理现在已经被如此详细地理解
The workings of the DNA molecule
are now understood in such detail
以至于我们能够证明一些真正令人震惊的事情
that we can demonstrate
something that is truly astounding.
从一种动物身上提取的基因可以在另一种动物身上发挥作用
A gene taken from one animal can function in another.
例如，将导致水母发光的基因
The gene that causes a jellyfish
to be luminous, for example,
移植到老鼠体内，就会使老鼠发光
transplanted into a mouse,
will make that mouse luminous.
遗传密♥码♥还能揭示血缘关系
The genetic code can also reveal relationships.
我们的法庭甚至接受DNA指纹
Even our law courts accept that DNA fingerprinting
能确定一个人是不是某个孩子的父亲
can establish whether a man is the father of
a particular child.
它也能揭示某一类动物是否与另一种动物有亲缘关系
And it can also reveal whether one kind of animal
is related to another.
例如，它证明了袋鼠 –
It proves, for example, that kangaroos –
在地面上生活的能以巨大跳跃奔跑的动物 –
ground-living animals that run with great leaps –
与已经开始爬树的树袋熊有着密切的关系
are closely related to koalas that have taken
to climbing trees.
这种以昆虫为食的鼩鼱同辈表亲是在空中飞来飞去
That insect-eating shrews have cousins that took
to the air
寻找昆虫的 – 蝙蝠
in search of insects – bats.
而大象家族的一个分支，在很久以前的地质历史中
And that one branch of the elephant family,
way back in geological history,
来到了水里，变成了海牛
took to the water and became sea cows.
因此，在达尔文的革命性著作出版150年后
So, 150 years after the publication of Darwin’s
revolutionary book,
现代遗传学已经证实了它的基本真理
modern genetics has confirmed its fundamental truth –
所有生命都是相关的
all life is related.
它使我们能够自信地构建
And it enables us to construct with confidence
展现生命历史的错综复杂之树
the complex tree that represents the history of life.
它起源于海洋
It began in the sea,
大约在3亿年前
some 3,000 million years ago.
复杂的化学分子开始成丛聚集
Complex chemical molecules began to clump together
形成微小的斑点 – 细胞
to form microscopic blobs – cells.
这些是生命之树生长的种子
These were the seeds from which the tree
of life developed.
它们能够分♥裂♥，像细菌一样自我复♥制♥
They were able to split,
replicating themselves as bacteria do.
随着时间推移，他们演化为不同的种群
And as time passed,
they diversified into different groups.
有一些仍然附属于另外一些，所以他们形成了链
Some remained attached to one another,
so that they formed chains.
我们今天知道它们是藻类
We know them today as algae.
其他那些形成了空心球体，他们自身坍缩
Others formed hollow balls
which collapsed upon themselves,
产生了一个有内腔的躯体
creating a body with an internal cavity.
它们是最早的多细胞生物 –
They were the first multi-celled organisms –
海绵动物是它们的直接后代
sponges are their direct descendents.
随着更多的变异出现，生命之树开始生长，变得更加多样化
As more variations appeared,
the tree of life grew and became more diverse.
一些生物体开始变得更灵活，并发展成开口的肠道
Some organisms became more mobile
and developed a mouth that opened into a gut.
其他的躯体由体内的杆加强
Others had bodies stiffened by an internal rod.
可以理解的是，它们的前端发育了感觉器官
They understandably developed sense organs
around their front end.
一个属于同一种类的种群躯体分♥裂♥成几部分
A related group had bodies that were divided
into segments
两边都有小小的突出部分，帮助他们在海底四处游动
with little projections on either side that helped them
to move around on the sea floor.
这些被分割的生物中有一些进化出硬的保护性皮肤
Some of these segmented creatures
developed hard protective skins
使它们的躯体有了一定的硬度
which gave their bodies some rigidity.
因此现在的海洋里充满了各种各样的动物
So now the seas were filled with a great variety of animals.
然后，大约4.5亿年前
And then, around 450 million years ago,
这些甲壳动物中的一些爬出水面，冒险登上了陆地
some of these armoured creatures crawled up,
out of the water and ventured onto land.
在这里，生命之树分支出许多不同的物种
And here, the tree of life branched into a multitude
of different species
以各种方式利用这个新环境
that exploited this new environment in all kinds of ways.
其中一族在他们的背上进化出细长的片状襟翼
One group of them developed
elongated flaps on their backs,
经过许多代之后，最终发展成翅膀
which, over many generations,
eventually developed into wings.
昆虫出现了
The insects had arrived.
生命进入空气中，并多样化成为无数的形式
Life moved into the air and diversified into myriad forms.
同时，在海洋里
Meanwhile, back in the seas,
那些躯体有硬杆的生物，用骨头把它包裹起来，使它更坚固
those creatures with the stiffening rod in their bodies
had strengthened it by encasing it in bone.
头骨发育了，有铰链状的下颚，可以攫取并保住猎物
A skull developed, with a hinged jaw that could grab
and hold on to prey.
他们长得更大，并进化出鳍
They grew bigger, and developed fins
鳍上的肌肉使他们能够获得游泳的速度和力量
equipped with muscles that enabled
them to swim with speed and power.
所以鱼类现在主宰了这个世界的水域
So fish now dominated the waters of the world.
其中一个族群进化出了能在水面上呼吸空气的能力
One group of them developed the ability to gulp air
from the water surface.
它们的肉鳍变成了支撑体重的腿。3.75亿年前
Their fleshy fins became weight-supporting legs
and 375 million years ago,
一些这种脊椎动物跟着昆虫来到陆地上
a few of these backboned creatures followed
the insects onto the land.
它们是皮肤潮湿的两栖动物，必须回到水里产卵
They were amphibians with wet skins
and they had to return to water to lay their eggs,
但它们的一些后代进化出干燥、有鳞的皮肤
but some of their descendents evolved dry, scaly skins
并通过产卵带防水壳的方式打破了与水的联♥系♥
and broke their link with water by laying eggs
with watertight shells.
这些爬行动物是今天乌龟、蛇、蜥蜴和鳄鱼的祖先
These creatures, the reptiles, were the ancestors of
today’s tortoises, snakes, lizards and crocodiles.
当然，其中也包括了当时统治这片土地的群体 – 恐龙
And of course they included the group that back
then came to dominate the land – the dinosaurs.
6500万年前，一场巨大的灾难突然降临地球
But 65 million years ago,
a great disaster overtook the Earth.
不管是什么原因，很大一部分动物被灭绝了
Whatever its cause,
a great proportion of animals were exterminated.
所有的恐龙都消失了，除了一个分支以外
All the dinosaurs disappeared, except for one branch
它们的鳞片已经变成了羽毛
whose scales had become modified into feathers.
它们就是鸟类
They were the birds.
当它们在天空中扩散时
While they spread through the skies,
一小群看似微不足道的幸存者在地下的数量开始增长
a small, seemingly insignificant group of survivors began to increase in numbers on the ground beneath.
这些生物与竞争对手的不同之处在于
These creatures differed from their competitors
它们的身体是温暖的，并用皮毛隔热 –
in that their bodies were warm
and insulated with coats of fur –
它们是最早的哺乳动物
they were the first mammals.
大灾难过后，许多土地都闲置着，现在他们有了机会
With much of the land left vacant after the great
catastrophe, they now had their chance.
他们温暖的、绝缘的身体使他们在任何时候都很活跃
Their warm, insulated bodies enabled
them to be active at all times,
无论是在晚上还是白天
at night as well as during the day.
在所有地方，从北极到热带
And in all places, from the Arctic to the Tropics.
无论是在水中还是在陆地上
In water as well as on land.
在草原上和树上
On grassy plains and up in the trees.
毫无疑问，我们与这些黑猩猩有着密切的关系
There can be no doubt about our close relationship
to these chimpanzees.
我们的身体如此相似
Our bodies are so similar,
我们的四肢和面部的比例可能不同
the proportions of our limbs or our faces may differ,
但在其他方面我们非常非常相似
but otherwise we are very, very similar.
我们内部器官的排列，血液的化学成分
The arrangement of our internal organs,
the chemistry of our blood,
身体的工作方式……所有这些几乎都是一样的
the way our bodies work…
All these are almost identical.
DNA 证实了这一点
And DNA confirms that.
事实上，我们与黑猩猩、其他猿类
Indeed, we are as closely related to chimpanzees
和猴子的关系，就像狮子与老虎
and the rest of the apes and monkeys as, say,
lions are to tigers
和其他猫科动物的关系一样密切
and to the rest of the cat family.
突然，一幅来自我们遥远过去的图像生动地曝光了-
Suddenly, an image from our remote past comes
vividly to light –
那个时代，我们遥远的祖先
the time when our distant ancestors,
为了适应不断变化的环境
in order to keep up with the changing environment,
不得不蹚水，把头露出水面
had to wade and keep their heads above water
以找寻食物
in order to find food.
那是一个我们的远祖
That crucial moment when our far distant ancestors
一步一步地远离类人猿、走向人类的关键时刻
took a step away from being apes and a step
towards humanity.
这所自然历史博物馆是世界上最重要的同类博物馆之一