达尔文和生命之树（2009）

它最终将提供答案
that would ultimately provide the answer.
一个在巴黎的波兰女人，玛丽·居里
A Polish woman working in Paris, Marie Curie,
发现一些岩石中含有一种叫做铀的元素
discovered that some rocks contained
an element called uranium
通过一种放射性衰变的过程，随着时间推移以稳定的速率衰减
that decays over time at a steady rate through
a process called radiation.
今天，在她这一非凡的发现一个世纪之后
Today, a century after she made her extraordinary discovery,
通过测量放射性变化
the method of dating by measuring
来确定年代的方法已经变得非常精细
changes in radioactivity has become greatly refined.
这是从查恩伍德森林中那些非常古老的岩石中提取的样本
This is a sample taken from those very ancient rocks
in Charnwood Forest.
这些微小的晶体已经有5.62亿年的历史了
And these tiny crystals are revealed
to be 562 million years old.
这为自然选择提供了
That provides more than enough time
足够的时间来产生化石，
for natural selection to produce the procession of fossils
最终形成我们今天所知的动植物的化石序列
that eventually leads to the living animals and plants
we know today.
但是还有另一种反对意见
But there was another objection.
如果一个物种中的所有动物都有一个共同的起源
If all animals within a group have a common origin,
那么为什么有些动物分布在
how is it that some kinds of animals are distributed
除南极洲以外的世界各大洲呢?
throughout the continents of the world,
except for Antarctica?
举例来说，欧洲和非洲的青蛙
How is it that, for example, frogs in Europe and Africa
在大西洋的另一边的
are also found here in South America,
南美洲也能找到
on the other side of the Atlantic Ocean,
别忘记青蛙有浸透性的皮肤，不能在海水中存活，
这是怎么做到的？
bearing in mind that frogs have permeable skins
and can’t survive in sea water?
达尔文自己有一些提议
Darwin himself had a couple of suggestions.
一种观点认为它们可能偶然以植物为筏飘浮过海
One was that they might have floated across accidentally
on rafts of vegetation,
另一种观点认为大♥陆♥之间可能有大♥陆♥桥
and the other is that maybe there were land bridges
between the continents,
但是连他自己也不能信服其中任何一种解释
but even he was not convinced by either explanation.
甚至到了1947年，当我还是剑桥大学地质学专业的学生时
Even as late as 1947,
when I was a geology student here at Cambridge,
也没有令人信服的解释
there was no convincing explanation.
的确，早在1912年，一位德国地质学家就提出
It’s true that back in 1912,
a German geologist had suggested
在非常遥远的古代某个时候
that at one time in the very remote, distant past,
我们今天所知道的地球上所有的大♥陆♥是聚在一起的
all the continents of the Earth that we know today
were grouped together
构成了一个巨大的超级大♥陆♥
to form one huge super-continent,
随着时间的推移，这个大♥陆♥分♥裂♥了，碎片化散开
and that over time this broke up and the pieces drifted apart.
这就提供了一个答案
That would have provided an answer.
但是当我问正在给我们讲课的地质学教授
But when I asked the professor of geology here
who was lecturing to us
他为什么不在讲课中告诉我们这个问题时
why he didn’t tell us about that in his lectures,
他回答说，我必须非常骄傲地说：
he replied, rather loftily I must say,
“当你能向我证明地球上有一种力量可以使大♥陆♥移♥动♥一毫米时
“When you can demonstrate to me that there is a force
on Earth that can move the continents by a millimetre,
“我会考虑，但在那之前，
这个想法是纯粹的胡言乱语，亲爱的孩子！”
“I will consider it, But until then,
the idea is sheer moonshine, dear boy!”
但是在20世纪60年代
But then, in the 1960s,
绘制海底详细地图成为可能
it became possible to map the sea floor in detail,
人们发现大♥陆♥不仅发生了变化
and it was discovered not only that
the continents have shifted
正如德国地质学家提出的方式移♥动♥
in just the way that the German geologist had suggested,
并且它们仍然在移♥动♥着
but that they were still moving.
新的岩石从地壳下面深处涌出
New rock wells up from deep below the Earth’s crust,
携带着大♥陆♥板块从大洋中脊往两边流动
and flows away on either side of the mid-ocean ridges,
carrying the continents with it.
两栖动物最初是在这片超级大♥陆♥上进化而来的
Amphibians had originally evolved on this super-continent
后来它们在各自的不同碎片漂移时跟着板块旅行
and had then travelled on each of its various fragments
as they drifted apart.
问题解决了！
Problem solved!
也许对大部分人来说，最大的问题是
Perhaps the biggest problem of all for most people
19世纪初英国圣公会牧师
was the argument put forward for the existence of God
威廉·佩利提出的关于上帝是否存在的争论
at the beginning of the 19th century
by an Anglican clergyman called William Paley.
他说，假设你在乡间散步，捡到了这样一个东西
He said, supposing you were walking
in the countryside and you picked up something like this.
你看了就会知道
You would know from looking at it
它被设计好了可以显示时间
that it had been designed to tell the time.
因此，必定存在一个设计者
There must, therefore, be a designer.
如果你观察自然界中错综复杂的结构，同样的争论也支持这一点
And the same argument would apply if you looked at
one of the intricate structures found in nature,
比如人类的眼睛
such as the human eye.
人类眼睛唯一可能的设计者是上帝
And the only designer of the human eye could be God.
反进化论者认为，眼睛只有在所有细节
Anti-evolutionists maintain that the eye would only work
都完整的情况下才能工作
if it was complete in all its details.
另一方面，达尔文认为眼睛已经成熟
Darwin, on the other hand,
argued that the eye had developed,
在很长一段时间内变得越来越复杂
becoming increasingly complex over a long period of time.
只有在发育的每一个阶段
That would only work if each stage of development
都比前一个阶段有所改进时，这才有效
was an improvement on the previous one,
今天，我们对动物王国的了解足够多，我们知道事实确实如此
and today we know enough about the animal kingdom
to know that that is indeed the case.
一些非常简单的动物除了一些感光点来辨认
Some very simple animals have nothing more than
light-sensitive spots
亮和暗的区别之外，什么也没有
that enable them to tell the difference
between light and dark.
如果一片这样的点形成，即使是最浅的凹陷
But if a patch of such spots formed even
the shallowest of pits,
凹陷的一个边缘会投下一个影子
one edge of the pit would throw a shadow,
从而揭示光的方向
and so reveal the direction of light.
如果凹陷变深并开始封闭，光线就会形成一个模糊的图像
If the pit got deeper and started to close,
then light would form a blurred image.
细胞分泌的粘液会使光线弯曲并聚焦
Mucus secreted by the cells would bend
the light and focus it.
如果黏液变硬，它就会形成一个合适的透镜
If this mucus hardened, it would form a proper lens
并传送一个更明亮、更清晰的图像
and transmit a brighter and clearer image.
所有这些复杂程度不同的
All these different fully-functional stages
功能完善的阶段，都可以在今天的活体动物中被发现
at different levels of complexity are found
in living animals today.
这个单细胞生物有一个那种感光点
This single-celled creature has one of those
light-sensitive spots.
扁形虫有一个小凹陷含有感光点
Flatworms have a small pit containing light spots,
因此他们能发觉掠食者的影子
so they can detect the shadow of a predator.
蜗牛的模糊视觉足够让它找到通往食物的路
A snail’s blurry vision is good enough to enable it
to find its way to food.
章鱼的眼睛有恰当的透镜，能像我们一样看到更多的细节
And the octopus has an eye with a proper lens
and can see as much detail as we can.
人类眼睛的结构不需要超自然设计者的协助
So the structure of the human eye does not demand
the assistance of a supernatural designer.
它能逐渐地进化
It can have evolved gradually,
每一个阶段带来一次真正的进步，
正如达尔文的理论所要求的那样
with each stage bringing a real advantage,
as Darwin’s theory demands.
自然选择，当然
Natural selection, of course,
需要动物的特性从一代传给下一代，代代传承
requires that an animal’s characteristics are handed
from one generation to the next.
很明显，孩子们长得像他们的父母
It’s obvious that children resemble their parents.
任何人都知道
Anyone knows that.
当你想到它的时候，那是怎么发生的呢？
But when you come to think of it,
how does that come about?
在达尔文时代，没有人知道
In Darwin’s time, nobody had the faintest idea
控制这一过程的机制或规则最模糊的概念
about the mechanism or the rules that
governed that process,
除了一个在捷克共和国布尔诺市工作的人
except perhaps for one man who was working
in the city of Brno,
就是达尔文在肯特郡写书的同一时间
in what is now the Czech Republic, at exactly the
same time that Darwin was writing his book in Kent.
那个人的名字叫格里高尔·孟德尔
That man’s name was Gregor Mendel.
他通过培育数千株豌豆植物
He discovered the laws of inheritance
观察它们如何从一代
by breeding thousands of pea plants
到下一代发生变化，发现了遗传规律
and observing how they changed from one
generation to the next.
他发现，虽然许多特征可以
He found that while many characteristics
一代一代地直接遗传给下一代
were passed down directly
from one generation to another,
但也有一些特征可以跳过一代。怎么会这样呢?
others could actually skip a generation.
How could that happen?
孟德尔解释说，每一种植物，每一种生物体
Mendel explained this by suggesting
that each plant, each organism,
都含有负责产生信息技术的因素
contained within it factors which were responsible
这些因素负责创造这些特殊的特征
for creating those particular characteristics.
今天，我们称之为基因
Today, we call those things genes,
但直到孟德尔时代100年后，人们才知道它们是如何工作的
but nobody had any idea how they
worked until 100 years after Mendel’s time.
后来在剑桥找到了答案
And then the answer was discovered in Cambridge.
1953年，在卡文迪什实验室，两位年轻的研究人员
In 1953, here in the Cavendish laboratories,
two young researchers,