达尔文和生命之树（2009）

这显然是某种大型动物的下颚，当达尔文发现它的时候
It’s obviously the lower jaw of some great animal,
and when Darwin discovered it,
还有一些皮肤和毛发附着在上面
it had bits of skin and hair attached to it,
所以一开始它被认为是一些未知物种的遗骸
so that at first it was thought to be the remains of
some unknown living species.
现在我们知道它是一种灭绝了大约1♥0♥0♥0♥0♥年的物种，
一种生活在地面上的巨型树懒
But now we know that it is a species that was extinct
for some 10,000 years, a giant ground sloth.
欧文对它进行了非常详细的研究
Owen examined it in great detail
最后描述了它的样子，并将其命名为达尔文尼磨齿兽
and eventually described it and gave
it the name of Mylodon darwinii,
以纪念它的发现者
in honour of its discoverer.
但这两位科学伟人之间的相互尊重并没有持续下去
But that mutual respect between two great men
of science was not to last.
达尔文航行归来不久，就在肯特郡的唐豪斯定居下来
Soon after his return from his voyage,
Darwin made his home here, in Down House, in Kent.
在这里，他写下了他的旅行记录
Here he wrote an account of his travels
并致力于详细的科学论文
and worked on detailed scientific treatises about corals
关于珊瑚和藤壶以及南美洲的地质和化石
and barnacles and the geology and fossils of South America.
他也对在加拉帕戈斯和其他地方看到的情况进行了深入思考
But he also pondered deeply on what he had seen
in the Galapagos and elsewhere.
也许物种并不是一成不变的
Maybe species were not fixed
每天，他都会在花♥园♥尽头种下的
Every day, he took a walk in this small spinney
这片小灌木林里散步
that he had planted at the end of his garden.
正是在这里，他开始思考自然历史的问题
And it was here that he came to
ponder on the problems of natural history,
包括奥秘中的奥秘 –
including that mystery of mysteries –
一个物种如何变成另一个物种
how could one species turn into another.
他注意到大多数动物，如果不是全部的话
He noted that most, if not all, animals
所产的后代要比为繁殖而活的后代多得多
produce many more young than live to breed themselves.
例如，这只雌性蓝山雀一年很可能产下十几个蛋 –
This female blue tit, for example,
may well lay a dozen eggs a year –
在她的一生中可能会产50个左右
perhaps 50 or so in her lifetime.
然而它只需要两只雏鸟存活就能完成繁衍
Yet only two of her chicks need
to survive and breed themselves
并维持蓝山雀数目
to maintain the numbers of the blue tit population.
当然，这些幸存者可能是最健康的
Those survivors, of course, are likely to be the healthiest
最适合他们所处的特殊的环境
and best suited to their particular environment.
他们的特性随后被继承
Their characteristics are then inherited.
因此，也许在经过多代之后
So perhaps, over many generations,
特别是如果环境发生变化，物种很可能也会发生变化
and particularly if there are environmental changes,
species may well change.
只有适者生存，这才是关键
Only the fittest survive, and that was the key.
他将这个过程称为“自然选择”
He called the process “natural selection”.
这就解释了他在从加拉帕戈斯带回的
That would explain the differences
that he had noted in the finches
雀鸟身上注意到的差异
that he had brought back from the Galapagos.
它们非常相似，除了它们的喙
They were very similar, except for their beaks.
这只鸟有一个非常纤细的喙，用来捕捉昆虫
This one has a very thin,
delicate beak which it uses to catch insects.
另一方面，这一只
This one, on the other hand,
来自一个有很多坚果的环境
which came from an environment
where there were a lot of nuts,
它有一个又大又重的喙，可以把坚果咬碎
has a big, heavy beak which enables it to crack them.
因此，也许
So maybe,
经过漫长的地质时间
over the vastness of geological time,
特别是当物种侵入新的环境时
and particularly if species were invading new environments,
这些变化将会是非常彻底的变化
those changes would amount to very radical changes indeed.
达尔文在他的笔记本上画了一个草图来说明他的想法
Darwin drew a sketch in one of his notebooks
to illustrate his idea,
展示了一个单一的祖先物种是如何发展成几个不同的物种
showing how a single ancestral species might give rise
to several different ones,
然后在上面写了一个试探性的“我认为”
and then wrote above it a tentative “I think”.
现在，他必须证明自己的理论
Now he had to prove his theory,
他花了数年时间收集了大量令人信服的证据
and he spent years gathering
abundant and convincing evidence.
他是一个非凡的写信人
He was an extraordinary letter writer.
他每天给世界各地的科学家和博物学家写信多达十几封
He wrote as many as a dozen letters
a day to scientists and naturalists all over the world.
他还意识到
He also realised,
从人们第一次开始驯养动物时开始
that when people had first started domesticating animals,
他们已经为他做了几个世纪的实验
they had been doing experiments for him – for centuries.
所有的家养狗都是一个单一的祖先物种的后代 – 狼
All domestic dogs are descended
from a single ancestral species – the wolf.
养狗的人选择了那些具有恰好取悦他们的特征的幼崽来养
Dog breeders select those pups that have the characteristics that happen to please them.
自然界当然选择的是那些最适应当地环境的幼小动物
Nature, of course, selects those young animals
that are best suited to a particular environment,
但这一过程在本质上是相同的
but the process is essentially the same,
在这两种情况下，都产生了惊人的多样性
and in both cases it has produced astonishing variety.
实际上，许多不同的品种
In effect, many of these different breeds
可以被视为不同的物种，因为它们没有，实际上也不能跨品种繁殖
could be considered different species because they do not,
indeed they cannot, inter-breed.
由于纯粹的机械原因，京巴狗没办法跟大丹狗交♥配♥
For purely mechanical reasons,there’s no way in which
a Pekingese can mate with a Great Dane.
当然，如果你采用人工授精
Of course, it’s true that if you used artificial insemination,
你确实能将几乎全部的这些品种拿来杂交
you could get crosses between almost any of these breeds,
那是因为人类在狗之间进行选择的历史
but that’s because human beings have been
selecting between dogs
只有几个世纪
for only a few centuries.
而自然界对动物的选择进行了数百万年
Nature has been selecting between animals
for millions of years –
数千万年，甚至数亿年
tens of millions, even hundreds of millions of years,
所以我们原本认为是品种的东西
so what might have started out as we would
consider to be breeds
现在变得如此不同，成为了物种
have now become so different they are species.
达尔文坐在唐豪斯里，写信给鸽子爱好者和兔子饲养者
Darwin, sitting in Down House,
wrote to pigeon fanciers and rabbit breeders,
询问他们的方法和结果的各种详细问题
asking all kinds of detailed questions
about their methods and results.
他自己成了一名乡村绅士，并经营着一座庄园
He himself, being a country
gentleman and running an estate,
懂得饲养马、羊和牛
knew about breeding horses and sheep and cattle.
他还对其温室里的植物进行了仔细的实验
And he also conducted careful experiments with
plants in his greenhouse.
达尔文知道，如果没有神的干预，物种就可以出现的想法
But Darwin knew that the idea that
species could appear without divine intervention
会让整个社会感到震惊，
would appal society in general,
而且也违背他妻子艾玛的信仰
and it was also contrary to the beliefs of his wife, Emma,
她是一个虔诚的基♥督♥徒
who was a devout Christian.
也许是出于这个原因，他非常注重工作的科学性
Perhaps for that reason,
he was keen to keep the focus of his work scientific.
他强调自己的宗教信仰不会被公众所吸引
He made a point of not being drawn in public
about his religious beliefs,
但在后半生，他不再去教堂做礼拜
but in the latter part of his life,
he withdrew from attending church.
星期天，他会护送艾玛和孩子到唐的教区教堂
On Sundays, he would escort Emma
and the children here to the parish church in Down,
但当他们开始礼拜时
but while they went into the service,
他留在外面，在乡间小路上散步
he remained outside and went for a walk in the country lanes.
也许是因为担心自己的理论会在某些方面引起公愤
Perhaps because he feared that his
theory would cause outrage in some quarters,
他年复一年地推迟出版
he delayed publishing it year after year after year.
但是他写了一个很长的摘要
But he wrote a long abstract of it,
然后在1844年7月5日，他给妻子写了这封信
and then on July 5th 1844, he wrote this letter to his wife.
“我亲爱的艾玛
“My dear Emma.
“我刚刚完成了我的物种理论的草稿……”
“I have just finished this sketch of my species theory…”
一些草稿长达240页
Some sketch – it was 240 pages long.
“我写下这些是为了防备我突然离开人世
“I therefore write this in case of my sudden death,
“我希望你会致力于它的出版”
“that you will devote to its publication.”
接着，他又列出了他的各个博物学家朋友
He then goes on to list his various naturalist friends
那些被要求编辑和检查它的人
who would be asked to edit it and check it,
他在信的结尾迷人地写道:
and he ends the letter charmingly,
“我亲爱的妻子……
“My dear wife…
“你的挚爱，C.R. 达尔文”
“yours affectionately, CR Darwin.”
在接下来的14年里，他继续积累证据并完善他的理论
He continued to accumulate evidence and refine
his theory for the next 14 years.
后来，形势突变
But then, his hand was forced.
1858年6月，在他从加拉帕戈斯群岛回来的22年后
In June 1858, 22 years after he got back from the Galapagos,
在唐的书房♥里，他收到了一个包裹
here in his study in Down, he received a package
是一位在现在的印度尼西亚工作的博物学家寄来的
from a naturalist who was working in what is now Indonesia.
他的名字叫阿尔弗雷德·罗素·华♥莱♥士♥
His name was Alfred Russell Wallace.
他和达尔文通信已经好几年了
He had been corresponding with Darwin for some years.
但这个包裹不一样
But this package was different.
它包含了一篇文章，阐述了与达尔文完全相同的观点……
It contained an essay that set out exactly the same
idea as Darwin’s…
自然选择的进化
of evolution by natural selection.
这个观点是华♥莱♥士♥因患疟疾发烧处于半昏迷状态时产生的
The idea had come to Wallace as he lay in his hut,
semi-delirious in a malarial fever.
尽管他的自然选择观点和达尔文的观点是一样的
But although his idea of natural selection was
the same as Darwin’s,