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3个隐藏在你身体里的惊人的“化石” – 译学馆
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3个隐藏在你身体里的惊人的“化石”

3 Incredible Examples of Evolution Hidden In Your Body

嗨 聪明人你好
Hey smart people.
我是Joe
Joe here.
查尔斯·达尔文花了五年时间环游世界
Charles Darwinspent 5 years circling the world,
去探索物种起源
to discover what became The Origin Of Species.
阿尔弗雷德·拉塞尔·华莱士花了八年时间
AlfredRussel Wallace spent 8 years traveling
走遍南亚来见证进化史
through South Asia to witness the story of evolution.
但如今你哪也不去 就能发现一样的事情
But you can discover the same thing today without going anywhere.
因为进化就发生在你的身体里
Because the story of evolution is right there in your body.
你的尾骨?
Your tailbone?
以前是条尾巴
Used to be a tail.
如果你会动耳神功 这得归功于你
If you can move your ears, that’s thanks to
和其他哺乳动物一样的肌肉群
muscles you share with other mammals.
你眼角的红点?
That pink bitin the corner of your eye?
那是第三眼睑的残余
A leftover of a third eyelid
我们还能在蜥蜴 鸟类 鱼类等其他动物身上发现这种特征
we can still find in lizards, birds ,fish, and others.
鸡皮疙瘩是我们和很多
Goosebumps are a feature we share with lots of animals
有体毛的动物的共性
that didn’t lose their body hair.
甚至打嗝 都能追溯到鱼类和蝌蚪的大脑
and even hiccups trace back to the brains of fish and tadpoles,
这个脑信号过去常用于把水从腮中挤出来
a brain signal they use to squeeze water through their gills.
在我们庞大的进化史中 这些身体的功能
These body parts are just a few scattered pages
仅仅是几个例子而已
in a larger story about our evolution.
还有其它隐藏在我们的身体里的“化石”
But there’s other fossils hidden inside our bodies
更清晰地讲述着
that tell an even clearer tale
我们是如何成为现在的模样
about how we came to be the way we are.
《聪明刷》
其中一个故事十分简单
One of these stories is so simple,
仅用一张图就能讲清楚
it can be told with a single picture.
第一章:2号染色体
CHAPTER 1:Chromosome 2
这些是染色体的图片
These are images of chromosomes,
大块头的DNA存在于我们的每个细胞里
the big chunks of DNA inside every one of our cells.
当我们观察人类染色体
when we look at images of human chromosomes
和其他类人猿染色体的图像时
next to those of other apes,
它们的排列非常相像
they line up nearly identically.
除了人类的2号染色体
Except for human chromosome 2.
似乎在猩猩的染色体中找不到和它相似的
It seems to have no match next to the other ape chromosomes.
更奇怪的是 人类共有46条染色体 23对
Even weirder, humans have 46 chromosomes in total, 23 pairs.
但是那些猩猩
but other apes
它们有48条染色体 24对
They have 48 chromosomes… 24 pairs.
这怎么解释呢?
What could explain this?
如果我们在进化上有关联
If we’re supposed to be related,
为什么我们人类却少了一对染色体
Why are we missing a chromosome
事实表明 并不是我们缺少了染色体
turns out we aren’t missing a chromosome at all.
而是在人类历史的某个时间段
Sometime during our species’ history,
这两条在其他猿类中至今仍然是分开的染色体
those two chromosomes that are still separate in other apes
被连接在一起 形成了我们的2号染色体
were welded to become our single human chromosome 2.
人类 黑猩猩 大猩猩 还有类人猿
Us, chimps, gorillas,orangutans,
我们今天所拥有的全部DNA
all inherited the DNA we have today

来自于我们有48条染色体的共同祖先
from some common ancestor with 48 chromosomes,
但是其中的两种在进化中被困住了
but two of us get stuck together along the way,
你甚至能看到两者有多么相似
and you can even see how they match up.
如果两条染色体粘合在一起
If two chromosomes were
你会想找到两个中点或者着丝粒
glued together you’d expect to find two centers or centromeres
我们找到了
And we do.
我们还想找到端粒
We’d also expect to find telomeres,
就是每个原始染色体在中间头对头连接的末端部分
the ends of each original chromosome, stuck head to head in the middle.
我们也找到了
And we do.
幸亏我们对人类基因组进行了排序
Thanks to sequencing the human genome,
才能定位出确切的
we can spot the exact DNA
融合发生的位置—在从序列终点开始的113602928个碱基上
base where this fusion happened: 113,602,928bases from the end.
进化论的化石就
A fossil of evolution,
隐藏在我们身体里
hidden in our own bodies.
在凯尔特人的神话里 有一个叫Tir nan Og的地方 一片青春永驻的土地
In Celtic mythology, there’s a place calledTír nan Óg: a land of eternal youth. When
当一个科学家发现某个蛋白质能使干细胞永久年轻时
one scientist discovered a protein that’s keeps stem cells forever young,
他以这一地名NANOG命名了该蛋白
he named it after this place: NANOG.
人类的NANOG基因在12号染色体上
The human NANOG gene is located on chromosome12.
至少该基因这一版是有效的
At least, the version of the gene that works.
在我们DNA中还分布着11种NANOG的受损版本
There are eleven other broken copies of NANOG spread throughout our DNA.
这些其他的版本
How did these extra copies
是怎么像乱丢的袜子一样在我们基因组分布的呢?
get spread through ourgenome like lost socks?
DNA复制时 有时相同的信息被错误地复制了两次
When DNA is replicated, sometimes the same bit gets mistakenly copied twice.
果然
And sure enough,
我们发现受损版本刚好和有效的NANOG基因相邻
we see one broken copy right next to the working NANOG gene,
像个混乱的DNA复印件
like a messed up DNA photocopy.
我们把这些损坏的基因叫作假基因
We call these broken genespseudogenes.
那么另外十条呢?
And what about the other ten?
这些假基因还有另一种传播方式
There’s another way these pseudogenes canspread.
在RNA用来合成蛋白质之前 NANOG
NANOG,like every gene, is copied, from DNA into RNA, letter by letter,
像每个基因那样 从DNA逐个碱基转录成RNA
before that RNA,is used to build a protein.
但是一旦经过了很长时间
But every once in a very long while,
RNA就错误地
that RNA gets mistakenly
逆转录成DNA
copied backwards, back into DNA
将这个基因的一个损坏的新版本送到我们的染色体上
pasting a new,broken version of the gene somewhere in our chromosomes.
在搜索数以亿记的碱基后
After searching the billions of letters
在我们的基因组 我们找到十个
in our genome, we’ve found ten
独立存在的NANOG残留片段
of these lonely NANOG leftovers in our DNA.
它们位置似乎是随机的 像被胡乱丢上去一样
Their locations seem random, like they were blindly tossed in.
现在 假设你要读取另一种动物的基因组
Now,say you were to read another animal’s genome,
在其储存的上亿个的DNA碱基中 你会发现
and you found these very same broken copies of NANOG, each pasted
那些非常相似的NANOG残留片段处于非常相似的位置上
in the very same locations, among billionsof letters of DNA.
这可能是个巧合
That would be a heckuva coincidence.
除非…… 这不是巧合
Unless… it wasn’t a coincidence.
这是我们在黑猩猩的
This is what we see when we search
基因组中寻找NANOG时观察到的
for NANOG in a chimpanzee’s genome.
原始的
The original,
十个单独的损坏副本
and ten of the lonely, broken copies,
都和我们一样 在相同的位置
all in the same locations as ours.
这说明
This only makes
可能在几百万年前
sense if, millions of years ago,
你我和黑猩猩有着共同的祖先
you and me and the chimpanzee share an ancestor whose
其DNA中已散落着这些损坏的基因
DNA was already littered with these brokengenes.
我们都继承了这个模式
We all inherited this pattern, because
因为我们有着同一条进化轨迹
we share an evolutionary link.
当然 与黑猩猩有共同的联系只是其中一点
Of course, it’s one thing to share a linkwith chimps.
那鸡呢?
But chickens?
这需要一些有力的证据
That would require some strong cluckin’ proof.
你和鸡有共同的特点吗?
One thing you have in common with a chicken?
你们都来自于一个卵
You both came from an egg.
在鸡蛋里面 成长的胚胎产生一种名为卵黄囊的东西
Inside a chicken egg, the growing embryo produces something called a yolk sac.
它包围着
It surrounds,
嗯……蛋黄 有助于逐渐吸收营养 形成一只鸡宝宝
well… the yolk, and helps gradually absorb nutrients to build a baby bird.
但是人类的卵子非常小
But human eggs are incredibly small,
只有十分之一毫米宽
only about a tenth of a millimeter across.
不像鸟或乌龟 人类的卵子不形成卵黄甚至外壳
Unlike birds or turtles, our eggs don’t make a yolk, or even a shell.
我们从母体获取营养和保护
We get our nutrients and protection from our mom’s body.
所以你会认为我们不需要卵黄 也不需要卵黄囊
So you’dthink–no yolk, no yolk sac.
但实际情况并非如此
But that’s not the case.
人类在孕期会产生一个空卵黄囊 但是中途就消失了
Humans make an empty yolk sac, and it disappears halfway through pregnancy.
这是一个线索:
This is a clue,
我们的受精卵 鸟类的蛋甚至是爬行动物的蛋有着相似的进化联系
that our eggs and bird eggs and even reptile eggs all share an evolutionary link.
但是我们能证明吗?
But can we prove it?
卵黄中有一种重要的物质叫卵黄生成素
There’s an essential ingredient in egg yolkscalled vitellogenin.
它是一种蛋白质
It’s a protein, which
这说明有一个承载着编码它的DNA的基因
means there’s a gene whose DNA codes howto build it.
卵生动物 脊椎动物都至少有
Egg-laying vertebrates all have
这个基因的一个副本
at least one copy of this gene.
但是 我们呢?
But what aboutus?
如果我们真的是从那些
If we really are descended from animals
一度下的蛋充满了卵黄的动物进化而来
that once laid eggs full of yolk,
我们能从人类的基因里面
can we find some leftover of that yolky gene hidden in
找到隐藏的卵黄基因遗迹吗?
human DNA?
2008年 研究人员发现:
In 2008, researchers found just that:
当他们对比人类的基因片段和鸡的基因片段时
Fragments of once-active egg yolk genes, hidden in our
他们发现 曾经活跃的卵黄基因片段就隐藏在我们的基因组中
own genome. and when they compared our versions to the chicken versions,
它们甚至有
they even had the
相同的临近基因
same neighboring genes around them.
这恰恰就是进化将会产生的
This isexactly what evolution would predict.
就像骨化石 我们看到我们祖先的遗迹
Just like fossil bones, we see remnants of our ancestors,
被损坏并且
broken and buried, in these
被埋在那些很难找到的地方
hard to find places.
世界上有许多关于创造的神话
There are many myths of creation around the world,
但大多数人都认可一个观点
and most agree on one thing: Humans
人类是特殊的 我们需要一个特别的故事
are special, and we need a special story
来讲述我们是怎样走到现在的
for how we got this way.
但当我们凑近打量自己的身体
When we take a close look
就会明白 这个特殊的故事就是进化的历程
at our own biology, we can see that special story is evolution,
也是我们与地球上
and it’s a story we
其他生物共享的进化故事 或多或少吧
share with every other living thing on Earth–somemore than others.
对于一些人来说 这种观点——我们的身体
To some people, the idea that humans–our bodies,
我们的大脑 我们的思想也都是
our brains, our thoughts–are also
进化的产物 去掉了一些人类的神奇色彩
the products of evolution removes some of the magic of being human.
但是也并不一定
But it doesn’t
当达尔文就这种人生观写到『这就是伟大』时
have to. When Darwin wrote “ there is grandeur
他的意思是:
in this view of life ” he meant that being
一个由进化塑造而来的物种就是完全不同的奇迹
a creature molded by evolution is a totally different kind
甚至当你知道它是如何实现时
of magic, the kind that still
进化的魔力依旧让你为之惊艳
amazes you, even when you know exactly how the magic is done.
保持你的好奇心
Stay curious.

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视频概述

人类与地球上的其它生物拥有着共同的基因片段,或多或者少,我们来自同一个祖先。

听录译者

收集自网络

翻译译者

YXG

审核员

审核员_SF

视频来源

https://www.youtube.com/watch?v=2GfKZlTRNjA

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