与摩根·弗里曼一起穿越虫洞（2010）

Through The Wormhole With Morgan Freeman S04E05

Part 1 April 19, 2021, 2:53 p.m.

生活中的每个人
Every single person who has ever lived
都源于一个男人和一个女人的基因
was created from the genes of one man and one woman.
但科技已经处于
But technology is on the brink
重写生殖规则的边缘
of rewriting the rules of procreation.
我们很快就能让两位父亲或两位母亲拥有自己的孩子
We could soon make children from two fathers or from two mothers.
婴儿可以在子♥宫♥外生长
Babies could grow outside the womb.
我们甚至还能创造杂交人类
We might even create hybrid people --
半人半兽
part human, part animal.
人类数百万年未曾改变的生殖方式
Human reproduction, unchanged for millions of years,
即将经历一场革命
is about to undergo a revolution.
性别会消失吗？
Will sex become extinct?
空间，时间，生命本身
Space, time, life itself.
宇宙之谜，尽在穿越虫洞
The secrets of the cosmos lie through the wormhole.
与摩根·弗里曼一起穿越虫洞（S04E05）
Through The Wormhole With Morgan Freeman (S04E05)
性别会消失吗？
Will Sex Become Extinct?
性非常神奇
Sex is amazing.
为什么这么说呢？
Why?
好吧，因为没有性，我们不可能诞生
Well, because without sex, none of us would be here.
我们都是最初的
We are all descendants
男性和女性的后代
of the very first human male and female,
圣经里说的是亚当和夏娃
the people the Bible calls Adam and Eve.
所有的人类历史中
And for almost all of human history,
我们生育孩子的方式从未改变
the way we have made babies has not changed at all.
不过人类生殖的美好新世界
But a brave new world of human reproduction
即将出现
is just around the corner.
新技术和不断进步的生物学
New technology and our evolving biology
将会改写未来的性
are about to rewrite the future of sex
改变男人和女人扮演的古老的角色
and change the age-old roles of men and women.
我还在读书时，希望能被选入田径队
When I was in school, I wanted to try out for the track team,
所以我决定和稳赢的对手比赛
so I thought I'd practice with a guaranteed win --
一个女生
against a girl.
各就各位。预备
On your mark. Get set.
开始！
Go!
加油，加油，加油，加油，加油！
Go, go, go, go, go!
让我惊讶的是，她竟然赢了——还是以明显的差距
Well, to my surprise, she won -- by a lot.
实际上，她最后成了奥林匹克冠军
In fact, she went on to become a olympic champion.
男人和女人总在竞争
Men and women have always competed
这是不同性别间的古老战场
in the age-old battle of the sexes.
如果大自然选择了一个赢家，人类会变成什么样子？
What will happen to humanity if nature picks a winner?
过去五亿年中，几乎所有的复杂生命
For the past half billion years, nearly all complex life
都通过有性生殖重组它们的基因
has reproduced through sexual recombination of their genes.
鸟类是这样
Birds do it.
蜜蜂是这样
Bees do it.
还有袋鼠也是这样
Even kangaroos do it.
但遗传学家詹妮·格雷夫斯认为
But geneticist Jenny Graves thinks the days
人类以两性产生后代的方式
of humans doing it to make offspring
可能时日不长了
could be numbered.
她通过这些远表兄妹的性别基因
She's peering into our future by looking at the sex genes
窥视我们的未来
of these distant cousins.
可爱的小东西
Dear little thing.
绝对很有趣的东西
Absolutely gorgeous.
你看它是个小男孩
And you can see it's a little boy.
是的，当然
Yes, I certainly can.
因为它的生殖器官很健全
Because he's well-endowed.
确实
Well-endowed indeed.
袋鼠看起来和人不大一样，但实际上
Kangaroos don't look much like humans, but in fact,
它们有着和我们很类似的基因
they have pretty much the same set of genes --
大约2万个基因
about, you know, 20,000 or so genes --
做着同样的工作
doing the same jobs.
基因是所有生物的基础
All living things are built from genes
它们由DNA组成
that are made up of DNA.
这些基因卷曲压缩成为染色体
Those genes are coiled up into clusters called chromosomes.
我们有23对染色体
We have 23 pairs of chromosomes.
人类和袋鼠的性别
Gender of both humans and kangaroos
都依赖于其中一对
depends on just one pair.
女孩有两个X染色体
Girls have two "X" Chromosomes.
男孩有一个X染色体和一个Y染色体
Boys have one "X" And one "Y."
我们从共同的祖先那里，遗传了这种组合
we inherited this scheme from a common ancestor.
袋鼠更像是哺乳动物的祖先
Kangaroos are much more like the ancestral mammal,
它们并没有发生很大的改变
and they haven't changed nearly as much,
这样它们就给了我们通往过去的窗口
so they give us a window on the past,
对它们的研究，确实增加了对我们自己基因组的了解
and they really tell us a lot about our own genome.
通过对袋鼠性染色体的研究
By looking at the sex chromosomes of kangaroos,
詹妮能够看到我们发生了多大程度的改变
Jenny can see how much our own have changed.
她也可以推测出我们性染色体的未来
She can also plot the future of our sex chromosomes.
詹妮的研究表明，这会是个坏消息
And according to Jenny, it's bad news.
男性人类，就像她的孙子费利克斯
Human males, like her grandson Felix,
正站在灭绝的道路上
are on the road to extinction.
好吧
All right.
我要用这些代表基因的积木
Well, I'm gonna build a chromosome
组建一个染色体
out of blocks of genes.
费利克斯，再给我拿一些蓝色积木吧
Felix, maybe you can hand me some more blue blocks.
男人和女人都有一个X染色体
Both men and women carry an "X" Chromosome.
在DNA这个微观世界中，它就像个摩天楼
In the microscopic world of DNA, it's a skyscraper,
一个大约1千“层”基因的高楼
a tower of around 1,000 genes.
但是男性特有的Y染色体
But the "Y" Chromosome, exclusive to men,
更像是一个破败的小屋
is more of a run-down shack.
这是女性的两个X染色体
So, this is a female with two "X" Chromosomes,
一条来自母亲，一条来自父亲
one from the mother, one from the father,
然后，这是男性的
and then this is a male.
他只有一条X染色体
He's only got one "X" Chromosome,
和一条非常小的Y染色体
and he's got a much smaller "Y" Chromosome.
这样它就有很少的基因
It's got hardly any genes on it.
所有的女性卵细胞中都有一条X染色体
All female eggs contain a single "X" Chromosome.
而男性几十亿个将要和卵细胞碰面的精细胞中
Of the billions of sperm cells a man sends towards a woman's egg,
一半数量含有一个X染色体，另一半则含有一个Y染色体
half contain an "X," The other half a single, puny "Y."
当一个携带X染色体的精细胞
when a sperm cell with an "X" Chromosome
先和卵细胞接触融合，产生的就是女孩
gets to the egg first, the result is a baby girl
一条X染色体来自妈妈，一条X染色体来自爸爸
with one "X" From mom and one "X" From dad.
如果将这两条
What happens is
X染色体放在一起，它们就可以部分交换
these two "X" Chromosomes get together, and they swap bits.
比方说，这里的一点可以与这里的交换
For instance, that bit there swaps with that bit there,
接下来也可能这里的一点也发生了交换
and then maybe this bit swaps with that bit,
结果你就会得到这种状态的染色体
and you end up with something that looks like that.
而这点是非常重要的
And this is really important
因为这表示X染色体
because it means that the "X" Chromosomes
可以自我修复
can repair themselves.
女性体内，X染色体上一些有害的基因突变
In women, any harmful genetic mutations on the "X" Chromosome
可以在传给下一代之前
can be swapped out with healthy genes
被正常的基因替换修复
before it gets passed to the next generation.
但男性就没办法修复Y染色体
But men have no way to repair their "Y" Chromosome.
因为没有第二条Y染色体
There's no second copy to fall back on.
这条Y染色体完全不会进行交换
This "Y" Chromosome doesn't swap pieces at all,
它就会一直保持着一小捆的状态
so it just stays in a little bundle,
而这对Y染色体来说是件坏事
and this is a bad thing for the "Y" Chromosome
因为如果它发生了错误、错配或者突变
because if there are mistakes and errors and mutations,
这就很糟糕了
that's too bad.
它没办法进行修复
There's no way of fixing them up.
最后的结果就是基因的丢失
And eventually what happens is you actually lose genes.
接着这条微小的Y染色体
And then this little teeny-weeny "Y"
就有很大的风险会全部丢失
is at great risk of being lost altogether.
这样，大约在四百万到五百万年中
And so, in maybe four or five million years,
Y染色体就会消失
there'll be nothing left.
没有了Y染色体
Without a "Y" Chromosome,
男性就会变得不育
men would become infertile.
那么接下来人类就会灭绝吗？
Would the extinction of humanity follow?
进化生物学家里维·莫伦想要知道
Evolutionary biologist Levi Morran wants to know
当一个种族不再进行有性生殖时会是什么样
what happens when a species can no longer sexually reproduce.
他正在通过运动解决这个问题的细节
He's working out the details by working out.
有许多次当我正致力于某个特定项目
There are times when I'm working on a specific project