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牙齿究竟是怎么形成的 – 译学馆
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牙齿究竟是怎么形成的

Where Do Teeth Come From?

嘿大家好
Hey smart people.
我是乔
Joe here.
几个月前 我儿子长出了他的第一颗牙齿
A couple of months ago, our son got his very first tooth.
过了大概三个月 他依然只有一颗牙齿
And then for like 3 months, he still only had one tooth.
他看起来蛮可爱的
He looked adorable.
但是也有一点点滑稽
But also a little bit ridiculous.
同时这也让我开始思考 我们的牙齿到底从哪来的呢
Now this got me thinking… where do teetheven come from.
也就是说 这是怎么发生的?
Like…how does that happen?
牙骨是如何从我们脸颊里面生长出来的?
How do bones start growing out of our faces? So,
所以我做了一些研究 而我发现的这些事实
I did some research, and what I found…
我不能当做看不见
I’ll never be able to unsee.
同样你也不能错过
And you probably won’t be able to unseeit either.
让我们一看究竟吧
Let’s check it out!
展开
[OPEN]
牙齿真是令人感到不可思议 它们以一种令人惊异的方式生长
Teeth are weird and awesome, and they grow in weird and awesome ways.
那么它们是如何长出来的呢
So where do they come from?
为了解这一点 我们必须往前追溯
To understand that, we have to go way back.
你出生之前
Before you were even born.
实际上在你有大脑之前
Actually before you even had a brain… no.
我的意思是你看上去大致像这样的时候
I mean when you looked roughly like this.
经过三周的发育 你的身体就像一个小圆盘
Around three weeks into development, your body was just a flat little disc.
那时你差不多就是一个平面体
You were pretty two-dimensional.
然后你卷进一个管子
Then you rolled yourself up into a tube.
这是你做过的最重要的事了
It’s one of the most important things you’veever done!
所以此处应有掌声
So congrats on that.
这个管子形成于
The tube that forms
胚胎时期 它周围环绕着非常重要的干细胞
from this embryonic origami is surrounded by incredibly important stem cells.
它们移动并形成了你身体中最重要的某些部分
They migrate and build some of your most important parts – the spinal cord, brain,
脊髓 大脑 骨头
the bones
在你靠近心脏部分的中耳区 还有你的牙齿
in your middle ear to parts of your heart… and your teeth.
大概会停留6到8周
About 6 to 8 ___ weeks in,
这些细胞的小部分在它们将要变化的地方形成碰撞
little groups of these cells form bumps under what will become
你的牙龈正在经历一次改变
your gums, and they undergo a transformation!
一些变成成牙质细胞 这些细胞形成牙质
Some become odontoblasts – these cells make dentin,
坚硬的纤维牙质是牙齿的核心部分
the tough, fibrous core of the tooth.
这些细胞除了在碰撞还在完成蜕变
But the cells on top of those bumps transform too,
它们转变成的成釉细胞构建了搪瓷
into ameloblasts, the cells that build enamel,
搪瓷是你牙齿最坚硬的外层
the hard outside layer of your teeth.
形成釉质的过程是一种奇妙的细胞纳米技术
The process of building enamel is some awesome cellular nanotechnology,
而这就发生在你的脸上
up in your face.
造釉细胞分泌一种化学混合物 然后硬化变成矿物质结晶
Enamel-building cells secrete a mixture of chemicals that hardens into mineral crystals.
细胞继续往上移动
The cell moves up,
然后在上一层的表面分泌更多的矿物质
and secretes more mineral on top of the last layer.
最终造釉细胞死亡 留下了长长的透明结晶体
Eventually the enamel-building cell dies off, leaving a long crystalline rod behind.
这些成千上万的结晶物排列堆积 形成了你的牙釉质
Millions of these rods packed together make up the enamel layer of your teeth.
这种矿物质大部分是羟磷灰石
This mineral is mostly hydroxyapatite – tough stuff
它们非常坚硬而且富含钙质和磷酸盐
that’s rich in calcium and phosphate.
基本上像你口腔的岩石
Basically rocks, in your mouth.
和岩石一样 它们可以在合适的条件下
And like rocks, they can last a really long time
存在很长很长的时间
under the right conditions.
多长时间呢?
How long?
你能相信三万年吗?
Would you believe thirty thousand years?
这位和我在一起的是
I’m here
德州脊椎动物古生物研究所的主管
with Matt Brown he’s the Director of the Texas Vertebrate
马特布朗先生
Paleontology Collection.
那个非常大的东西是什么?
What is that enormous thing right there?
这个巨大的牙齿是剑齿虎的犬齿
This giant tooth right here is the canine tooth
这是一种有巨大牙齿的
of a saber-toothed cat from an animal
猫科动物
called Smilodon.
也常被叫做巨齿虎
What’s often called a saber-toothed tiger.
我们来看看这个单独从尸骨中脱出的牙齿
We’re looking at this individual tooth that’s fallen out of the skull.
当我们看一个化石
When we look at a
它看起来好像是普通的骨头 上面有其他的矿物质
fossil like a regular bone other minerals have taken the place
它们有点像岩石
of that bone and it’s
但是这更像是上釉的物质
sort of rock but this is pretty much enameled
比如猫科动物长出的牙齿
like the tooth the way that that cat grew it.
对 我现在手里拿着的
Yeah, what I’m holding here
就是活着的剑齿虎
in my hand is pretty much what was walking around inside
身体里长出的牙齿
of the living Smilodon.
还有什么旧的牙齿准备给我们看吗?
Got anymore old teeth for us to look at?
当然有 我们大概有一百来万的牙齿吧
We sure do, we’ve got probably about a millionof them.
这些是乳齿象的牙齿
So these are teeth from mastodons and you can see
你可以看到这些牙齿
that these teeth here they look pretty
它们看起来非常像我们的臼齿了
familiar as teeth they look very similar to to even some of our molars.
这颗牙齿有一个巨大的洞
This tooth here has a giant cavity in it just
就像我的牙齿一样
like my teeth we have got you can see
你在化石记录中也可以看到同样的情况
the same thing in the fossil record.
这提醒我们这些动物曾经活生生的存在过
It’s a reminder that these animals were aliveand walking around.
还有 乳齿象从来不刷牙
And the mastodon didn’t brush their teeth.
大概是这样
That’s probably the case.

Yeah.
我觉得我们可以看看更早一些的牙齿
I bet we can go even older.
好啊
We can.
这是暴龙左边脸的部分
This is part of the left side of the face
我们现在看到的
of a Tyrannosaurus and we’re looking at
这副躯壳的牙齿可是
teeth here preserved in this skull that are
七千万年前的
about 70 million years old that tooth is not
这些牙齿并不杂乱 反而很干净
messing around but very clean much
牙齿很健康 也许它们会刷牙
better dental health and they may have been brushing
或者也许不吃肉会更少蛀牙哦
or maybe a meat diet is better for less cavities.
我们还能再看看更早一些的牙齿吧
I bet we can go even older.
当然可以
We sure can.
我们现在站在侏罗纪世纪的展柜前
We’re standing in front of a cabinet from the Jurassic period.
这是大概
This is about a
1.95亿年前的双脊龙
hundred ninety five million year old dinosaur called Dilophosaurus and we’re
的牙釉质
looking at the enamel again. All right
好吧 你还有更早的吗?有啊
You got anything older? We do. So our last
我们最后一站就是这个宾夕法尼亚州的展柜
stop is this cabinet here in the Pennsylvanian some of
里面有我们这栋楼里两百万个化石中
the oldest teeth that we have in this building with
最古老的牙齿
about 2 million fossils in it and so we’re
我们现在看到的是3亿年前的牙齿
looking at a 300 million year old tooth
它们和这些动物们
with enamel that would be very very
嘴里的牙齿其实非常非常像
similar to the enamel that was swimming around in this animals mouth.
这是持续了3亿年
That is some long lasting teeth 300 million
绝不可能被错认的鲨鱼的牙齿
years old and that’s unmistakably a
这足以做成一条杀人项链了
shark tooth. That’d make a killer necklace.
所以生产牙釉质就像在你嘴里生产岩石
So building enamel is like making rocks inyour mouth.
当所有这些纳米制造牙釉质过程完成 你的乳牙最终形成了
When all this enamel nano-fabrication is complete, your baby teeth finally bust out.
而它们会在你的口腔下留下一个个的空位
And they each leave behind an empty space.
感谢干细胞 就在这里
And it’s here, thanks to stem cells,
同样的牙齿制造过程重复发生
that the same tooth-growing process repeats to
直到你长出恒牙
form your permanent teeth. So,
也就是在你出生前 你的乳牙就开始生长
your baby teeth started growing even beforeyou were born.
当你的乳牙长出后
And by the time your baby teeth came in,
你的恒牙就接着在后面
your permanent teeth were already growing in behind
继续生长
them.
也就意味着某个时刻 你的头骨是这样的!
That means at one point your skull lookedlike this!
是的 这完全是恐怖噩梦
Yeah… it’s pure nightmare fuel.
早说了 你不可能当做没看见的
Told you you wouldn’t be able to unsee it.
当你的乳牙感觉到后面恒牙在生长
As your baby teeth feel those adult teeth growing
它们的根部开始溶解
in behind them, their root dissolves
然后它们就脱落了
and they fall out.
最终成年人的牙齿会有28到32颗牙
Eventually you get between 28 and 32 teeth in your adult mouth.
但当这些恒牙长出后
But after those adult teeth grow in,
所有纳米结晶体后的干细胞就自我消亡
all the stem cells that laid down the crystal nanorods self-destruct,
所以你只能有这一副替换牙
so that’s the only set ofreplacement teeth you get.
那为什么我们不能保留那些生出牙齿的干细胞呢?
But why don’t we keep our teeth-growingstem cells?
科学家们还不能完全确定
Scientists aren’t totally sure yet.
不过也许有一天他们可以找到能长出新牙的方法
But maybe one day they could figure out a way to grow new teeth,
然后把人类变成
and turn us into human
鲨鱼
sharks.
转念一想 还是算了
On second thought, maybe not.
刷牙和牙线也不是那么恐怖啦
Brushing and flossing is much less frightening.
这就是牙齿的生长
So that’s how teeth grow.
在你有大脑之前
Before you even had a brain,
一支特殊的细胞队伍爬到你脑里
a special army of cells crawled to your head, and set up
然后在你的头骨里建造纳米晶体工厂 再生产出岩石
nano-crystal factories to basically buildrocks inside your skull.
我想有人应该告诉牙仙子
I think someone should tell the Tooth Fairy
这个故事可不止一美元哦!
that THAT story is worth more than a dollar.
永远保持好奇心
Stay curious

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视频概述

牙齿的形成过程,还有一些古老的牙齿化石

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翻译译者

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视频来源

https://www.youtube.com/watch?v=lNrVVHzJOSc

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