解释一切（2018）

[upbeat music playing]
护肤品广♥告♥不使用超大特写镜头 是有原因的
[narrator] There's a reason skin care commercials don't zoom in that close.
否则一片原始 且生机勃勃的平原 便会呈现出来
And if they do, it's this pristine, animated landscape.
皮肤的超级大特写 可能会让人感到不适
A real close-up of skin can be a little unsettling.
这什么啊？
Ew. What is that?
[gasps]
就算是最完美的皮肤
[narrator] Even the most perfect skin
也不过是一片粗糙又破裂的地带
is a rough and broken terrain,
遍布着油腻的沟渠和的毛发
crisscrossed with oily gullies and studded with hairs.
在这个奇怪的地域
And in this strange land,
会有恶龙出没
there be dragons.
科学家相信每一位成年人的脸上 都生有这些蠕形蟎虫
Scientists believe these Demodex mites are on the face of every adult human.
几乎可以确认 有些螨虫 现在就身在你脸上的毛囊之中
There are almost certainly some burrowed into your face follicles right now.
而且它们只是其中一种生物
And they are far from alone.
我们的皮肤上聚集了大量的 细菌与真菌
Our skin hosts vast herds of bacteria, fungi,
甚至微小的病毒
and even miniscule viruses.
这并不是有害的感染
This isn't a harmful infestation.
实际上 我们还真需要 这些微小的乘客
In fact, we need many of these microscopic passengers
来保持我们皮肤的健康
to keep our skin healthy.
但护肤品公♥司♥跟我们讲的却是另一套
But skin care companies tell a very different story.
大致内容不外乎 往脸上涂
Mainly, that what you need
一堆护肤产品才是正道
is an overwhelming array of products.
首款祛痘凝胶
[announcers] The first acne-proofing gel cleanser.
玻尿酸精华液 -微雕乳液
Hyaluronic acid serum. -Micro-sculpting cream.
既是洁面乳 也是面膜
It's a cleanser and a mask.
补水保湿是健康皮肤的基础
Hydration is the foundation of healthy skin.
起床后就拥有更年轻的皮肤 只需五分钟…
Wake up to younger-looking skin in just five…
-[voices overlapping] -[silence]
我们能够相信这些产品广♥告♥中 所承诺的功效吗？
[narrator] Can we trust all these products to do what they promise?
获得健康靓丽的皮肤有什么秘诀吗？
And is there some secret to healthy, beautiful skin?
我们从皮肤开始入手
[man 1] Let's begin with the skin,
从医生的角度来观察一下
by taking a look at it from the doctor's point of view.
她的皮肤可真好 这是最让我惊艳的一点
She has lovely skin. That's what I was most impressed by.
如果你能保持皮肤健康
[man 2] If you keep your skin clean, there's less chance
疾病就拿你没有办法
that a disease will be able to get started.
如果我的皮肤看起来靓丽又健康
If my skin's fresh and healthy-looking,
那是因为我基础打得好
I guess it's 'cause I've gotten down to basics.
从下巴到耳朵
From your chin to your ears.
从鼻孔到太阳穴
From your nostrils to the temples.
健康的皮肤就是美妙的皮肤
[man 3] The healthy skin is a beautiful skin.
剧名：皮肤
关于皮肤 专家们最想让你知道的是…
[Okonedo] If there's one thing the experts want you to know about skin, it's that…
这是我们最大的器官
It is our largest organ.
我们最大的器官
Our largest organ.
我们最大的器官
Our largest organ.
皮肤是你的免疫系统
[Okonedo] Skin is your immune system's
第一道防线 也是最有效的防线
first and best line of defense.
我喜欢用砖墙当比喻
I like to use the analogy of a brick wall.
砖块就是细胞
So, the bricks are the cells,
灰泥就是我们的天然油脂
and the mortar is our natural oils.
这面墙 也就是表皮
[Okonedo] This wall, the epidermis,
每个月都会完全重建一次
is completely rebuilt about once a month.
新的细胞出生于这里
New cells are born down here
慢慢上升到皮表 进而脱落
and make their way to the surface, where they flake off.
你可以看到的毛孔实际上是 毛囊的开口
The pores you can see are actually the openings of hair follicles.
这些毛孔并不只是毛多的地方才有 而是遍布于全身
They're nearly everywhere on your body, not just the places that look hairy.
和毛囊相连接的腺体所分泌出的 油蜡状物质叫做皮脂
Glands attached to the follicles put out an oily, waxy substance called sebum.
来帮助让我们的皮肤润滑 并保持其酸性
[Skotnicki] That helps lubricate our skin and acidify our skin.
你的皮肤并不是中性的 而是接近于5的弱酸性
[Okonedo] Your skin's pH isn't neutral. It's closer to five.
这让有害细菌难以存活
And that makes it harder for harmful bacteria to grow.
如果起防护作用的砖墙裂开了
If your protective brick wall breaks down,
异物与病菌就会很容易侵入
it's easier for foreign particles or germs to get in.
你的免疫系统会立即采取行动
Your immune system will leap into action,
你的皮肤会变红发痒
your skin will get red and itchy.
而这群免疫细胞会发现并攻击入侵者
And this whole army of immune cells will detect and attack the intruders.
当然还有皮肤最了不起的功能
And then, of course, there's the most remarkable feature of your skin.
一大群拿皮肤当做家园的生物
The host of creatures who call it home.
远在人类出现的数十亿年前
Billions of years before we evolved,
微生物占据了全球的每一个角落
microbes colonized every corner of the globe.
从北极冰河
From Arctic glaciers,
到硫潭
to sulfurous pools,
到海底火山口
to volcanic vents in the ocean floor.
在皮肤出现之后
When skin finally showed up,
只不过又多了一个 可以占据的栖息地而已
that was just one more habitat to colonize.
你的皮肤上有数不过来 多种多样的细菌、真菌
You actually have trillions of different bacteria, fungi,
病毒、原生动物
viruses, protozoa,
甚至是小型昆虫
even small insects.
皮肤所承载的环境是非常多样化的
The skin has a very striking diversity of different environments.
你的脸颊是一滩油腻腻的沼泽
[Okonedo] Your face is an oily marshland.
你的腋窝是黑暗潮湿的雨林
Your armpits are dark, wet jungles.
你的小臂是干燥的热带草原
Your forearms are dry savannas.
当你降生于世的时候 你的微生物群系首先形成
Your microbiome is first formed when you are born into the world.
突然间 你母亲的生物群系就在你那里落了脚
You're suddenly populated by your mother's biome,
而这就形成了一种坚固的基础
and that forms the sort of concrete foundation
会伴随你接下来的人生
that's going to stick with you for the rest of your life.
随着你的成长 它会不断发展
[Okonedo] And as you grow, it continues to develop,
起到决定作用的 是你的人生经历
shaped by your experiences.
譬如 你住哪里 你有没有宠物
[Oh] So, that can be where you live, if you have pets,
和谁住在一起
who you live with,
每天都要接触谁
and who you encounter on a regular basis.
每个人身上的生物群系 都有独特的特质
Each of us have kind of a unique signature.
科学家们在近几十年来
[Okonedo] Scientists spent the last couple of decades
一直在研究哪一个物种 究竟生活在何处
learning which species live where.
而现在他们正在努力研究 这些小生灵究竟有何目的
Now they're trying to figure out what all those critters are up to.
我们的脚趾缝里住有杆菌属
There's a bacillus bacteria living in between our toes
它们喜食我们汗液里的一种 叫做白胺酸的混合物
that eats a compound in our sweat called leucine,
汗脚之所以臭臭的就是这个原因
and it contributes to that rank and sweaty foot smell.
我们为何要与产生体臭的
Why on earth would we want to coevolve with this microbe
微生物共同进化呢？
that produces bad odors?
其实 这种杆菌
It turns out that this bacillus
是真菌感染的强效抑制剂
is a very potent inhibitor of fungal infections.
我们的脚会产生大量的白胺酸
[Okonedo] Our feet produce a weird amount of leucine.
就像是我们的身体 为这些细菌摆出了盛宴
It's almost as if our bodies are laying out a feast for these bacteria
所以它能防止我们得脚癣
so they'll keep us from getting athlete's foot.
然后还有表皮葡萄球菌
Then there's Staphylococcus epidermidis,
坐落在身体各个部位
which is found at different sites all over the body.
我们超爱表皮葡萄球菌
Yeah, we love staph epidermidis.
它会招募一种免疫细胞
It can recruit immune cell types
这种细胞可以治愈我们的伤口 并且对抗感染
that allow us to heal wounds and combat infection.
它们会杀死病原菌
They can kill pathogenic bacteria. -[bacteria shouts]
抗生素也可以做到这件事
[Okonedo] Antibiotics can do that too.
[bacteria scream]
可通常也会把有益菌一起消灭
Though helpful bacteria are often collateral damage,
而且一些病原体会演变出耐药性
and some pathogens are evolving resistance to these drugs.
这种骇人的趋势席卷世界
It's a terrifying trend around the world,
特别是在医院中
especially in hospitals.
茱莉亚吴的实验室通过基因工程 让表皮葡萄球菌
Julia Oh's lab is genetically engineering a strain of epidermidis
攻击其中一种最常见的耐药菌
to attack one of the most common antibiotic-resistant bacteria.
就像是那种专门搜索歼灭的机器人
Basically like a search and destroy bot.
这种增强型的表皮葡萄球菌 只有在感觉到
[Okonedo] This souped-up epidermidis only attacks
一种特殊的病原菌存在的时候 才会发动攻击
when it senses this one particular pathogen.
然后产生出一种类似凝固汽油弹 一样的武器
[Oh] And then produces a kind of napalm in response.
最后 科学家认为这些微生物
[Okonedo] And finally, scientists think that microbes
可以训练我们的免疫系统 知道谁是敌人谁是朋友
train our immune systems to tell friend from foe,
所以我们只需要 对有害之物做出反应就好
so we only react to things that are actually harmful.
我们并不能完全确定 如果没有微生物群系会发生什么
We don't know exactly what would happen without our microbiomes.
我们从未培养过无菌人
We've never made germ-free people.
但我却培养出来过
But we have made germ-free
无菌小白鼠
mice.
它们在被养育的时候从未接触过 任何活体微生物
They grow up not having been exposed to any live microbes.
它们才是真正的与世隔绝
They live their lives in a bubble.
这些小白鼠都出现了不同种类的缺陷
And these mice have all sorts of different defects.
因为年幼时期没接受过微生物的历练 它们的免疫系统会感到