Being human, we each view ourselves as a unique and independent individual, but we're never alone!
身为人类，我们视自己为独一无二的个体，但我们永远不孤独！
Millions of microscopic beings inhabit our bodies, and no two bodies are the same.
上百万的微生物以我们的身体为家，每个人的身体都不一样。
Each is a different habitat for microbial communities:
每个身体都是微生物群落独一无二的栖息地：
from the arid deserts of our skin, to the villages on our lips, and the cities in our mouths.
从荒漠般的皮肤表面，到嘴唇上的微生物村落，还有口腔内的微型城镇。
Even every tooth is its own distinctive neighborhood, and our guts are teaming metropolises of interacting microbes.
甚至每一只牙齿都是独特的社区，而我们的肠道则如同挤满了微生物的大都会。
And in these bustling streets of our guts,
在车水马龙的肠道中，
we see a constant influx of food, and every microbe has a job to do.
有源源不绝的食物，而每一种微生物都各司其职。
Here's a cellulolytic bacteria, for example.
比如说，纤维素降解菌。
Their one job is to break down cellulose, a common compound in vegetables, into sugars.
它们的唯一工作就是把纤维素，一种在蔬菜中常见的分子，降解成糖类。
Those simple sugars then move along to the respirators,
这些简单糖类会被输送至进行呼吸作用的细菌，
another set of microbes that snatch up these simple sugars and burn them as fuel.
这些微生物会吸收简单糖类，并将之作为生物能源消耗掉。
As food travels through our digestive tract,
当食物通过我们的消化道时，
it reaches the fermentors who extract energy from these sugars by converting them into chemicals,
发酵性细菌会通过将糖类进行转化，来吸取化学反应中的能量，
like alcohol and hydrogen gas, which they spew out as waste products.
并将产生的酒精和氢气当做废料排出体外。
Deeper in the depths of our gut city, the syntrophs eke out a living off the fermenters' trash.
在肠道城市的更深处，互营细菌以发酵细菌产生的废料维持生命。
At each step of this process, energy is released,
这个过程中的每一步都会释放出能量，
and that energy is absorbed by the cells of the digestive tract.
而这些能量会被消化道的细胞吸收。
This city we just saw is different in everyone.
个人体内的微生物城市都不尽相同。

Every person has a unique and diverse community of gut microbes that can process food in different ways.
每个人都有既独特又多元的肠菌群体，可以以不同的方式处理食物。
One person's gut microbes may be capable of releasing only a fraction of the calories that another person's gut microbes can extract.
某人的肠内菌可能只会释放出食物中少部分的卡路里，但另一个人的肠内菌却能全盘释出。
So, what determines the membership of our gut microbial community?
那么是什么因素决定了我们的肠道里有哪些细菌呢?
Well, things like our genetic makeup and the microbes we encounter throughout our lives can contribute to our microbial ecosystems.
其实，我们的基因以及我们一生中接触到的菌种，都能影响我们体内的微生物生态体系。
The food we eat also influences which microbes live in our gut.
我们吃的食物也会影响哪些微生物会寄居在我们的肠道内。
For example, food made of complex molecules, like an apple, requires a lot of different microbial workers to break it down.
譬如说，由复杂分子构成的食物，比如苹果，需要许多不同的微生物同时分解。
But, if a food is made of simple molecules, like a lollipop, some of these workers are put out of a job.
但是，由简单分子构成的食物，比如棒棒糖，会使一些微生物失业。
Those workers leave the city, never to return.
而这些微生物就此出城，再也不会回来了。
What doesn't function well are gut microbial communities with only a few different types of workers.
而缺乏物种多样性的肠内菌落无法良好地运作。
For example, humans who suffer from diseases like diabetes or chronic gut inflamation
例如，患有糖尿病或肠躁症的人，
typically have less microbial variety in their guts.
他们肠内的菌种贫乏。
We don't fully understand the best way to manage our individual microbial societies,
我们还不了解如何最有效地管理体内的微生物社区，
but it is likely that lifestyle changes, such as eating a varied diet of complex, plant-based foods,
但是生活方式的改变，比如摄取多样、复杂的植物性食物，
can help revitalize our microbial ecosystems in our gut and across the entire landscape of our body.
可以帮助活化我们肠内、以及身体各处的微生物生态结构。
So, we are really not alone in our body.
所以我们真的不是独占我们身体的物种。
Our bodies are homes to millions of different microbes, and we need them just as much as they need us.
有上百万种微生物以我们的身体为家，而我们必须互相依存。
As we learn more about how our microbes interact with each other and with our bodies,
随着我们对于这些微生物彼此之间，以及与我们的身体之间相互作用的深入了解，
we will reveal how we can nurture this complex, invisible world that shapes our personal identity, our health, and our well-being.
我们就能了解如何滋养这个复杂、隐秘的世界，它影响了我们的个人特征、我们的健康以及我们的幸福。