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A pungent blend of onions, cheese, and cat urine with hints of... is that... wet goat?
一股刺激的味道混合着洋葱、芝士、猫尿还有点别的什么...这是羊膻味儿么？
Most of us don't need more than one whiff to identify that generally unpleasant, characteristic smell we call body odor.
大多数人只需要轻轻一闻就能辨别出这种令人不悦的独特味道，我们称之为体臭。
But it's a surprisingly complex phenomenon influenced by our genetic makeup, age, diet, and hygiene.
但它实际是一个出奇复杂的现象，其影响来自基因构成、年龄、饮食和卫生情况。
So what is this odor, exactly? Where does it come from? And can we do anything about it?
这种气味到底是什么呢？它是怎么产生的？我们能拿它怎么办？
To start, you just need two things to produce that familiar scent:
首先，产生这种熟悉的气味需要两个东西：
your armpit's own secretions and the bacteria that feed on them.
腋窝的分泌物以及分泌物上滋生的细菌。
Most people associate body odor with sweat, and it's an important piece of the puzzle.
大多数人会将体臭和汗联系在一起，这是体臭之谜的重要一环。
Your body has millions of sweat glands, and they come in two major types:
你的身体中拥有数百万个汗腺主要分成两类：
eccrine glands are found all over your skin and secrete mainly water and salt.
一种是遍布全身的小汗腺，分泌的主要是水和盐。
Apocrine glands, on the other hand, develop at puberty in your armpits and a few other places on your body.
另一种是大汗腺，在青春期时发育，位于腋窝和身体其他几个部位。
The sweat they secrete is full of proteins and fats.
大汗腺分泌的汗液中有大量蛋白质和脂肪。
By themselves, these secretions are usually odorless. That's where bacteria come in.
这些分泌物通常本身是无味的，但分泌物会产生细菌。
Every square centimeter of our bodies is covered with thousands of bacteria.
在我们的身体上每平方厘米都覆盖着数千个细菌。
Many microorganisms thrive in moist environments, like our armpits.
许多微生物会在潮湿的环境中茁壮成长，比如腋窝。
There, you can find about a million bacteria per square centimeter, one of the highest concentrations anywhere on the skin.
在那里，每平方厘米约有100万个细菌，这是我们体表细菌最集中的地方之一。
Lurking in this throng of microorganisms are species of Corynebacteria, Staphylococci, Micrococci, and others.
这一大群微生物中藏着的细菌有：棒状杆菌、葡萄球菌、微球菌和其他细菌。
When these bacteria feed on the proteins and fats in apocrine sweat,
这些细菌以大汗腺的汗液中的蛋白质和脂肪为食，
they turn the odorless compounds into new ones that can smell very unpleasant.
他们将无味的化合物转变成很难闻的新化合物。
Some of the worst offenders may be sulfur-containing chemicals; those give body odor its oniony aroma.
一些罪魁祸首可能是含硫化合物，洋葱味的体臭就是这么来的。
Carboxylic acids are in the mix, too, adding notes of cheese.
羧酸也混在其中，增加了芝士的味道。
These molecules waft up from the armpit and can be sucked directly into our noses,
这些分子从腋窝散发出来，可以直接吸入我们的鼻子中，
where they're trapped and detected by an array of specialized receptors.
大量的特殊神经末梢会捕捉并探测到这些气味。
Those can recognize odor molecules at concentrations of less than one in a million.
它们会识别气味分子，即使密度只有百万分之一。
So what determines how strong your body odor might be?
那体臭的强度取决于什么呢？
It depends on the resident microbial populations in your armpit, and the nutrients that your glands provide them with.
这取决于腋窝处寄生的的微生物总数，以及汗腺为这些微生物提供的营养物质种类。
Your genes help determine what compounds you produce, and in what quantity, so everyone has a slightly different set.
你的基因决定了产生出的化合物类型和数量大小，因此每个人的情况都有点差异。
In fact, a gene variant that virtually eliminates body odor is common in people of East Asian descent.
事实上，有的基因变种几乎可以消除体味，这在东亚人身上非常普遍。
Adrenaline increases the ratio of apocrine to eccrine sweat, so body odor can be more intense when you're nervous.
肾上腺素会提高大汗腺相对小汗腺的汗液比率，所以在你紧张之时体臭会更加严重。
Bacterial composition and concentration also varies between individuals and plays a part.
细菌组成和细菌密度因人而异，都有重要作用。
Even what you eat can have a small effect on how you smell.
甚至你吃了什么都会稍微影响你的体味。
So how can we deal with body odor?
那么我们如何解决体臭问题呢？
Washing the armpits with soap and water helps but won't remove all the bacteria
用香皂和水清洗腋窝有一定作用，但无法去除所有细菌，
since many are buried in deeper layers of the skin.
因为很多细菌都存在于皮肤的更深层。
Deodorants, however, inhibit bacterial activity and mask odors at the same time.
香体剂会抑制细菌活动并同时掩饰气味。
Antiperspirants work by forming tiny gel plugs that block sweat glands, drying out the armpits.
止汗剂通过产生细小的啫喱堵塞住汗腺，从而使腋窝保持干燥。
While we continue to battle body odor, scientists are trying to understand it.
在我们持续与体臭作斗争之时，科学家们正试图了解它。
We don't know why the brain often interprets these particular odors as off-putting.
我们尚不清楚为何大脑会认为这些特定气味令人讨厌。
But some researchers have proposed that secretions from the armpit could have a positive function, too,
但是一些研究者提出腋窝的分泌物也存在积极作用，
like cementing social bonds and providing a means of chemical communication.
例如巩固社交联系，提供一种化学层面的交流。
We don't know yet if that's the case.
我们不知道这是否属实。
For now, body odor seems to be just another smelly part of the human condition.
到目前为止，体味似乎只是人体状态中有臭味的一部分而已。
