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SciShow recently began producing its fifth year of content. Something that we are extremely proud of.
SciShow 近期开始制作它第五年的内容 对于这些内容 我们是非常满意的
And we're also proud of the community that's grown around these videos.
以及我们对于围绕这些视频所展开的讨论感到非常的骄傲
We've covered a lot of topics, both trivial and profound,
我们过去讨论的主题涵盖那些不重要的和具有社会意义的
and we worked very hard to capture both our fascination and excitement
还有就是 我们一直很努力地去试图捕捉住存在于我们工作中的魅力和刺激
as well as our deep desire to always get things right.
我们渴望着得到真理
And over the last year, you may have noticed a comment on, we think, every - single - SciShow video, asking us one question.
在过去的一年中 你可能注意到了 在SciShow视频中的每一条 询问我们问题的评论
We have ignored this question long enough, it is time we took it on.
但是我们却在很长的时间里忽视了这个问题 是时候该把它解决了
litojonny wants to know, why does he have hair around his anus?
Litojonny 想要知道为什么他的屁屁周围会有汗毛呢？
Well jonny, the reason we haven't answered you is because, you know,
嗯… 之所以我们一直没有给予你答案 是因为
like despite the fact that everyone gets their own personal pocket sized supercomputer,
就好比去试图描述一个 事实 就是每个人都有自己口袋大小的超级计算机
and that we can send robots to Mars, and convert the entire face of a planet to human use,
我们可以发送一个机器人到火星 变换这个星球的整个面貌 为人类所使用
we still do not really know WHY humans have butt hair.
我们仍然不晓得为什么人类有臀毛
And it may not surprise you to learn,
你可能不会惊讶
that not a whole lot of research has been done on the "Why" part of this question about butt hair.
为什么没有很多关于人类屁屁上有毛的完善研究 去回答“为什么”
But a fair amount of study has gone into the medical problems that butt hair can cause.
不过 大量的研究已经可以证明这些汗毛可以直接影响我们的健康
For example: Pilonidal Disease is a chronic skin infection caused by hairs that get embedded near the top of the butt crack,
比如 藏毛症是一种慢性皮肤感染 它是由于嵌入式对接裂纹顶端附近毛发所引起的
which, if you want to impress your doctor, you can describe by its technical name: the intergluteal cleft.
如果你想给你的主治医生留下足够的印象的话 你可以描述一下它的学名 臀间裂
So as the owner of the butt yourself, you probably know that butt hair does seem to have more downsides than upsides.
所以说啊 作为你自己屁股的所有者 你大概可能知道屁屁上的汗毛大多出现在下边而不是上面
So given that, what - if any - purpose does it serve?
所以 它存在的目的到底是什么？
Well there are a few theories out there
其实 已经有少部分理论
and maybe some enterprising scientist out there, watching right now, can do some research on them.
和一些有胆量的科学家才会去做关于屁屁上汗毛的研究
But here's what has been proposed.
但是 有些理论表明了如下的观点
Theory number 1: Butt hair exists, because there's just no significant evolutionary pressure against butt hair.
理论1: 屁屁上汗毛之所以存在 是因为从进化角度来讲 这些汗毛对于生物体生存是无关紧要的
Sure, it's sometimes inconvenient, and, depending on the moment in cultural history, it might be considered unsightly,
当时 基于文化历史 这个理论有时候站不住脚 因为 屁屁上的汗毛可能会被认为很污秽
but it appears, that butt hair has never been a significant reason for one human not to make babies with another human.
但是它的存在 确实是没有任何重要原因的 对于一个从未与异性生孩子的人来讲
It's important to keep in mind, that not every bit of our physiology needs an evolutionary purpose,
一定要谨记住 我们生理上每一部分的存在有时候并不需要进化论去解释
so butt hair might just be another side effect of unintelligent design.
所以 你屁屁上的汗毛可能仅仅是愚蠢设计影响的另一方面
Theory number 2: Scent communication
理论2: 气味交流
Body odor definitely has a negative connotation in today's world,
身体的气味在现代社会绝对是一个消极的交流方式
but there's little doubt that communication through scent has played an important role in the evolution of humans.
但是 有些质疑表明 人们通过气味交流 可能会在人类进化上产生一个重要的作用
After all, that's likely why we have body hair in the same areas where we produce body odors.
毕竟 这可能更倾向于为什么我们的体毛会出现在可能产生体味的区域
The hair is there to hold onto sebaceous, or oily, secretions, that have their own smell,
毛发可能锁住那些分泌的油脂 分泌物 最终有了自己的味道
and are also consumed by bacteria, that create even more smells.
也给细菌创造出来可以分解这些油脂的区域 从而产生更多的体味
Since we all produce different smell compounds, and all have our own microbiomes,
因为我们产生不同气味的化合物（特质脂质） 和不同的微生物（特指细菌）
each individual human actually smells different.
实际上 每个人的气味都是不一样的
And if our early human ancestors were anything like other animals, and they probably were,
假如人类的祖先和其他动物一样的话
their personal smell probably helped with everything from broadcasting territorial rights to attracting mates.
他们独特的气味很有可能帮助他们去占有领土或是吸引异性
Butt hair then may be just another way our oldest human ancestors enhanced their smell profiles.
所以 屁屁上的汗毛也许只是早期人类提高他们的气味影响的另一种方式
Theory number 3: Friction.
理论3: 摩擦
In addition to giving off smells, humans have also always done a great deal of walking and running.
这些汗毛除了会散发出味道以外 在人类行走和跑步的同时
And skin rubbing on skin (especially in areas where that skin may be moist and dirty),
皮肤间会有摩擦（尤其是在湿润或者并不干净的区域）
can cause irritation, rashes, and even serious, debilitating infection.
会刺激皮肤 引发皮疹 甚至是严重的衰退感染
It's even possible, that those sebaceous or waxy secretions, that help produce body odor,
也可能是 那些分泌油脂或蜡状分泌物会促进人们产生体味
are held in place by body hairs to provide an added benefit, acting like a kind of natural anti-chafing cream.
但是啊 体毛也有一个另外的好处 就像是天然的润滑剂
Now this theory, of the ones that we have talked about, is most appealing to me, personally,
目前 这条理论对于我个人而言是最有吸引力的
but it's very difficult to test, because shaving, or otherwise removing butt hair,
但是这条理论很难去验证 因为 如果让一个人刮掉他的胡子 或是除去屁屁上汗毛之后
and then having someone run 20 miles on a treadmill, is not a good experimental design.
再在跑步机上跑20英里 可能并不是一个合理的实验设计
Because, there's no way to know, whether any irritation is caused by the lack of hair,
我们无从得知 皮肤的刺激到底是不是因为我们缺少汗毛
or whatever technique was used to remove the hair. None of which sound fun to me.
还是 科技是否被用于除毛 目前没有一个解释可以吸引我
But I have come up with an alternative experimental design that I like quite a lot.
但是 我想出了一个更有趣的实验设计方案
Just interviewing a few hundred runners about how much they need to worry about butt chafing,
就是 去采访几百个跑步运动员 “他们到底有多担心他们的屁股会发炎？”
and then measure the density of their anal pelage,
然后在测量他们屁屁上的汗毛密度
to see if there's any correlation between whether they chafe and how hirsute their buts are.
从而得知 在他们的皮肤受刺激程度和他们拥有的毛发程度之间到底有没有关联
Which is not an experiment that I want to to do personally.
其实 我并不是很想做这个实验
But if there's an expert out there, in anatomy and physiology, who is up for tackling this prickly problem, please, take it on.
但是如果有能够解决这一棘手问题的解剖学或生理学的专家的话 请求 把他推荐给我们
And if you get any useful data, definitely let us, and litojonny, know, how it went.
还有 如果你有任何有用的相关数据 请一定要让我们和Litojonny知道
Thank you for watching this episode of SciShow, especially to litojonny, for being so persistent...
再次感谢你们观看这集SciShow视频 尤其是要感谢Litojonny持之以恒的提问
Ah.. What are you gonna do now? We've answered your question, you're gonna come up with a new one?
嗯…那你现在要怎么做呢？ 我们已经回答了你的这个问题 你还要再想一个新问题出来吗？
I challenge you, to come up with a new one.
我向你的 新问题发出挑战
Thank you for watching and if you want to go to youtube.com/SciShow and subscribe, that would be great.
感谢收看 如果你们想去YouTube.com/SciShow订阅我们的话 那就太好了
