Sinusitis, or sinus infections, are incredibly common and no fun whatsoever.

鼻竇炎，或稱為鼻竇感染，是種非常常見的疾病，而其症狀可不是鬧著玩的。

Anywhere from thirty to thirty-five million sinus infection diagnoses are made every year in the US.

每年光在美國就有三千萬到三千五百萬人確診鼻竇炎。

They're one of those sicknesses that usually go away on their own, but they're a nuisance nonetheless.

這是那種會自己痊癒的疾病，但患病時還是相當令人厭煩。

And in fact, our tendency to get sinus infections might actually be a quirk of human evolution.

事實上，我們之所以會得鼻竇炎的原因，可能和人類的古怪演化方式有關。

There's dust, pollution, and pathogens like viruses and bacteria in every breath we take, and one tool that our body uses to keep us healthy is our nasal cavities.

我們呼吸的每一口空氣中都含有粉塵、汙染物，以及如病毒與細菌等的病原體，而我們的身體用以抵禦它們並讓我們保持健康的其中一個工具便是我們的鼻腔。

Within the fleshy nose itself, hair and mucus catch big dust particles, which is a good first line of defense for keeping our lungs clean.

在我們肉肉的鼻子裡，纖毛與鼻涕會攔截較大的粉塵粒子，作為保持我們肺部清潔的第一層優秀防線。

From there, our breath enters a series of air-filled chambers behind the facial bones called the paranasal sinuses.

從那裏開始，我們的呼吸會經過一系列位於面部骨骼後方，稱做鼻竇的空心腔室。

Paranasal for around the nose, sinus for empty space.

竇的意思是空腔，合起來便是鼻子附近空腔的意思。

Their first job is to warm and humidify air, making it easier to breathe when it gets down to the lungs.

它們的第一份工作是將空氣加熱並潤濕，讓空氣抵達肺部後能更容易被呼吸。

The next line of defense is mucus — and it's totally normal.

下一道防線則是鼻涕，而這是完全正常的分泌物。

We're all secreting at least a little mucus all the time.

我們的人體時時刻刻都會產出至少一點點的鼻涕。

Each of our sinuses are lined with cells that can make more or less mucus depending on the situation.

我們的鼻竇上有著能夠視情況調整鼻涕分泌量多寡的細胞。

They're also coated in cells that have little hair-like structures called cilia.

它們也被表面有著髮狀結構，被稱為纖毛的細胞給包覆著。

These things wiggle back and forth to keep this mucus moving down collection ducts in each of our sinuses where they drain into the nasal cavity, then into the throat.

這些纖毛會往前後往復移動，在鼻竇中向下將鼻涕推往鼻腔，接著再推送到喉嚨中。

This becomes more complicated when you get a sinus infection.

而這樣的過程在鼻竇被感染時變得複雜許多。

Which is exactly what it sounds like: infection from pathogens or allergens that stick around in your sinuses, like from a cold or flu, which then causes inflammation of these mucus membranes.

鼻竇感染顧名思義就是有病原體或是過敏原，因為我們受寒或得流感等原因而在鼻竇附近卡住了，並讓這些黏膜開始發炎。

Most of the time, these pipes and chambers flow freely, and we can take big clear breaths.

大部分的時候，這些管道與腔室之間能自由流通，讓我們能盡情呼吸。

But when sinuses have to deal with germs, it results in clogged up noses and difficulty breathing.

但當鼻竇要處理細菌時，就會導致鼻子堵塞，讓我們難以呼吸。

Viruses cause the majority of sinus infections, but bacteria can trigger them as well.

大多數的鼻竇感染是由病毒所引起的，但細菌也會引發感染。

When you do get a sinus infection, that wet mucus becomes thicker and more viscous, which causes the typical symptoms: congestion, headache, and difficulty breathing.

當你得了鼻竇炎時，那溼潤的鼻涕會變得更厚重黏稠，導致了典型的鼻竇炎症狀：鼻塞、頭痛和呼吸困難。

And those symptoms might be made worse by the plumbing of our sinuses.

而這些症狀可能會因為我們的鼻竇管線的配置而變得更糟。

Each sinus has a mucus collection duct, or what are called ostia, to shuttle its discarded mucous to the nose and throat.

每個鼻竇中都有個被稱為竇管的鼻涕收集管道，用來把不要的鼻涕運送到鼻子和喉嚨去。

It's basically plumbing for snot.

它基本上就是鼻涕的水管管線。

Well, for most of our sinuses like the frontal sinuses behind the forehead or the sphenoid sinuses a few centimeters behind our eyes, the collection duct is towards the bottom of the sinus.

我們大部分的鼻竇，如在額頭後方的額竇與在眼睛後方數公分的蝶竇，其竇管都是往鼻竇的底部傳送鼻涕的。

The ethmoid sinus has a bunch of tiny cavities that it drains out of, but it still drains downward.

篩竇雖然有著許多能將鼻涕排出的小小氣室，但排水方向還是向下的。

The big exception then is the maxillary sinuses: the ones behind our maxillas, or upper lip and cheeks area.

最大的例外是我們的上頷竇：也就是在我們上頷骨，上嘴唇與臉頰區域後方的鼻竇。

These are our biggest sinuses, at about 15 milliliters, and the ones that most often get infected.

這些是我們最大的鼻竇，容量約為 15 毫升，並且也是最容易被感染的鼻竇。

And for most humans, we have one collection duct towards the top innermost wall of the maxillary sinus.

對於大多數人類來說，我們有一條通往上頷竇最頂層腔壁的輸送管道。

Having the collection duct at the top of the sinus might keep us from draining all that collected snot more efficiently.

在鼻竇最上方有著一條管道能讓我們更有效率地把積累的鼻涕排出。

Which, in turn, might predispose humans to sinus infections.

但這樣卻也可能讓人類的鼻竇更容易被感染。

On one hand, if you have a sinus infection, your cilia have to wick a bunch of thick, viscous mucus towards the collection duct against gravity,

一方面，當鼻竇受到感染時，你的纖毛必須把一堆黏稠厚重的黏液逆著地心引力向上輸送，

and that mechanism tends not to work as well when we have an infection.

而這樣的機制在鼻竇受到感染時，並沒有辦法順暢運作。

So we end up with more and more bacteria which creates infinite snot and makes symptoms worse.

於是細菌便累積得越來越多，製造出更多的鼻涕，讓症狀變得更加嚴重。

On the other hand, that duct might act like an overflow drain.

另一方面，那個管道也能起到溢流排水管的作用。

That's why it sometimes helps to lie down or bend forward when you have a sinus infection: it helps drain mucus towards the ducts.

這就是為什麼當你得鼻竇炎時，躺下來或是將身體前傾有助於改善症狀的原因：這樣做有助於疏導鼻涕通過管道。

Obviously, that doesn't remove the infection, but it might help for a little bit.

這樣做很顯然並不能解決感染的問題，但至少能起點幫助。

Ultimately, the location of the maxillary ostia is a consequence of evolving from ancestors that walked around on four legs.

歸根結底，我們上頜骨竇管的位置是由以四足行走的祖先進化而來的結果。

Asking whether our bodies would work better if it had different anatomy is a hard question to test scientifically, so researchers might compare our anatomy to a different animal's.

我們很難用科學方式來驗證如果我們的身體構造不同的話，究竟能不能運作得更好，因此科學家們便轉而將我們的身體構造與其他的動物比較。

Like in the past decade, scientists published a paper where they filled human sinuses and goat sinuses with a saline solution and measured how quickly they drained.

在過去的十年間，科學家們發表了一篇研究報告，內容是將鹽水溶液打進人類與山羊的鼻竇裡，然後測量兩者排出溶液的速度。

In an upright position, the human sinuses didn't drain that well, but when they were tilted forward, they drained as quickly as the goats' did.

在直立的狀態下，人類鼻竇的排水效果不怎麼好，但是當向前傾斜時，它們排水的速度和山羊的一樣快。

On a practical level, different scientists also showed that moving into the quadrupedal head position, essentially just leaning forward, does relieve sinusitis symptoms.

在實作層面上，不同的科學家們也揭示了當人以四足方式行走，基本上就是整個身體往前傾時，確實能減緩鼻竇炎的症狀。

That makes them think that the location of the sinus ostia was appropriate for our four-legged ancestors, but not for modern humans on two legs.

這讓他們認為我們鼻竇管的位置適合我們四足行走的祖先，但對以雙足行走的現代人來說行不通。

But, it's also worth remembering that everyone has slightly different nasal anatomy which might predispose some people to sinus infections more than others.

但是值得注意的是，每個人的鼻腔構造都有些許的不同，而這可能導致有些人更容易得鼻竇炎。

While our sinuses might be designed less than ideally, having a big brain was more important, so we're left with the nasty, snotty consequences of evolution.

雖然我們鼻竇的設計並不是那麼的理想，但人類的巨大腦部是很重要的演化結果，因此讓我們最後演化出了這樣亂七八糟，令人鼻水橫流的結果。

While we can't go back in time to say if this was a good or bad design, our sinuses are something that make us human.

雖然我們沒辦法回到演化前，藉此來判斷這個設計究竟是好是壞，但我們的鼻竇確實是讓我們成為人類的關鍵。

Thanks for watching this episode of Seeker Human.

感謝收看本集的 Seeker 人類。

We're so excited to get more episodes of Human to you just a little bit, so make sure you're subscribed on YouTube and following us on social media. 

我們不久後就將再為各位帶來新一集的「人類」，因此記得在 YouTube 上訂閱我們的頻道，並在社交媒體上追蹤我們。