Soon after, scientists realized that these animals were, in fact, tiny arachnids.

不久之後，科學家們意識到，這些動物其實是微小的蛛形綱動物。

And now we know they belong to a group of mites, which scientists named demodex, that contains more than 100 different species that live in and around mammals' hair follicles.

現在我們知道，它們屬於蟎蟲類，科學家將其命名為蟎蟲（demodex），其中包含 100 多個不同的物種，它們生活在哺乳動物的毛囊中和毛囊周圍。

Two of these species—demodex follicularum and brevis—specifically inhabit human follicles.

其中有兩個物種--毛囊寄生蟲（demodex follicularum）和毛囊寄生蟲（brevis）--專門棲息在人類的毛囊中。

And not just some peoples.

而且不僅僅是某些人。

Nearly everyone is thought to host mites from at least one of these two demodex species.

幾乎每個人都被認為至少寄生有這兩種蟎蟲中的一種。

One person's face might harbor hundreds or even thousands of individual mites.

一個人的臉上可能藏有數百甚至數千只蟎蟲。

So yes, on any given day, microscopic arachnids are probably eating, mating, and laying eggs inside your pores.

所以是的，在任何一天，微型蛛形綱動物都可能在你的毛孔中進食、交配和產卵。

So is this okay?

這樣可以嗎？

Many mighty mysteries remain, in part because of how difficult it is to keep demodex alive and investigate them off our skin.

許多強大的謎團依然存在，部分原因是讓蝨子存活並從我們的皮膚上清除它們是多麼困難。

But scientists have begun teasing out the truth, and it turns out that our entanglement is probably just about as old as we are.

但科學家們已經開始揭開真相，原來我們的糾纏可能和我們的年齡一樣大。

It seems that the mites' ancestors developed and diversified alongside mammals, moving into their pores and feeding off the oily secretions in their hosts' follicles.

蟎蟲的祖先似乎是與哺乳動物一起發展和多樣化的，它們進入哺乳動物的毛孔，以宿主毛囊中的油性分泌物為食。

Then we humans eventually came about with our very own follicular mites to accompany us, and we've been inseparable ever since.

後來，我們人類終於有了自己的毛囊蟎陪伴，從此我們就形影不離了。

Babies seem to inherit demodex mites through direct contact, like during birth and breastfeeding.

嬰兒似乎會通過直接接觸（如在出生和母乳餵養期間）遺傳脫墨蟎。

And a person's mite population tends to grow after puberty, probably in response to changes in our hormones, oiliness, and immune responses.

青春期過後，人體內的蟎蟲數量往往會增加，這可能是由於我們的荷爾蒙、油性和免疫反應發生了變化。

The mites mostly reside on our faces, especially our noses, where our pores and oil glands are larger.

蟎蟲主要棲息在我們的臉上，尤其是鼻子，因為那裡的毛孔和油脂腺較大。

They take approximately one week to reach adulthood, and spend the remainder of their lives—about another week—either face down in our pores or traversing the expanse of our faces.

它們大約需要一週的時間才能長大成人，剩下的時間--大約一週--要麼臉朝下呆在我們的毛孔裡，要麼在我們的臉上游走。

As you might expect, based on the fact that they're usually embedded within our skin, our daily routines are pretty tightly synced.

正如您所預料的那樣，由於它們通常嵌入在我們的皮膚中，是以我們的日常工作與它們的同步性相當緊密。

Around dusk, our bodies secrete the hormone melatonin, which helps prime us for sleep.

黃昏前後，我們的身體會分泌褪黑激素，幫助我們進入睡眠狀態。

For demodex, however, melatonin is thought to serve as their stimulating nocturnal cue.

然而，褪黑激素被認為是一種刺激性的夜間線索。

So as night falls and we become less active, our resident demodex mites liven up.

是以，當夜幕降臨，我們變得不那麼活躍時，我們的寄生性除蟎就會活躍起來。

In fact, because they're regularly tucked away in our pores or out exploring in the dark, they've lost the genes that give them UV protection altogether.

事實上，由於它們經常藏在我們的毛孔裡或在黑暗中探索，它們已經完全失去了保護紫外線的基因。

Over the course of an evening, some adults shimmy out of our pores in search of mates, moving at speeds of around 1 cm an hour across our facial terrain.

傍晚時分，一些成蟲從我們的毛孔中鑽出來尋找配偶，它們以每小時 1 釐米左右的速度在我們的面部地形上移動。

And then they pop back into our pores to lay their eggs.

然後，它們又鑽進我們的毛孔產卵。

Scientists estimate that one pore can hold a family of around 14 mites.

科學家估計，一個毛孔可以容納一個家族約 14 只蟎蟲。

Demodex are on virtually everyone's faces— including those with healthy skin and little inflammation.

幾乎每個人的臉上都有蛻皮蟲，包括那些皮膚健康、發炎較少的人。

It seems that demodex mites are only associated with skin issues in cases where some kind of immune dysfunction is at play.

似乎只有在某種免疫功能失調的情況下，脫蝨蟎才會與皮膚問題聯繫在一起。

Like when someone's immune system reacts strongly to the mite's presence or doesn't adequately suppress their populations.

比如，某人的免疫系統對蟎蟲的存在反應強烈，或者沒有充分抑制蟎蟲的數量。

All of which can cause inflammation.

所有這些都會引起發炎。

For most people, however, follicular mites are harmless.

不過，對於大多數人來說，毛囊蟎是無害的。

And most people maintain their original mite lineages, even as they travel or move to new parts of the world.

大多數人都能保持原有的蟎蟲血統，即使他們旅行或移居到世界上新的地方。

What's more, it seems that different lineages of mites evolved alongside different populations of people.

更重要的是，不同的蟎類似乎與不同的人群一起進化。

So scientists may be able to tell your ancestry by merely studying the mites that colonize your face.

是以，科學家也許可以通過研究臉上的蟎蟲來了解你的祖先。

Because mite populations stick with one person, however, they have limited breeding opportunities, which reduces their overall genetic diversity.

然而，由於蟎蟲種群只與一個人在一起，它們的繁殖機會有限，這就降低了它們的整體遺傳多樣性。

This might have set our follicular mites on a path for extinction.

這可能使我們的毛囊蟎走上了滅絕之路。

But that would be a long ways off.

但那還遙遙無期。

In the meantime, you can look at yourself in the mirror and rest assured that your face is, in fact, teeming with a multitude of mites.

在此期間，您可以照照鏡子，確信自己的臉上確實有很多蟎蟲。

And with that, nighty-night and sleep tight.

晚安，睡個好覺。