I mean, they're weird, right?

我是說，他們很奇怪，對吧？

They sit way back in our mouths, they don't grow in until we're basically full-grown adults, if they grow in at all, and then most of the time they end up causing problems and have to be pulled out.

它們在我們口腔中的位置很靠後，直到我們長大成人後才長出來，如果它們真的長出來的話。

This might make you wonder if wisdom teeth are such oddballs and troublemakers, why they're even there in the first place.

這可能會讓你產生這樣的疑問：如果智齒是如此古怪和麻煩的東西，那為什麼還要長在那裡呢？

Well, it's because they're there.

那是因為他們在那裡。

Let us explain.

讓我們來解釋一下。

[♪ INTRO ♪)]

[♪ INTRO ♪)]

Way in the back of our jaws, behind our premolars, we have teeth called molars.

在我們頜骨的後方，也就是前臼齒的後面，有一種叫做臼齒的牙齒。

When we're young, two molars develop in each of the four corners of our mouths.

小時候，我們口腔的四個角各長出兩顆臼齒。

Much later in our lives, we get our final teeth, the third molars, aka wisdom teeth.

到了晚年，我們會長出最後一顆牙齒--第三磨牙，也就是智齒。

These usually don't emerge from the gums until our late teens or early twenties.

這些牙齦通常要到十幾歲或二十出頭才會出現。

In English, we call them wisdom teeth because they show up around the age of adulthood.

在英語中，我們稱它們為智齒，因為它們會在成年前後出現。

In Thai, they're called huddling teeth, since there's not a lot of space back there, so they end up squeezed in.

在泰語中，它們被稱為 "蜷縮的牙齒"，因為後面的空間不大，所以它們最終會擠在一起。

And in Spanish, they're called judgment molars, for similar reasons to English, in that it's when you have sound judgment, but it sounds cooler.

在西班牙語中，臼齒被稱為 "判斷臼齒"，原因與英語相似，都是指你有正確的判斷力，但聽起來更酷。

But wisdom teeth aren't just painful, they can cause serious dental problems.

但智齒不僅會讓人疼痛，還會導致嚴重的牙科問題。

Due to the lack of space for them, these teeth often become impacted, meaning they don't grow properly.

由於沒有足夠的空間，這些牙齒經常會受到影響，即無法正常生長。

They might come in crooked or not fully emerge from the gums.

它們可能是歪的，或者沒有完全從牙齦中長出來。

Impacted teeth can cause swelling in the gums, damage other nearby teeth, and even lead to serious problems like tooth decay.

撞壞的牙齒會導致牙齦腫脹，損害附近的其他牙齒，甚至導致蛀牙等嚴重問題。

Wisdom teeth aren't the only teeth that can become impacted, but they are by far the most common culprits.

智齒並不是唯一會發生阻生的牙齒，但卻是迄今為止最常見的罪魁禍首。

Around 98% of all impacted teeth are wisdom teeth, and well over half of all people may end up with at least one impacted wisdom tooth.

大約 98% 的阻生牙都是智齒，一半以上的人最終可能至少有一顆阻生智齒。

In fact, the lack of space is probably the reason these teeth come in so late.

事實上，空間不足可能是這些牙齒萌出較晚的原因。

They have to wait until their jaw is developed enough to handle the strain of their arrival.

它們必須等到下巴發育到足以承受到來時的壓力。

And even then, they still cause all these problems.

即便如此，它們還是會帶來這些問題。

And that's if they even bother showing up at all.

這還是在他們費心露面的情況下。

It's very common for wisdom teeth to simply not develop.

智齒不發育的情況很常見。

Around 1 in 5 people are completely missing one or more of their wisdom teeth.

約有五分之一的人完全缺失一顆或多顆智齒。

So I say again, wisdom teeth are weird.

所以我再說一遍，智齒很奇怪。

Not only do they cause problems, but we clearly don't need them to survive since so many of us either never grow them or get them removed.

它們不僅會造成問題，而且我們顯然不需要它們來生存，因為我們中的很多人要麼從不長它們，要麼就把它們移走了。

And this leaves us wondering why we even have them at all.

這讓我們不禁要問，為什麼我們還要擁有它們。

Thanks to Aeropress for supporting this SciShow video.

感謝 Aeropress 對 SciShow 視頻的支持。

If you're a SciShow viewer and also a coffee lover, you can go to aeropress.com slash scishow to get 20% off.

如果您是 SciShow 的觀眾，同時也是咖啡愛好者，您可以登錄 aeropress.com slash scishow 獲得八折優惠。

Now, your insatiable need for coffee does not stop just because you're traveling.

現在，您對咖啡的無限需求不會因為旅行而停止。

But it does mean that sometimes you've had to lower your standards.

但這確實意味著有時你不得不降低標準。

And that's why the Aeropress Go Plus was designed for brewing on the go.

這就是 Aeropress Go Plus 專為外出沖泡而設計的原因。

So you don't have to sacrifice the coffee you enjoy for a life of adventure.

是以，您不必為了冒險生活而犧牲您喜歡的咖啡。

They can go hand in hand or customize tumbler in hand, as the case may be.

它們可以齊頭並進，也可以根據具體情況定製滾揉機。

In just a few minutes, you can get the best qualities of a variety of coffee brewing methods all in one cup.

只需幾分鐘，您就能在一杯咖啡中享受到各種咖啡沖泡方法的最佳品質。

You can indulge in a modern combination of French press, pour over, and espresso.

您可以盡情享受法式壓榨咖啡、翻煮咖啡和意式濃縮咖啡的現代組合。

So before your next trip, consider visiting aeropress.com slash scishow and using the promo code scishow to save 20% off your order.

是以，在您下次旅行前，請考慮訪問 aeropress.com slash scishow，並使用優惠代碼 scishow，為您的訂單節省 20% 的折扣。

Well, like so many things that don't fit quite right, wisdom teeth are hand-me-downs.

就像很多不合適的東西一樣，智齒也是 "二手貨"。

Our ape ancestors had wisdom teeth, and so do our close cousins like chimpanzees and gorillas, but theirs rarely become impacted like ours do.

我們的猿類祖先有智齒，我們的近親如黑猩猩和大猩猩也有，但它們的智齒很少像我們的智齒那樣受到影響。

And that's because, as you might have guessed, they have bigger mouths.

這是因為，正如你可能已經猜到的那樣，它們的嘴巴更大。

Our ancestors, like our living cousins, had bigger and broader jaws.

我們的祖先和我們的表親一樣，擁有更大更寬的下頜。

But in our lineage, starting with species like Homo erectus, the shape of our skulls began to change.

但在我們的血統中，從直立人等物種開始，我們頭骨的形狀開始發生變化。

Our cranium got bigger to accommodate our expanding brains, and at the same time, our jaws grew shorter and narrower, leaving less space for our wisdom teeth.

我們的頭蓋骨變大了，以容納不斷膨脹的大腦，與此同時，我們的下頜變短變窄，為智齒留下的空間變小了。

Over time, our wisdom teeth developed later and later in life, and they even began to disappear.

隨著時間的推移，我們的智齒髮育得越來越晚，甚至開始消失。

There are skulls of early Homo species with third molars that never developed, and this has become more common in modern humans.

在早期智人的頭骨中，有一些第三臼齒從未發育，而這種情況在現代人中變得更加常見。

But exactly why our jaws became smaller is a bit of a mystery.

但是，我們的下巴究竟為什麼會變小，這還是個謎。

The most obvious suspect is our changing diet.

最明顯的疑點是我們不斷變化的飲食習慣。

Our distant ancestors, species like Australopithecus, ate lots of tough foods like nuts and raw veggies, and their big, strong jaws and teeth were great for that.

我們遙遠的祖先，如澳類人猿，吃很多堅硬的食物，如堅果和生蔬菜，它們粗壯的下頜和牙齒非常適合這些食物。

Over time, some of our ancestors, like Homo erectus, changed their diet, eating more meat, and then eventually using technology like stone tools and fire to make food easier to eat.

隨著時間的推移，我們的一些祖先，如直立人，改變了他們的飲食習慣，吃更多的肉類，並最終使用石器和火等技術使食物更容易入口。

Fire can be used to cook food, which makes it softer, and tools can cut or crush food into smaller pieces that are easier to swallow.

火可以用來烹飪食物，使食物變得更軟，工具可以將食物切割或粉碎成更容易吞嚥的小塊。

As ancient humans got better at preparing meals, it took a lot of the work out of chewing.

隨著古人類越來越擅長準備飯菜，咀嚼的工作量也隨之減少。

This also meant that there was less pressure to develop big, strong jaws.

這也意味著，發展大而強壯的下頜的壓力較小。

We can even see a similar trend among living humans.

我們甚至可以在活人身上看到類似的趨勢。

People who live in highly industrialized societies, where we have lots of cooking tools and ready-made meals, have more wisdom tooth problems compared to hunter-gatherer societies.

在高度工業化的社會中，我們有很多烹飪工具和現成的飯菜，與狩獵採集社會相比，生活在高度工業化社會中的人有更多的智齒問題。

In fact, impacted wisdom teeth are ten times more common in industrialized people than in hunter-gatherers.

事實上，工業化國家的人患智齒阻生症的機率是狩獵採集者的十倍。

It seems that chewing tough food while we grow up can help strengthen our jaws, making them more resilient to the potential problems of wisdom teeth.

看來，在成長過程中咀嚼堅硬的食物有助於強化我們的頜骨，使其更能抵禦智齒帶來的潛在問題。

Yet, plausible as it seems, diet isn't the whole story.

然而，儘管看似有理，但飲食並不是故事的全部。

Some researchers have looked at trends across primate teeth, and they've found that the size of certain teeth does line up with diet, but molar size tends to have more to do with body size and ancestry.

一些研究人員研究了靈長類動物牙齒的變化趨勢，發現某些牙齒的大小確實與飲食有關，但臼齒的大小往往與體型和祖先有更大的關係。

And other studies have found that certain genetic factors are important in determining whether or not wisdom teeth develop in humans.

還有一些研究發現，某些遺傳因素對人類是否長出智齒有重要影響。

But we also know it's not all about genetics, since studies on the teeth of twins have found that the environment we grow up in can affect our wisdom tooth development.

但我們也知道，這並不全是遺傳的問題，因為對雙胞胎牙齒的研究發現，我們的成長環境會影響智齒的發育。

And even more confusing, the effects of genetics and environment are different for wisdom teeth in the upper jaw versus the lower jaw.

更令人困惑的是，遺傳和環境對上顎和下顎智齒的影響是不同的。

So our diet is clearly a significant factor in the evolutionary path of our wisdom teeth, but it's clearly not the only one.

是以，我們的飲食顯然是智齒進化過程中的一個重要因素，但顯然不是唯一的因素。

And that means there's plenty we still don't know about why wisdom teeth are so weird, or why they cause so many problems in our mouths, or why they're still here at all.

這就意味著，對於智齒為何如此怪異，為何會給我們的口腔帶來如此多的問題，為何智齒仍然存在，我們還有很多不瞭解的地方。

One thing is pretty clear.

有一點非常明確。

Our wisdom teeth have changed a lot since the days of our ancient ancestors.

自遠古祖先時代以來，我們的智齒髮生了很大變化。

They develop later in our lives, cause more dental issues, and more frequently fail to develop.

它們在我們生命中出現的時間較晚，引起的牙科問題也更多，而且更容易發育不良。

But if evolution ever does get rid of them completely, wisdom tooth extractions will be a thing of the past.

不過，如果進化真的能徹底擺脫智齒，拔智齒也將成為過去。

And our descendants will have to find other excuses to lay on the couch and eat ice cream.

而我們的後代將不得不找其他藉口躺在沙發上吃冰淇淋。

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