When a team of archaeologists recently came across some 15,000-year-old human remains, they made an interesting discovery. The teeth of those ancient humans were riddled with holes. Their cavities were caused by the same thing that still plagues us today: specific tiny microbes that live in our mouths.
一隊考古學家近來無意間找到一些有一萬五千年歷史的人類遺骸時，他們發現一個很有趣的現象。那些古人類的牙齒上滿是坑洞。造成他們蛀牙的原因和現在仍不斷困擾著我們的一樣：居住在我們口腔內的特定微生物。
These microbes are with us soon after birth. We typically pick them up as babies from our mothers' mouths. And as our teeth erupt, they naturally begin to accumulate communities of bacteria. Depending on what we eat, and specifically how much sugar we consume, certain microbes can overpopulate and cause cavities.
這些微生物在我們出生不久後就跟著我們。我們通常是在嬰兒時期從母親的嘴巴染到那些微生物。長牙時，牙齒自然就開始累積細菌群。視我們吃下肚的食物而定，特別是我們攝取的糖量，某些微生物可能會繁殖過多然後造成蛀牙。
Diets high in sugary foods cause an explosion of bacteria called mutans streptococci in our mouths. Like humans, these microorganisms love sugar, using it as a molecular building block and energy source. As they consume it, the bacteria generate by-products in the form of acids, such as lactic acid. The mutans streptococci are resistant to this acid, but unfortunately, our teeth aren't. While each human tooth is coated in a hardy, protective layer of enamel, it's no match for acid. That degrades the armor over time, leaching away its calcium minerals. Gradually, acid wears down a pathway for bacteria into the tooth's secondary layer called the dentin.
富含甜食的飲食會造成口腔內一種叫作轉糖鏈球菌群的細菌激增。和人類一樣，這些微生物愛死糖了，他們把糖當作分子建築原料和能源。當這些細菌消耗糖分時，他們會生成酸類副產品，像是乳酸。轉糖鏈球菌群不怕這種酸，但很不幸地，我們的牙齒不一樣。儘管人類的牙齒覆有一層堅強的琺瑯質防護層，它還是不是酸類的對手。酸會隨時間摧毀這層盔甲，侵蝕掉牙齒的鈣質。慢慢地，酸侵蝕出一條通道讓細菌進到牙齒的第二層，牙本質。
Since blood vessels and nerves in our teeth are enclosed deep within, at this stage, the expanding cavity doesn't hurt. But if the damage extends beyond the dentin, the bacterial invasion progresses, causing excruciating pain as the nerves become exposed. Without treatment, the whole tooth may become infected and require removal, all due to those sugar-loving bacteria.
因為我們牙齒中的血管和神經都被包在內部深處，在這個階段，擴散的蛀牙區塊還不會痛。但若損害超出牙本質範圍，細菌的入侵持續進行，那在神經暴露出來時就會導致劇烈疼痛。不治療的話，整顆牙齒可能都會受感染然後有拔除的必要，這全是因為那些愛吃糖的細菌。
The more sugar our food contains, the more our teeth are put at risk. Those cavemen would hardly have indulged in sugary treats, however. So, what caused their cavities? In meat-heavy diets, there would have been a low risk of cavities developing because lean meat contains very little sugar. But that's not all our early human ancestors ate. Cavemen would also have consumed root vegetables, nuts, and grains, all of which contain carbohydrates. When exposed to enzymes in the saliva, carbohydrates get broken down into simpler sugars, which can become the fodder for those ravenous mouth bacteria.
我們的食物含有越多糖，我們的牙齒就越不安全。不過那些穴居人當時很難盡情享用甜點。那麼，是什麼造成他們蛀牙呢？富含肉類的飲食，蛀牙發生的風險很低，因為瘦肉含有極少糖份。不過我們早期的人類祖先可不是只吃肉。穴居人們還會吃根莖蔬菜、堅果和穀物，那裡面全都有碳水化合物。當碳水化合物接觸到唾液中的酶時，它就會被分解成較簡單的糖，那可能成為口腔內那些飢腸轆轆的細菌的糧食。
So, while ancient humans did eat less sugar compared to us, their teeth were still exposed to sugars. That doesn't mean they were unable to treat their cavities, though. Archaeological remains show that about 14,000 years ago, humans were already using sharpened flint to remove bits of rotten teeth. Ancient humans even made rudimentary drills to smooth out the rough holes left behind and beeswax to plug cavities, like modern-day fillings. Today, we have much more sophisticated techniques and tools, which is fortunate because we also need to contend with our more damaging, sugar-guzzling ways.
因此，雖然古人類吃的糖比我們少，他們的牙齒還是有接觸到糖類。不過那不代表古人類沒辦法治療他們的蛀牙。考古遺跡顯示，大約一萬四千年前，人類就已經在使用磨利的打火石來除去牙齒蛀掉的部份。古人類甚至做出簡易的牙鑽來磨平蛀牙留下的坑坑洞洞，然後用蜂蠟堵住蛀牙洞，就像現代的填料一樣。我們如今有更先進精密的技術和工具，那是很幸運的事，因為我們同時也得面對我們更具破壞性、大量攝取糖分的飲食方式。
After the Industrial Revolution, the human incidence of cavities surged because suddenly, we had technological advances that made refined sugar cheaper and accessible. Today, an incredible 92 percent of American adults have had cavities in their teeth. Some people are more susceptible to cavities due to genes that may cause certain weaknesses, like softer enamel, but for most, high sugar consumption is to blame.
工業革命後，人類的蛀牙發生率爆增，因為突然間，我們擁有技術優勢，能讓精製糖變得更便宜、更好取得。如今，有過蛀牙的美國成人比例是驚人的百分之九十二。有些人比較容易罹患蛀牙，原因是基因可能會造成某些缺陷，像是較軟的琺瑯質，不過多數人蛀牙是因為吃太多糖。
However, we have developed other ways of minimizing cavities besides reducing our intake of sugar and starch. In most toothpastes and many water supplies, we use tiny amounts of fluoride. That strengthens teeth and encourages the growth of enamel crystals that build up a tooth's defenses against acid. When cavities do develop, we use tooth fillings to fill and close off the infected area, preventing them from getting worse. The best way to avoid a cavity is still cutting down on sugar intake and practicing good oral hygiene to get rid of the bacteria and their food sources. That includes regular tooth brushing, flossing, and avoiding sugary, starchy, and sticky foods that cling to your teeth between meals. Gradually, the population of sugar-loving microbes in your mouth will decline.
然而，我們已經發明出其它降低蛀牙發生率的方法，除了減少糖分和澱粉攝取量外。在大部份的牙膏和許多供水中，我們會使用微量的氟化物。氟化物能強健牙齒並刺激琺瑯質生長，建立牙齒對酸的抵抗力。當蛀牙真的發生時，我們利用牙齒填料來填補並關閉受感染的區域，避免蛀牙惡化。避免蛀牙的最佳方法還是減少糖分攝取，以及實踐良好的口腔衛生習慣來消滅細菌和他們的食物來源。那包含定時刷牙、剔牙，正餐之間不要吃甜食、澱粉類食物和會黏在牙齒上的那些黏黏的食物。漸漸地，你嘴巴裡那些愛吃糖的微生物數量就會下降。
Unlike the cavemen of yesteryear, today we have the knowledge required to avert a cavity calamity—we just need to use it.
不同於過往的穴居人，我們如今擁有避免蛀牙災難發生所需的知識－－我們只要好好運用就行了。
