Half an hour later, I walk out of a shop selling “African groceries” carrying a stone that had cost me 99p. I gingerly put a small piece in my mouth. The grit sucks all of the water from my tongue, forming a paste that sticks to the roof of my mouth like peanut butter.

果然，半个钟头以后，我怀揣着一块耗资99便士的泥巴,从一家号称售卖“非洲食品杂货”的铺子里迈步走出。随后，我轻手轻脚地掰开一小块放到嘴里。霎时间，土里的沙砾吸干了我舌头上的全部水分，接着就跟块浆糊似的粘在我口腔顶部，那质感有点像花生酱。

I briefly entertain the thought that it tasted a little bit like smoked meat, before deciding that no, actually it tasted much more like dirt.

刹那见，我萌生出一个念头，感觉它尝起来有一点儿像烟熏肉。但马上，我就枪毙了这个想法，说实在的，它尝起来真正就是泥土的味道啊。

I wondered what it is that gets so many people hooked.

所以，我就纳了闷了，为什么有这么多人吃土吃上瘾。

“Everyone has their reasons,” says Monique, another Cameroonian student. “Simple desire is one, or else to treat nausea and stomach pain. The clay calms the pain by acting as a gastric dressing.”

莫妮克（Monique）说：“每个人都有自己的原因”，她是另外一名来自喀麦隆的学生，“有些人纯粹是为了满足自己的欲望而吃土，还有些人是为了治疗反胃恶心和胃痛而吃土。黏土到了胃里，会形成一层保护膜，进而缓解胃的疼痛。”

Could this be it? Instead of an illness, is geophagy a treatment?

果真如此吗？难道食土癖非但不是一种怪病，反而还是一种治病的疗法？

In fact, three key explanations have been proposed for why people eat dirt, and Monique’s answer touches on one of them.

事实上，对于人们吃土的原因，已有三种主要的解释性论述，而莫妮克的回答便涉及到了其中之一。

Not all dirt is created equal. Kaolin belongs to a specific group of clay minerals, and these seem to be the most popular when people crave a mouthful of earth.

不同的泥土生成的方式也有所不同。高岭土从属于一种特别的矿物质黏土类型，而这些矿物质黏土似乎也是最受食土族群喜爱的黏土。

Clay is very good at binding to things, so when Monique talks about it calming gastric pains, it could be doing just that by binding with or blocking harmful toxins and pathogens in the digestive system.

黏土是非常好的粘合材料。所以，当莫妮克提到吃土缓解胃痛时，它的作用原理应该就是：黏土进入消化系统后吸附有害有毒物质、阻碍病原体入侵。

Experiments with rats andobservations of monkeys indicate that other animals may seek non-food substances to combat ingested poisons, and various traditional food preparation practices involve mixing food with clays to extract toxins andmake it palatable. Acorns are generally unpleasant to eat, for example, but the traditional production of acorn bread in both California and Sardinia involves grinding the nuts up with clay that seems to reduce the concentration of unpalatable tannic acid they contain.

根据小白鼠实验和对猴子的观察，专家发现除了人类，其他动物也会通过摄入非食物类物质来对抗体内的毒素。而在各种传统的食物烹制过程中，都有这么一个步骤：在食物中混合些污泥，进而将食物中的毒素提取出来，同时让食物更加美味可口。比如说，橡子其实是味道极涩的一种坚果，但在美国加州和意大利的撒丁岛，橡子面包是一种传统的食物。为了减少橡子中苦涩的丹宁酸的含量，人们用泥块将橡子的果仁碾碎，从而使橡子面包更可口。

The second hypothesis is perhaps more intuitive: clay could provide nutrients that are not present in conventional food items. Anaemia is often associated with geophagy, so perhaps eating iron-rich soil is an instinctive attempt to remedy iron deficiency.

而第二个猜想或许更为直观：黏土可以为我们提供别的传统食物没有的营养物质。贫血症常常和食土癖联系在一起，而对于同时有贫血症和食土癖的人来说，含铁量丰富的泥土或许就是他们福音。

There’s also a suggestion that geophagy is a response to extreme hunger, or micronutrient deficiencies that make non-food items attractive. This hypothesis is non-adaptive, meaning it fits with the idea that eating earth is a negative behaviour with no benefits.

另外一个意见则认为，食土癖是在极度饥饿时产生的一个反应，又或许是人体微量营养素的缺乏导致人们对非食物类物质产生食欲。这一假设认为吃土是非适应性的行为（即生物体与环境表现不适合）。换言之，这一假设认为吃土是一个负面的行为，并不能给人带来任何好处。

The first two hypotheses, on the other hand, suggest adaptive reasons for geophagy, and they go some way to explaining its distribution, too.

前两种假设则与之相反，认为食土癖存在适应性原因，而且它们也解释了食土习俗在热带地区相对盛行的原因。

“We predicted that it would happen most in the tropics, because that’s where there is the greatest density of pathogens,” says Young. Furthermore, children and pregnant women are two groups that might need extra nutrients or protection against disease, as their immune responses are weaker.

塞拉•杨指出：“我们判断，热带地区是发生最多食土行为的地区，因为那里是病原体最集中的地区”。而且，由于儿童和孕妇的免疫力相对较弱，他们是最需要营养和保护以抵抗疾病入侵的两大群体。