Can you read in the car? If so, consider yourself pretty lucky. For one-third of the population, looking at a book while moving along in a car or a boat or train or plane quickly makes them sick to their stomach. But why do we get motion sickness in the first place? Well, believe it or not, scientists aren't exactly sure. The most common theory has to do with mismatched sensory signals. When you travel in a car, your body gets two different messages. Your eyes are seeing the inside of a vehicle, which doesn't seem to be moving. Meanwhile, your ear is telling your brain you're accelerating. Wait, your ear? Your ear has another important function besides hearing. In its innermost part lies a group of structures known as the vestibular system, which gives us our sense of balance and movement. Inside there are three semicircular tubules that can sense rotation, one for each dimension of space. And there are also two hair-lined sacks filled with fluid. When you move, the fluid shifts and tickles the hairs, telling your brain if you're moving horizontally or vertically. All this tells your body which direction you're moving in, how much you've accelerated, even at what angle. In a car, your vestibular system correctly senses your movement, but your eyes don't see it, especially when glued to a book. The opposite can happen. You're at the movies, and the camera makes a sweeping move. This time, your eyes think you're moving while your ear knows you're sitting still. But why does this conflicting information make us feel so terrible? Scientists aren't sure, but they think there's an evolutionary explanation. Fast moving vehicles and video recordings have only existed in the last couple of centuries, a blink in evolutionary time. For most of our history, there wasn't that much that could cause this sensory mix-up, except for poisons. And because poisons are not the best thing for survival, our bodies evolved a direct but unpleasant way to get rid of what we ate that was causing the confusion. It's a pretty reasonable theory, but it leaves things unexplained, like why women are more affected by motion sickness than men, or why passengers get more nauseous than drivers. Another theory suggests that the cause is more about the way some unfamiliar situations make it harder to maintain our natural body posture. Studies show that being immersed in water or just changing your stance can greatly reduce the effects of motion sickness. But we don't really know what's going on. We know the more common remedies for car queasiness -- looking at the horizon, over-the-counter pills, chewing gum, but none are totally reliable nor can they handle intense motion sickness and sometimes the stakes are far higher than just not being bored during a long car ride. At NASA, where astronauts are hurled into space at 17,000 miles per hour, motion sickness is a serious problem. In addition to researching the latest space-age technologies, NASA also spends a lot of time figuring out how to keep astronauts from vomiting up their space rations. Like understanding the mysteries of sleep or curing the common cold, motion sickness is one of those seemingly simple problems that, despite amazing scientific progress, we still know very little about. Perhaps one day the exact cause of motion sickness will be found, and with it, a completely effective way to prevent it, but that day is still on the horizon.
你可以在车上阅读吗? 如果可以的话, 你算是挺幸运的了。 因为对大约1/3的人口来说, 在移动中的汽车上、 船上、 火车上、 或者飞机上阅读 很快就会让他们觉得反胃噁心 但是首先,我们为什么 会有这种”晕动症“呢? 这个嘛,信不信由你 其实科学家都不是很确定 最广为接受的理论是晕动症 跟感官讯号错配有关。 当你坐到车上, 你的身体会接受到 两种非常不同的信息。 你的眼睛看见车的内部, 感觉车好像没有在动。 同时,你的耳朵却在告诉你的脑袋 你在加速的状态中 等等,你的耳朵? 对呀,你的耳朵其实 除了听觉外还有另外一个重要的作用。 在它最深处的位置有一组架构 叫作前庭系统, 给予人们平衡和动感的感知。 这个系统里面有三条半圆细管 以感知转动, 每一条都负责一个空间维度。 另外系统还有两个有毛发排列的囊袋 里面充满液体。 所以当你移动时 液体也会跟着移动并触动到毛发 告诉你的大脑 你到底是在横向移动 还是垂直移动。 把这些元素结合一起, 身体就会感知 你往哪边移动, 加快的速度有多少, 甚至是在什么坡度上移动。 所以,当你坐车的时候, 你的前庭系统能够 准确地感知到你在移动, 可你的眼睛却看不到这个状态, 尤其是当你的注意力停留在书本上的时候。 相反的情况也可能出现。 譬如说,你坐在电影院里 电影有个镜头是快速横扫整个场景的。 这次,是你的眼睛 认为你在移动 而你的耳朵则知道你其实稳坐不动。 可为什么这种相互矛盾的咨询 会让我们如此不适? 科学家其实也没有一个确定的答案, 但是他们认为这个现象 可以跟人类进化问题有关。 我们知道, 快速移动的交通工具和拍摄录影 都只在最后两个世纪才出现, 从宏观来讲其实跟 眨一下眼没有分别。 在人类的历史上, 也没有那么多情况 导致这种感官混淆的问题发生 除了毒药外。 而因为毒药 对生存不利, 我们的身体演化出一种直接 但不怎么让人舒服的方法 来让我们摆脱我们可能吃进去 而造成冲突的东西。 这个理论看起来挺合理, 但它留下很多部分没有解释 譬如,为什么女人比男人 更受晕动病影响呢? 再譬如,为什么乘客比司机 会更容易噁心不适? 另一个理论解释说 背后的原因可能跟 不熟悉的环境 使身体更难 保持自然的姿势有关。 研究显示 沉浸在水中 或单纯改变站姿 可以大大降低 晕动症的不适。 不过就像我刚刚说的, 我们不是很清楚真正原因。 我们知道的是晕车 最常见的舒缓措施有-- 往地平线看, 嚼香口胶, 服用成药-- 但这些方法并不完全可靠 也无法处理 非常强烈的晕动症 而这方面的研究比 是否会在長途車上 因为不能读书覺得无聊 意义来得更重要。 在美国国家宇航局, 宇航员以每小时 17000英里的高速进入太空, 晕动症对他们来讲 是一个严重的问题。 因此,除了研究 最新的太空科技, 美国国家宇航局也花了大量时间 尝试寻求方法 不让宇航员吐在 他们小心准备的太空配给上。 跟了解睡眠之谜 和治愈普通感冒一样, 尽管科学进步神速 但晕动症仍然是其中一个, 看见来很简单,但是 我们却了解很少的难题。 可能終有一天 我们会发掘晕动症的确切起因。 而因为它, 有效避免这个问题的方法也会出现, 但那一天仍在遥远的未来。