|
Why We Walk in Circles
为什么我们会走成两个大圆圈
"Pin the Tail on the Donkey" is always fun when you're watching rather than pinning. It is somewhat surprising to see how the blindfolded performers act. Instead of going straight, they always wander off to one side or the other. The greater the distance to the donkey, the farther they go astray. Have you ever wondered why they are unable to walk straight ahead?
It is a well-known fact that a person will move in a circle when he cannot use his eyes to control his direction. Dark nights, dense fogs, blinding snowstorms, thick forests - all these can keep a traveler from seeing where he is going. Then he is unable to move in any fixed direction, but walks in circles.
Animals act the same way. You have probably heard the saying "running around like a chicken with its head cut off." Well, a chicken with its head cut off actually does run around in circles. Blind birds fly in circles. And a blindfolded dog will swim in circles.
A Norwegian biologist, F.O.Guldberg, decided that this problem of circular movement was worth investigating. He collected many true stories on the subject.
One of his stories is about people rowing on a lake during a fog on a dark night. One group of rowers who tried to cross three miles of water in foggy weather never succeeded in reaching their goal. Without knowing it, they rowed in two large circles. When they finally got to the shore, they discovered that they were at the spot they had started from.
After studying many stories such as this, Professor Guldberg wrote an article in which he discussed "Circular Motion as the Basic Motion of Animals." A simple example will help you to understand his explanation of why we walk in circles.
Have you ever wound up a toy automobile and started it off across the floor? Then you know that it will rarely travel in a straight path. It will travel, instead, in some kind of arc, or curve. If it is to travel in a straight line, the wheels on both sides have to be of exactly equal size. If they are not, the little automobile turns toward the side with the smaller wheels.
Circular movement in walking is caused in much the same way. Usually a man walking will "watch his step" and "look where he is going." He needs his senses, especially his eyes, to get to the point he intends to reach. When he cannot use his eyes to guide his steps, he will walk straight only if he takes a step of the same length with each foot.
In most people, however, muscle development is not the same in both legs, so that it is probable that the steps will be uneven. The difference may be so small that no one is aware of it. But small as it is, it can cause circular movement.
Let us suppose that a man's left foot takes a step 20 inches long and that his right foot takes a step 30 inches long. Now suppose he takes ten step - five with his left foot and five with his right. His left foot will travel 100 inches. His right foot will travel 150 inches. This sounds impossible. One foot cannot remain 50 inches behind the other. What really happens? At each step the man turns a little bit to the left. Sooner or later he makes a complete circle. The tracks of his feet, however, make two circles, one inside the other. His left foot makes the smaller circle because it is taking larger steps. This is why a person may walk in an arc when he sets out in a straight line.
The muscles of a man's arms are no more identical than the muscles of his legs. This explains why the rowers who set out to cross the lake at night rowed in a circle. By the same rule, a bird's wings do not develop evenly, and so it will fly in circles when blinded. Thus, dear readers, our circular mystery has a very straight answer.
观看别人做"去把尾巴给毛驴安上"的游戏，比自己亲自去做更逗人。看到了被蒙住眼睛的参加游戏表演的人所走的路线着实有点儿让人吃惊。他们都不走直线，总是要由一边偏离到另一边。参加游戏比赛的人距离毛驴越远，他们偏离目标毛驴也越远。
一个人若不用眼睛来掌握走路的方向，就会走成一个大圈。这一事实是众所周知的。每遇到漆黑的夜晚，浓浓的大雾，伸手不见五指的暴风雪，浓密森林--这一切都会使路上的行人看不见是在往哪个方向走。这时他就不能按既定的目标前进，只能走成一个大圆圈。
动物也会这样。你也许听过这样一句老话："像砍掉脑袋的鸡一样转着圈跑。"是的，一只被砍掉了脑袋的鸡确实会转着圈跑的。瞎了眼睛的鸟也都是转着圈飞的。一双被蒙住了眼睛的狗也会转着大圈游泳。一位挪威的生物学家哥尔柏格认为绕圈运动的问题确实值得调查研究。关于这一课题他汇集了很多实际事例。
他汇集的实例之一就是在一个浓雾黑夜里，人们在湖面上划般。在大雾的天气里，一帮想要横渡三英里的水面的划船手永远也不能成功地划到他们的目的地。不知不觉地，他们都把船划行路线划成两个大圈。在他们缍上个岸后，才发现又划回到了他们原来出发的地点。
在研究过很多诸如此类的实际经历之后，哥尔柏格教授写了一篇题为《动物的基本运动模式是圆周运动》的论文。一个很简单的的例子，就可以帮助你弄明白他的论点：为什么我们会走成两个大圆圈。
你有没有把一辆玩具汽车上好发条以后，把它放到地板上让它从头跑到那头的经历？那么，你就会知道小汽车几乎很少顺着直线跑，那么它左右两边的车轮的大小必须是正好绝对相等的。
步行时绕大圆周运动的规律在很大程度上是由同一原理引起的。通常一个人走路时会看着脚下所踩的步子，会看着所要去的方向。一个人需要用他们的各种器官，特别是要用两只眼睛，才能走到他打算要去的地点。只有当一个人的两只脚所迈出的每一步的长短都完全相同时，这个人才可以不用眼睛来引导脚步而能够顺着一条直线往前走。
但是，在绝大多数人左右两腿肌肉的发育并不是一样的，结果很可能左右两脚所迈的步子长短是不一致的。迈步子长短的差距是非常小的，以致于没有人会意识到这一微小的差距。尽管这个差距很小，但结果却导致了圆周运动。
我们假定某一人的左脚迈一步是20英寸长，右脚万一步是30英寸长。现在假设这个人迈了十步--左脚迈五步，右脚也迈五步。他的左脚总共走了100英寸，他的右脚总共走了150英寸。这听起来让人觉得不可能。到底是怎么回事呢？每迈一步这个人就稍微向左转了一点点。迟早，他会走成一个大圆圈。于是他的两只脚所走过的圆圈稍微小一点，因为左脚迈的步子小。他的右脚所走的圈比较大，因为右脚的每一步都大一点。这就是一个人在出发时本来是想走的直线，结果却走成了一条弧线的原因。
一个人的两只胳膊肌肉的发育和他的两只腿的肌肉的发育也是不同的。这足可以说明这些在夜间出发去横渡湖面的划船手缍把船划行的路线划成了一个大圆圈的道理。同理，鸟的左右两个翅膀的发育也是不均衡的，所以如果它的眼睛瞎了以后，也会绕圆圈飞行。由此可见，亲爱的读者，这就是我们的圆圈运动之迷的最直截了当的答案。 |