Human Hand – The Most Wonderful Tool
The most wonderful tool in the world is the human hand. Man is called “a tool-using animal” because no other animal in the world ever made tools for itself. But man could never have made all the wonderful tools he uses if he had not himself had these two most wonderful tools of all—his two hands. If we look at a skeleton hand, we find it is made up of a large number of bones. In the wrist there are eight small bones, in the palm five, and in the fingers and thumb fourteen. In the living hand, these bones are joined together by strong but supple muscles. The joint that joins the hand to the arm is called the wrist, and it is a beautifully poised ball-socket, which enables the hand to turn in almost any way.
What makes the human hand so wonderful a tool is the fact that the thumb is so placed that it can be brought opposite to the four fingers. Monkeys have hands ; but some have no thumbs, and some have a thumb that is not opposite the fingers ; only the chimpanzee has a hand anything like the human hand. To see how important is the human thumb in its peculiar position, try to hold a book or write a letter, or do any bit of manual work, with your hand with-out using your thumb. As Professor Drummond put it: “The thumb is not an additional finger, but a finger so arranged as to be opposable to the other fingers, and thus possesses a practical efficacy greater than all the fingers put together. It is this which gives the organ the power to seize, to hold, to manipulate, to do higher work ; this simple mechanical device, in short, endows the hand of intelligence with all its capacity and skill.”
It took long ages to evolve the human hand„ the most perfect instrument nature has made. Is the hand likely to evolve still further in future ages into a still more wonderful instrument ? The answer is, No. Man’s invention of tools has prevented further development. “The fatal day came, the fatal day for the Hand, when he who bore it made a new discovery. It was the discovery of Tools. Henceforth what the Hand used to do, and was slowly becoming adapted to do better, was to be done by external appliances…. Tools are external hands. Levers are the extensions of the bones of the arm. Hammers are the callous substitutes for the first. Knives do the work of nails. The vice and the pincers replace the fingers. The day that Cave-man first split the marrow bone of a bear by sticking a stick into it, and striking it home with a stone—that day the doom of the Hand was sealed.”
