We take a grip on things by using our muscles to exploit the development of the human thumb. The importance of this thumb is that it can be moved across the palm of the hand to touch the index finger. In contrast the digits of a monkey’s hand are more rigid. This difference explains why a human being can handle an instrument with such precision.
The mechanism of the hand is operated by way of the wrist, a hinge joint composed of eight small bones (carpals) packed firmly together to give elastic stability. Below the wrist project five small, long bones (metacarpals) which give the palm firmness. Four of the bones have hinge joints and are connected to the thumb allows it to move round and meet the fingers and palm, thus providing a firm grip.
Possession of such a hand has enabled man to form a society and culture based on the use of tools. It is thought the hand developed from the five-rayed forepaw of an early vertebrate. However, occasionally a child is born with an extra tiny thumb or little finger and some people believe that the forepaw was originally seven-rayed.
The human thumb has length longer in proportion than that of an ape. About 92% of human being is right handed, but apes tend to use both hands with equal ease.
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