The Human brain consists basically of three parts

The cerebrum, cerebellum and medulla obtangata.

The cerebrum is the most predominant and consists of two hemispheres, the right, and the left. These two hemispheres are joined at the base by a strip of tissue called the corpus callous. It is well known that the two hemispheres of the cerebrum control respond to external stimuli from opposite sides of the body. For example if we touch a hot object with our right hand, the sensory nerve fibers in the skin start sending a series of Electro chemical pulses through the nerves. These travelling at about 100 ft/sec reach the spinal cord with in Milliseconds. Crossing over to the left side of the spinal cord, they reach the left side of the brain, where the signals are processed giving us a sensation of heat.

If the brain decided the object is hot enough to burn the skin it sends out signals through the nerves to the right hand muscles to contract and withdraw the hand. Similarly, any sensation from the left half of the body is conveyed to the right half of the brain. For some unknown reason which defies, any explanation each half of the body is connected to the opposite half of the brain.

Neurologists have also found that the two cerebral hemispheres play different roles and have special abilities and functions. For instance, language and logical functions like mathematics and sequential tasks are handed by the left cerebral hemisphere. On the other hand, visual and spatial configurations geometric patterns abstract thought and creatively are controlled by the right hemisphere of the brain, while solving a geometrical problem we use the right.

Although each half of the brain controls specific activities any information received by one hemisphere is instantly transferable, also the other hemisphere through the corpus callous a bundle of nerve tissue containing about 200 million nerves cells. The corpuses callous thus co- ordinate the functions of the two hemispheres as a single whole. And it is this bundle of tissue; recent research suggests that lead to handedness in humans.

In two things humans are vastly different to animals. Human use language for communication and have used tools. The use of tools requires fine sequential movement of limbs, hands, and fingers. The left hemisphere best controls this task and so is language ability. Because of this it has been suggested that our right-handedness was a process of evaluation, it was only by chance that the left hemisphere of the brain specialized in language developed and so language was created a means of communication. As a corollary the left hemispheres took over control of the right side of our body and made us right handed.

Our right-handedness therefore seems to be due to our “split brains.” In the case of the left-handers, the exact role of the increased corpus callus and its effects on handedness are not clear. As research intensifies neurologists are still groping for a cause.