The cerebrum:

From an evolutionary point of view, the cerebrum is the newest and most highly developed part of the brain. It is involved with the more complex functions and is generally considered to be the structure that most separates humans from other animals. The cerebrum is divided down the middle from front to back into two halves: the right and the left cerebral hemispheres. Each hemisphere controls the activities of the opposite side of the body--that is, the left cerebral hemisphere controls the right side of the body and the right hemisphere controls the left side. Although in many ways the two hemispheres are mirror images of one another, there are functional distinctions between them. In most people, the areas that control the development and use of language are located in the left hemisphere, while areas that govern three-dimensional visualization and musical and artistic creation are located in the right hemisphere.

The cerebral hemispheres are separated by a deep groove called the longitudinal cerebral fissure. At the base of this fissure lies a thick bundle of nerve fibers, called the corpus callosum, which provides a communication link between the two hemispheres. Two major furrows--the central sulcus and the lateral sulcus--are arbitrarily used to divide each hemisphere into four sections: the frontal, parietal (top rear), temporal (lower), and occipital (rear) lobes.

The back part of the frontal lobe contains areas that govern movement of the opposite side of the body. Damage to this region results in paralysis. In front of this region is an area of the frontal lobe called the premotor cortex, where complex movements are orchestrated. Still farther forward is the prefrontal cortex, which exerts an inhibitory control over actions. Such distinctly human abilities as foreseeing the consequences of an action, exercising self-restraint, and developing moral and ethical standards depend on the normal functioning of the prefrontal cortex.

In the following verse, the Qur’an hints of the existence of a cerebrum in every living creature, and modern science proved that animals have cerebrums.

"I put my trust in Allah, my Lord and your Lord! There is not a moving (living) creature but He has grasp of its forelock. Verily, my Lord is on the Straight Path (the truth).” (11: 56)

Brains in Other Animals:

The brains of invertebrates consist of clusters of nerve- cell bodies at the end of a series of nerve cords. The vertebrate brain is essentially an enlargement of the front end of the spinal cord. Vertebrate brains can be divided into three distinct regions: the hindbrain, the midbrain, and the forebrain. The hindbrain is composed of the medulla oblongata and the cerebellum. The upper portion of the midbrain evolved from the optic lobes, two structures involved with vision. In fish and amphibians the midbrain serves as the main center for integrating information from the sense organs. In mammals the midbrain is greatly reduced, serving primarily as a connecting link between the hindbrain and the forebrain.

The forebrain includes the cerebrum, thalamus, and hypothalamus. The cerebrum was originally part of the olfactory lobes, two structures involved with smell. (The olfactory lobes are seen as projections on the front of each of the cerebral hemispheres. They have bulbous growths, called olfactory bulbs, in which the olfactory nerves terminate.) In humans and other higher vertebrates, the cerebrum has enlarged and grown over the rest of the brain. This growth and the increased complexity of neuron networks in the cerebrum have made possible a greater flexibility of response and adaptation to the environment, whereas the behavior of such less advanced vertebrates as reptiles is instinctive and relatively invariant because it is based on comparatively inflexible network arrangements within the brain.

In general, larger species possess larger brains, though the size of the brain is not necessarily related to intelligence or any other behavioral trait. It is more likely that traits such as intelligence and creativity are more closely correlated to efficient information processing in the brain and to the formation of complex neuron networks.