Final answer:
All primates share three main brain regions: the forebrain, midbrain, and hindbrain. The human brain is different due to a major increase in mass and the complex folding of the neocortex, which occupy about 76% of its mass, enabling advanced cognitive functions.
Step-by-step explanation:
The three main regions of the brain that are shared by all primates include the forebrain, midbrain, and hindbrain. The forebrain comprises the cerebral cortex, responsible for higher functions; the midbrain and hindbrain handle more autonomic functions. Primates, including humans, tend to have a larger cerebrum compared to the rest of the brain, which allows for higher levels of intelligence and complex social interactions.
The human brain differs in its increased mass compared to other species, particularly in the neocortex. In humans, the neocortex accounts for about 76% of the brain's mass and is associated with advanced cognitive abilities such as language and consciousness. The human neocortex is also notably more folded, increasing its surface area and mental capabilities.
Through evolutionary history, the human brain has undergone significant encephalization, making it considerably larger than that of our closest relatives such as chimpanzees. This enlarged brain size in humans is a result of evolutionary pressures that favored higher cognitive functions and complex social behaviors. The human cerebrum is distinctly separated into two halves - the right and left cerebral hemispheres - by the longitudinal fissure and is characterized by the large white matter pathway of the corpus callosum facilitating communication between hemispheres.