Myelin has a white appearance. Myelinization occurs both before and after birth and can be affected by diet. Glial cells multiply dramatically from fetal age four months to the child's second birthday. The cerebral cortex is the largest part of the human brain, and it is the last of the brain structures to stop growing. Within the cortex, the last part to develop and myelinate is the frontal lobe, which is responsible for thought, consciousness, planning, and socially acceptable behavior in general.
Humans have two hemispheres which control the opposite side of the body.
We have a property of the brain called lateralization, which means that the two sides do different things. There is some evidence that men's brains are more highly lateralized than women's. While I will cite the study in the appropriate chapter lecture, the pragmatic meaning of this is that strokes later in life damage men more than women because women have a tendency to use both sides of the brain regardless of what they are doing. This brings us to the issue of plasticity. If a brain is damaged, other parts can take over for the damaged part, as long as the damaged part is not something that sustains life, like the brain stem.