The Ecology of Humans (27) The Brain Through Life

The Brain Through Life

The human brain goes through 5 life stages: 1) conception to birth (0–10 months); 2) infancy into childhood (birth–6 years); 3) youngster through teenager (7–22 years); 4) adult (23–65 years); 5) aging (65 years onwards).

Into the World

Differentiation of the nervous system and brain in a fetus begins at about 3 weeks. In the 4th week, the brain is a tiny bulb at the end of a neural tube. By the 8th week the main sections of the brain have formed.

A newborn has as many neurons as an adult, but the number of glial cells continues to grow.

The brain begins to create sensory maps at birth based upon the new world it has entered. Like the subtle energy variations in an early universe, these initial brain pathways can shape lasting proclivities.

Infancy into Childhood

The brain at birth is 25% of its adult weight. Brain weight more than doubles in the 1st year.

Most brain growth occurs within the first 2 years from proliferating glia. The brain attains 90% of its adult size by age 6.