During the first few months of life, the human brain develops at a considerable rate. ]]>Mesa Community College]]> states that at birth, the brain is 30 percent of its adult size; by the time the child is a year old, her brain is 55 percent of its adult size. Between birth and the child's first year of life, the myelin sheath is deposited, which protects the axons of the neuron and insulates the signal being sent between the neurons. Mesa Community College notes that when the child is sitting, standing and walking, the neural pathways are functionally complete.
]]>North Dakota State University]]> notes that emotional and social development occur between birth and age 12, though emotional attachment develops between birth and 18 months. Research published in ]]>Neuron]]> found that infants start detecting the emotional tone in spoken language as early as 7 months old.