The human brain develops through the formation of connections between its roughly 100 billion neurons. In adults these neurons average about one thousand synaptic connections each, producing around one hundred trillion pathways that enable every physical action, sensory experience, and intellectual function. Infants are born with a full complement of neurons, yet only one quarter to one half initially possess synapses. Between birth and age three the remaining neurons rapidly form connections at a rate of nearly one trillion new synapses each day, yielding approximately one quadrillion pathways—ten times the adult total. This explosive growth equips young children to absorb knowledge and skills at a pace far exceeding that of adults. Around age twelve the brain begins to prune unused synapses, eliminating eighty to ninety percent of them and leaving only those pathways that have been regularly exercised. Consequently, stimulation in the first twelve years determines how much capacity is retained for life. When children are deliberately challenged with language, music, reading, mathematics, physical skills, and especially the reading and memorization of Scripture, the corresponding synapses remain and become permanent features of adult thought and behavior. This early, consistent training therefore equips the next generation to keep the way of the Lord, to practice righteousness and justice, and to be prepared for the promises God has spoken concerning His Kingdom.

The brain of an elderly person develops greater plasticity than is commonly assumed, allowing the right and left hemispheres to interact harmoniously and thereby expanding creative possibilities. This development enables many individuals over sixty to begin or intensify creative activities, as seen in the case of Giuseppe Verdi completing major work at age eighty-two. Although processing speed may decrease, flexibility increases, which supports more accurate decision-making and reduced exposure to negative emotions. Intellectual activity reaches its peak around age seventy, when the brain operates at full strength. A key element in this development is the continued growth of the myelin sheath, composed of protein and fatty substances, which insulates nerves and permits electrical impulses to travel efficiently. Myelin production peaks between ages sixty and eighty, raising intellectual abilities by as much as three hundred percent compared with average levels. From age sixty onward, both hemispheres are employed simultaneously in problem-solving, permitting seniors to handle increasingly complex tasks. Seniors demonstrate superior performance in orienting attention, ignoring distractions, inductive reasoning, verbal abilities, spatial reasoning, basic calculations, and accentuating positive emotions. Neurons themselves do not die off; instead, unused connections may fade, while absent-mindedness often results from information overload rather than decline. When a person maintains a healthy lifestyle that includes physical activity and mental engagement, intellectual abilities continue to grow and reach their highest point between ages eighty and ninety. These developments in brain function align with the observation that wisdom and understanding accompany length of days when found in the way of righteousness, and they support the promise that the righteous shall still bear fruit in old age and flourish like a palm tree or cedar.

The developing brain is highly susceptible to conditioning that replaces natural aversions with violent responses. Vasoconstriction narrows blood vessels and shuts down the forebrain during intense anger or excitement, allowing the midbrain to dominate with reflexive behaviors indistinguishable from those of animals. This process overrides the God-given resistance to killing one's own kind that is hardwired into humans through the spirit in man, a resistance evident across species in nonlethal territorial conflicts. In children, brain development compounds the effect: at eighteen months they can mimic screen actions, yet the brain region enabling them to grasp the source of information does not function until ages six or seven, leaving them unable to separate fantasy from reality. Repeated exposure to violence therefore registers as actual events, associating suffering and death with pleasure through classical conditioning that pairs graphic images with snacks and entertainment. Operant conditioning further embeds stimulus-response patterns, training point-and-shoot reflexes identical to those produced by interactive video games. These mechanisms parallel military desensitization techniques of brutalization, classical conditioning, operant conditioning, and role modeling, systematically eroding the forebrain's higher functions and hardening the heart against God's law. The result is a carnal mind set on enmity toward God, where sinful thoughts arise naturally from within and become controlling dispositions. Only deliberate renewal through repentance, the indwelling of the Holy Spirit, and active pursuit of peace can reshape the conditioned mind into the character of Jesus Christ.