ABSTRACT
Purpose: Recently, purpose in life (PIL) drawn from existentialism and the concept of ikigai [meaning in his/her life] from Japanese classical literature have been recognized as effective ways to manage stress. PIL/ikigai is related to a function of the prefrontal lobe of the brain and influences happiness. However, many factors, including negative experiences, seem to inhibit development of PIL/ikigai and prefrontal lobe function. Using established evidence, the author discusses these issues in relation to increasing happiness. Established Evidence: Genetic factors that affect prefrontal lobe function have not significantly changed since modern humans first emerged, but epigenetic changes caused by stress and chemicals influence gene expression. Development of the prefrontal lobe is influenced by sensory and motor experiences, the parent–infant relationship, stress, chemicals, and pollution. PIL/ikigai develops through positive experiences of playing and spending sufficient time in beautiful natural surroundings in cooperation with others and setting challenging goals and achieving them in conjunction with forming positive impressions. Historically, individuals who lived in natural surroundings, relied on cooperative relationships in their daily lives, and traveled on foot to obtain food. Humans today have the convenience of being able to obtain food in an urban setting. However, pollution, whether by disruption of the environment or pesticides, causes epigenetic changes that can lead to disease. Conclusion: Individuals should play more often and spend more time in beautiful natural surroundings in cooperation with others and set challenging goals and achieve them in conjunction with forming positive impressions. Environmental disruption and pesticide use should be minimized. In this way, increasing PIL/ikigai and fostering development of prefrontal lobe structure and function may increase overall levels of happiness.
ABSTRACT
The prefrontal lobe, which is more evolved in humans compared to other mammals, has extensive connections with many other areas of the brain including the thalamus, hypothalamus, hippocampus, and amygdala. The prefrontal lobe functions include ambition, cognition, emotions, information evaluation, mental integration, voluntary activity, and organized response. Violent behavior is related to aggression, with less serotonin, gamma-aminobutyric acid interaction, more dopamine, and more testosterone. Violent behavior is reinforced by negative experiences including viewing of violence in childhood and successful problem solving by violence. Every person has a natural and intrinsic need to establish the meaning of life, relative to ambition. Purpose in life (PIL)/ikigai means an attitude to establish the meaning of life. The term PIL/ikigai has been commonly used in daily life for many years in Japan. PIL/ikigai contributes to a greater ability to cope with stress, i.e., greater pleasure and comfort as well as less anxiety and confusion during stressful situations. This process leads to increasing serotonin and decreasing testosterone. PIL/ikigai is reinforced by positive experiences, including being moved by persons and events, success in challenging events, spending time in beautiful natural surroundings, and warm-hearted human relations. Moderate aerobic exercise, e.g., walking and running, causes pleasure. This process results in improvement of the autonomic nervous system, i.e., optimal balance between the sympathetic nervous system and parasympathetic nervous system, and optimally balanced secretions of dopamine, -endorphin, and serotonin. PIL/ikigai, performing aerobic exercise and violent behavior are prefrontal lobe functions. Prefrontal lobe function develops even during adulthood as the result of experiences. Thus, PIL/ikigai and moderate aerobic exercise may prevent and improve violent behavior.