Behave is Robert Sapolsky’s comprehensive exploration of the multifaceted influences on behavior. The book delves into how genetics, neurobiology, endocrinology, and environmental factors interact to shape human actions. Sapolsky combines insights from neuroscience, psychology, anthropology, and sociology, illustrating that behavior cannot be reduced to simple causes but is the result of a complex interplay of factors acting at different levels—from immediate brain reactions to long-evolved cultural contexts. The work is notable for its accessible synthesis of science and its philosophical reflection on free will, responsibility, and the nature of human behavior.

1. Genetics and Epigenetics – Innate predispositions and gene-environment interactions that shape neurological and behavioral traits.
2. Neurobiology – Brain structures and neural pathways that govern immediate reactions and longer-term behavioral patterns.
3. Endocrinology – Hormonal influences that affect mood, aggression, stress responses, and social bonding.
4. Developmental and Life History Factors – How early experiences and critical periods influence brain wiring and behavior over time.
5. Social and Cultural Context – The role of societal norms, relationships, and cultural history in shaping behavior.
6. Evolutionary Background – The deep-rooted evolutionary processes that inform instincts, survival strategies, and social dynamics.

1. Genetics and Epigenetics
   • An individual may inherit a genetic predisposition for high stress reactivity, which can be modified by early-life nurturing or trauma.
   • Epigenetic changes—like DNA methylation due to prolonged stress—can influence vulnerability to depression.

2. Neurobiology
   • A hyperactive amygdala might cause a heightened response to perceived threats, influencing a person’s tendency toward anxiety.
   • Damage to the frontal cortex can impair decision-making and impulse control, dramatically altering behavior.

3. Endocrinology
   • Elevated cortisol levels during chronic stress can affect learning and memory, shaping responses to future challenges.
   • Testosterone fluctuations can influence aggression and risk-taking behaviors in competitive contexts.

4. Developmental and Life History Factors
   • Early childhood experiences, such as secure attachment or neglect, can determine emotional regulation later in life.
   • Critical periods in brain development can set long-lasting behavioral patterns; for example, language acquisition or social skills.

5. Social and Cultural Context
   • Cultural norms dictate acceptable behavior, such as the expectation of independence in some societies versus community reliance in others.
   • Peer influence during adolescence can shape risk-taking behaviors and social identity.

6. Evolutionary Background
   • The fight-or-flight response is rooted in survival strategies animals evolved to escape predators.
   • Social hierarchies observed in primates reflect evolutionary pressures that also influence human competition and cooperation.