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Behave by Robert Sapolsky Summary and Key Lessons

“Behave: The Biology of Humans at Our Best and Worst” by Robert Sapolsky is an examination of human behavior, exploring its biological underpinnings and complexities. 

Here, Sapolsky, a professor of biology and neurology, delves deeply into the science of why we do what we do, ranging from our best to our worst behaviors. He integrates various scientific disciplines, including neuroscience, genetics, psychology, and evolutionary biology, to explain the multifaceted nature of human actions.

Full Summary

In the beginning of the book, Sapolsky focuses on the role of the brain in dictating behavior. He delves into the importance of brain regions such as the amygdala and prefrontal cortex in emotional responses and decision-making. 

Sapolsky also explores the impact of hormones like testosterone and oxytocin on behavior, challenging popular misconceptions about their roles. For instance, he dispels the myth that testosterone directly causes aggression, explaining that its effects are more nuanced and context-dependent. 

This neurological and hormonal context sets the stage for understanding the immediate causes of a behavior.

Sapolsky then expands the discussion to the influence of genes and evolution on human behavior. He explains how certain behaviors may have been advantageous in our evolutionary past, shaping the human brain and genetic predispositions. 

However, he also emphasizes that genes are not destiny; they interact with the environment in complex ways that influence behavior. This intersection of genetics and environment highlights the importance of epigenetics, where environmental factors can affect gene expression without altering the DNA sequence itself. This part of the book underscores the complex interplay between nature and nurture in shaping human behavior.

In the next part of the book, Sapolsky addresses the cultural and societal aspects that influence behavior. He examines how cultural norms, social structures, and individual experiences can profoundly impact how we act and interact with others. 

Sapolsky also delves into the realm of moral and ethical behavior, discussing how different societies have varying standards and how these are reflected in individual actions. 

This section provides a broader context, showing how biological predispositions are shaped and sometimes overridden by cultural and societal factors.

Finally, Sapolsky explores the implications of this multi-layered understanding of behavior for areas such as the criminal justice system, education, and health

He argues for a more empathetic and scientifically informed approach to dealing with human behavior, especially in areas like criminal justice, where traditional views of free will and moral responsibility often prevail. 

By understanding the complex biological, psychological, and societal factors that drive behavior, Sapolsky suggests we can better address issues like crime, education, and mental health with more effective and humane strategies.

behave by robert sapolsky summary

Key Lessons

1. The Complex Interplay of Biology and Environment in Shaping Behavior

Human behavior is the result of a complex interplay between genetic, neurological, hormonal, and environmental factors. 

Sapolsky emphasizes that it’s not just about “nature” or “nurture,” but a continuous interaction between both. 

For example, while genes might predispose an individual to certain behaviors, the expression of these genes is often influenced by environmental factors. 

This complexity is evident in the discussion of how stress experienced during early development can alter gene expression, potentially impacting behavior throughout life.


This lesson encourages a more nuanced understanding of human actions, moving away from simplistic explanations that focus solely on genetics or environment. 

It suggests that addressing behavioral issues, whether in education, healthcare, or criminal justice, requires considering both an individual’s biological makeup and their environmental experiences.

2. Rethinking the Role of Hormones and Neurobiology in Behavior

Common perceptions about hormones like testosterone and neurotransmitters are often oversimplified. 

Sapolsky dispels myths, such as the direct causation of aggression by testosterone, illustrating that the relationship between hormones and behavior is context-dependent and influenced by numerous factors. 

He also explains how different regions of the brain, like the prefrontal cortex and amygdala, play a role in our emotional and rational decision-making processes.


This lesson is crucial for understanding and managing behaviors in ourselves and others. 

It suggests that interventions aimed at modifying behavior (such as in therapeutic settings or education) need to consider the underlying neurobiological and hormonal contexts, which can vary greatly among individuals.

3. The Importance of Empathy and Understanding in Addressing Behavioral Issues

Sapolsky argues for a more empathetic approach to dealing with human behavior, especially in systems like criminal justice. 

By understanding the myriad factors that contribute to behavior, we can approach issues such as crime and mental health with greater compassion and effectiveness. 

This perspective is vital in reconsidering how society punishes or rehabilitates individuals, recognizing the role of factors beyond their immediate control.


This lesson has profound implications for policy-making, education, and social work. It suggests that a more informed and empathetic approach to behavioral issues can lead to more humane and effective solutions. 

For instance, in criminal justice, understanding the biological and environmental factors that contribute to criminal behavior can lead to more rehabilitative and less punitive approaches.

Final Thoughts

Throughout “Behave,” Sapolsky blends scientific rigor with engaging storytelling, making complex concepts accessible and compelling. 

His book is not just an exploration of the biological bases of behavior but an invitation to view human actions through a more empathetic and nuanced lens. 

Sapolsky challenges readers to reconsider their preconceptions about why people behave the way they do, offering a richer understanding of the human condition.