Behave

The Biology of Humans at Our Best and Worst

Robert M. Sapolsky

24 min read
1m 4s intro

Brief summary

Human behavior is not caused by any single factor, but by a cascade of influences stretching from one second to one million years ago. Understanding our best and worst actions requires looking at brain chemistry, hormones, childhood, culture, and evolution all at once.

Who it's for

This book is for anyone who wants a comprehensive, multi-layered scientific explanation for why humans act the way they do.

Behave

Audio & text in the Readsome app

Understanding the Context of Human Behavior

Humans possess a deeply confused and contradictory relationship with violence. We might imagine inflicting severe pain on a historical tyrant, feeling a raw desire for retribution, while simultaneously advocating for global peace. We pay to watch physical combat in stadiums, use military metaphors in corporate boardrooms, and celebrate aggressive athletes on the field.

Our struggle is not actually with the physical act of violence itself, but with the context surrounding it. The exact same physical movement of pulling a trigger can represent a horrific, premeditated crime or an act of self-sacrificing love to protect a family. Defining human behavior is a difficult task because our labels are shaped entirely by our own values and perspectives. A biologist might observe a territorial dispute, while a criminologist sees a violent assault.

To truly understand why we act the way we do, we must look past simple explanations and examine a long chain of causes. If a behavior occurs, we must ask what happened in the brain a second before, but we also have to look at the sights and sounds that triggered that brain activity minutes earlier. We must consider the hormones that circulated hours before, the childhood experiences that shaped the brain's structure over decades, and the evolutionary forces that molded our ancestors. Relying on a single explanation, such as blaming a behavior entirely on a specific gene or a single traumatic event, causes us to lose the full picture of humanity.

While we share the exact same stress hormones as a fish and the same pleasure chemicals as a rodent, we use this underlying biology in bizarrely unique ways. We can feel a rush of nurturing hormones for a baby panda or experience severe physical stress while merely thinking about our own mortality. We are the only species that can harm others over abstract ideologies or express deep contempt through a polite, passive-aggressive smile.

In the end, the meaning of any human action depends entirely on its specific context. The brain can process pulling a weapon's trigger and applying a medical bandage as the exact same moral act if both are perceived as the right thing to do in a specific moment. We do not hate aggression itself; we only hate the wrong kind of aggression. Our journey is not about labeling behaviors as purely good or evil, but about understanding the complex biology behind our best and worst moments.

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About the author

Robert M. Sapolsky

Robert M. Sapolsky is an American neuroscientist, primatologist, and author who serves as a professor of biology, neurology, and neurosurgery at Stanford University. His primary research focuses on the effects of stress on the brain, drawing from decades of field study on wild baboons to understand the links between social behavior, personality, and stress-related diseases. Sapolsky is widely recognized for his work on the biological underpinnings of behavior, which challenges the existence of free will.

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