Behave Summary

1-Sentence-Summary: Behave sets out to explain the reason behind human behavior, good or bad, by exploring the influences of brain chemistry and our environment.

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Have you ever wondered to yourself, “why did I just do that?” Or have the actions of others left you similarly puzzled? Finding out exactly why humans do the things we do is difficult. No one facet of science explains why we act the way we do. This is why if we want to explain human behavior, we must adopt an interdisciplinary approach.

World-renowned neuroscientist and Stanford professor Robert M. Sapolsky encourages us to embrace the multifaceted explanation of why we act the way we do. In his book, Behave: The Biology of Humans at Our Best and Worst, he details the influences on our behavior. He includes those that happen seconds before, such as neurological responses, to thousands of years prior, such as the genetics that hardwired our brains. 

We may not be able to explain all of the puzzling human behavior we see. But this book will certainly give you a better idea of why we do the things we do.

Here are 3 awesome lessons I’ve learned from this book:

  1. Your amygdala and prefrontal cortex are in a constant war with one another.
  2. Sensory cues immediately around us influence our behavior without us realizing it.   
  3. Cultural factors impact the way we see the world around us, and the way we treat others. 

Are you ready to uncover some of the hidden causes of human behavior, good and bad? Let’s learn!

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Lesson 1: The amygdala and prefrontal cortex are always battling each other.

When it comes to aggressive behavior, two main parts of the brain take part. The first is the amygdala, which is in the cerebral cortex and is the reason for fear and aggression. It identifies threats in a matter of milliseconds and is often inaccurate. The part of the brain that calms feelings of aggression and helps you think rationally is the frontal cortex. It takes a little longer to react, but helps relax what is often an overreaction from our amygdala.

These two are in a constant battle. The amygdala keeps you safe from threats, and the frontal cortex helps you act like a rational person. If one of these is thrown out of balance, it is impossible to control the effects.

An example of this is Phineas Gage, a man who had an iron rod puncture his skull. It destroyed his frontal cortex, but he amazingly survived. Without his frontal cortex, his personality entirely changed. He began to have violent mood swings and swear, which he had never done before. Without the amygdala being kept in check by the frontal cortex, he was unable to control his aggression. 

Some scientists think that the reason that some people are racists or violent is because of an overdeveloped amygdala. We also know many violent criminals have suffered injuries to their frontal cortex, and psychopaths have less brain activity in this area. This is just one example of how brain structure influences behavior.

Lesson 2: We may not realize it, but sensory cues around us make us behave in certain ways.

Our five senses constantly send information in the form of sensory cues to our brain. Visual cues, like the faces of strangers, alter our perception and our behavior toward them. The human brain is very attuned to skin color. An example of this is when images of people’s faces are shown to white people, the amygdala is much more likely to activate if the person shown is of a different race.

Thankfully, this activation only happens for a split second, and the frontal cortex quickly sets in and quells this fearful response in non-racists. 

In addition, criminals with more characteristically “African” faces are more likely to have a longer sentence than someone else who commits a similar crime. This has led some defense attorneys to try strategies like having their black clients wear clunky, more stereotypical white glasses in an attempt to sway the jury. 

Our immediate social environment also plays a role in our behavior. An example of this is when males are around females they are more likely to take risks and buy more expensive items. We’ve all probably witnessed this kind of behavior, which can be explained by the male brain giving off mating signals in the presence of a female.

Lesson 3: Society and culture influence behavior as well.

It is true that biology and brain chemistry determines a lot of what we do. But there is no denying that some behaviors are socially conditioned. Take Honduras, where murders are 450 times more common than Singapore. Growing up in either of these countries will inevitably impact the way you behave. 

We learn of two types of cultures: collectivist and individualist. China is an example of a collectivist culture, who define themselves by relationships with others and place the needs of the whole above the one. In an individualist culture, like in the United States, people tend to define themselves by their own achievements and like to stand out from the crowd. 

Brain activation is actually different for the two groups when viewing a picture of themselves. Someone from an individualist culture will experience more brain activity when viewing a picture of themselves than of a relative, while a collectivist will not. It also changes the way they take in sensory information. When an individualist is shown a picture of a person standing in a complex scene, they will remember the details of the person, while a collectivist will remember more details from the scene. 

This also affects morals. A collectivist culture often holds the greater good above the needs of the one, so if they need to imprison someone, even if they may be innocent, they might do it to prevent a riot. On the other hand, an individualist culture would let them have a trial first, even at the risk of having a riot.

Behave Review

Behave is fascinating, informative, and eye-opening. It takes on an impressively broad look at how so many different factors, some often overlooked, influence our everyday behavior. Sapolsky goes all-in by looking at every side of the story, from the tiny connections in our brain, to the influence of genetics and evolution that go back for centuries. To me it really feels like this book is the most comprehensive answer you’ll ever get to the question of why we do what we do.

Who would I recommend the Behave summary to?

The 19-year-old who is considering studying psychology, the 32-year-old teacher who wants to understand why her students behave the way they do, and anyone who is interested in understanding their own mind a little better.

Last Updated on August 18, 2022

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Luke Rowley

With over 450 summaries that he contributed to Four Minute Books, first as a part-time writer, then as our full-time Managing Editor until late 2021, Luke is our second-most prolific writer. He's also a professional, licensed engineer, working in the solar industry. Next to his day job, he also runs Goal Engineering, a website dedicated to achieving your goals with a unique, 4-4-4 system. Luke is also a husband, father, 75 Hard finisher, and lover of the outdoors. He lives in Utah with his wife and 3 kids.