Summary of Behave by Robert Sapolsky

BookSummaryClub Blog Summary of Behave by Robert Sapolsky

There are always moments in life when we question our behaviour. Why did I do that? What was I thinking? Our behaviour can sometimes be a mystery even to us. Therefore, it comes as no surprise that it is influenced by many different things. Each behavioural outcome is unique to a person as everyone is exposed to different things. But at some point, we have come across individuals from the same household, who are exposed to exactly the same people and environment and who behave differently to each other. Why does this occur?

Human behaviour is ultimately a combination of neurological and environmental factors. Some of these factors are a part of our evolutionary history and others are a result of modern society but they all work together to influence human behaviour. 

In this book summary readers will discover:

  • The brain and human behaviour
  • How our senses influence our behaviour
  • The part that hormones play
  • How our behaviour is shaped by our experiences
  • Cultural factors 

Key lesson one: The brain and human behaviour

Human behaviour is determined by the brain. But how? Well, to understand how, we first have to understand the brain itself. Before we act upon anything, the regions of our brain process the information surrounding us. This usually entails scanning our immediate environment and identifying any threats. In doing so, our brain can connect to our learned experiences to determine how we should act. This seems like a pretty long process but it takes mere seconds to run its course. 

Even years before we behave in a certain way, the society we were raised in will play a role. We are very impressionable at a young age and what we are exposed to will influence us in later years. Looking back even further, even before we were born, learned behaviours by our ancestors have an influence on human behaviour as well.

To understand how the brain influences behaviour, let’s consider aggressive behaviour. Brain scans have identified the amygdala as the region associated with fear, anxiety and aggressiveness and the frontal cortex is responsible for regulating emotions, strategic decisions and resisting impulses. Before the decision is made to behave aggressively, the amygdala and the frontal cortex work furiously to make several quick decisions on how to act. The way in which these parts of the brain influence behaviour were demonstrated in two interesting cases. 

In 1848, Phineas Gage had an iron rod impaled his skull, destroying his frontal cortex. Even though he survived, he began to suffer mood swings, swear and was exceedingly grumpy and impatient. His frontal cortex was no longer able to control his aggression and overall behaviour. The second case came later in 1966, when Charles Whitman, a normally happily married man went to see his doctor because he kept getting headaches and it made him have violent tendencies. A few days later he murdered his wife, mother and carried out a mass shooting at a local university. He left a note saying that he could not understand why he felt the need to act out in this manner. However, a later autopsy found a tumour pressing against his amygdala. This could have caused the neurological changes which influenced him to be violent. Modern-day research into these areas has also found that violent criminals seem to have some damage to the frontal cortex due to concussions. Violent psychopaths also have less activity in these areas of the brain. 

So, there are regions of the brain that can heavily influence behaviour. But this is just aggression, what about other behaviours?

Key lesson two: How our senses influence our behaviour

Our senses are constantly sending signals to our brain. It happens continuously, whether we are conscious of it or not and it influences our brain and behaviours in interesting ways. For example, experiments have been done to determine how people will react to strangers. White subjects were shown a series of images of faces for one-tenth of a second. The amygdala was found to activate when faces of different ethnicity were shown. When the images were shown for longer periods of time, the frontal cortex will rationalize and mollify the amygdala’s response. This was true for all nonracist people. 

In a similar experiment, different types of music were played to determine the effects of auditory cues. Rap music was found to increase amygdala activity while death metal music seemed to have the opposite effect on the amygdala. Why? Once again, this experiment proved racist tendencies as rap music is associated with African-American culture whilst death metal is associated with white people.

These perceptions alter the behaviour of African-American people in order to seem less threatening. Lawyers ask their clients to dress differently or wear glasses so they seem more refined. One student even whistled musical pieces by Vivaldi as he walked home at night so that he did not come across as threatening. 

Another interesting behavioural implication due to sensory cues has to do with male and female interactions. When males are in the presence of females, they tend to take risks more so than usual. They even spend more money and buy luxury items. The fact that there are females around is a sensory cue to the brain which then influence mating behaviours. This behaviour by males is an attempt to impress females and increase their chances of mating.

Key lesson three: The part that hormones play

Hormones also have an interesting effect on behaviour. They are chemical messengers after all and they are known to affect different parts of the brain. The relationship between hormones and behaviour, however, is not as straightforward as one would imagine. 

Once again considering aggression, it has been proven time and time again that there is a clear correlation between testosterone and aggression. But in a clear chicken and egg situation, which comes first? In terms of aggression, prisoners who were aggressive had higher levels of testosterone. It was not the testosterone to blame for the aggressiveness, but the aggressiveness which increased the testosterone. But no matter, the amygdala is still activated by testosterone. The higher testosterone levels, the increase in aggressive behaviour and also the decrease in feelings of fear. If you have less fear, this could lead to more impulsive decisions and risk-taking behaviour. However, this is only true if the individual is already inclined toward aggressive behaviour. It is a vicious cycle, to say the least. 

In contrast, oxytocin, which is basically one of the happy chemicals, inhibits amygdala activity. This is why oxytocin promotes social behaviour amongst humans. Oxytocin is released when romantic partners have physical contact or when a mother bonds with her child.   

Stress hormones or glucocorticoids also have an effect on behaviour. When they are present in your body for a long period of time, they have a negative effect on your immune system and increase the risk of high blood pressure and infection. Stress makes it harder for your pre-frontal cortex to regulate your amygdala which makes your irrational fears stronger. Stress hormones also affect higher brain functions which is why people can’t think properly if they are stressed. 

Key lesson four: How our behaviour is shaped by our experiences

The pre-frontal cortex does not develop fully until humans are in their mid-20s. This makes the years prior to this extremely important for brain development. Behavioural traits can therefore differ between adolescents and adults. This is why young people tend to be impulsive, take more risks and are more susceptible to peer pressure. It can also be linked to the violent behaviour seen in adolescents and young adults.

However, it is not just an underdeveloped pre-frontal cortex that influences behaviour. The experiences we have in our childhood can also have an effect on our behaviour when we are older. Children are able to take in information much faster than humans due to their high neural plasticity. If a child has negative experiences, this will manifest as adult behaviour. In fact, 33 per cent of children who were physically abused will grow up to abuse their own children. 

Furthermore, combined negative experiences like childhood poverty and violence can cause and underdevelopment of the pre-frontal cortex and overdevelopment in the amygdala respectively. As a result, the pre-frontal cortex can no longer inhibit the impulsive decisions made by the amygdala. This leads to poor behavioural regulation and increased violent tendencies in adult years. However, it is important to note that some people experience extreme adversity in their childhoods and end up being very successful, functioning adults. The effects of childhood experiences o

Key lesson five: Cultural factors 

Our childhood experiences are one thing, but there are cultural, ecological and geographical factors that also affect our behaviours. 

First, consider the cultural differences imposed on people. Individualist cultures, like in the United States, are focused on individual rights and personal achievements. Collectivist cultures, like those found in East Asia, focus on the needs of the group over the individual. The way in which our brain processes sensory cues differ in these cultural groups and therefore produces different behaviours. The best example of this is the different moral system between the two. Collectivist cultures place greater importance on the needs of many. It is always about the greater good. However, this means they are more willing to put innocent people in prison to stop a riot. In individualist cultures, this would never occur as an individual has to go through due process before imprisonment.

Another important example of cultural impact is if you consider people who have grown up in an area with high crime rates. Their exposure to this crime will lead to their behaviour being completely different to others who have grown up in safety. You have to look no further than children who have experienced war in their country versus those who have not. 

The key takeaway from Behave is:

The way humans behave is a result of the interaction between our brains and our environment as well as the experiences we have in the society we live in. It is a complex series of events all of which begin when we are very young. The amygdala and pre-frontal cortex are central to determining the behaviour that humans exhibit. Understanding how all these factors work together to influence our behaviour is imperative to understanding ourselves.

How can I implement the lessons learned in Behave:

Pay more attention to what influences your behaviour. By truly analysing the sensory cues which activate your behavioural responses, you might be able to control your behaviour better. This is extremely helpful if you have a short temper or are often inhibited by fear. By rationalizing your amygdala’s response, you can potentially alter your behaviour. All it takes is a little bit of knowledge and some patience.

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