Nepali Wanderer

Introduction

“Behave” is a book by Robert Sapolsky, a renowned neuroscientist and primatologist. With his extensive expertise in diverse fields, Sapolsky integrates insights from biology, psychology, ecology, and anthropology in this book. A seemingly simple action is influenced by numerous factors, ranging from milliseconds before the action to millions of years before. These actions also have different meanings depending on the context, even down to the neural circuitry level. For example, shooting a menacing villain is different from shooting an innocent person, even biologically. Thus, to understand and explain our behaviours, a multidisciplinary approach is necessary to dissect each set of influences, from milliseconds to millions of years before.

Milliseconds to Seconds Before Behaviour

Our behaviour starts in the brain, so we need to begin at the neurological level. For an action to occur, it involves the activation of neural circuits, the role of neurotransmitters, and the interaction between different brain regions. To simplify, we can compare the roles of two regions: the prefrontal cortex and the amygdala. The prefrontal cortex is crucial for higher-order functions like decision-making and impulse control, while the amygdala processes emotions, especially fear and aggression. For example, if someone encounters a snake, the amygdala triggers an immediate fear response. The prefrontal cortex then assesses the information and context, modulating this response (like toning down the fear if the snake is in a zoo). However, this coordination of different regions is heavily influenced by factors just milliseconds prior. The brain itself has a plastic nature, allowing its wiring to be influenced over the years. Thus, we need to go further back in time and dissect each factor.

Seconds to Hours Before Behaviour

The interplay in the brain is heavily influenced by hormones. Hormones such as cortisol, adrenaline, oxytocin, and testosterone can influence behaviour in various ways. Adrenaline prepares the body for quick reactions by increasing heart rate and blood flow to muscles, while cortisol helps mobilise energy reserves. However, the same cortisol that helps manage acute stress can have detrimental effects at higher levels (caused by chronic stress), highlighting the context-dependent nature of hormones. The same oxytocin that enhances bonding within a group (like between a mother and infant or a couple) might also contribute to in-group favoritism and out-group hostility. The context-dependent nature is also seen in testosterone. Contrary to popular belief, testosterone doesn’t increase aggression; rather, it increases whatever behaviour is necessary for dominance. If it’s being social, it increases sociability. In our world, aggression is often used for dominance, hence we see an increase in aggression.

To link it with the milliseconds of neural action, we can think of cues the brain receives before making decisions. From external visual (like seeing an attractive mate) to olfactory (smelling fear) to internal state senses (like tensed muscles, faster heartbeat), these cues are influenced by the hormones discussed above. For example, in stress situations related to cortisol, the amygdala dominates the prefrontal cortex. This prioritises speed over accuracy, which makes sense in a fight-or-flight scenario. However, in modern environments, it can lead to impulsive decisions aimed at immediate survival, which might not be beneficial in the long run.

Days to Months Before Behaviour

Our recent experiences also influence our behaviour at various levels. In terms of memory and learning, positive or negative reinforcement from past events shapes our actions. For example, if you recently received praise for speaking up in front of seniors, you’re more likely to do so again. Stress and fatigue levels also affect behaviour. If you have been exposed to regular stress in the past few weeks, it subdues your prefrontal cortex, leading to irrational decisions. Making decisions, for instance, depletes our cognitive resources, so if you have already made many decisions in a day (like driving in heavy traffic), it affects your decision-making later on. Sleep is another factor that heavily influences our behaviour. Several nights of poor sleep can make a person more irritable and prone to impulsive decisions.

Months to Years Before Behaviour

Developmental influences can heavily shape our behaviour through both biological and cultural factors. The plastic nature of the brain (known as neural plasticity) allows environmental aspects (like childhood experiences) to shape its wiring. For example, adverse experiences in childhood can lead to a reduced prefrontal cortex (decision-making), reduced hippocampus (memory, learning), but an increased amygdala (fear and aggression). Thus, for the same external cue, a person with an increased amygdala can display more extreme impulsive behaviours.

Genes also affect our behaviours. However, Sapolsky emphasises the importance of not viewing genes in isolation when explaining behaviour. Rather than acting as automatic machines, genes are activated by the environment, making it crucial to understand behaviour through the lens of gene-environment interaction.

For instance, genetic differences can explain why humans are smarter than chimpanzees. However, to explain why one student is smarter than another, genes alone are insufficient. Environmental factors (nurture) often play a larger role, as individuals in unfavorable environments struggle more regardless of their genetic makeup. Only when environmental factors are similar (ideally constant) do genes play a significant role in differences.

Also, it is important to analyse gene-environment interactions in studying population differences rather than individual cases. For example, if a certain disease requires both a specific gene and diet, determining which factor is more influential depends on their prevalence. If the gene is common and the diet is rare, the diet plays a larger role. Conversely, if the diet is common and the gene is rare, the gene is more influential. Context is always important, and we need to consider variance in behaviour rather than behaviour alone.

Culture also heavily shapes our behaviour. Sapolsky dissects two cultures at length: the collectivist culture prominent in the East and the individualist culture prominent in the West. Collectivist cultures value group interest and inter-dependence, while individualist cultures value self-interest and independence. This affects how they view the world (collectivists focus on the overall scene, while individualists focus on the central character) and how they cope with mistakes (collectivists are more affected by shame, while individualists are more affected by guilt). The same action of speaking in front of a class is influenced by whether a person comes from an individualist culture (where it is more encouraged) or a collectivist culture. Similar cultural influences can be seen in nomadic pastoral societies. Since the threat of theft is more serious in pastoral societies, retaliation and violence are deemed necessary, promoting military behaviours.

Years to Millions of Years Before Behaviour

The cultural factors discussed above are heavily shaped by environmental ecological factors. For example, the collectivist vs. individualist culture is shaped by the predominant crops in the region. Collectivist cultures have developed in rice-dominant regions, while individualist cultures have developed in wheat-dominant regions. This seemingly simple difference has deep influence when you delve into the farming requirements. Rice requires intensive labor and cooperation for planting and irrigation, demanding coordination among multiple families or the community. Thus, people in these societies prioritise group goals over individual goals and have strong community bonds. In comparison, wheat farming is less labor-intensive and suitable for individual or small family farming. This independence leads to more individualistic cultures where people prioritise personal goals and self-reliance.

Ecology shapes not only organisational structures but also philosophical beliefs, such as beliefs about gods. Monotheistic religions (like Judaism, Christianity, and Islam) have flourished in less diverse (mono) environments like deserts. In contrast, polytheistic religions (like Hinduism) have flourished in regions rich in biodiversity.

Then comes evolutionary factors, which have shaped our behaviours over millennia, influencing everything from aggression and cooperation to mating strategies. These behaviours have evolved based on their ability to increase the likelihood of survival and reproduction. For example, our tendency to form social tribes and bonds evolved because it enhanced survival in ancestral environments. We can trace these roots even before the origin of humans, examining our primate heritage. Studying primate behaviour offers valuable insights into our evolutionary origins. For instance, the hierarchical structures observed in primates suggest that our drive for status and recognition has deep evolutionary roots.

My Takeaway

My biggest takeaway from the book has been understanding the interplay between nature and nurture, a topic that has always fascinated me. The book prompted me to see genetic effects not in isolation but as part of a gene-environment interaction. The rectangle analogy was particularly enlightening: asking whether genes or environment influence a particular action more is like asking whether length or breadth influences the area of a rectangle more. We can only ask this question to explain differences among rectangles (for example, if all rectangles have similar length but differing breadth, then breadth influences the variance in area). This connects with my background in data science, where variance often provides more insight than just the mean and links to a concept called R-squared in statistics. Examples like wheat vs. rice and agriculture vs. pastoral lifestyles have also highlighted the importance of ecological factors in understanding our cultural values, beliefs, and behaviours.

Finally, reading this book felt like reading at least two dense books: one from pure biology and one from anthropology. This is not surprising, considering Sapolsky’s expertise in both disciplines. However, it also meant a challenging read, which I realised even more while writing this summary. Writing this summary required multiple re-reads of sections and help from the internet, like ChatGPT. This challenge, of course, led to a much clearer understanding of the book (which is why anyone who reads should write!).