Book summary #4 Behave — The Biology of Humans at Our Best and Worst

by Robert Sapolsky

This is a reading project I have started this year. I am focusing 80% of my reading time on 1 topic per year (and this year’s topic is Biology!). As part of the project, I am also pushing myself to write more (because that’s the best way to learn) and share book summaries from time to time. Previous book summaries about biology can be found on Medium too.

How I “met” Robert Sapolsky (the Author)

In the summer of 2015, my cousin, who has been suffering from depression in the past 14 years, got diagnosed with schizophrenia. I only heard about this from my mom a couple of months later. And she added: don’t let your aunt know that I told you — they didn’t want anyone else to know.

I wanted to help. And I thought the best way to help is to learn as much as I can about schizophrenia. That’s how I found Robert Sapolsky’s Human Behavioral Biology lectures online. He talked about the neurobiological and environmental origin of mental health issues, particularly depression and schizophrenia. Learning about the neuroscience behind depressions and schizophrenia was a scary and liberating experience. Scary and liberating because one realizes just how common (and in some sense, normal) these mental issues are and how much it is outside one’s self-control. However, with all the effort put into learning, I still failed to help my cousin in any way. My aunt and uncle didn’t want to talk about it with me; and they still thought anti-depressant and electro-therapy alone are sufficient and didn’t want to find systematic treatment, including a therapist. I could go on and on about mental health treatments in China — but let’s save this for another time

The one good thing that came out of that bizarre period of time, is that I realized just how much I love everything about Robert Sapolsky. He is a primatologist, behavioral biologist, neuroscientist, and neuroendocrinologist (I had to google what Neuroendocrinology means..) The list goes on. The most remarkable thing about him (apart from his deep expertise in almost everything biology and his thought-leadership in topics such as consciousness and morality) is that he spent 8–10 hours a day, 4 months a year and 21 years in remote Kenya following, studying and documenting a troop of Savannah Baboons. I have my utmost respect towards him for the dedication, persistence, mastery and often times, the humility that comes with it. Sapolsky has it all. And most importantly, his ridiculous sense of dry humor makes him a very entertaining speaker and writer — watch his talk at Stanford and be prepared to be amazed from beginning to end.

About the book

‘Behave’ is a fairly new book — published in May 2017. I first read it in 2017 and read it again a month ago (because it’s THAT good). Another one of his classics is ‘Why Zebra’s Don’t Have Ulcers’ — also really good. I will consider writing a book summary for that one when I get a chance to re-read it.

Mukherjee’s “The Gene” is about zooming into that micro-world of molecules to understand the code of life. Sapolsky’s “Behave” is about zooming out to the centuries and millennia before us to understand how the code was written in the first place, and why. Both are breathtaking in its own ways — it’s like watching a movie of life playing out in front of you.

This summary is written in four parts. Part A, B and C look inside our brain and explore how the three most important functions of our Brain works: Pleasure and motivation; fear and aggression; and executive control. Part D looks outside of our brain and dives into some of the most interesting studies about the environment and its influence on our mindsets and behaviors.

Before we dive in, a super duper simplified intro of our brain and some terms that we will use in the following sections.

Over simplified intro of our brain — three layers of our brain (metaphorical layers, not real layers)

• Layer 1 Reptilian brain: It’s the oldest of three and controls vital functions such as breathing, heart rate, body temperature, and balance. It makes your heart beat faster when you are cold
• Layer 2 Limbic brain: This part emerged in the first mammals and is associated with our emotional life and plays a big part in memory formation. It includes the hypothalamus (hunger, thirst, pain and sexual drives), the hippocampus (memories), the amygdala (fear, anxiety, and aggression), and several other nearby areas. When you feel scared, layer 2 will send signals to layer 1 to speed up your heart rate with emotion
• Layer 3 Neocortex: It first assumed importance in primates (proportionally much larger) and is believed to be responsible for executive function, abstract thoughts, imagination and language abilities — all the cool stuff we do. When you read a thriller, layer 3 tells layer 2 to feel scared, which in turn tells layer 1 to make your heart beat faster

Part A: Pleasure and motivation — the dopamine system

The neurotransmitter, Dopamine, is central to understanding reward, pleasure, and motivation. Neurotransmitters are chemical messengers released by neurons to pass signals to the next neuron. It’s one way (the fastest way) that information flows in our brain and in our body. Some famous neurotransmitters are dopamine (pleasure), serotonin (relaxation and sense of security) and oxytocin (intimacy and trust).

Various types of rewards trigger the release dopamine — food, sex, alcohol, the usual. Most drugs (cocaine, heroin, etc.) also mess with your dopamine system by releasing large amount of dopamine at a time — but often makes it harder to feel pleasure with the same amount of stimuli in the future. Chronic stress depletes dopamine and decreases sensitivity of dopamine neurons to stimulation — leading to classic symptoms of depression: the inability to feel pleasure. Many anti-depressant either increases dopamine release, or increases sensitivity of neurons to dopamine stimuli (by increasing dopamine receptors)

Two things that make dopamine system really interesting — and the fertile ground for behavior science research on happiness and motivation:

1. Habituation: When a monkey presses a lever, he gets 1 grape — 1 unit of dopamine is released. The next time he presses a lever, he gets 2 grapes. Woah! 2 units of dopamine is released. But as the monkey keeps getting 2 grapes with 1 press, the dopamine level goes back to 1 unit. And now give the monkey 1 grape, the dopamine level is below 1 unit — hedonic adaptation! Unfortunately, the system has to work that way. We live in a world with a full range of stimuli — from food to watching the final episode of Game of Thrones. In order to accommodate the pleasures of both, dopamine responses are relative to the reward value of the alternatives — it has to constantly rescale itself to accommodate all sorts of stimuli. Put it another way, it’s the relative reward value compared to expectation (what we think the alternative is) that matters.
2. The anticipation of reward: Back to the monkey experiment. Light comes in first and then a lever shows up. The monkey presses the lever and gets a grape. Over time, the monkey can be conditioned to have dopamine release with just the light — because it signals that a reward is coming. What’s even crazier is that when the rule changed to that the monkey only gets the reward 50% of the time — dopamine release increases. Anticipatory dopamine release peaks with the greatest uncertainty as to whether a reward will occur.

In summary, dopamine is not about the happiness of the reward, it’s about the happiness of the pursuit of reward that has a decent chance of occurring. This should sound weirdly familiar to all of us — because this is so central to how motivation works. Understanding dopamine system helps us understand and work on motivation in life — so much of Ed Batista’s art of self-coaching stuff is related to this as well.

Part B: Fear and aggression — amygdala

When it comes to our worst behaviors, we have to talk about Amygdala (part of layer 2, limbic brain). It is central to mediating aggression, along with other behaviors that tell us a lot about aggression. Researchers have long understood the connection between Amygdala and aggression — animals demonstrate a significantly lower level of aggression with damaged Amygdala. However, if you ask an Amygdala expert what behaviors does this part of brain bring to mind, aggression won’t even top the list — it will be fear and anxiety. You can’t understand aggression without understanding fear. Numerous research documented that Amygdala reacts to fear and anxiety stimuli — in PTSD sufferers, the amygdala is over-reactive to mildly fearful stimuli and is slow in calming down afterward. Neuroimage also shows that people who have long-term PTSD have expanded amygdala — that’s why chronicle stress can make a person easily scared, anxious and aggressive.

Two important notes about amygdala:

1. The tendency, not causation: Like so many other things in this book, the brain/behavior relationship we observe is often about the tendency, not predictability. Fear and aggression are not inevitably intertwined — not all fear causes aggression, and not all aggression is rooted in fear. Fear typically increases aggressive behaviors only in those who are already prone to aggression but does not have much impact on those who are not prone to aggression
2. Amygdala shortcut: Because amygdala (part of layer 2, limbic brain) can get sensory signals from layer 1, it can be informed of something scary before the cortex has a clue. Typically, the amygdala will consult the frontal cortex (which we will talk about next) for some executive decision making on how to react — but when the amygdala is extremely excited, it can respond to stimuli directly, bypassing the cortex brain. Tragically, the amygdala is not very good at accurately processing information (that’s not it’s job anyway) and when the cortex is bypassed, bad things can happen. For example, the amygdala sees what looks like a handgun, feels scared and reacts immediately, without a chance for the frontal cortex to get in and realize it’s actually a cell phone.

Part C: Executive function — Frontal Cortex

Prefrontal Cortex (PFC) is the cerebral cortex which covers the front part of the frontal lobe. The basic activity of this part of the brain is orchestrating thoughts and actions in accordance with one’s internal goals — planning, decision making, personality expression, and social behaviors. Think of your body as a spaceship, the brain as the pilot cabin — your PFC is the little pilot sitting in front of the control panel, contemplating your next move.

There are two things I found particularly interesting about the PFC:

1. It is an expensive function, metabolically. It’s much easier to stay on “auto-pilot” mode where our limbic system takes actions based on our animal instinct — like eating that sinful chocolate cake, or binge-watching Netflix. PFC helps us do the hard thing when it’s the right thing to do. But PFC interference requires lots of energy — willpower is not just a metaphor. Studies have shown that people tend to have lower executive control when they are tired, hungry or distracted. You probably have heard about the famous Israeli judge study where judges on average granted 60% of request for parole after lunch and 0% before lunch.
2. It is the last part of the brain to mature. PFC is the crown jewel of our brain. It is also the part that distinguishes us the most from the rest of species — we have the largest (percentage of volume) and the most developed PFC. Interestingly, it’s also the part that is last to mature in our brain. PFC is not fully developed until the mid-20s — this part of the brain that most defines us is largely impacted by the environment.

A small detour on the classic gene/environment discussion to explain how this works. 95% of our DNA is non-coding — not transcribed into proteins. Some of the 95% are junk — remaining of past genes deactivated by evolution. But some are the “gene regulators” — an instruction menu for when to switch particular genes “on” and “off”. Those gene regulators are impacted by environmental factors — everything from inside the cell, such as hormone levels outside the cell, such as childhood experiences.

This is not to say that genes are irrelevant. In fact, all behavioral traits are affected to some degree by genetic variability — that’s because they specify the structure of all proteins that eventually form every neurotransmitter (which then determine how we react to each stimulus). Genes are really important, but their effect is largely context dependent — ask not what a gene does, ask what it does in a particular environment. Numerous twin studies have proven this point. Genes are not about inevitability, they are about potentials, vulnerabilities, tendencies, and propensities.

A couple of profound and everyday implications from understanding how PFC works :

• Do not make any life-changing decisions when you are hungry, tired, distracted or angry — your PFC might not be very happy about the decisions when it’s back online. And pre-order your salad lunch before you get too hungry and can’t say no to that burger!
• When teenagers are acting weirdly emotional and compulsive — give them some benefits of the doubt. Their underdeveloped prefrontal cortex is acting above its pay grade
• Genes are not deterministic. We are who we are also because the experiences we go through and the choices we make. Neuro plasticity (and with it, growth mindset) is so promising and exciting because it radiates optimism

Discussion about PFC is not complete until we take another detour to talk about moral reasoning. So here we go:

Kohlberg’s monumental research identifies roughly three stages of moral development:

• Stage 1: Moral judgment is about self-interest — would I be punished or rewarded if I do this? What’s in it for me? Typically kids up to age 8–10 are at this level
• Stage 2: Moral judgment is about norms and laws — who would benefit or be hurt if I do this? Do I like them? What would others do? What would people think of me if I do? What’s the law? What would happen if everyone broke the law? Most adolescents and adults are at this level
• Stage 3: Moral judgment reflects conscience — What are the ultimate consequence of this action? Are those consequences in accordance with my own moral stance? Is my moral stance regarding this more vital than some law, a stance for which I’d pay the ultimate price if need be? Can I live with myself afterward? — This is a stage where rules and applications come from within and reflect conscience. At this stage, one recognizes that what’s right and what’s legal are not necessarily the same. Kohlberg found that hardly anyone can be consistently at this level

One interesting finding related to this — liberals tend to be at a higher level of Kohlberg’s moral stages than conservatives. The latter cares about law and order, is less comfortable with ambiguity and often sees things as a threat (because it can disrupt the current order). Does that mean liberals are intellectually more capable at moral reasoning than conservatives? Not really. Studies show that both are equally capable of moral reasoning but conservatives are less motivated to do so — there’s less need for reflection on consciences if you firmly believe in authority, law, and order.

Pard D: Collectivism vs. Individualism and its impact on mindsets and behaviors

As someone who was born and raised in a collectivism culture, and then spent most of my adult life so far in individualism culture, I have experienced the drastic difference in the way people think and act. I identify more with individualism culture now — I value a sense of self and individual rights and am willing to trade-off harmony and a closer-knit social/family network for that. However, I deeply understand the root of collectivism and come face to face with it whenever I spend time with my parents. They don’t get it why the abstract notion of freedom of speech is more important than stability and economic growth of the country- and I don’t judge them. I have come to realize that there’s no absolute right or wrong in this discussion. You can’t start to judge collectivism culture without understanding where it came from and why it can be a good thing under certain context

Disclaimer — everything I wrote above is about average, there are plenty of individual variations. And such differences are very context driven, and not rooted in genetic variation (e.g., it takes about one generation for East Asian Americans to become “individualist” culture)

Let’s begin with how different cultures traditionally made a living. In East Asia (collectivism culture), rice is the main source of calories. Rice farming requires a massive amount of communal work — terracing mountains, building irrigation systems and harvesting crops. On the opposite side, in Europe (individualism culture), wheat and meat are the main sources of calories. Both wheat farming and herding are individual tasks — often times farmers and herders spend days alone.

This naturally led to two different cultures:

1. In traditional collectivism culture, people value conformity and harmony because of the need for collaboration and social trust. People tend to think in a more utilitarian way and are willing to sacrifice individual benefits for their group (hence explains a greater willingness for an innocent person to be jailed in order to prevent a riot). Those societies are more relational and norm enforcement is more about shame — What will people think if I did that?
2. In typical individualism culture, people value autonomy, individual rights, uniqueness, and personal achievements. Norm enforcement is more about guilt — Can I live with myself if I did that?

Those differences manifest itself in multiple interesting ways:

• Parents from collectivism culture value calmness and conformity (a good kid is a quiet kid who listens to parents and teachers). Parents from individualism culture value high-energy and personal opinion (a good kid is someone who speaks up in class and offers interesting thoughts)
• When describing a picture of a flock of fish and 1 single fish by itself in the front. Mothers from collectivism culture will tell their kids as “the fish did something wrong and is now isolated by the group”. Mothers from individualism culture will tell their kids “It’s great to be a leader”. I have always been told the former when I grew up — and I had to re-learn that instinct in western society and be comfortable with “being different”
• People from collectivism culture think about things in relational terms. When presented with several lines of different lengths, they are much better at estimating which line is longer; while people from individualism culture are better at estimating the absolute length of each line. There’s even documented difference in eye movements when reading a picture — collectivism group scan through the whole picture for holistic information; individualism group tend to focus on the center of the picture

More interestingly, there are also genetic differences among these two groups. There are several variants of the D4 gene (the gene that codes protein that forms dopamine receptor, and is directly related to how sensitive a person is to dopamine release). The 7R variant of the D4 gene is the least sensitive to dopamine release, often associated with novelty seeking, extroversion and impulsivity. Guess what — 7R is found in roughly 23% of Europeans and European Americans, but 1% of Eastern Asians. Now one might ask: does the gene leads to cultural differences or does culture differences select the gene variants? Research suggests that the answer is neither. Brains shape culture, which shapes brains, which then shape culture… They are coevolved

One of the reasons I think biology is so fascinating is that it changes our view of the world — the behaviors one might regard as irrational, stupid or wrong might make perfect sense in a different context. Western society always holds strong judgment towards collectivism culture. Freedom and individual rights are regarded as moral high-ground. I don’t disagree with that. But freedom and individual rights come at a price. Collectivism culture, historically, has chosen to compromise those in exchange for harmony, tighter relations, and more trust. It worked for those societies for centuries. Whether this type of thinking still works in modern society is a slightly different discussion. However, I do believe that judgment towards the entire collectivism culture is unfair. It’s important to take the others’ perspectives here to understand the historical context of those mindsets and behaviors and know that such genetic and environmental traces take longer to change than what the modern society might expect.

Final thought: What’s biology’s place in social judgment and criminal justice system?

One of the contrarian truth I believe in is that the future human beings will look back in time and be horrified at the way our society judges and penalizes “bad behaviors” today. We will look at our current criminal justice system with the same appalling feeling we have when reading about the medieval witch hunt.

We are only a few baby steps into understanding how brain impacts behaviors. This leaves huge, unexplained gaps that we automatically fill in with “free will” — and hold people accountable for that. As we make progress in neuroscience research, I think those gaps will gradually be filled with science; and that we will realize our worst (and best) behaviors are impacted by many factors outside our “free will”.

If indeed our actions are impacted by those unknown factors outside of control, how should we think about rewarding good behaviors and penalizing bad behaviors? How should we think about the criminal justice system? Sapolsky thinks that because we are far away from fully understanding it, we should at least try not to act irrevocably. We should change our mindset from “punishment” to “protection”. It’s less about punishing the criminal because they did something horrible (that might or might not result from his free-will) It’s about knowing that something might be wrong with their brain (that we don’t know yet), we should take actions to protect the endangered (the public) from the dangerous (offender). Much the same way we treat a car with a broken brake — we ban it off the streets, we fix it, but we don’t punish it. Of course, I do realize that there are so many practical challenges with this thinking. For one, if we don’t have a punishment system — how do we deter people from letting their impulse make them do bad things?

As a final thought: my cousin has been staying at home for over 10 years because of her depression. The extended family always talks about her (behind her back) in a judging way — they think she is lazy and useless; that she got her self into such a mess; and that she didn’t even try to get a second chance in life. Multiple times I heard them telling the young kids in the family: “work hard! Otherwise, you will end up like her!”. Even my mom and dad, both well-educated and completely aware that mental health issues are real, still fail to see her condition as a “real disease”. If it is that difficult to fully accept that it’s her disease, not her “free will” that leads to her behaviors — then how do we expect people to really believe and accept that some of the worst criminal actions might also come from factors outside our control?