PDF Summary:Behave, by Robert Sapolsky

Robert Sapolsky, a professor of biology and neurology at Stanford University, wrote Behave: The Biology of Humans at Our Best and Worst to explore the myriad influences on human behavior.

As a child, Sapolsky became both fascinated and horrified with the atrocities of the Holocaust, and strove to understand the science behind how people could do such terrible things. That fascination grew into a lifelong study of science and people and led directly to this book.

In this guide, we’ve divided Sapolsky’s ideas along classic “nature versus nurture” lines—in other words, how much are we influenced by our own innate tendencies versus our surroundings and how we were raised? Our commentary will provide background information on Sapolsky’s ideas, explore interesting details to deepen your understanding of the subjects, and examine some scientific theories that conflict with Sapolsky’s.

(continued)...

(Shortform note: As people age—especially men—reduced testosterone levels can cause physical and emotional changes. Most notably, people may experience decreased bone and muscle strength, as well as a loss of motivation and a generally depressed mood. Doctors have found that testosterone therapy can reverse some of these effects in aging men. Some men have reported feeling younger and stronger after taking testosterone supplements, but there’s little scientific evidence supporting it as a treatment for those with normal testosterone levels for their age.)

Evolved Behaviors

Our brains and hormones—and all of the “natural” effects on our behaviors—work the way they do because of evolution: Ancestors who behaved in certain ways were more likely to survive and reproduce, passing on the genes that caused them to behave in those ways. So now, many generations later, those genes still survive in us and influence our behavior.

Let’s examine a few broad categories of human behavior closely related to survival and reproduction.

(Shortform note: In The Selfish Gene, Richard Dawkins makes the case that human behaviors are becoming less genetically driven as we continue to evolve. In particular, he believes that our advanced brains—our consciousness—give us the ability to go against our genetically programmed instructions. For example, our genes should compel us to have as many children as we can feasibly raise, but many people choose not to reproduce at all. However, even Dawkins doesn’t think we’ll ever be totally free of genetic imperatives; if nothing else, we’ll always be driven to keep ourselves alive.)

Kin Selection: Protecting Your Family

Kin selection is a term in evolutionary biology that means potentially sacrificing your own welfare or reproductive success in favor of your relatives’—for example, risking your life by fighting off a home intruder to protect your family. It evolved because, by definition, your relatives share many of your genes, so keeping them alive helps pass those genes on.

Sapolsky says that kin selection explains a great number of human behaviors, but that we can also find countless examples of people going against what kin selection should dictate. For instance, we can read news articles about people killing family members, or millionaires donating incredible amounts of money to strangers.

Sapolsky’s theory is that humans do follow kin selection, but the way we decide who our “kin” are isn’t entirely rational. On the one hand, we can look at total strangers and find similarities to ourselves. On the other hand, we can reject even our closest family members if they, for instance, behave in ways we find unacceptable.

Furthermore, we can be manipulated into feeling more or less related to others. Propaganda can paint groups of people as dangerous and monstrous—barely even human, let alone kin. And, conversely, campaigns emphasizing people’s humanity and similarities to us have been crucial in everything from promoting LGBTQ+ rights to raising funds for cancer research.

Hamilton’s Rule of Kin Selection

Hamilton’s rule quickly and efficiently explains kin selection. Hamilton’s rule is the equation r * B > C, (r times B is greater than C), where r is relatedness, B is the benefit to the recipient, and C is the cost to the one taking action.

For example, your sibling has 50% of the same genes as you do (on average), so your r is 0.5. Therefore, if an action would have more than twice as much benefit to your sibling as cost to you, kin selection dictates that you would perform that action. A half-sibling would have an r of 0.25, so the benefits would have to be more than four times greater than the cost to you.

While this equation only directly applies to people who are genetically related to you, it can provide a hint about how far you’d be willing to go for someone. How close do you feel to this other person? For example, do you think of him like a brother, or is your relationship more like close cousins? How you answer those questions could change the r value of Hamilton’s rule, even when it should logically be zero.

Reciprocal Altruism: Helping Each Other

A related phenomenon (no pun intended) is reciprocal altruism—the theory that it’s often advantageous for unrelated individuals to work together. To give a common example, grooming behavior is common among animals that live in groups—any member of the group will groom any other member, because making sure nobody’s carrying fleas or ticks benefits the whole group.

Sapolsky says that human society was founded on reciprocal altruism. Hunter-gatherer societies, the earliest known type of human civilization, relied heavily on nonrelatives working together to keep everyone safe and fed. Therefore, reciprocal altruism is in our genes at least as strongly as kin selection is.

Reciprocal Altruism and the Tit for Tat Strategy

In The Selfish Gene, evolutionary biologist Richard Dawkins uses the Prisoner’s Dilemma to illustrate how reciprocal altruism could have evolved. In the Prisoner’s Dilemma, two players have the choice to “cooperate” or “betray,” and each must choose without knowing what the other player picked. The possible results are:

• Both cooperate—both players gain a small number of points.

• One cooperates, the other betrays—the cooperating player loses a large number of points, the betrayer gains a large number of points.

• Both betray—both players lose a small number of points.

Professor Robert Axelrod hosted a Prisoner’s Dilemma tournament, where he asked people to design computer algorithms that would play hundreds of rounds of Prisoner’s Dilemma against each other. The winner was a simple program called Tit for Tat, which would always start out cooperative, then for each subsequent round it would copy what its opponent did the round before. It was mathematically impossible for Tit for Tat to win any individual match, but over the course of the tournament it racked up more total points than any other program.

Dawkins argues that the Tit for Tat program demonstrates why reciprocal altruism works better than more aggressive strategies: Aggressive individuals think of life as a zero-sum game—one where there must be a winner and a loser—and therefore they worry about defeating their opponents rather than simply doing well for themselves. However, in Prisoner’s Dilemma (and in life), all players can do well for themselves by cooperating and not worrying about “winning.”

Empathy and Compassion

Finally, empathy (echoing another person’s feelings) and compassion (acting to improve another person’s situation) have their place in our behaviors.

On the surface, empathy and compassion don’t seem to follow the same kind of evolutionary logic as kin selection or reciprocal altruism—we don’t seem to benefit from sharing another’s pain, or from acting to alleviate it. However, Sapolsky says that compassionate acts can (and usually do) have selfish aspects to them: A boost to our reputation, a sense of pride in our actions, or just the pleasant rush of dopamine that comes from doing a good deed.

It’s still not totally clear how empathy and compassion evolved, but it seems obvious that helping others is somehow advantageous. One theory Sapolsky favors is that empathy and compassion go hand-in-hand with our evolving brains and cultures: As we get better at reasoning and rational thought, we realize more and more that helping strangers benefits all of us.

(Shortform note: As a partial counterpoint to Sapolsky, many animals show signs of empathy and compassion toward one another. It’s likely that our evolving brains made us better able to rationalize those feelings, and perhaps to foster them where they wouldn’t otherwise exist, but it’s misleading to say that only species with highly developed brains display empathy.)

Part 2: Nurture: Culture, Family, Environment, and Stimuli

While biology explains internal influences on human behavior, Sapolsky says that external influences—including how we’re raised, where we are at a given moment, and what’s happening around us—are even more important in determining how we act.

Culture: How We’re Raised

Humans, like many other animals, instinctively want to fit in. We want to be part of the in-group, so we obey our culture’s rules, follow its beliefs, and expect others to do the same. Realizing that we’re not matching the people around us can cause serious anxiety—just imagine showing up to a fancy party in jeans and a t-shirt.

Interestingly, studies show that our most deeply held values aren’t things that we consciously think about following. For example, someone who’s been raised to be honest doesn’t decide to tell the truth or overcome the temptation to lie; that temptation never arises in the first place. In other words, you’ll reflexively follow whatever core values you were raised with, unless you make an active effort to do otherwise.

Two Types of Culture

In The Culture Map, cross-cultural management expert Erin Meyer discusses two different styles of culture, which she calls “peach cultures” and “coconut cultures.”

• Peach cultures are outwardly friendly, but keep what’s important to them deep inside and only share it with a select few people—like how a peach has soft flesh with a hard inner pit. The US is an example of a peach culture.

• Coconut cultures are the opposite: Outwardly cold and distant, but much more willing to share their true selves once you break through that shell. Russia is an example of a coconut culture.

These differences come down to different core values. Someone raised in a peach culture will reflexively treat people politely, yet find it very difficult to open up to others. Someone raised in a coconut culture will find it difficult to be warm and welcoming to strangers.

Religion: What We Believe

Throughout history, one of the most influential parts of a person’s upbringing has been his or her religion. Sapolsky says that all religions share a few traits in common, which makes them ideal for understanding cultural effects on behavior:

• Religions are a powerful in-group versus out-group catalyst. Religious communities can offer strong emotional and material support to their members, but they can be hostile—sometimes violently so—toward people who don’t follow that religion.
• Religions teach rules and codes of ethics. These rules often come with promised rewards for following them, and severe punishments (in this life or in the afterlife) for breaking them.
• Believers practice rituals: fixed, familiar behaviors that promote feelings of control, comfort, and belonging. Examples include prayer, meditation, singing and dancing, and coming-of-age ceremonies.

Three Levels of Belief

Beliefs such as religion influence our behaviors in various ways, based largely on how strongly we hold those beliefs and how emotionally invested we are in them. In Awaken the Giant Within, Tony Robbins breaks down beliefs into three categories:

1. Opinions: the weakest kind of belief, with little emotional investment. For example, preferring tea to coffee is an opinion—someone might state that preference but wouldn’t feel the need to defend it and might even find that opinion changing over time.

2. Beliefs: much stronger than opinions and based on personal experiences or information from trusted sources. People generally aren’t willing to listen to anything that contradicts a belief; they’ll ignore or deny any such information. However, close friends or trusted authorities on that subject may be able to change those people’s minds over time.

3. Convictions: the strongest type of belief and central to our understanding of the world, and we shield them with intense emotions. We’re likely to become angry and combative if anyone—even a close friend—so much as questions one of our convictions.

Environment

So far, we’ve discussed how biology and neurology shape our behavior through nature and how culture affects our behavior through nurture. Now we’ll examine the most direct influences on our behaviors: our immediate surroundings and our mental states when we take action.

Physical Environment

Sapolsky says people will instinctively act in ways that match their physical surroundings. For instance, people are more likely to commit crimes when evidence of other crimes is present—they might drop their trash on the ground if there are signs of vandalism nearby. In more general terms, people are more likely to violate social and ethical norms if it seems like others have already done so. However, Sapolsky says that the reverse is also true: People are more likely to behave themselves and follow the rules if the environment is clean and orderly.

Our physical environments can also affect us biologically. For example, if you see a dangerous animal, your body will activate genes that cause you to produce adrenaline, so you’ll be ready to fight or run away. Conversely, locking eyes with a child or a pet causes you to produce extra oxytocin, producing feelings of love and kinship.

(Shortform note: Sapolsky mainly discusses the immediate effects of what we can observe around us, but our physical environment affects us in many other, longer-term ways too. For example, certain types of air pollution can cause changes in behavior, mood, and overall health, with effects ranging from irritability to allergies and asthma. Similarly, exposure to heavy metals such as lead can cause increased aggression, fatigue, and memory loss.)

Moral Environment

How close we are to a situation—physically and emotionally—greatly affects how we respond to it. For instance, we might jump into action if we see a child in danger but not feel compelled to act if we read a story about child abuse. Similarly, if we know the child who’s in danger, we’re much more likely to do something about it.

How directly we act upon a situation also changes how we approach it. Notably, people generally consider allowing a bad thing to happen to be much more acceptable than doing a bad thing personally; in Sapolsky’s terms, omission (failing to prevent an act) isn’t as bad as commission (committing the act). For example, I might allow someone else to vandalize a disliked neighbor’s house, even if I would never vandalize it myself.

Finally, as with many things, we aren’t totally rational in our moralizing. People who would never steal physical copies of music albums or video games will happily (and illegally) download them from the internet. The reduced risk of getting caught may explain that to some extent, but there’s also the fact that clicking a download link doesn’t really feel like stealing, and thus pirating feels more acceptable than tucking a CD into your jacket does. There’s also a greater sense of distance—both physical and emotional—between you and the victim: Rather than stealing from a shopkeeper whom you can see and talk to, you’re stealing from an artist who might be on the other side of the world.

Developing Morality

Obviously, people don’t all share the same morals—even people raised in the same cultures can have wildly different ideas of what’s right and wrong, based on their own experiences and predispositions.

To help understand how a person develops a personal moral code, psychologist Lawrence Kohlberg breaks moral development into three stages, with each stage helping to shape the ones that come after it:

1. Pre-conventional: the earliest and least-developed stage of morality, where the person’s ideas of right and wrong are based on obeying authority figures and avoiding punishment. In other words, the person doesn’t yet have what we’d recognize as a moral code, just a set of rules to follow.

2. Conventional: the stage of morality when the person simply accepts what society says is right and wrong. This differs from the previous stage because the person is now doing what he or she believes is right, rather than just seeking praise and avoiding punishment. In other words, the person does have a moral code, it’s just a reflection of the moral codes of others.

3. Post-conventional: the final stage of moral development, when the person begins developing his or her own moral code. That code will be heavily influenced by the previous two stages, but at this point the person recognizes that people have different ideas of what’s right and what’s wrong. For example, one person might believe that stealing is always wrong, while another might believe that stealing to feed your family is the right thing to do.

Social Environment

Just like our physical environment and moral codes can influence how we behave, so too can the people who are around us. For a clear and easy example, imagine how you act around your best friend compared to how you act around your boss—in most cases, your behavior will be wildly different.

We’ve already discussed the human tendency to divide people into in-groups and out-groups, but we also subdivide our in-groups into ranks—in Sapolsky’s words, we have hierarchies. We tend to feel closer to those who are close in rank to us in those hierarchies. For example, an office worker would likely feel more kinship with his coworkers than with either the company CEO or the janitor.

A hierarchy is different from typical “us versus them” dynamics because all members are still part of the same group, and (at least in theory) all work together for the common good.

Furthermore, Sapolsky points out that the effects of our social environments go beyond influences from people we personally know. For instance, men tend to become more aggressive and take greater risks when women are present. Also, in situations where helping someone would be inconvenient (but not dangerous), the more people there are present, the less likely anyone is to step forward to help—the so-called “Bystander Effect.”

In situations where helping would be dangerous, however, people are actually more likely to step in if there are witnesses nearby. That might be because of the chance to be recognized as a hero, or perhaps simply because it seems more likely that we’ll have backup if things get out of hand.

Friendship Is a Special Type of Social Environment

The people around us at any given time may affect our behavior in that moment, but the people we spend a great deal of time around can have much more profound and longer-lasting impacts. Behaviors and habits tend to spread throughout friend groups, including eating habits, how often we exercise, whether we smoke, and how much alcohol we drink.

Furthermore, studies have shown that spending time with friends leads to increased happiness and overall higher quality of life. Interestingly, the effects are based less on how many friends we have and more on how close those friendships are. In other words, it’s better to have a few good friends than dozens of acquaintances.

Responses to Stress

Stress increases amygdala function while suppressing the frontal cortex—in other words, it makes us more prone to reflexive, habitual, and selfish behavior, and less able to regulate that behavior with logic and reason.

Furthermore, Sapolsky says that one of the most effective ways to reduce stress is to behave aggressively toward someone else. For example, someone who’s stressed out at work is more likely to lash out verbally or physically at “safe” targets like a spouse or a child, because that helps relieve the stress. Note that Sapolsky does not excuse this behavior; he’s merely offering a partial explanation of the neurology behind it.

The Effects of Chronic Stress

While short-term stress can make us unpleasant (or even dangerous) to be around, long-term stress is known to have devastating effects on the body and mind. Mayo Clinic says that chronic stress—and long-term exposure to stress-related hormones such as cortisol—can lead to numerous health problems, including:

• Anxiety and depression

• Heart disease

• Insomnia

• Memory loss

Furthermore, unhealthy stress management techniques like drinking alcohol and overeating only compound these problems. Instead, Mayo Clinic recommends learning some healthy coping mechanisms like working out, or indulging in a hobby.

In When the Body Says No, physician and psychologist Gabor Maté also discusses some of the diseases that chronic stress can give rise to, including multiple sclerosis, irritable bowel syndrome, arthritis, and even cancer. According to Maté, many of these diseases appear more frequently and more severely in people who suffered childhood trauma and neglect, and he argues that they must be cured with a holistic treatment regimen that encompasses physical, mental, and emotional health.

What About Free Will?

This guide has covered numerous factors that influence our behaviors, but at the end of the day, can we still make a conscious choice about what to do? Sapolsky doesn’t think so—he believes that free will is an artificial construct we use to fill the gaps in our understanding of human behavior. If this is right, then, logically, someday we’ll close up all of those gaps and have no more need (or space) for the idea of free will.

While giving up the concept of free will is a disturbing notion, Sapolsky has some thoughts about why doing so would only change things for the better:

Dangerous people will still be arrested and—if needed—punished. Just because it’s not their “fault” doesn’t mean that dangerous people would be allowed to walk around freely. What it does mean is that justice would no longer focus on punishment, except as a means to discourage them from relapsing into their bad behavior. Instead, the focus would be on fixing whatever caused them to act that way in the first place.

(Shortform note: Studies have shown that rehabilitation is more effective—and cheaper—than punishment-focused prison systems. When prisoners receive health care and mental health treatment, learn marketable skills, and have the opportunity for an education, violence rates in prison drop significantly and prisoners are far less likely to reoffend after release.)

People would still take credit for their good deeds. While it doesn’t make logical sense for people to feel pride in their actions if they didn’t “choose” those actions, it’s unlikely that we’ll ever completely separate ourselves from our egos. Sapolsky’s hope is that we’ll eventually use our concept of free will for harmless things—for instance, taking pride in your skill at a game, or your taste in clothing—instead of using it as a reason to judge and punish others.

Selflessness in Religion and Science

While Sapolsky says that people will probably never separate themselves from their egos, many religions throughout history have urged us to do just that:

• Christianity teaches that self-centered thoughts like pride and greed are among the worst sins a person can commit, while selfless acts—charity, diligence, and humility—are among the greatest virtues a person can have.

• Hinduism teaches that all things come from God, are part of God, and will return to God (rather than from ourselves).

• Buddhism says that we have no “self” as most people think of it. Rather, each of us is one tiny part of a single, universal whole. Buddhism also teaches that all suffering comes from thinking of ourselves as separate from what’s around us.

If we truly have no free will—if we’re nothing but the culmination of our biology and our experiences—then science agrees with religion that we should let go of pride, selfishness, and egotism.