It took me a couple months of stops and starts to finish this one. It was always interesting, but often dense, interspersed with more than a few casual asides and meanders. This is a big book in every sense of the word. Sapolsky is a neurobiologist, who spends much of his career studying primates in the wild. This book, however, is on the complexity of what makes humans behave the way we do. Sapolsky is concerned that many fields, from neurobiology to evolutionary biology, to behavioral psychology, to anthropology, to economics, are stove-piped and do not communicate across disciplines. Even within the study of the brain some experts focus only on the amygdala, while others on the prefrontal cortex. Sapolsky seeks to break down these walls. His focus is on the various effects that apply on the human body over the course of time.
Sapolsky begins with the effects one second before a given event. The layers of the brain are complicated and talk back and forth with each other. Nonetheless, Paul MacLean conceptualized the idea of the “triune brain” where there are three layers- layer 1 which controls automatic, regulatory function, layer 2 which handles emotions, and layer 3, the neocortex on the surface of the brain, which deals with “cognition, memory storage, sensory process, abstractions, philosophy, and naval gazing.” This layer evolved last and primates devote proportionally more brain space to it than other animals. The limbic system is central to emotions. The hypothalamus influences autonomic function, allowing layer 2 to talk to layer 1. “The sympathetic nervous system (SNS) mediates the body’s response to arousing circumstances…. The SNS mediates the “four Fs- fear, fight, flight, and sex.”” In contrast, the parasympathetic nervous system controls calm, vegetative states, such as digestion. The cortex, in layer 3, decodes much of the sensory information. It commands movement, deciphers language, stores memory, computes spatial and mathematical problems, and executes executive decisions. However, the frontal cortex and limbic systems are intertwined, communicating in both directions. They can stimulate and inhibit each other, sometimes coordinating and sometimes working at cross purposes. The amygdala has been thought to control aggression and is highly activated during sensations of fear and anxiousness. “In PTSD sufferers the amygdala is overreactive to mildly fearful stimuli and is slow in calming down after being activated.” It actually permanently expands in size in severe cases of PTSD. For normal people, “the amygdala injects implicit distrust and vigilance into social decision making.” Surprisingly, some sensory information can shortcut the cortex and directly go to the amygdala so that you sense fear before the cortex can process it. The frontal cortex seeks to control longterm action, regulate emotions, and reign in impulsivity. It is central to empathy. It “makes you do the harder thing when it’s the right thing to do…. It’s the prefrontal cortex (PFC) that is “the decider.”… The PFC is essential for categorical thinking, for organizing and thinking about bits of information with different labels.” The frontal cortex tracks the rules in life. If it is taxed with “cognitive load”, either through a complicated or strenuous problem or through multitasking, then its performance declines significantly. After a heavy cognitive load task, humans also become less prosocial and more impulsive (for example, cheating on their healthy diets). “During REM sleep, when dreaming occurs, the frontal cortex goes off-line, and dream scriptwriters run wild.” The dorsolateral prefrontal cortex (dlPFC) “is the decider of deciders, the most rational, cognitive, utilitarian, unsentimental part of the PFC…. The ventromedial PFC…. is all about the impact of emotion on decision making” leading some neuroscientists to call it an honorary member of the limbic system. Finally, the mesolimbic dopamine pathway uses the ventral tegmental area (tegmentum) to target nucleus accumbens. The mesocortical dopamine pathway targets the PFC, but no other part of the cortex. “The dopaminergic system is about reward- various pleasurable stimuli activate tegmental neurons, triggering the release of dopamine.” In hungry as opposed to satiated individuals, a picture of food releases dopamine. If accumbens are activated while listening to music, it is more likely a customer will buy it. Punishing norm violators also releases dopamine. Crucially, it is often social interaction that affects dopamine. “Losing a lottery had no effect, while losing a bidding war [at an auction] inhibited dopamine release.” It also relies on expectations, coordinating bidirectionally with the cognitive brain. “Get what you expected, and there’s a steady-state dribble of dopamine. Get more reward and/or get it sooner than expected, and there’s a big burst; less and/or later, a decrease.” Neurons release the inhibitory neurotransmitter GABA in such cases. “In habituation…. the reward that once elicited a big dopamine response becomes less exciting” to the system. Furthermore, “once reward contingencies are learned, dopamine is less about reward than about its anticipation,” as the system releases it in expectation before actual contact. An additional neurotransmitter is serotonin. “Low serotonin didn’t predict premeditated, instrumental violence. It predicted impulsive aggression, as well as cognitive impulsivity…. Other studies linked low serotonin to impulsive suicide.”
Next Sapolsky focuses on the seconds to minutes before an event. “Across species the dominant sensory modality- vision, sound, whichever- has the most direct access to the limbic system.” These sensory effects are often unconscious. The interoceptive system also plays a huge role because “you decide what you feel based on signals from your body…. Some brain regions with starring roles in processing social emotions- the PFC, insular cortex, anterior cingulate cortex, and the amygdala- receive lots of interoceptive information.”
Sapolsky moves on to the hours to days before an event. “There is a weak and inconsistent association between testosterone levels and aggression in [human] adults.” Testosterone does increase confidence and optimism, while reducing fear and anxiety. It also increases impulsivity and risk taking by decreasing activity in the PFC by decoupling it from the amygdala, while the amygdala communicates more instead with the thalamus. Increased levels of testosterone is pleasurable. But the effects are also context dependent. “This context dependency means that rather than causing X, testosterone amplifies the power of something else to cause X…. Rising testosterone levels increase aggression only at the time of a challenge…. Watching your favorite team win raises testosterone levels, showing that the rise is less about muscle activity than about the psychology of dominance, identification, and self-esteem.” It is also affected by expectations. A better than expected performance can increase testosterone, while subpar victory decreases it. “When testosterone rises after a challenge, it doesn’t prompt aggression. Instead it prompts whatever behaviors are needed to maintain status.” In cases where high status is given to acts of generosity, people with higher testosterone levels act more generously. Oxytocin is another hormone that regulates social situations. “Oxytocin is central to female mammals nursing, wanting to nurse their child, and remembering which one is their child…. Circulating oxytocin levels are elevated in couples when they’ve first hooked up. Furthermore, the higher the levels, the more physical affection, the more behaviors are synchronized, the more long-lasting the relationship, and the happier interviewers rate couples to be.” This goes beyond human couples. Dogs and their owners create mutual loops of increased oxytocin levels. People with high levels of oxytocin are also foolishly trusting in social economic games, but not in those against a computer! “Stated scientifically, “oxytocin inoculated betrayal aversion among investors”; stated caustically, oxytocin makes people irrational dupes; stated more angelically, oxytocin makes people turn the other cheek.” Oxytocin, in general, makes people more charitable and sensitive to social approval. It also increases social competence. People with elevated oxytocin “look at eyes longer, increasing accuracy in reading emotions. Moreover, oxytocin enhances activity in the temporoparietal juncture (that region involved in Theory of Mind) when people do a social-recognition task. The hormone increases the accuracy of assessments of other people’s thoughts, with a gender twist- women improve at detecting kinship relations, while men improve at detecting dominance relations.” However, oxytocin’s effects are modulated by tribal instincts. “When playing against strangers, oxytocin decreases cooperation, enhances envy when luck is bad, and enhances gloating when it’s good…. Oxytocin makes you more prosocial to people like you….but spontaneously lousy to Others who are a threat.” It helps create and amplify an Us versus Them dynamic. Finally, hormone ratios can be more important than absolute levels, “hormone levels are extremely dynamic, with hundredfold changes in some within hours” and there is extreme variability across species. Another huge challenge to the body system is stress. Homeostasis “means having an ideal body temperature, heart rate, glucose level, and so on. A “stressor” is anything that disrupts homeostatic balance…. Stress response rapidly mobilizes energy into circulation from storage sites in your body. Furthermore, heart rate and blood pressure increase, delivering that circulating energy to exercising muscles faster. Moreover, during stress, long-term building projects- growth, tissue repair, and reproduction- are postponed…. Beta-endorphin is secreted, the immune system is stimulated, and blood clotting is enhanced, all useful following a painful injury. Moreover, glucocorticoids reach the brain, rapidly enhancing aspects of cognition and sensory acuity.” This makes sense in a short burst, but can be damaging over time. “If you are constantly but incorrectly convinced that you’re about to be thrown out of balance, you’re being an anxious, neurotic, paranoid, or hostile primate who is psychologically stressed…. Chronic stress suppresses immunity…. The core of psychological stress is loss of control and predictability…. Collectively, stress or glucocorticoid administration decreases accuracy when rapidly assessing emotions of faces…. [The] glucocorticoids don’t cause action potentials in amygdaloid neurons, don’t invent excitation. Instead they amplify preexisting excitation…. Stress makes it easier to learn a fear association and to consolidate it into a long-term memory…. Stress also makes it harder to unlearn fear, to “extinguish” a conditioned fear association…. Prolonged administration of high glucocorticoid levels to healthy subjects impaired working memory…. These stress effects on frontal function also make us perseverative- in a rut, set in our ways, running on automatic, being habitual…. Major stressors make people of both genders more risk taking. But moderate stressors bias men toward, women away from, risk taking.” Basically, stress impairs overall risk assessment. Many animals also exhibit stress induced displacement aggression. We all take it out on others. Stress induces selfishness. It makes people less altruistic concerning personal (but not impersonal) moral decisions. “The amygdala becomes overactive and more coupled to pathways of habitual behavior…. Frontal function- working memory, impulse control, executive decision making, risk assessment, and task shifting- is impaired.”
Sapolsky moves further back in time to tackle the days to months before an event. New synapses can grow in the brain between neurons. New axon receptors can also form to redirect brain traffic. “When a person who is deaf and adept at American Sign Language watches someone signing, there is activation of the part of their auditory cortex normally activated by speech.” Recently, it has been discovered that even new neurons grow in adults. “There’s considerable adult neurogenesis in the hippocampus (where roughly 3 percent of neurons are replaced each month) and lesser amounts in the cortex.” However, neuroplasticity is still little understood.
Sapolsky next moves back to adolescence. “The final brain region to fully mature (in terms of synapse number, myelination, and metabolism) is the frontal cortex, not going fully online until the midtwenties…. No part of the adult brain is more shaped by adolescence than the frontal cortex…. Nothing about adolescence can be understood outside the context of delayed frontocortical maturation…. It’s the time of life of maximal risk taking, novelty seeking, and affiliation with peers.” The frontal cortex actually matures as its neurons decrease. “The fetal brain generates far more neurons than are found in the adult…. Neuronal overproduction followed by competitive pruning (which has been termed “neural Darwinism”) allowed the evolution of more optimized neural circuitry.” In adolescence, this creates gradually improved “working memory, flexible rule use, executive organization, and frontal inhibitory regulation…. Adolescents also improve at mentalization tasks (understanding someone else’s perspective)”, cognitively, if not emotionally. Adolescents also “experience bigger-than-expected rewards more positively then do adults and smaller-than-expected rewards as aversive.” Adolescents are also affected by their peers more than adults. “In neuroimaging studies, peers egging subjects (by intercom) lessens vmPFC activity and enhances ventral striatal activity in adolescents but not adults…. Ask adults to think about what they imagine others think of them, then about what they think of themselves. Two different, partially overlapping networks of frontal and limbic structures activate for the two tasks. But with adolescents the two profiles are the same. “What do you think about yourself?” is neurally answered with “What everyone else thinks about me.”” Because of their less developed frontal cortex, rejection actually hurts adolescents more. “By definition the frontal cortex is the brain region least constrained by genes and most sculpted by experience.”
Sapolsky goes backwards in development to the crib and the womb. “Neuron formation, migration, and synaptogenesis are mostly prenatal in humans. In contrast, there is little myelin at birth, particularly in evolutionarily newer brain regions…. myelination proceeds for a quarter century…. Myelination is most consequential when enwrapping the longest axons, in neurons that communicate the greatest distances. Thus myelination particularly facilitates brain regions talking to one another.” By the ages of ten to twelve empathy is more generalized and abstracted. Consequently, this is when stereotypes also form. Kids also begin to derive comfort from reconciliation after a conflict, which decreases their glucocorticoid secretion and anxiety. Kids also slowly begin to exhibit willpower. “Maturation of willpower is more about distraction and reappraisal strategies than about stoicism.” Kids also learn behavioral context. “Mothers and peers don’t teach the motoric features of fixed action patterns; those are hardwired. They teach when, where, and to whom- the appropriate context for those behaviors.” Childhood adversity “increases the odds of an adult having (a) depression, anxiety, and/or substance abuse; (b) impaired cognitive capabilities, particularly related to frontocortical function; (c) impaired impulse control and emotion regulation; (d) antisocial behavior, including violence; and (e) relationships that replicate the adversities of childhood…. Early life stress permanently blunts the ability of the brain to rein in glucocorticoid secretion.” Again, peers often mediate parental influence. Peer interactions teach social competence. Play is a form of social teaching. “Kids in individualist cultures acquire Theory of Mind later than collectivist-culture kids and activate pertinent circuits more to achieve the same degree of competence. For a collectivist child, social competence is all about taking someone else’s perspective.” Humans are affected by their environment even before birth. We may prefer foods our mothers ate during pregnancy. “Prenatal testosterone plays a major role in explaining sex differences in aggression and affiliative prosocial behaviors in humans…. Prenatal testosterone exposure influences digit length. Specifically, while the second finger is usually shorter than the fourth finger, the difference (the “2D:4D ratio”) is greater in men than in women.” A major environmental factor is maternal stress levels. “Stress alters maternal blood pressure and immune defenses, which impact a fetus. Most important, stressed mothers secrete glucocorticoids, which enter fetal circulation.” Glucocorticoids’ create negative consequences “through organizational effects on fetal brain construction and decreasing levels of growth factors, numbers of neurons and synapses, and so on.”
Sapolsky goes further back to when the egg was just fertilized. It is important to remember that 95% of DNA is noncoding. Furthermore, “saying the a gene “decides” when it is transcribed is like saying that a recipe decides when a cake is baked.” Relating to humans particularly, “the more genomically complex the organism, the larger the percentage of the genome devoted to gene regulation by the environment.” Epigenetics also affects gene activation later in life. Furthermore, “dogma was that all the epigenetic marks (i.e., changes in the DNA or surrounding proteins) were erased in eggs and sperm. But it turns out the epigenetic marks can be passed on by both (e.g., make male mice diabetic, and they pass the trait to their offspring via epigenetic changes in the sperm.” DNA is also affected by alternative splicing, which “can generate multiple unique proteins from a single stretch of DNA” and transposable genetic elements or transposons, which are randomly inserted into stretches of code. “Evolution is heavily about changing regulation of gene transcription, rather than the genes themselves…. Epigenetics can allow environmental effects to be lifelong, or even multigenerational.” Furthermore, “it’s difficult to quantitatively assess the relative contributions of genes and environment to a particular trait when they interact.” That means, “it’s not meaningful to ask what a gene does, just what it does in a particular environment.” These can be physical or social human environments. And, of course, compared to other species on Earth, humans live in the most varied range of habitats possible. Furthermore, depending on the environment, genes can become more of or less of a factor. “Heritability of various aspects of cognitive development is very high (e.g. around 70 percent of IQ) in kids from high-socioeconomic status (SES) families but is only around 10 percent in low-SES kids.” Being poor is no good for anyone, but once you become rich, genes begin to matter. Most traits are also highly polygenic. Hundreds of genetic variants are implicated in regulating height, all in combination. Furthermore, “the single genetic variant identified that most powerfully predicted height explained all of 0.4 percent- four tenths of one percent- of the variation in height, and all those hundreds of variants put together explained only about 10 percent of the variation.” Genes cannot be looked at in isolation, but must be studied in combination with hundreds of other genes and as influenced by countless of different environments. “Genes aren’t about inevitability. Instead they’re about context-dependent tendencies, propensities, potentials, and vulnerabilities.”
Sapolsky continues to look back in time- centuries to millennia before conception. Culture can affect biology and vice versa. For example, “subjects from individualist cultures strongly activate the (emotional) vmPFC when looking at pictures of themselves, compared to looking at a picture of a relative or friend; in contrast, the activation is far less for East Asian subjects.” Relatedly, “consider a monkey, a bear, and a banana. Which two go together? Westerners think categorically and choose the monkey and bear- they’re both animals. East Asians think relationally and link the monkey and banana- if you’re thinking of a monkey, also think of food it will need.” Traits like aggression can also be influenced by culture. Both people living in high density areas, like cities, and in honor cultures, like the American South, tend to behave more aggressively. However, culture only affects those with a predisposition to aggressive behavior. Again, your environment and biology interact and influence each other, sometimes in self-reenforcing loops of behavior.
Evolution is not about survival of the fittest, but about reproductive success. Sometimes these are at odds. Antagonistic pleiotropy are traits that increase reproductive fitness, but decrease your lifespan. “Primates’ prostates have high metabolic rates, enhancing sperm motility. Upside: enhanced fertility; downside: increased risk of prostate cancer.” Other examples include salmon spawning and male peacock tails. Evolution also only selects for the present. Living species are not “better” or “more evolved” than extinct species. Group selection is also largely a myth. “Animals don’t behave for the good of the species. They behave to maximize the number of copies of their genes passed into the next generation.” That is done primarily through individual selection and kin selection. “Competitive infanticide has been documented…. in 119 species” when a new mate enters the scene. “The extent to which a male primate cares for infants reflects the certainty of paternity.” A third factor in evolution is “reciprocal altruism”, defined by Robert Trivers as, “incurring a fitness cost to enhance a nonrelative’s fitness, with the expectation of reciprocation…. Social interactions have to be frequent enough that the altruist and the indebted are likely to encounter each other again. And individuals must be able to recognize each other.” There is even parent-offspring conflict in evolution. “As long as Mom nurses she is unlikely to ovulate, curtailing her future reproductive potential. Baboon moms evolved to wean their kids at the age where they can feed themselves, and baboon kids evolved to try to delay that day. Interestingly, as females age, with decreasing likelihood of a future child, they become less forceful in weaning.” This conflict starts even before birth. “Fetus and Mom have a metabolic struggle involving insulin, the pancreatic hormones secreted when blood glucose levels rise, which triggers glucose entry into target cells. The fetus releases a hormone that makes Mom’s cells unresponsive to insulin (i.e. insulin resistant), as well as an enzyme that degrades Mom’s insulin. Thus Mom absorbs less glucose from her bloodstream, leaving more for the fetus.” Neo-group selection is when A dominates B, but a group of Bs dominates a group of As or “the circumstance of a genetically influenced trait that, while adaptive on an individual level, emerges as maladaptive when shared by a group and where there is competition between groups…. Cultures magnify the intensity of between-group selection and lessen within-group selection.” Group selection is rarely seen in the animal kingdom, but might be most strongly prevalent in humans because of our dependence on culture.
Sapolsky next goes on to discuss in-group and out-group relations. Oxytocin production exaggerates an Us vs. Them mentality. However, creating an Us relationship sometimes requires only the most meaningless of commonalities- hair style, car model, music preferences. Mimicry is pleasing, activating mesolimbic dopamine, increasing pair bonding. Arbitrary markers that link to values and beliefs, such as national flags, often gradually take on a value and power of their own. “By age three to four, kids already group people by race and gender, have more negative views of such Thems, and perceive other-race faces as being angrier than same-race faces…. Infants learn same-race faces better than other-race.” This is learned behavior often conditioned by adults, such as in statements like “good morning, boys and girls,” which teaches children to see the world by that dichotomy. “Children adopted before age eight by someone of a different race develop expertise at face recognition of the adoptive parent’s race.” When forced to think about Them, feelings of disgust often activate in the insular cortex. The same regions in the brain are activated when told to think of rotten food and a drug addict. “People with the strongest negative attitudes toward immigrants, foreigners, and socially deviant groups tend to have low thresholds for interpersonal disgust (e.g., are resistant to wearing a stranger’s clothes or sitting in a warm seat just vacated).” Thems are also simpler and more homogenous than Us. They are monolithic and interchangeable, not individuals. Sometimes it is hormonal. “White women, when ovulating, have more negative attitudes towards African American men.” Even minorities tend to identify with the Us/Them dichotomy of the majority. “Roughly 40 to 50 percent of African Americans, gays and lesbians, and women show automatic IAT (Implicit Association Test) biases in favor of whites, heterosexuals, and men, respectively.” Groups also exacerbate. However, internally this can lead to cohesion. “Groups with highly hostile interactions with neighbors tend to have minimal internal conflict.” Each human, unlike most animals, belongs to multiple categories of Us and Them simultaneously. We are parts of multiple groups and shift our prioritizing of these groups, based on context, with ease. Perspective taking, consciously focusing on stereotypes, making implicit biases explicit, and thinking at the level of the individual all help in counteracting Us/Them mentalities.
Sapolsky next covers hierarchy, conformity, and obedience. “Hierarchies establish a status quo by ritualizing inequalities.” They are ranking systems that formalize unequal access to limited resources. Humans have evolved biologically as we have evolved socially. The bigger the average size of the social group in a species “the larger the brain, relative to total body size and the larger the neo-cortex, relative to total brain size.” Along with all primates, attaining alpha status might require brawn, but maintaining rank “is about social intelligence and impulse control: knowing which provocations to ignore and which coalitions to form, understanding other individuals' actions.” Furthermore, amongst humans, “the larger the size of someone’s social network (often calculated by the number of email/texting relationships), the larger the vmPFC, orbital PFC, and amygdala, and the better the person’s Theory of Mind-related skills.” Much of this social interaction is subconscious. It takes only forty milliseconds to distinguish between a dominant and subordinate facial expression. “One study showed kids, ages five to thirteen, pairs of faces of candidates from obscure elections and asked them whom they’d prefer as captain of a hypothetical boat trip. And kids picked the winner 71 percent of the time.” The decision between obedience or resistance can also be effected by cognitive load, the interoceptive system, and feelings of disgust or stress. “People become more conservative when tired, in pain, or distracted with a cognitive task…. Stick subjects in a room with a smelly garbage can, and they become more socially conservative…. People are more likely to conform and obey at times of stress, ranging from time pressure to a real or imagined outside threat to a novel context. In stressful settings rules gain power.” Animals are wired to conform to the group. “A chimp is more likely to copy an action if he sees three other individuals do it once than if one other individual does it three times…. A male grouse courts a female who, alas, doesn’t feel magic in the air and rebuffs him. The researchers then make him seem like the hottest stud on the prairie- by surrounding him with some rapt, stuffed female grouse. Soon the reluctant maiden is all over him, pushing her statuesque rivals aside.” Humans are the same. “It takes less than 200 milliseconds for your brain to register that the group has picked a different answer from yours, and less than 380 milliseconds for a profile of activation that predicts changing your opinion…. When we choose incorrectly in a task, the dopaminergic decline is less if we made the decision as part of a group…. The discovery that you are out of step activates the amygdala and insular cortex; the more activation, the greater your likelihood of changing your mind, and the more persistent the change (as opposed to the transient change of compliant public conformity)…. When you get the news that everyone else disagrees with you, there is also activation of the (emotional) vmPFC, the anterior cingulate cortex, and the nucleus accumbens. This is a network mobilized during reinforcement learning, where you learn to modify your behavior when there is a mismatch between what you expected to happen and what actually did.”
Sapolsky next takes on morality. “Logical and moral reasoning about the correctness of an economic or ethical decision, respectively, both activate the (cognitive) dlPFC.” When moral dilemmas are considered, intuitions about intentionality come into play. However, “intuitions discount heavily over space and time. Exactly the myopia about cause and effect you’d expect from a brain system that operates rapidly and automatically.” We also can be harsher when viewing the morals of others than ourselves. It is harder to judge intentions. “We use different brain circuits when contemplating our own moral failings (heavy activation of the vmPFC) versus those of others (more of the insula and dlPFC)…. We judge ourselves by our internal motives and everyone else by their external actions. And thus, in considering our own misdeeds, we have more access to mitigating, situational information.” Modern humans have adapted to be prosocial even with strangers. Market integration predicts both making fairer offers in economic games and altruistic third-party punishment of deviators, even at expense to oneself. The larger the community size and the more religious, the more incidence of third-party punishment. “Large religions invent gods who do third-party punishment.” Culture also plays a key role in shaping morality. “Collectivist cultures enforce with shame, while individualistic cultures use guilt…. Shame requires an audience, is about honor. Guilt is for cultures that treasure privacy and is about conscience. Shame is a negative assessment of the entire individual, guilt that of an act, making it possible to hate the sin but love the sinner. Effective shaming requires a conformist, homogenous population; effective guilt requires respect for law. Feeling shame is about wanting to hide; feeling guilt is about wanting to make amends.” Social interaction and approbation comes through language and specifically gossip. “Anthropologists, studying everyone from hunter-gatherers to urbanites, have found that about two thirds of everyday conversation is gossip, with the vast majority of it being negative…. Gossip (with the goal of shaming) is a weapon of the weak against the powerful. It has always been fast and cheap.”
Sapolsky continues by discussing feeling the pain of others. Empathy is felt through the anterior cingulate cortex (ACC). The ACC processes interoceptive information, “funnels literal gut feelings into intuitions and metaphorical gut feelings influencing frontal function” and works out conflicts and discrepancies from what is expected. It seeks the underlying meaning of pain and therefore is as concerned with social pain, such as social exclusion, anxiety, disgust, and embarrassment, as with physical pain. “By adulthood the insula (and to a lesser degree the amygdala) is nearly as intertwined with experiencing empathy as is the ACC…. There is more engagement of the dmPFC when observing someone in emotional pain than physical pain. Likewise when the pain is presented more abstractly…. Resonating with someone else’s pain is also a cognitive task when it is a type of pain that you haven’t experienced…. We have a stronger sensorimotor response in our hands when the hand we see being poked with a needle is of our race…. Feeling the same degree of empathy or achieving the same level of perspective taking for a Them as for an Us requires greater frontocortical activation. This is the domain where you musty suppress the automatic and implicit urges to be indifferent, if not repulsed, and do the creative, motivated work of finding the affective commonalities.”
Sapolsky next goes on to tackle free will. He maintains that you either believe that there is absolutely no free will or that there is some sort of soul or homunculus that exists outside of the biological realm. “Even if 99.99 percent of your actions are biologically determined…. and it is only once a decade that you claim to have chosen out of “free will” to floss your teeth from left to right instead of the reverse, you’ve tacitly invoked a homunculus operating outside of the rules of science.” He quotes the philosopher Hilary Bok, “The claim that a person chose her actions does not conflict with the claim that some neural processes or states caused it; it simply redescribes it.” Sapolsky goes on to quote the philosopher Shaun Nichols, “It seems like something has to give, either our commitment to free will or our commitment to the idea that every event is completely caused by the preceding events.”
Sapolsky concludes by discussing war and peace. He suggests as humans have expanded their trading networks peace has spread too. From between family, to neighbors and friends, to countrymen, to distant strangers, the advantages of mutual trade brought with it a disincentive to kill one another. Cooperation increases when interactions could be open ended, there are multiple levels of cooperation to build trust, and reputations are apparent so that third parties can monitor and engage in indirect reciprocity. Religion, on the other hand, has been a double edged sword. “Reciting a familiar prayer activates mesolimbic dopaminergic systems. Improvising one activates regions associated with Theory of Mind, as you try to understand a deity’s perspective…. More activation of this Theory of Mind network correlates with a more personified image of a deity.” In a study of sixty-seven countries, the greater the belief in hell the lower the national crime rate. The belief in heaven had no effect. Finally, some cheerful thoughts about actual war. “Of the 27,000 single-load muskets from the field [at the Battle of Gettysburg], almost 24,000 of them were loaded and unfired; 12,000 were loaded multiple times, 6,000 loaded three to ten times…. Similarly, in World War II only 15 to 20 percent of riflemen ever fired their guns.” Studies of PTSD have revealed something fascinating. Drone pilots’ rates of PTSD are just as high as for soldiers on the ground. “The deepest trauma is not the fear of being killed. It’s doing the close-up, individuated killing.”
Sapolsky’s book is mammoth. It seeks to balance nature and nurture- biology and culture. Obviously, there are loops that reinforce and build on each other. Everything, including the effects of our genes and hormones, is context dependent. The book’s only overarching theme might be that the human body is amazingly complicated. For all of his statistics, Sapolsky is at pains to emphasize that they are all just averages. No individual human acts exactly in all the ways that would be predicted by looking at any formula or textbook.
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