Summary

Sapolsky works backward from the behavior through the preceding second, hormones, development, genes, culture, and evolution to show that biology is multifactorial and relentlessly context-dependent. That frame changes how to think about aggression, morality, empathy, hierarchy, and free will.

“Doing the right thing is always context-dependent”

“Cognition and affect always interact - what’s interesting is when dominates”

“Virtually everyone immediately grasps the logic and appeal of utilitarianism, yet eventually hits a point of realizing it’s not a good guide for everyday moral decision making”

Key Takeaways

Notes

Introduction

• We don’t hate violence, we just hate it in the wrong context
• Book explores the biology of violence, aggression, and competition
• Also biology of cooperation, affiliation, reconciliation, empathy, and altruism
• Goal is to think holistically, not categorically (skews)
• Must always think interdisciplinary
• We’re biological creatures driven by human nature

1: The Behavior

• Terms like violence are highly context-dependent and have varying definitions across fields of study

2: One Second Before

• 3 functional domains of the brain:
  • Layer 1: automatic
  • Layer 2: emotions
  • Layer 3: neocortex
• ↑ simplistic examples:
  • Considerable overlap anatomically
  • Info flow is not strictly top down
  • Layers are not separable
  • Didn’t evolve one at a time
• SNS, PNS
• Brain lateralization
• Amygdala → aggression, pain, disgust
• Pavlovian conditioning
• “The frontal cortex makes you do the harder thing when it’s the right thing to do”
• Pre-frontal cortex (PFC): choses between conflicting options
• Cognitive load with new task + multitasking, eventually offloaded thru repetition to cerebellum
• People with larger social networks have larger PFCs(!)
• Dopamine system*
  • Scale-free / adaptive
  • Pleasure is in anticipation
  • Released more when intermittently reinforced
• Humans uniquely delay gratification

3: Seconds to Minutes Before

• Ethology: the science of interviewing an animal in it’s own language
• Operant conditioning
• We’re astonishingly good at noticing race and behave subconsciously according to it
• ↑ also gender, social status presentation
• Eyes give away the most info
• Pheromones
• Body influences emotion (eg. muscle tension → stress, smile → happy)
• Words unconsciously shift thoughts and feelings
• Biases based on group membership
• Environment (eg. broken window theory)
• Takeaway: we’re less rational than we like to think

4: Hours to Days Before

• Aggression is more about conditioning than testosterone levels
• “Testosterone makes us more willing to do what it takes to obtain and maintain status”
  • Less facial mimicking
  • Increases confidence + optimism
  • Success boosts testosterone
  • Highly context-dependent
  • Generally antisocial
• Oxytocin
  • Facilitates (not causes) familial behavior
  • Decreases stress
  • Enhances trust + affiliation
  • But also more ethnocentric and zerophobic
  • Generally more pro-social
  • Also more socially competent
  • Context dependent: leads to in-group preference (racism)
• Estrogen / androgen:
  • Once again, context-dependent
• Cortisol / stress:
  • Only useful acutely, not chronically
  • Inverted U of benefit
  • Stress fosters aggression
  • Biased towards selfishness
• “In a world in which status is awarded for the best of our behaviors, testosterone would be the most pro-social hormone in our existence”

5: Days to Months Before

• “The Organization of Behavior” seminal book
  • Synapses strengthened, not neurons created
• Long-term potentiation (LTP):
• Long-term depression (LTD): sharpens signal by erasing what’s extraneous
• Neuroplasticity and remapping senses upon brain damage
• Adult neurogenesis actually proven after much controversy
• Experience, health, hormone fluctuations can change brain part sizes in a matter of months

6: Adolescence

• Brain doesn’t mature until 20s
• Neural Darwinism: pruning during adolescence
• Emotion, critical thinking
• Cognitive reappraisal:
• Risk taking + novelty seeking
• 3x more prone to peer pressure
• Too much empathy → strong emotions, preventing supportive action (counterproductive)
• Reason for all of ↑? So the brain has time to “get it right” - wiring sensitivity etc.

7: Childhood

• Stages of development
  • Sensory-motor stage (0-2y)
  • Pre-operational stage (2-7y)
  • Concrete operational (7-12y)
  • Formal operations (12y+)
    • Abstraction, reasoning, metacognition
• Theory of mind (ToM), perspective taking, enhanced empathy, sense of justice
• 3 stages of moral development:
  1. Pre-conventional reasoning: what will I think?
  2. Conventional reasoning: what will others think? laws? Relational
  3. Post-conventional reasoning: egotistical, varying perspectives, law not as truth
• ↑ lots of exceptions, context dependent
• Willpower: distraction + reappraisal > stoicism
• Attachment theory
  • Evolved so always attached to mother, regardless of quality of care
• Childhood adversity impairs PFC development
  • Learned helplessness (depression)
• 4 parenting styles:
  1. Authoritative (↑ demand, ↑ responsiveness)
  2. Authoritarian
  3. Permissive
  4. Neglectful (↓, ↓)
• Peer influence > parent influence at a surprisingly young age
• Social play
• Individual vs collectivist cultures
• Class
• ↑↑ environment
• Transgender behavior / genitalia split depending on trimester of testosterone exposure in womb
• Adult behavior has epigenetic affects

8: Genetics

• Progress in finding “the gene for that”
• Environment regulates genes (TFs)
  • The larger the organism, the more genetics dedicated to regulation
• Transposons reshuffle genes, useful for adaption (eg. neurons)
• So actually, genes “don’t determine much”
• —
• Twin studies prove genetic components in IQ, behavior, personality, sexuality
• Controversy in validity of twin studies → likely overestimation of genetic factor
• Heritability is still highly environmental
• Gene-environment interaction: genes and environment have a two-way interaction in driving behavior
• Classical behavior genetics: study of ↑
• —
• Argues against gene determinism (especially for court cases)
• “Don’t ask what a gene does - ask what a gene does in a particular context.”
• Studies: height and BMI are highly polygenic (no gene accounts for > 0.5%)
  • Likely 100s of genes

9: Centuries to Millennia Before

• How culture and biology coevolve
• Culture: “that complex whole which includes knowledge, belief, art, morals, law, custom, and any other capabilities and habits acquired by man as a member of society”
• Caveat: so many smaller or random or combinatorial factors
• Individual vs collectivist cultures
  • Reason for US individualism: had to be rebel to migrate
  • Reason for China collectivism: rice farming, lack of migration
• Pastoral → southern culture of honor
• Stratified vs egalitarian society
  • Social capital:
    • Generalized trust?
    • How many organizations does a person participate in?
  • Kindness, health, violence
  • Feeling poor is a better predictor of health as being poor
• Population size, density, homogeneity
  • Urbanization requires stronger laws, norms
  • Exaggerates existing social tendencies (violence, seclusion)
• Residue of cultural crises
• —
• Hobbes or Rousseau?
  • The Better Angels of Our Nature
  • Nomadic HG war is rare
  • Cultural norms are the primary driver
  • Answer? A mix of both

10: The Evolution of Behavior

• Natural selection based on ability to reproduce
• The Selfish Gene
• Kin selection
  • Study: highest reproductive success with 3-4th cousins
• Arms race / red queen scenario
• Prisoners dilemma
  • The Evolution of Cooperation
• 3 foundations of evolution of behavior:
  1. Individual selection
  2. Kin selection
  3. Reciprocal altruism
• Imprinted genes: depends on which parent it’s inherited from (eg. father encourages more fetal growth, mother genes less)
• Genotype or phenotype selection?
  • Multi-level selection: both, and group level
  • Neo group selection: trait may be maladaptive to individual but good for group
• We’re not naturally polygamous or monogamous - somewhere in between
• Punctuated equilibrium: evolutionary changes happen suddenly
  • Eg. lactose tolerance
• Us-them

11: Us Versus Them

• In-group behavior
• Group preference, even if arbitrary or non-visible
• Mimicking
• Oxytocin exaggerates us-vs-them
• Zero-sum thinking problem
• Disgusted by others beliefs (neuro)
• Viewing them as monolithic, interchangeable
• Post-hoc justification
• Confirmation bias
• Gender, age, occupation > race in preference
• Rapid shifting of us-them
• Two main axes:
  • Competence (agency)
  • Warmth
• Unanimous preference for lighter skin
• Techniques to reduce:
  • Priming
  • Perspective taking
  • Make biases explicit
  • Shift grouping priorities
  • Them → us (commonalities)
• Contact theory: reduce stereotyping

12: Hierarchy, Obedience, & Resistance

• Hierarchies ritualize inequality
• Dunbar’s number: brain size + group size tightly correlated across species → 150 for humans
• Status signaled in the face and less so body
• “Maintaining high rank is about social intelligence and impulse control”
• Study: middle management most stressed (responsibly + low autonomy)
• 2/3 of poorer health of lower classes due to psychological baggage
  • Feeling poor, not being poor
• Beer test for elections
• Beauty is good stereotype
• Study: conservatives are less intelligent, deal with ambiguity worse, have less integrative reasoning skills (situational)
• 6 foundations of morality:
  1. Care vs harm
  2. Fairness vs cheating
  3. Liberty vs oppression
  4. Loyalty vs betrayal
  5. Authority vs subversion
  6. Sanctity vs degradation
• ↑ liberals prefer 1-3, conservatives 4-6
• Conservatives more fearful and think more about mortality, but happier
  • Possible explanation: easier time justifying existing system
• Political leaning ~50% genetic (with caveats)
• Social conformity
  • Primary lesson from studies: situations matter
• ↑ limitations of prisoner, shock experiments:
  • Coercion
  • Diffusion of responsibility
  • De-individuate
  • …

13: Morality

• Fairness is biologically + socially evolved
• Reasoning vs intuition
• Situational; framing
• “Cheating is not limited by risk, it is limited by the ability to rationalize the cheating to ourselves” - Ariely
• 3 foundations: (maps to the 6 above)
  • Autonomy
  • Community
  • Spirituality
• Anti-social punishment: punish for being too nice to avoid setting norm
• ↑ fair markets help immensely
• Collectivist vs individualist cultures
• Collectivist shame, individualist guilt
  • External judgement of group
  • Internal judgement of self
• 3 broad ethical philosophies:
  1. Virtue ethics: you’ll have to live with yourself (mostly retired)
  2. Deontology: based on act (30%)
  3. Consequentialism: emphasis on outcome (30%)
     • Basically classical utilitarianism
• ↑ basically ends vs means
• Dual process model: in reality, we usually mix valuing means and ends (40%)
• “Virtually everyone immediately grasps the logic and appeal of utilitarianism, yet eventually hits a point of realizing it’s not a good guide for everyday moral decision making”
  • Slippery slopes, desensitization, unintended consequences, intended consequences
• Tragedy of common sense morality: everyone / culture has a different definition
• More time to think increases “calculated greed” - more individualistic
• We’re incredible liars - especially when we can rationalize (eg. dice roll study)
• Morality is mostly habitual / instinctual

14: Empathy & Help

• When does empathy lead us to actually do something helpful + when we do act, whose benefit is it actually for?
• Compassion: where your emotionally resonant state actually leads you to help
• Sensory-motor contagion → basis for empathy
• ACC in frontal cortex drives perception of pain - physical and otherwise
• Importance of being relatable, social, attractive for empathy
• Stalin death of 1 vs 1 million
• Mirror neurons mediate mirror learning by observation - not necessarily empathy
  • Generally very overhyped
• ”Aroused empathy causes tunnel vision compassion that can end up misplaced”
  • Eg. on individual over systemic, self > other, doctor etc.
• Utilitarianism is good, but hard to actually do
• “Scratching altruist” criticism should be relaxed - at least they’re still donating

15: Metaphors & Neural Reuse

• Metaphors: “the height of our symbolic use of language”
• Pain ↔ disgust + depression (cognitive)
• Macbeth effect: more likely to want to clean physically after lie
  • Also stress, falling apart (OCD)
• Intermixing of real and metaphorical
  • Eg. warm coffee = subjects rated to have warmer personality
• Neural reuse: ↑ brain appropriated existing regions for abstract conceptualization

16: Free Will

• No one actually believes in total free will (eg. seizures)
• Insanity defense = mitigated free will
• If death penalty doesn’t apply to children, should it also not for adults with impaired forebrain dev’t?
• Causation vs compulsion
• Controversial study: your brain decides to move before you consciously do (wrist flick and experiment)
• Praise effort > achievement
• “The biology of the behaviors that interest us is in all cases multifactorial” (thesis of the book)
• Free will still broadly accepted, but is becoming more and more confined
• “What must be abolished are the views that punishment can be deserved, and that punishing can be virtuous.”

17: War & Peace

• The Better Angels of Our Nature
  • Moral Flynn effect: society-wide IQ increase, but for morals too
• Religion → violence
• Group contact actually increases contact (despite contact theory for individuals + sustained contact)
• Beware empathic manipulation
• Indirect reciprocity (stranger)
• Apologies based on individual’s orientation:
  • Workings of a collective system: failure of that system
  • Relationships: empathic
  • Autonomous + independent: compensation
• Cognitive reappraisal: “hatred is exhausting. Forgiveness, or even just indifference, is freeing.”
• Make your implicit biases explicit
• Irrational optimism
• Cooperation naturally evolves (eg. trench warfare)

Epilogue

• Habit, distraction, reappraisal > willpower
• Brains and cultures coevolve
• Hormones modulate + sensitize
• “Cognition and affect always interact - what’s interesting is when dominates”
• Genes have different effects in different environments - context!
• Shaped minimally by genes, maximally by context + experience
• Genes are potentials + vulnerabilities
• Us > them
• “Doing the right thing is always context-dependent”