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68dab7c
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A critical realization roared through the research community: the physiological stress-response can be modulated by psychological factors. Two identical stressors with the same extent of allostatic disruption can be perceived, can be appraised differently, and the whole show changes from there.
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Robert M. Sapolsky |
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bd09c0e
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Crucially, the brain region most involved in feeling afraid and anxious is most involved in generating aggression.
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Robert M. Sapolsky |
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754849b
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Hunter-gatherer societies have typically been egalitarian, as we'll soon see, throughout hominin history. Inequality emerged when stuff, things to possess and accumulate, was invented following animal domestication and the development of agriculture. The more stuff, reflecting surplus, job specialization, and technological sophistication, the greater the potential inequality. Moreover, inequality expands enormously when cultures invent inhe..
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wealth
egalitarian
western-society
resources
hunter-gatherers
class
culture
inequality
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Robert M. Sapolsky |
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77add36
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Dunbar's
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Robert M. Sapolsky |
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9c809d7
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The authors first replicated this effect, showing that watching a short film clip of something physically disgusting made subjects more morally judgmental--unless they had washed their hands after watching the film. Another study suggests that the washing decreases emotional arousal, as it decreased the diameter of subjects' pupils.
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Robert M. Sapolsky |
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0f342c6
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Furthermore, as shown with neuroimaging, when contemplating mouthwash versus soap, those who had just spoken a lie activated parts of the sensorimotor cortex related to the mouth (i.e., the subjects were more aware of their mouths at the time); those who had written the lie activated the cortical regions mapping onto their hand.
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Robert M. Sapolsky |
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eaee640
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Say I decide that it would be a good thing to insert pictures here demonstrating cultural relativism, displaying an act that is commonsensical in one culture but deeply distressing in another. I know, I think, I'll get some pictures of a Southeast Asian dog meat market. Like me, most readers will likely resonate with dogs. Good plan! On to Google Images and the result is that I spend hours transfixed, unable to stop, torturing myself with p..
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morality
cultural-relativism
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Robert M. Sapolsky |
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88a1a0d
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Other work has shown that when people are hungry, they become less generous with money and show more future discounting (i.e., are more likely to want reward X now, rather than wait for reward 2X).
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Robert M. Sapolsky |
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a215abf
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growing strong from adversity is mostly a luxury for those who are better off.
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Robert M. Sapolsky |
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2577046
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This is the essence of learning. The lecturer says something, and it goes in one ear and out the other. The factoid is repeated; same thing. It's repeated enough times and--aha!--the lightbulb goes on and suddenly you get it. At a synaptic level, the axon terminal having to repeatedly release glutamate is the lecturer droning on repetitively; the moment when the postsynaptic threshold is passed and the NMDA receptors first activate is the d..
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Robert M. Sapolsky |
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aceae43
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Consider this: the human genome codes for about 1,500 different TFs, contains 4,000,000 TF-binding sites, and the average cell uses about 200,000 such sites to generate its distinctive gene-expression profile.5 This is boggling.
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Robert M. Sapolsky |
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ac06302
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People see essentialism embedded in bloodlines--i.e., genes.
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Robert M. Sapolsky |
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17275e6
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Another gene/environment interaction pertains to depression, a disease involving serotonin abnormalities.33 A gene called 5HTT codes for a transporter that removes serotonin from the synapse; having a particular 5HTT variant increases the risk of depression ... but only when coupled with childhood trauma.fn23 What's the effect of 5HTT variant on depression risk? It depends on childhood trauma exposure. What's the effect of childhood trauma ..
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Robert M. Sapolsky |
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76bb0d6
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What is that 95 percent? Some is junk--remnants of pseudogenes inactivated by evolution.fn4,3 But buried in that are the keys to the kingdom, the instruction manual for when to transcribe particular genes, the on/off switches for gene transcription. A gene doesn't "decide" when to be photocopied into RNA, to generate its protein. Instead, before the start of the stretch of DNA coding for that gene is a short stretch called a promoterfn5--th..
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Robert M. Sapolsky |
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08ea148
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Now consider a genome consisting of genes A and B, meaning three different transcription profiles--A is transcribed, B is transcribed, A and B are transcribed--requiring three different TFs (assuming you activate only one at a time). Three genes, seven transcription profiles: A, B, C, A + B, A + C, B + C, A + B + C. Seven different TFs. Four genes, fifteen profiles. Five genes, thirty-one profiles.fn7 As the number of genes in a genome incr..
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Robert M. Sapolsky |
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2ade1e2
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In other words, the more genomically complex the organism, the larger the percentage of the genome devoted to gene regulation by the environment.
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Robert M. Sapolsky |
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815a07d
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there are studies showing that one oxytocin receptor gene variant is associated with extreme aggression in kids, as well as a callous, unemotional style that foreshadows adult psychopathy.54 Moreover, another variant is associated with social disconnection in kids and unstable adult relationships. But unfortunately these findings are uninterpretable because no one knows if these variants produce more, less, or the usual amount of oxytocin s..
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Robert M. Sapolsky |
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d848f64
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Women prefer the smell of moderately related over unrelated men. And in a study of 160 years of data concerning every couple in Iceland (which is a mecca for human geneticists, given its genetic and socioeconomic homogeneity), the highest reproductive success arose from third- and fourth-cousin marriages.
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Robert M. Sapolsky |
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f3103bc
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Our prototypical behavior has occurred. How was it influenced by events when the egg and sperm that formed that person joined, creating their genome--the chromosomes, the sequences of DNA--destined to be duplicated in every cell in that future person's body? What role did those genes play in causing that behavior?
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Robert M. Sapolsky |
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de6c6fa
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Perhaps the best moral is that when doing science (or perhaps when doing anything at all in a society as judgmental as our own), be very careful and very certain before pronouncing something to be the norm--because at that instant, you have made it supremely difficult to ever again look objectively at an exception to that supposed norm.
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Robert M. Sapolsky |
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ae51397
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The picture is complicated further--AIS individuals raised female have higher-than-expected rates of being gay, and of having an other-than-female or neither-female-nor-male-sex/gender self-identification.
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Robert M. Sapolsky |
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2af5a9f
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Men with more "masculine" 2D:4D ratios tend toward higher levels of aggression and math scores; more assertive personalities; higher rates of ADHD and autism (diseases with strong male biases); and decreased risk of depression and anxiety (disorders with a female skew). The faces and handwriting of such men are judged to be more "masculine." Furthermore, some reports show a decreased likelihood of being gay."
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Robert M. Sapolsky |
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b112ef9
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The 2D:4D ratio is so variable, and the sex difference so small, that you can't determine someone's sex by knowing it. But it does tell you something about the extent of fetal testosterone exposure. So what does the extent of exposure (as assessed by the ratio) predict about adult behavior? Men with more "masculine" 2D:4D ratios tend toward higher levels of aggression and math scores; more assertive personalities; higher rates of ADHD and a..
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Robert M. Sapolsky |
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e00f147
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What's a heritability score? "What does a gene do?" is at least two questions. How does a gene influence average levels of a trait? How does a gene influence variation among people in levels of that trait?"
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Robert M. Sapolsky |
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eb2eba1
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These are crucially different. For example, how much do genes have to do with people's scores averaging 100 on this thing called an IQ test? Then how much do genes have to do with one person scoring higher than another?
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Robert M. Sapolsky |
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def1423
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If genes strongly influence average levels of a trait, that trait is strongly inherited. If genes strongly influence the extent of variability around that average level, that trait has high heritability.
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Robert M. Sapolsky |
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5f0057f
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MAO-A variants show other important gene/environment interactions. For example, in one study the low-activity MAO-A variant predicts criminality, but only if coupled with high testosterone levels
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Robert M. Sapolsky |
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2d2875c
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Secure-attachment 7Rs show more generosity than average. Thus 7R has something to do with generosity--but its effect is entirely context dependent.
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Robert M. Sapolsky |
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8219ed8
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Study a gene in only one environment and, by definition, you've eliminated the ability to see if it works differently in other environments (in other words, if other environments regulate the gene differently). And thus you've artificially inflated the importance of the genetic contribution. The more environments in which you study a genetic trait, the more novel environmental effects will be revealed, decreasing the heritability score. Sci..
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Robert M. Sapolsky |
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92bcab8
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All of that was eventually shown--there's considerable adult neuro-genesis in the hippocampus (where roughly 3 percent of neurons are replaced each month) and lesser amounts in the cortex.22 It happens in humans throughout adult life. Hippocampal neurogenesis, for example, is enhanced by learning, exercise, estrogen, antidepressants, environmental enrichment, and brain injuryfn9 and inhibited by various stressors.fn10,23 Moreover, the new h..
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Robert M. Sapolsky |
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b73258a
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Someone does something lousy and selfish to you in a game, and the extent of insular and amygdaloid activation predicts how much outrage you feel and how much revenge you take.
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Robert M. Sapolsky |
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733d32d
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Castration decreases sexual urges in the subset of sex offenders with intense, obsessive, and pathological urges. But otherwise castration doesn't decrease recidivism rates; as stated in one meta-analysis, "hostile rapists and those who commit sex crimes motivated by power or anger are not amenable to treatment with [the antiandrogenic drugs]."
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Robert M. Sapolsky |
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795e982
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The explains why basal levels of testosterone have little to do with subsequent aggression, and why increases in testosterone due to puberty, sexual stimulation, or the start of mating season don't increase aggression either.
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Robert M. Sapolsky |
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36f3ad7
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In a typical study, higher testosterone levels would be observed in those male prisoners with higher rates of aggression. But being aggressive stimulates testosterone secretion; no wonder more aggressive individuals had higher levels.
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Robert M. Sapolsky |
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fc962f1
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John Archer in a definitive 2006 review, "There is a weak and inconsistent association between testosterone levels and aggression in [human] adults, and ... administration of testosterone to volunteers typically does not increase their aggression." The brain doesn't pay attention to fluctuations of testosterone levels within the normal range."
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Robert M. Sapolsky |
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8a54077
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Being fearless, overconfident, and delusionally optimistic sure feels good. No surprise, then, that testosterone can be pleasurable.
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Robert M. Sapolsky |
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cb1355a
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Thus transcription factors regulate genes. What regulates transcription factors? The answer devastates the concept of genetic determinism: the environment.
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Robert M. Sapolsky |
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8c15f72
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What does the frontal cortex do? Its list of expertise includes working memory, executive function (organizing knowledge strategically, and then initiating an action based on an executive decision), gratification postponement, long-term planning, regulation of emotions, and reining in impulsivity.35
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Robert M. Sapolsky |
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1d18b43
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Starting with a 1979 study, low levels of serotonin in the brain were shown to be associated with elevated levels of human aggression, with end points ranging from psychological measures of hostility to overt violence.
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Robert M. Sapolsky |
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0e2f850
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Did destruction of the human amygdala lessen aggression? Pretty clearly so, when violence was a reflexive, inchoate outburst preceding a seizure.
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Robert M. Sapolsky |
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761d143
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Infuse oxytocin into the brain of a virgin rat, and she'll act maternally--retrieving, grooming, and licking pups. Block the actions of oxytocin in a rodent mother,fn6,23 and she'll stop maternal behaviors, including nursing.
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Robert M. Sapolsky |
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401ab3e
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With chronic stress the nucleus accumbens is depleted of dopamine, biasing rats toward social subordination and biasing humans toward depression.
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Robert M. Sapolsky |
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8e6b72f
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And you'd better bet that changes along the lines of those presented in this chapter occurred in the brains of anyone transformed by these transformations. A different world makes for a different worldview, which means a different brain. And the more tangible and real the neurobiology underlying such change seems, the easier it is to imagine that it can happen again.
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Robert M. Sapolsky |
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9ad81aa
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Words have power. They can save, cure, uplift, devastate, deflate, and kill. And unconscious priming with words influences pro- and antisocial behaviors.
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Robert M. Sapolsky |