Better Angels of Our Nature is a book written by Dr. Steven Pinker, professor of psychology at Harvard. These are some notes from the book describing the results of some of the biological and psychological studies cited in the book. The book also has many pages of information on the history of violence and statistics about wars and other conflicts.
• The human genome contains genes that appear to defend against the prion diseases transmitted by cannibalism.
• Studies show that people with a tendency toward violence are more likely to act on it when they are under the influence of alcohol.
• Eight percent of the men who live within the former territory of the Mongol Empire may be descended from Genghis Khan.
• Surveys of university students found that between 70 and 90 percent of men and between 50 and 80 percent of women admitted to having at least one homicidal fantasy in the preceding year.
• The insula in the human brain is active when study subjects think they are getting an unfair deal from another person, while it is much less active when the subject receives an unfair deal from a computer.
• Brain scanning research of violent people with antisocial personality disorder discovered that the orbital regions and the amygdala were smaller and less metabolically active.
• An experiment found that people with antisocial personality disorder have unresponsive nervous systems when asked to complete an embarrassing task such as composing and delivering a speech about their own faults.
• A study involving fMRI showed that the temporoparietal junction was involved in forgiveness.
• A brain scanning study demonstrated that visceral morality involves the amygdala and orbital cortex, whereas utilitarian morality is computed in the dorsolateral prefrontal cortex.
• Psychopaths commit half of all serious crimes.
• Studies of street violence show that the presence of an audience doubles the likelihood that an argument between two men will escalate to violence.
• In nonstate societies, dominant men have more wives, more girlfriends, and more affairs with other men’s wives.
• A nucleus in the anterior preoptic portion of the hypothalamus is twice as large in men as it is in women.
• Violence is linked to high levels of self-esteem, particularly unearned self-esteem.
• Men’s testosterone levels rise when they personally defeat an opponent in a competition such as wrestling or tennis.
• Men’s testosterone levels rise or fall when a favored political candidate wins or loses an election.
• The majority of homicidal fantasies in university students are revenge fantasies.
• An experiment found that people who weren’t able to retaliate after being insulted drank more alcohol afterwards.
• A study found that part of the striatum in the brain was activated when people were contemplating revenge.
• A study found that the striatum and orbital cortex in men activated in proportion to the men’s desire for revenge.
• Experiments show that people punish cheaters more severely when they think an audience is watching.
• A neuroimaging study of Japanese students demonstrated that the feeling of schadenfreude is associated with increased activation of the striatum.
• The circuits for sexuality and aggression are intertwined in the limbic system, and both respond to testosterone.
• Psychopaths have less of a response in their amygdala and orbital cortex to signs of others’ feelings of distress.
• A neuroimaging study found that the potential for immediate gratification led to activation in the striatum and medial orbital cortex.
• A study of wife-batterers found that they had greater activity in the insula and striatum and less activity in the dorsolateral frontal cortex.
• A study found that children who were impulsive and emotionally volatile at age three were far more likely to be convicted of a crime at age twenty-one.
• Placebo-controlled studies show that dietary supplements reduce the rate of impulsive violence in prisoners.
• A study of identical twins reared apart found that 38 percent of the variation in aggression could be explained by heredity.
• An adoption study estimated the heritability of aggressive behavior as 70 percent.
• An analysis of twin and adoption studies estimated the heritability of aggressive behavior as 44 percent and the heritability of criminality as 75 percent.
• Research shows that the distribution of gray matter in the cerebral cortex is almost identical in identical twins and much less similar in fraternal twins.
• A study found that men with genes that code for more sensitive versions of the testosterone receptor were overrepresented in a sample of murderers.
• An analysis of thirty-six Prisoner’s Dilemma experiments showed that schools with higher average SAT scores have greater rates of cooperation in the game.
