AP Bio: Genome Blog 10, Chromosome 11: Personality

In "Chromosome 11: Personality," Ridley begins the twelfth chapter of Genome by quoting Heraclitus, who says, "A man's character is his fate" (161).  Afterward, he begins talking about a gene on chromosome 11 called D4DR.  He explains that "a 'long' D4DR gene implies a low responsiveness to dopamine in certain parts of the brain, whereas a 'short' D4DR gene implies a high responsiveness" (163).  In an experiment, he found that people with the long gene were more novelty-seeking than people with short genes.  For example, long-gened people had more sexual partners than short-gened people.  Ridley mentions that dopamine and norepinephrine are monoamines, as is serotonin.  He describes serotonin as another "chemical manifestation of personality" (167) and that it is "the brain's punishment chemical" (168) because it "abets...anxiety and depression" (168).  However, Ridley ends the chapter on a note that "social influences upon behaviours work through the switching on and off of genes" (172).