The emotion of disgust appears to be in the insula and putamen. It is
an evolutionary emotion which sometimes serves a useful purpose, as in
avoiding putrid meat; however, it also can cause the persecution of the
deformed, a common occurrence among both animals and humans. The
instinctive disgust often felt for homosexuality, incest, and sex with
children and animals probably has a similar evolutionary origin.
The putamen is part of the basal ganglia, the reptile brain of Sagan's
and MacClean's Triune Brain. I think the insula is part of the limbic
system, or "rat brain" or "paleomammalian brain". This is said to be the
emotional part of the brain. Irrational attitudes come from the
reptilian brain, or basal ganglia. Emotions come from the paleomammalian
brain, or limbic system.
Many of the ideas of religion and politics are based on primitive
instincts. In an enlightened society, laws and social policies will be
based on science, reason, and love. These irrational emotions are
determined partially by genes, and vary from person to person. Some
people feel disgust at homosexuality. Some don't.
Some people feel disgust or pity about cruelty to animals. Some don't.
Irrational paranoid emotions leading to witch hunts are also partly
genetic. Many people, such as feminists and fundamentalist Christians,
seem to have a tendency to somehow blame all suffering on someone else's
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