Lower status → less serotonin
The higher your self-esteem and social rank relative to those around you, the higher your serotonin level is. Experiments with monkeys reveals that it is the social behaviour that comes first. Serotonin is richly present in dominant monkeys and much more dilute in the brains of subordinates. Cause or effect? Almost everybody assumed the chemical was at least partly the cause: it just stands to reason that the dominant behaviour results from the chemical, not vice versa. It turns out to be the reverse: serotonin levels respond to the monkey’s perception of its own position in the hierarchy, not vice versa.
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Lower serotonin → aggression
Monkeys fed on low-cholesterol diets become more aggressive and bad-tempered (even if they are not losing weight), and the cause seems to be a drop in serotonin levels.
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