Hormones, Sex, and Society
Scientists have known for years that hormones exert a profound control over male and female biology. They influence whether an embryo develops into a male or female fetus. They kick in during puberty and promote gender-specific characteristics, such as facial hair in men and breasts in women. They also stimulate the production of male sperm and female ova.
These actions have led to the widespread use of hormones in mainstream and fringe medicine for years. A major part of sexual reassignment procedures involves the long-term administration of hormones like estrogen or testosterone. Athletes seeking a competitive edge and middle-aged men seeking to prolong the vigor of youth sometimes use testosteroneoften inducing aggressive behavior in the process.
While the connection between sex hormones and behavior has been known for years, scientists have only recently made significant headway in demonstrating how profoundly one affects the other by altering the levels of male and female hormones in laboratory animals.
Female mice in the laboratory normally exhibit what one might consider classic motherly behaviorsmating with male mice and nurturing their young. But female mice with a genetic trait making them unable to sense the hormone estrogen lose their interest in sex and spend less time caring for their offspring.
Fortified by testosterone, male mice in the laboratory display behaviors tending toward the aggressive. They will fight with each other, try to mount female mice and mark their territory with urine. Deprived of testosterone, however, castrated male mice no longer behave so aggressively.
Scientists have long suspected that sex hormones ultimately influence gene expression in the brain-. About six years ago, Shah and his colleagues set out to find such genes by using DNA microarrays, a routine laboratory assay, to
|Contact: Jason Socrates Bardi|
University of California - San Francisco