They found 16 genes that were expressed differently between males and females in the hypothalamus and showed that such differences were regulated by sex hormones. But in identifying these 16 genes, Shah and his colleagues also discovered they could tease apart classic, male and female hormone-driven behaviors into individual elementseach governed by its own genes.
The situation is analogous to the way a house draws its power from the grid. A sex hormone is similar to the main breaker that connects the house to the utility pole and regulates electricity to the entire house.
Individual genes influenced by sex hormones are like the light switches in each room, making it possible to turn the lights on in the kitchen while leaving the bedroom dark.
Sex and BehaviorMore than the Sum of Parts?
Much like a main electrical box with many breaker switches, male and female behaviors are actually made up of many behaviors, like sex drive or an inclination to fight. Shah and his colleagues demonstrated this by manipulating the genes separately, sometimes with drugs, to turn them off.
Specifically, they showed that they could selectively knock out some male behaviors so that males continued to fight and mark territory normally but altered their mating routine with females. Likewise they could modulate female mouse behaviors to make them maintain active interest in sex but spend less time caring for their young, or vice versa.
"Other components of male and females behaviors appeared unchanged," Shah said. The implications of this simple observation that a complex human behavior may be composed of numerous genetically controlled elements are both intriguing and daunting, he added. Moreover, it is likely, Shah said, that there are many additional genes that will be discovered to be sex h
|Contact: Jason Socrates Bardi|
University of California - San Francisco