Let's turn briefly to another hormone that affects human behavior. It is called serotonin, and it carries information from one nerve cell to another. Thus, it is called a "neurotransmitter." Serotonin's purpose is to pacify or soothe the emotions and to help an individual control his or her impulsive behavior. It also facilitates good judgment. Studies of monkeys in the wild revealed that those with low serotonin levels were more likely to take dangerous leaps from branch to branch. (Sounds rather like me in the pear tree, doesn't it?) Rats with inadequate serotonin tended to be more aggressive and violent. Studies of the spinal fluid of murderers indicated that many of them have very low levels of this hormone, as do arsonists and those with hair-trigger tempers. Depression and suicidal tendencies are related to insufficient serotonin.
If testosterone is the gasoline that powers the brain, serotonin slows the speed and helps one steer. And ... you guessed it. Females typically have more of it than males.
Book: Bringing Up BoysBy Dr. James Dobson