When Shelley Taylor of UCLA published her "tend and befriend" theory, it sparked a lot of interest -- and it still intrigues people. Taylor proposed that in times of danger or stress, women don't necessarily go into fight-or-flight mode. Instead, she said, their instinct is to seek the comfort of others, particularly other women.
This behavior had adaptive advantages, according to her theory: In prehistoric times, children -- the next generation -- couldn't survive without mothers. Women who were pregnant or nursing needed to stay close to their babies. If there was danger, the next generation's best chance for survival was for them to hunker down, stay still and hope for the best.
Men, who were more expendable in terms of their offspring's survival, needed that adrenaline jolt to defend their families and clan.
Women's increased sensitivity to oxytocin seems to be the basis of tend-and-befriend behavior. Oxytocin is calming, and the bond it creates between mother and child, as well as between friends, encourages women to come together.
Af fMRI study at the University of Pennsylvania found that this difference is mirrored in differences in brain function. Under stress, men's brains tended to become activated in the right prefrontal cortex, the part of the brain responsible for the fight-or-flight response, according to the article. (I thought it was the amygdala.)
Women tended to show more activation in the limbic system (of which the amygdala is part), the part of the brain responsible for emotional responses.
According to the study, Gender difference in neurological response to psychological stress, the men's stress response correlated with increased cortisol levels, while the women's did not. (They did not check for elevated oxytocin.)
Here is the article in Science Daily.