Ever feel that stress makes you more cranky, hot-headed or irritable? For men in particular, we think of stress as generating testosterone-fueled aggression – thus instances of road rage, or the need to “blow off steam” after work with a trip to the gym or a bar. On the other hand, in circumstances of extreme stress such as during natural disasters like Hurricane Sandy, we hear moving accounts of people going out of their way to help others. Hurricane Sandy has led to a flourish of supportive tweets and Facebook messages directed to people on the East Coast. The tsunami in Asia a couple of years ago led to a huge influx of financial support to help afflicted areas. Many who lived in New York City during 9/11 remember that, for a few days afterward, the boundaries and class divisions between people dissolved: people greeted each other on the street and were more considerate, sensitive to each other, and gentle than normal.

The classic view is that, under stress, men respond with "fight or flight,” i.e. they become aggressive or leave the scene, whereas women are more prone to “tend and befriend,” as has been shown in research by Shelley Taylor. A new study by Markus Heinrichs and Bernadette von Dawans at the University of Freiburg, Germany, however, suggests that acute stress may actually lead to greater cooperative, social, and friendly behavior, even in men. This more positive and social response could help explain the human connection that happens during times of crises, a connection that may be responsible, at least in part, for our collective survival as a species.