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.

In Heinrichs’ and Dawans’ study, male participants were assigned to either an experimental group, with a stress procedure (a public speaking exercise followed by a complicated mental arithmetics), or a control group with no stress. They all were then asked to play an economics game involving potential financial gain based on the choices they make. In this game, they could choose to cooperate with others and trust them or not. The researchers found that, rather than becoming more aggressive after stress, men in the stress group actually became more trusting of others, displayed more trustworthy behavior themselves, and were more likely to cooperate and share profits. The researchers also found that these results were not due to weakened judgment in the stress group: the stress group did not differ from the control groups in their ability to make decisions or their willingness to sanction another participant who behaved unfairly.

One reason why stress may lead to cooperative behavior is our profound need for social connection. Human beings are fundamentally social animals and it is the protective nature of our social relationships that has allowed our species to thrive. Decades of research shows that social connection is a fundamental human need linked to both psychological and and physical health including a stronger immune system, faster recovery from disease and even longevity.

Social connection may be particularly important under stress because stress naturally leads to a sense of vulnerability and loss of control. A study by Benjamin Converse and colleagues at the University of Virginia found that feeling out of control (through a reminder of one’s mortality) leads to greater generosity and helpfulness while research at Stanford University by Aneeta Rattan and Krishna Savani showed that the opposite is true when we are primed with feelings of self-determination and control. Think back to a time when you felt out of control, for example during a romantic break-up, when you had an empty bank account, or lost a job. Chances are your feeling of vulnerability and feelings of lack of control may have made you seek the comfort of others in some way. Brene Brown, Professor at the University of Houston Graduate College of Social Work and expert in the field of social connection, explains that vulnerability is a core ingredient of social bonding.

War is one of the greatest stresses anyone could ever encounter yet it also often leads to deep human friendships and incredible acts of heroism and sacrifice for one other. In my research with returning veterans, I have often heard them speak of the tight bond that occurs between servicemembers on the battlefield — one of the most stressful situations that exists. Countless soldiers have perished running into a line of fire to save an injured brother-in-arms. Some believe that it these experiences of profound human bonding that, despite the acute anguishes of war, makes some veterans long to return to war.

If stress leads to bonding, why then do we sometimes experience stress as making us cranky? The cause may be explained by a difference between acute and chronic stress. We know from research by Robert Sapolsky that acute stress prepares the body for resistance (physiological readiness, increased immune response, and heightened awareness) but that chronic stress slowly beats down the body. It may be that “acute” stress, i.e. a one-time stressful experience may lead to social bonding, as shown in the study, but that “chronic” stress, i.e. repeated exposure to stress over a long period, might wear us out. More research is needed to thoroughly examine the impact of chronic stress on social behavior.

Acute stress may help remind us of a fundamental truth: our common humanity. Understanding our shared vulnerability — life makes no promises — may be frightening, but it can inspire kindness, connection, and desire to stand together and support each other. Acute stress, as unpleasant as it may be, may also be an opportunity to experience the most beautiful aspects of life: social connection and love.

Are you a scientist who specializes in neuroscience, cognitive science, or psychology? And have you read a recent peer-reviewed paper that you would like to write about? Please send suggestions to Mind Matters editor Gareth Cook, a Pulitzer prize-winning journalist at the Boston Globe. He can be reached at garethideas AT gmail.com or Twitter @garethideas.