Story posted June 15, 2006
Are men neurologically patterned to view other men as threats? Do women naturally "tend and befriend" other women?
These social stereotypes may actually have physiological origins, according to a new study published by Associate Professor of Neuroscience Richmond Thompson.
The study, which appeared in the May 2006 journal Proceedings of the National Academy of Sciences, is the outcome of nearly a decade of research by Thompson and colleagues on the hormone vasopressin - a peptide long known for its role in the regulation of physiological processes, such as water retention and blood pressure.
In recent years, researchers have discovered that vasopressin also acts within the brain to regulate various social behaviors, such as aggression, courtship and pair bonding among research animals.
Thompson has been studying its effect on social behavior across several species, including goldfish and newts.
Last summer, Thompson and his colleagues began investigating vasopressin's social effects on humans - with some intriguing preliminary results.
In studies undertaken at Bowdoin College, groups of men and women were given nasally administered doses of vasopressin, or a control substance, saline. As expected, vasopressin generally increased anxiety. Unexpectedly, however, men and women showed different social responses when asked to perform a research task.
When exposed to pictures of happy models, "men given vasopressin showed a suite of aggressive tendencies typical of 'fight or flight' responses," notes Thompson. "That included facial responses as well as decreased ratings of how friendly they thought other men were.
"Women given vasopressin, on the other hand, showed responses consistent with more collegial behavior. They rated the women in their pictures as being more friendly and approachable than did women given the control, and they exhibited facial muscle activities such as smiling."
Thompson is cautious about drawing broad conclusions, but says these early, sex-specific findings suggest that "men and women have evolved alternative social strategies in conditions of stress. A wealth of data already suggested that vasopressin played an important role in the regulation of social strategies during vertebrate evolution, but there has been little causal evidence that this was true in humans."
Future research may include studies examining the breakdown of vasopressin, which some researchers suspect is linked to symptoms of autism.
Thompson was assisted in his study by Scott Orr of Harvard Medical School and Dr. Jeff Benson of Bowdoin College. Bowdoin student Meaghan Kennedy '06 also helped him with the research.
"The neurochemistry of social behavior is a vast area of exploration," says Thompson. "Our study is just a piece in the ongoing puzzle to understand what makes human beings tick."
This summer, Thompson returns to his studies of goldfish - seeking to understand more about the effects of vasotocin, the analogous chemical in fish.