Sensory organ differentiates male/female behavior in some mammals

For years, scientists have searched in vain for slivers of the brain that might drive the dramatic differences between male and female behavior. Now biologists at Harvard University say these efforts may have fallen flat because such differences may not arise in the brain at all.

Rather, they say, the epicenter of sex-specific behavior in many species may be a small sensory organ found in the noses of all terrestrial vertebrates except higher primates. Their work, appearing this week in the journal Nature, indicates that defects in this organ, known as the vomeronasal organ, lead female mice to adopt male behaviors such as mounting and pelvic thrusting while abandoning female behaviors such as nesting and nursing.

"These results are flabbergasting," says Catherine Dulac, Higgins Professor of Molecular and Cellular Biology in Harvard's Faculty of Arts and Sciences and an investigator with the Howard Hughes Medical Institute. "Nobody had imagined that a simple mutation like this could induce females to behave so thoroughly like males."