Scientists identify gene for sexual behavior in male flies

A single gene may determine whether a male fruit fly is interested in males or females. How genes control behavior is not very well understood. Scientists are trying to understand how genes control behaviors in simpler animals to get ideas about how it could work in more complicated ones. When male flies come in contact with females, they perform a very unique ‘song and dance. This shows this males interest and attracts the female's attention. Normal female flies never do this routine.

This courtship ritual of the fly is an inborn behavior. All males can do the same routine without seeing other flies do it. And the behavior doesn't change much through learning or in different environments.  One gene that looks promising is the Fruitless (fru) gene. When a male fly's Fru gene is defective, he no longer has any interest in females. He won't dance or sing for them. What makes Fru so special is that it has such a specific effect when it is broken. Mutating it changes the fly's mating behavior without changing anything else.