But they make inappropriate choices. They attempt to mate with male and female flies almost indiscriminately. That's what led us to name the gene as we did. Apart from the abnormal behavior they exhibit, the exterior appearance of mutant flies seems normal. But closer inspection reveals a number of neural defects-again, differing between males and females.
Mutant females lack nerves that normally connect with uterine muscles to stimulate egg-laying.
Mutant males possess abnormalities in their abdominal wall innervation, making it difficult for them to curl their abdomens and assume a proper mating position. The big question, of course, is whether the sexual behavior of fruit flies has any bearing on that of human beings. That gene also affects sexual behavior, but through a pathway independent of the one used by the dissatisfaction gene-telling the researchers that it's possible to have complex patterns of genes controlling complicated behavior patterns. Because mutations in sexual behavior, unlike many other neurological defects, are not lethal to an organism, investigators can study the effects of these mutations throughout the organism's lifetime. Eventually, he believes, it should be possible to apply findings thus made to the broader questions of neurogenetics and behavior.