For the most part, fruit flies are a peaceful species. Fights over food are rare occurrences and sharing is pretty typical. Drop some artificially produced pheromones into the mix, (or, as in another case, deprive them) and suddenly the tranquil scene transforms into something from a battlefield. As MSNBC reports, they quickly start karate chopping and judo wrestling their opponents, rearing up on their hind legs and snapping down violently, and grappling with their forelegs.
Eventually, one dominant fly chases away all the others.
This crazy violent atmosphere is the work of 11-cis-vaccenylacetate, a newly discovered chemical pheromone that triggers aggression in fruit flies. The pheromone is naturally found in the hard exoskeletons of the flies and is thought to be released when the fly gets bumped — in essence, a kind of crowd control. When synthesized in its chemical form, however, it wrecks havoc on any number of flies within "smelling" distance.
Of course, as interesting as these effects are on fruit flies, scientists are also curious about how such non-visual stimuli might affect humans. "Aggression pheromones are used not only in insects but in mammals as well," said David Anderson, a scientist at Cal Tech and co-author of the study that appeared in the journal Nature. "But whether we use aggression-promoting pheromones is speculation."
The armpits of men have been shown to release pheromones that potentially contribute to sexual attraction, so it's not outside the realm of possibility that there's something in us that may also spur anger. For now, however, scientists say our brains are much too developed to react to a single pheromone that strongly.