When a group of flies dive-bomb towards your plate, chances are you'll instinctively swat the buggers, riling them up further. But are you actually making the flies angry? A recent Caltech study confirms that male flies indeed have "rage" pheromones.
Here's some "mad" science for you - in the online journal Nature, Caltech researchers David Anderson and Limang Wang report that common vinegar flies (Drosophila melanogaster) produce an aggression-inciting pheromone that is intercepted by neurons in the flies' antennae. The researchers noted that the pheromone is released when male flies are in groups, such as times when they're competing for food:
To do this test, they trapped between 20 and 100 "donor" male flies-so called because they "donate" the volatile pheromones into the surrounding environment-in a tiny cage surrounded by a fine mesh screen. The screen allowed pheromones to escape, but kept the donor flies inside.
The researchers then measured the effect these donor flies had on the aggressiveness of a pair of "tester" male flies placed on top of the cage. The tester flies were close enough to sense the pheromone, but were prevented from coming into contact with the donor males by the mesh screen. "Remarkably," says Anderson, "the presence of the caged donor flies strongly increased aggression between the tester flies, and this aggression-promoting effect increased with a higher number of donor male flies."
Most importantly, the effect of the donor flies on the aggressiveness of the tester flies could be blocked by inactivating, in the tester flies' antennae, the neurons that sense the aggression pheromone.
"These experiments suggested that the presence of high densities of male flies in a local environment can indeed promote aggression through their release of cVA and its detection by other flies," Wang explains.
Anderson and Wang have not ruled out that such a similar "anger" pheromone exists in large groups of humans. May we submit our peers' behavior at Comic Cons as evidence?