The first observation that animals communicate with chemicals was made by French naturalist Jean-Henri Fabre in the 1870s, who noted that male moths flew from miles around to visit a female moth Fabre had caged in his lab.
Fabre suspected that she was emitting an odor that was luring the fellas, but he couldn't prove it.
As it turned out, that didn't matter much since the scientific establishment didn't take Fabre seriously. He did not work in a university and had the temerity to admit girls to his school science classes. Some scientist!
Still, the phenomenon was so remarkable that other biologists found that moths could indeed home in on members of their own species, even from several miles downwind. Eventually, it was clear that Fabre was right -- a chemical was carrying the signal (The "come hither" message was not, as some assumed, carried as a radio signal sent to the insect's antennae).
The big breakthrough came in 1959, when, after 20 years work (and after dissecting half-a-million silkworm moths), German chemist Adolf Butenandt identified an alcohol that carried the silkworm moth's attractive message. That discovery ushered in a flood of pheromone research, as entomologists poked around and found the system to be quite common in the exoskelatinous (defined) crowd. (Fortunately, modern chemical analysis tools have slashed the bug-death toll for today's pheromone researchers). Here's more on the discoveries.
It turns out that the social insects (including ants, bees and termites) are a particularly rich source of pheromones, which they use to communicate about food, predators and social relationships. For example, a queen bee releases a pheromone that signals to her sisters, the worker bees, to defer reproducing. The queen then produces the next generation of genetically identical workers. (When an old queen dies, the workers select a female in the pupal stage, which goes on a mating flight.)
In sum, ants use at least 10 different chemical signals, ranging from simple carbon dioxide, which helps promote clustering for working on joint tasks, to a complex "colony odor," which serves as a "chemical address" for an individual colony.
Some of these juicy scientific morsels were gleaned from "Bombardier Beetles and Fever Trees" (see bibliography), which covers many aspects of natural chemistry.
It's not just the bugs
In fact, according to Charles Wysocki, a neuroscientist at Monell Chemical Senses Center in Philadelphia, "some amphibians, most reptiles, and most mammals have a vomeronasal organ." In birds, however, the structure is only present during embryonic stages. Wysocki has spent more than 20 years tracking down the structure and function of the VNO in various animals.
In most of the species that have a VNO, it is wired to the amygdala, a primitive brain structure implicated in rage, emotion, fear and memory, Wysocki says. The wiring then goes to the hypothalamus, the brain's headquarters for primitive responses to fear, food and temptation, not to mention blood pressure, heart rate, body temperature and a host of other critical physiological functions. All in all, the VNO could affect a monster list of fundamental attributes.
Going mainstream
What with all the research, pheromones have gone mainstream. Insect pheromones are commonly used to trap the little pests so they can be conveniently killed without spraying a bunch of nasty pesticides around. And it's common knowledge that if you want to excite male gypsy moths, you just spray a female's pheromones on some leaves, and the boy moths will start acting like frat brothers on Saturday night.
But could pheromones actually have the same effect on real frat brothers?
In other words, could what we don't consciously smell hurt -- or help -- us?
