There’s villainous, and then there’s kidnapping children and using mind-control to turn them into weapons. Black Widow, the latest addition to the MCU, reveals a sinister scheme wherein human behavior is modified through chemical manipulation. General Dreykov, the architect of the Red Room, effectively builds a force field around himself by way of pheromones — if you can smell him, you can't hurt him.
The titular Avenger finds a way around this barrier, of course, and we won’t spoil how she manages it here. But it does cause one to wonder... are pheromones capable of forcing action or inaction against an individual’s will? Or does Dreykov's pheromone plan smell fishy?
Despite their ubiquity in the public consciousness, the idea of pheromones is a relatively new one, having been first proposed by P. Karlson and M. Luscher in 1959. The distinction was made at that time between hormones, which act within the body, and other chemical reactions happening outside the body as a form of communication between members of the same species.
Early research centered on silk moths, and they remain a model example of pheromone communication today. Female silk moths excrete a chemical known as bombykol, which acts as an attractant over vast distances. Moreover, this communication occurs with staggeringly small amounts of pheromone.
Those early researchers harvested bombykol from 313,000 female silk moths, resulting in a total collection of 5.3 mg. Once in the air, male moths must be able to receive the chemical message through their antennae and respond. Examinations of male moth antennae suggest they are capable of detecting a single molecule of bombykol in the air follow it back along air trails to its source. Powerful stuff.
This, in and of itself, doesn’t necessarily lead to the conclusion that the male moth’s behavior is controlled by bombykol. Perhaps they are simply responding to a signal which has always resulted in favorable outcomes in the past. When you hear a dinner bell ringing, there’s a reasonable expectation of food, so to speak. But research at the University of Tokyo adds a wrinkle.
At the National Institute of Agrobiological Sciences, researchers created male silk moths which had their pheromone receptors modified to mirror those of diamondback moths. When these males were exposed to the diamondback moth pheromones, they responded in the same way they usually do to bombykol, with “full sexual behavior.”
This tells us a couple of things, namely the male moths are responding solely to chemical manipulation, and that their behavior can be changed such that they act outside of their best interests: pursuing mates with which they are incapable of procreating.
It should be no surprise that insects communicate largely in this way. Insects are capable of enacting relatively complex behaviors despite lacking relatively complex brains. Much of how they interpret the world around them is through associated smell. It makes sense when you consider that, for those insects, the smells they use to navigate their world have remained largely static.
For as long as silk moths have been around, female silk moths have excreted bombykol. There is a one-to-one relationship. At least until humans get involved. It’s the reason E.O. Wilson was able to trick a colony of ants into thinking one of their number was dead when it wasn’t. Certain smells mean specific things and that’s good enough for insects to keep on thriving.
So, it makes good sense that pheromones would be an effective way of manipulating behavior within a species. Evolution is, by and large, only interested in good enough. What’s good enough for insects, however, isn’t always good enough for other animals or for humans.
Part of the trouble is in defining what, precisely, a pheromone is. If it’s any external chemical compound capable of communicating some information or influencing the behavior of other members of a species, then pheromones absolutely exist in mammals including humans.
Many mammals mark their territory by rubbing their bodies against trees or by urinating and defecating around their claimed space. Likewise, human body odors have a way of putting up a barrier. Have you ever been near someone suffering an illness and been able to smell it?
The trouble is, there’s some debate within the scientific community about whether or not pheromones exist in humans at all.
What we see in insects are specific chemical compounds, specific molecules, which elicit a particular behavior among members of their species. The compound can be defined, and the behavior is consistent from individual to individual. If this sort of chemical relationship exists in humans, we haven’t found it yet.
It’s an interesting idea, one which understandably captured people’s imaginations, especially people who work in the perfume industry. The notion of particular scents capable of eliciting guaranteed emotional or behavioral responses is the sort of thing that might make you a billion dollars. It would also make you a supervillain.
The reason pheromones probably don’t work among humans is the same reason they work so well among insects: complexity, or lack of it. Insects like moths aren’t great at learning. If they were, they wouldn’t crash into your window at night, mistaking your lamp for the moon. Insects need pheromones in order to understand their world, so they’ve adapted to respond to them.
Humans, and other complex animals, on the other hand, rely more on learned behavior and personal experience. We don’t even all like the same pizza toppings, so why would we all react in the same way to a particular scent? It’s true that each of us can be manipulated by particular smells or chemical compounds. The smell of freshly baked bread may cause a salivary response, but that’s likely learned and isn’t universal — at least not across all smells and all individuals.
Pheromone response in humans only exists in direct relationship to how broadly you define what a pheromone is. And in every case we’ve seen so far, they can only influence, not control. A particular smell may make Romanoff want to keep her distance from Dreykov, but it couldn’t stop her from punching him if she wanted that more.
In the end, it’s good she’s a Black Widow, not a moth.