"The organ, according to the investigations I have conducted so far, exists in all mammals. It is located in the foremost part of the nasal cavity, in close contact with the nasal cartilage, on the above-mentioned palatal elongations of the intermaxillary bone. It is so carefully concealed that it has avoided discovery by the very discerning eyes of several anatomists... The thing that in particular has hidden this organ from the eyes of the observers is a cartilaginous capsule that surrounds the parts comprising the organ... This secretory organ is even more remarkable because it has its own large and specific nerves."

-- Ludvig Jacobson, 1831

Vertebrates tend to have at least one of two organs for sensing chemicals in the air around them: An olfactory epithelium (OE), and/or a vomeronasal organ (VNO), aka Jacobson's organ. These are two structurally distinct, different organs. For years the general consensus is that the OE is for sniffing out general chemicals, and the VNO is specifically for pheromones.^[1] Nowadays, we know things are a little fuzzier than that,^[2] but the general heuristic of "the VNO mostly deals with pheromones" seems to hold true.

Most tetrapods -- vertebrates with four limbs -- have both a VNO and OE. Primates are a bit of an exception. We know that at some point human fetuses have a VNO, or at least an organ that sure looks a hell of a lot like a VNO. But it seems to degrade by week 36,^[3] or perhaps even at 19 weeks^[4] (pregnancy generally lasts 40 weeks). Whether or not most humans react have any functional remains of a VNO, or if those pheromones you can buy from the back of trade magazines actually do anything, can be answered with an awkward shrug and a "probably not," rather than any statements of absolute certainty.

Zeitgabberim have no time for such uncertainty in their lives. Essentially all zeitgabberim grow a functional VNO before or during the turning point. For those who were bitten rather than given Rumase under medical supervision, the last thing many a non-infected can remember before their seizure is a slow but persistent nosebleed.

A survey conducted by my colleagues revealed that zeitgabberim have slight differences in VNO structure. I will not restate the full study here, but the summary is worth noting — out of all 500 patients who allowed us to put an endoscope into their nose, all except one could have their VNO structure fall into one of seven categorizations. Checking the medical history of the single outlier revealed that she had suffered severe head and facial trauma circa 2018, which likely explains why her VNO defies the well-established seven categories.

Aforementioned back-of-the-magazine pheromones are generally focused making you sexually attractive. Zeitgabberim, what with their drooling smiles and flesh-stained mouths, do not need to rely on chemicals to find mates, but rather lowering their standards. Doctor Mbeki can attest to this.

All zeitgabberim (barring the occasional mutant) give off pheromones from glands located near the armpits. The pheromone that appears in the highest concentration is similar in structure and function to the "aggregate" pheromone found in swarming bees. So similar, in fact, that bees have been known to swarm directly on top of infected who neglect to shower frequently. This pheromone also helps foster a sense of community, although exactly how it works neurologically is poorly understood. It seems that the "aggregate" pheromone also helps infected identify each other as infected, i.e., not edible. The other pheromone all zeitgabberim tend to give off is "alarm," although only startled. This pheromone is the reason why attacks on Taqfleck are met with immediate heavy resistance, but also why using sirens when driving an ambulance through Ap Aniš may cause more traffic as a chain of bystanders enter a RAASC and act unpredictably.

It should be noted that this is distinct from the non-pheromonal scents zeitgabberim give off. The scents that allow me to identify a patient's age, hormonal sex, general health, etc, are not pheromones, as they do not trigger a behavioral response in me. But there are a handful of chemicals which straddle the definition of pheromone and mere scent, most famously the ones associated with menstrual cycles. It has been proposed these chemicals are the only true non-infected pheromone, as studies indicate non-infected dancers receive different tips depending on where they are in their menstrual cycle.^[5] Zeitgabberim are more consciously aware of these scents than non-infected, but do not have the money to tip their dancers.

Let us put aside menstrual matters for the time being. It been discovered that zeitgabberim will respond to at least six other natural pheromones, each one pushing them towards some sort of behavior. These pheromones include the "appeasement" pheromone of mammals, causing the same behaviors in zeitgabberim as they do other animals. Other pheromones tested cause totally different behaviors in zeitgabberim than they do their usual species — one found in coyote urine causes zeitgabberim to avoid the area, although this response could well be the same one rabbits have to that scent. As with the aggregate pheromone, this is not something they are forced to do, but they are also generally not fully aware of it, meaning it is not something that a zeitgabberim would necessarily even consider "resisting." Exactly why they would react to pheromones they cannot produce is not known.

Particularly alarming was the recent discovery that a pheromone used in rabbits to induce suckling, when exposed to zeitgabberim, causes ██████████████████. Given that the Rumase is a synthetic genedrug whose cursed inventors deleted all their internal notes after the Millbrae Massacre, we can only speculate as to whether this is an accidental "glitch" or intentional. If intentional, the implications of this are horrific. To make matters worse, these symptoms match the ones our soldiers in San Francisco face when attacked with chokegas. No one has successfully managed to seize a canister of chokegas for chemical analysis, but it is extremely suspicious that the conniving ███████████████, who are known to have been involved in the development of Rumase, also have a weapon capable of targeting zeitgabberim alone. We are blessed that this chemical's properties make it unsuited for long-term dispersal. If it were as good at spreading through the air as the aggregate pheromone, we would be finished. Perhaps it is a blessing that we only seem capable of releasing "alarm" and "aggregate" into the air, and do so unconsciously. Yes, our behavior is influenced by these chemicals and more, but only one of them ("alarm") has safety implications for day-to-day life in Licentia.

With that being said: A handful of infected, such as ████, have been reported to have the ability to "turn" their fellow zeitgabberim away from them, indicating a level of control over releasing the aggregate pheromone, or the ability to release an entirely different pheromone that causes avoidance behavior. Some theorize more direct control is possible. These reports are unconfirmed. In fact, after discussing these reports with ███████████, I am inclined to believe they're total hogwash, and to discourage anyone from wasting their time investigating further.

1. https://journals.biologists.com/jeb/article/201/21/2913/7889/Structure-and-function-of-the-vomeronasal-organ, as summarized in this abstract: https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.22415#bib39
2. https://www.frontiersin.org/articles/10.3389/fnana.2011.00003/full
3. https://journals.lww.com/neuroreport/abstract/1993/07000/sensory_receptor_like_cells_in_the_human_foetal.7.aspx
4. https://onlinelibrary.wiley.com/doi/10.1111/j.1699-0463.1996.tb04929.x, as summarized by https://journals.biologists.com/jeb/article/201/21/2913/7889/Structure-and-function-of-the-vomeronasal-organ
5. https://time.com/wp-content/uploads/2015/02/cycle_effects_on_tips.pdf