The world of smells is fascinating. Although it is probably the least developed sense in human beings, thanks to this sense we are able to perceive very diverse aromas that have different effects on us, and even taste what we eat.

But not all we can pick up when we inhale are odors. The vast majority of mammals have an internal organ that is capable of detecting pheromones. We are talking about the vomeronasal organ, common to a large number of mammals and whose existence and functionality in humans has often been discussed.

The vomeronasal organ: description and location

We call vomeronasal organ to a structure present in a great amount of living beings and in the human being (although depending on the study it is stated that it is part of all human beings or that only a percentage of them possess it), which serves as an auxiliary organ of the olfactory system .

It is about a group of sensitive receptors specialized in the capture of pheromones , chemical signals left by living beings and that serve as a message to other beings, whether they are of the same species or not. These receptors are connected to bipolar neurons that have connections with the hypothalamus and the olfactory bulb.

The vomeronasal organ is also called Jacobson’s organ after Ludwig Lewin Jacobson , who gave it its original name (vomeronasal organ) after studying the structure Frederik Ruysch had seen and described (being the first to do so) after observing a structure on the anterior part of the nasal septum of a corpse. Jacobson also visualized this organ in various animals and noted a lack of development of this structure in the case of humans.

In the human being this organ is a bilateral tube that can have several forms, being the most habitual one that of a conical sack, and that is located in a previous way to the vomit bone and below the respiratory mucosa. It is communicated with the nasal cavity and is covered with epithelial tissue .

In many animals there is an internal pump formed by blood vessels that, when contracting, allow pheromones to be absorbed and captured. However, this does not occur in humans, being a membranous organ that does not have a great vascularization.

Functions of the Jacobson’s Organ

The existence of the vomeronasal organ is a reality in a large majority of land animals. The main function associated with this organ is to capture the signals emitted by other members of the same species in order to transmit certain information . The capture of pheromones allows animals to choose reproductive partners with immune systems that are very different from their own (something that benefits possible offspring), to detect the state of health of an animal of the same species, to warn possible sexual partners of this mating stage or to mark a social status.

Also is very useful to many animals when detecting and hunting their prey , as in the case of the snakes (in fact, the typical movement of the snake’s tongue helps to bring the pheromones in and closer to this organ).

However, in other animals it does not appear to have a functionality, as in the case of aquatic mammals (dolphins and whales) and certain species of bats and apes.

Functions in humans

As far as human beings are concerned, as we have mentioned before their functionality has been highly discussed . Traditionally, the vomeronasal organ has been considered a vestigial organ inherited from our ancestors and without a role in our organism, like the coccyx, wisdom teeth or nipples in man.

However, it has been observed that exposure to certain pheromones in the human vomeronasal organ can generate changes at the physiological level . In fact, it has been found that some aspects of our behavior or even our biology can depend on or vary through exposure to pheromones. The best known example is that of sexual attraction: there are people who, being unknown, are instinctively attracted to us, regardless of their physical appearance or personality.

There is also another aspect that occurs regularly and whose explanation is also hormonal: when several women live together continuously for a while, their menstrual cycles tend to synchronize. The presence of men cohabiting with women can also alter the menstrual cycle. Similarly, it has been observed that exposure to some hormones relaxes behaviour and decreases the level of aggression in men, or may increase their level of testosterone.

Finally, it is also known that there are certain pheromones emitted by mothers and babies that have a certain role in the union and bond between mother and child and the behaviour of any of them can be modified depending on the capture by the vomeronasal organ of some of them.

Commercial exploitation of pheromones

However, it must be taken into account that the existence of this organ and the role of pheromones in aspects such as sexual attraction has been taken advantage of by a large number of brands to try to sell their products, selling different perfumes or even preparations with pheromones on a commercial level.

In this sense we must take into account that first of all we ourselves already emit pheromones, and the mixture of our own with those of other preparations can be confusing or even unpleasant, and we must take into account that sexual and romantic attraction is not limited only to the hormones we release.

In addition, it must be considered that different pheromones can have different effects depending on who captures them (for example, as we have said before at the level of sexual attraction, someone with an immune system very different from ours is usually more appetizing).

Bibliographic references:

  • Naser, A.; Fullá, J.M.; Varas, M.A.; Nazar, S. (2008). The human vomeronasal organ. Journal of otolaryngology and head and neck surgery, 68 (2). Santiago.
  • Zeller, F.L. (2007). Normal anatomy and frequency of the vomeronasal Jacobson’s organ (VNO) in human fetuses. Rev. Argentina de Urología, 1 (72).