The biggest reason is simply that we are mammals. It occurs during the change at puberty. If we were any other type of mammal we could be looking for this sort of thing. Our smells change at puberty (apocrine & sebaceous glands, axillary/pubic hair, etc.)
Pheromones allow you to go for the gender of your choice. In the breeding season, sexually mature males start to get smelly. It was going to be 100 years before the molecules were identified. Regardless, it was the smelliest males that got the most sexual attraction. It’s the same type of thing that seems to be happening to humans at least from my point of view. All the smells develop at puberty.
Although there is some dispute about this I am fairly convinced that mammals do have pheromones. There are all kinds of molecules. There are lots of small ones and big ones. There are also some large peptides; ESP1 is the one transferred from the male tear ducts from his tears to the females nose.
In humans, our sense of smell is really quite good. It is true that our sensitivity is very much less than a dogs. So in terms of picking the up traces of smell, humans are probably as good as mouse or dog. Our noses just have to be closer to the source or experience more of it.
What’s wrong with putative human pheromones?
Even they do not think they are pheromones and if they do they do not think they are really good. There is a good reason for that. The reason of course is there is no direct evidence to support the claims.
There is no evidence that underlies and supports other claims of pheromones in other species for this work on humans.
Two waves of putative human pheromones
The first of these were bases on a simple coincidence. So, basically these molecules were found in pigs and human armpits. That was enough, The second wave is in someway even stranger. It is based on a conference paper with no methods section nor evidence for the molecules. Yet, there have been over 150 publications on it. And 25 years of study. People have tried to expose this without success.
So the first wave of molecules occurred between the 1970s to the 1980s. This includes androstenone and androstenol. It is based simply on coincidence: pheromones in pigs, some found in human armpits, and so it must be found in humans. The molecules look a little bit like testosterone so the idea was these could be human pheromones.
Unfortunately, there was no bioassay evidence that there are human pheromones. The crucial thing was for people to know how complicated the secretions were. You could literally buy it in a can. It’s used by pig farmers to breed their animals.
For these steroidal molecules there is no evidence. They created a circumstantial argument that these molecules were special. Instead, we have:
- Specific anosmia’s
- Induced sensitivity
- Differences between sexes in production/perception
None of these are special to these steroids.
That’s an argument that should not be made to the general public. If the general population can’t smell them then it means it’s something that probably cant be labeled as a real human pheromone. If you can’t smell it, and then you sniff it a lot, over a period of weeks or month you won’t even notice it. You increase your sensitivity. After that period you can smell it better.
Apparently, there are differences in the sexes and how they can reproduce them independently. There was even a suggestion that in different stages of the menstrual cycle certain women were better able to smell it than others. All of these things turned out to be in closer analysis to be false.
It’s nothing necessary terribly sexy. This was just a circumstantial argument just to specify their specialist. In fact, there was no direct evidence and correlation with pheromones. The second wave came from 1991 symposium sponsored by the Erox corporation which coincidentally was patenting human pheromones as fragrances.
It was at that conference that Monti-Bloch & Grosser (1991) were publishing this paper: The Effect of putative pheromones on the electrical activity of the human vomeronasal organ and olfactory epithelium. Nobody else has found a vomeronasal organ in humans that actually works and is functional in adults. This is the method for chemical stimuli that is concerned. These putative pheromones were supplied by the Erox corporation.
There is no account of how the molecules were collected, isolated, identified, biased, synthesized, and tested. None of that exists. When the patent was published there was no details in that either.
So, it’s quite remarkable these two steroid molecules were proposed with any evidence at all. Androstenone was produced by males and effected females. The weird thing is that previously it had only been recorded in the urine of pregnant women in the third trimester. There was no record of it given off any other way or that it might be a signal.
All’s we know is that the molecules were supplied by the corporation EROX and the later patents do not give any more details. Nothing might have happened. It was a conference. However, something did happen.
A paper appeared in 2000 in a respectable journal called Jacob and McClintock (2000) Psychological state and mood effects of steroidal chemo signals in women and men.
What was more important was that the second author had a very good reputation as a scientist and they used these two molecules. Why? Because they were used at the conference and they were patented. That was the source of the information. Because they were respectable scientists in a reasonable journal an enormous number of people started to treat the molecules as respectable.
There is always a need for scientists to come up with a different story for something new to say.
How did this happen?
- Using Androstenone removed need for labs and chemistry
- Growing literature assumed these were putative human pheromones
- Self-referential literature – no-one critically looking at source paper
- Positive publicities bias and lack of replication