The nose knows
Although the nitty-gritty of their dispersal remains obscure, pheromonal detection mechanisms are becoming clearer. Scientists have long thought that a specialized structure in animals' noses, called a vomeronasal organ (VNO), detects pheromones. The problem with that theory when applied to humans, however, is that the tiny VNO duct behind each of our nostrils is not always present, plus the genes for its receptors seem to be inoperative. But as it turns out, regular mammalian nasal tissue seems to be able to pick up pheromones just fine—at least in some animals. For example, sows, upon smelling a pheromone in boars' saliva, assume a mating stance, even if researchers plug the pigs' VNOs. In humans, a 2011 study showed that when volunteers were exposed to androstadienone, all their brains showed a reaction, even if they lacked VNOs or had their VNOs blocked. "The VNO need not be the pheromone-sensing organ," Wysocki says. "The olfactory system can be the input."
Other work suggests that less familiar inputs might exist for a human pheromonal network. Investigations continue into a possible pheromone nerve, known as cranial nerve 0, or the terminal nerve. [For more about the terminal nerve, read "Sex and the Secret Nerve," by Douglas Fields, in Scientific American MIND, February/March 2007.] Initially discovered in sharks in 1878 and humans in 1913, this pair of nerves runs from the nose directly into the brain in front of cranial nerve 1, the olfactory nerve (the traditional first of a dozen recognized cranial nerves). Animal research points to important sexual, pheromonal roles for the terminal nerve. Hamsters with severed terminal nerves fail to mate, and when male zebra fish get an electrical zap to theirs, the fish ejaculate. In humans, just what part the terminal nerve might have for adults remains sketchy, Wysocki says. It does have one clear purpose, however: During fetal development, the terminal nerve works as a pathway for certain sex hormones to migrate into the brain crucial for later development during puberty.
Whether or not pheromones initially affect sexual attraction, other research has indicated that humans might be using a different set of subtle smell cues to help select our mates. Variation in the major histocompatibility complex (MHC), an important set of immune system genes, imbues each of us with a unique "odorprint," like a fingerprint. "With the exception of identical twins, no two individuals are likely to have the same odorprint," Wysocki says. In nature, the sexual union of unlike MHCs yields offspring with more diverse and thus more robust immune systems. Instinct may also guide us in this manner: Previous research has revealed that human females preferred the musk of sweaty T-shirts worn by men with suitably different MHC genes.
Because scores, if not hundreds, of unidentified odorants comprise an odorprint, Oxford's Wyatt has argued that it cannot be considered a pheromone in the classic sense. Evidently, the complex cloud of aromas we emit needs a lot more parsing before science closes the book on pheromones. The olfactory cues of many insects remain better understood than our possible covert realm of social and sexual chemistry. "The real problem," Wyatt says, "is simply a lack of knowledge so far as humans are concerned." Wysocki agrees: "There's no good literature in the biomedical field to support that sexual-attractant pheromones exist," he says. "But that is not to say they aren't out there. I think we have to go in with an open mind.
Until more is known, then, those on Valentine's Day dates should probably just follow their noses.
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11 Comments
Add CommentThe stuff on infants and maternal scent hormones is very cool.
Reply | Report Abuse | Link to thisHuman women don't actually synchronize their menstrual cycles, though. Because menstruation is cyclical and lasts for several days, the chances of *apparent* synchrony are very high, and large-scale studies have shown that it's precisely what you'd expect at random (i.e., women living together are not synchronized any more than random women would be if you tracked their cycles). This, compounded with the human tendency to only notice confirming evidence, leads to the illusion of synchrony. (see Yang & Schank, 2006: http://www.springerlink.com/content/6v72apa1y5955ya7/)
I'm always interested in how people who identify as gay, bisexual, lesbian or transgendered/intersexed identify pheromones. Almost every study done on solely heterosexual people could be redone with non-hetero identified participants and could really help understand sexual identity and gender identity a lot more. Some of us are straight. Straight people are wired to mate. Fascinating! Shocking! Now tell us something about something we don't know all about!
Reply | Report Abuse | Link to thisYou are correct in pointing out that female menstrual synchrony occurs only due to 'menstrual wander' - the temporary overlap that can occur between 2 women's variable menstrual cycle durations. The study results were deliberately falsified to reflect the researcher's bias; she chose to stop the reporting of data just when 2 women's cycles became synchronized. After the point of synchrony, invariably the two womens' cycles tended to become eevntually unsynchronized.
Reply | Report Abuse | Link to thisSure, we can keep on looking forever for the putative human pheromones - and never finding one, one can always say that it will eventually be found with further investigations. But the point is, do we really need pheromones in the first place to tell us what to do sexually?
Pheromones are part of the system of sexual instincts in animals species that promote and regulate sexual reproduction. I believe that animals need them because they would otherwise not know how to accomplish reproduction, and would have no reason to reproduce either- ie. other than keeping the species alive, and perpetuating their genes, that is.
Humans on the other hand to know what causes reproduction - ie. sexual intercourse between a male and female - and until relatively recent history also hade vested interests in reproducing, namely to produce children that could look after them when they grew old and feeble.
So, really at some point in human evolution - when our intelligence level increased sufficiently - we no longer had a need for a sexual instinct, and correspondingly, for the existence of pheromones.
I think the reason I was interviewed for the "Sex and the Secret Nerve" article was because I had just published a chapter in the Handbook of the Evolution of Human Sexuality: "The Mind's Eyes: Human pheromones, neuroscience, and male sexual preferences."
Reply | Report Abuse | Link to thisNext up is my article in press for Socioaffective Neuroscience & Psychology. "Human pheromones and food odors: Epigenetic influences on the socioaffective nature of evolved behaviors."
Abstract: Olfactory cues directly link the environment to gene expression. Two types of olfactory cues, food odors and social odors, alter genetically predisposed hormone-mediated activity in the mammalian brain. The honeybee is a model organism for understanding the epigenetic link from food odors and social odors to neural networks of the mammalian brain, which ultimately determine human behavior. Pertinent aspects that extend the honeybee model to human behavior include bottom-up followed by top-down gene, cell, tissue, organ, organ-system, and organism reciprocity; neurophysiological effects of food odors and of sexually dimorphic, species-specific social odors; a model of motor function required for social selection that precedes sexual selection; and hormonal effects that link current neuroscience to social science affects on the development of animal behavior. As the psychological influence of food odors and social orders is examined in detail, the socioaffective nature of olfactory cues on the biologically based development of sexual preferences across all species that sexually reproduce becomes clearer.
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It is difficult for me to comprehend any scientific reasoning that might underlie controversial opinions about human pheromones. Clearly the molecular biology is the same across species from microbes to man, and so is the importance of chemical/olfactory receptors, food odors, and the social odors called pheromones. Given the ubiquitous nature of food odors, how could any reasonable person doubt the existence of human pheromones? Is anyone foolish enough to posit that each of us responds to food odors with stereotypical behaviors, or that the visual appeal of food is more important to our behavior than is its chemical appeal?
I find it very reassuring that some capitalist lab hasn't yet managed to hack the human olfactory system with a genuine pheromonal aphrodisiac. Maybe our luck won't hold out forever, and we'll find a way to override human judgment through pheromones to make us amorous or violent or pliant or whatever else suits the smell-masters.
Reply | Report Abuse | Link to thisIf not for the complex intracellular signalling that is required for conversion of a chemical signal to the common language of electrical signalling in the mammalian brain, we might already have a synthetic food with equal appeal to all. Instead, we have spices with genetically predisposed appeal, which is partially determined by mother-infant intrauterine chemical communication facilitated by the placenta.
Reply | Report Abuse | Link to thisThe effect of the spices on hormones associated with ingestive behavior are somewhat predictable but not species-specific. The added complexity of species-specificity when it comes to pheromones, social preferences for conspecifics, and mate choice makes any stereotypical effect on hormones and their affects on behavior less predictable.
This does not mean that human pheromone-enhancement of visual appeal is any less feasible than learning how to spice up the appeal of food. And the ability to spice up the visual appeal of another person with pheromones, as we have done, attests to the likelihood that the same neurophysiological mechanisms are involved in the development of food preferences and mate preferences in all mammals.
Diatribes and definitions of human pheromones can only lead back to biological facts that have already been detailed across species. Progress in molecular biology may make understanding these facts more difficult, but it will not change them.
If you have borderline personality disorder, there is a human pheromone for sale on ebay that remedies that.
Reply | Report Abuse | Link to thisIf you suffer from suicidal ideation, there is a human pheromone for sale on ebay that remedies that.
If you feel compelled to runaway from home, there is a human pheromone for sale on ebay that is a remedy for that.
If you lust for criminal activity, there is a human pheromone remedy for delinquency and criminal behavior on ebay.
If you lust sexually after little children, there is a human pheromone remedy for pedophilia, child molesters on ebay.
Human beings have difficulty recognizing human pheromones. We cannot identify them correctly. We find them odorless, colorless, and tasteless. Many people have further difficulty even in thinking about human pheromones. There is a whole in both our perception spectrum as well as our cognition spectrum. It doesn't help that pheromones work insidiously as well. When relieved of some loathsome malady, we humans do not cheer the great discoverer doctor, we shrug our shoulders and confabulate excuses and just know in our hearts that humans do not respond to pheromones. Yes, it may be that human beings have the largest pheromone-sensing receptor fields of any species--the 'brush border" microvillar cells that line most of only the human upper respiratory system. Yes, it may be that we human beings have the largest and most active scent glands than any species. Or perhaps we should just ignore the obvious? Women lick males (and vice versa) because there is something there to lick. The something that is there has the stereochemistry of butterfly pheromones. Children kiss their fathers, again, because there is something there to pick up with those kisses. It is something that we need, just like vitamins. If we have a pheromone deficiency, we suffer sociopathy, perversion, and death. The something that is there is a human-only chemical signature, with a human-only marker component, sebaleic acid. You don't smell it. You don't see it. You can't even taste it. You kiss it. Why? Because it is there!
The FDA refuses to regulate human pheromones, because human pheromones are impossible, eh? Pheromones are the most potent drugs imaginable. FDA should change course and help America win the wars on crime, addictive drugs (not alcohol), and jihad.
Bubba Nicholson
Senior Scientist in Charge
Nicholson Science
Tampa, FL
USA
NicholsonScience@hotmail.com
It's for sale if you want it.
Reply | Report Abuse | Link to thisHuman pheromones and food odors: epigenetic influences on the socioaffective nature of evolved behaviors by James V. Kohl (Published: 15 March 2012) Citation: Socioaffective Neuroscience & Psychology 2012, 2: 17338 – DOI: 10.3402/snp.v2i0.17338 (open access)
Reply | Report Abuse | Link to thisConclusion (excerpts)
"... when viewed from the consistency of animal models and conditioned behaviors, food odors are obviously more important to food selection than is our visual perception of food. Animal models affirm that food odor makes food either appealing or unappealing. Animal models reaffirm that it is the pheromones of other animals that makes them either appealing or unappealing."
"Olfaction and odor receptors provide a clear evolutionary trail that can be followed from unicellular organisms to insects to humans."
Brilliant. That explains why sexual desire is absent in the human species.
Reply | Report Abuse | Link to thisWhy not read what hunders of people just like you have to say about pheromones and whether they work or not?
Reply | Report Abuse | Link to thisWhat would you rather accept as gospel, scientific studies seeking only concrete, provable and repeatable evidence, or real world experiences from hundreds people just like you?
http://pherotruth.com is a pheromones forum and contains information on a number of pheromone companies, products and thousands of member reviews on pheromone products, which one work, which don't, how well they do work, and the type of effects they elicit.
If you are at all curious about pheromones, have questions or would like to talk to people that have been using them years stop by and say hello, everyone is friendly and always willing to help out someone new to the pheromone world or answer any questions.