Editing Pheromone (section)

=== Stimulators of the vomeronasal organ ===
The human [[vomeronasal organ]] has [[epithelia]] that may be able to serve as a chemical sensory organ; however, the genes that encode the VNO receptors are nonfunctional [[pseudogene]]s in humans.<ref name= Grammer/> Also, while there are sensory neurons in the human VNO there seem to be no connections between the VNO and the central nervous system. The associated olfactory bulb is present in the fetus, but regresses and vanishes in the adult brain. There have been some reports that the human VNO does function, but only responds to hormones in a "sex-specific manner". There also have been pheromone receptor genes found in olfactory mucosa.<ref name= Grammer/> There have been no experiments that compare people lacking the VNO, and people that have it. It is disputed on whether the chemicals are reaching the brain through the VNO or other tissues.<ref name= Hays/>

In 2006, it was shown that a second mouse [[odorant receptor|receptor]] sub-class is found in the [[olfactory epithelium]]. Called the [[trace amine-associated receptor]]s (TAAR), some are activated by volatile [[amine]]s found in mouse urine, including one putative mouse pheromone.<ref>{{cite journal | vauthors = Liberles SD, Buck LB | title = A second class of chemosensory receptors in the olfactory epithelium | journal = Nature | volume = 442 | issue = 7103 | pages = 645–650 | date = August 2006 | pmid = 16878137 | doi = 10.1038/nature05066 | s2cid = 2864195 | bibcode = 2006Natur.442..645L }}</ref> [[Ortholog]]ous receptors exist in humans providing, the authors propose, evidence for a mechanism of human pheromone detection.<ref>{{cite journal | vauthors = Pearson H | title = Mouse data hint at human pheromones | journal = Nature | volume = 442 | issue = 7102 | pages = 495 | date = August 2006 | pmid = 16885951 | doi = 10.1038/442495a | bibcode = 2006Natur.442..495P | doi-access = free }}</ref>

Although there are disputes about the mechanisms by which pheromones function, there is evidence that pheromones do affect humans.<ref name= Wysocki>{{cite journal | vauthors = Wysocki CJ, Preti G | title = Facts, fallacies, fears, and frustrations with human pheromones | journal = The Anatomical Record Part A: Discoveries in Molecular, Cellular, and Evolutionary Biology | volume = 281 | issue = 1 | pages = 1201–1211 | date = November 2004 | pmid = 15470677 | doi = 10.1002/ar.a.20125 | doi-access = free }}</ref> Despite this evidence, it has not been conclusively shown that humans have functional pheromones. Those experiments suggesting that certain pheromones have a positive effect on humans are countered by others indicating they have no effect whatsoever.<ref name= Hays/>

A possible theory being studied now is that these axillary odors are being used to provide information about the immune system. Milinski and colleagues found that the artificial odors that people chose are determined in part by their [[major histocompatibility complex]]es (MHC) combination.<ref name= Milinski>{{cite journal | vauthors = Milinski M | title= Evidence for MHC-correlated perfume preferences in humans| journal= Behavioral Ecology| volume= 12| issue= 2| pages= 140–9| year= 2001 |doi=10.1093/beheco/12.2.140 | doi-access= free}}</ref> Information about an individual's immune system could be used as a way of "sexual selection" so that the female could obtain good genes for her offspring.<ref name= Grammer/> [[Claus Wedekind]] and colleagues found that both men and women prefer the axillary odors of people whose MHC is different from their own.<ref name= "Wedekind">{{cite journal | vauthors = Wedekind C, Seebeck T, Bettens F, Paepke AJ | title = MHC-dependent mate preferences in humans | journal = Proceedings. Biological Sciences | volume = 260 | issue = 1359 | pages = 245–249 | date = June 1995 | pmid = 7630893 | doi = 10.1098/rspb.1995.0087 | s2cid = 34971350 | bibcode = 1995RSPSB.260..245W }}</ref>

Some body spray advertisers claim that their products contain human sexual pheromones that act as an [[aphrodisiac]]. Despite these claims, no pheromonal substance has ever been demonstrated to directly influence human behavior in a [[peer review]]ed study.<ref name = Hays/><ref name="Neu"/>{{Disputed inline|Dated claim of no demonstration in peer-reviewed studies|date=March 2018}} Thus, the role of pheromones in human behavior remains speculative and controversial.<ref name = Purves>{{cite book | vauthors = Purves D, Brannon EM, Cabeza R, LaBar KS, Huettel SA, Platt ML, Woldorff M | title = Principles of Cognitive Neuroscience | publisher = Sinauer | year = 2008 | isbn=978-0-87893-694-6}}</ref>