Pheromone
A pheromone (from Ancient Greek φέρω (phérō) 'to bear' and hormone) is a secreted or excreted chemical factor that triggers a social response in members of the same species.
[3] The portmanteau word "pheromone" was coined by Peter Karlson and Martin Lüscher in 1959, based on the Greek φέρω phérō ('I carry') and ὁρμων hórmōn ('stimulating').
They were researched earlier by various scientists, including Jean-Henri Fabre, Joseph A. Lintner, Adolf Butenandt, and ethologist Karl von Frisch who called them various names, such as "alarm substances".
[6] Aggregation pheromones function in mate choice, overcoming host resistance by mass attack, and defense against predators.
[7] Aggregation pheromones have been found in members of the Coleoptera, Collembola,[8] Diptera, Hemiptera, Dictyoptera, and Orthoptera.
Alarmed pronghorn, Antilocapra americana flair their white rump hair and exposes two highly odoriferous glands that releases a compound described having the odor "reminiscent of buttered popcorn".
In social seabirds, the preen gland is used to mark nests, nuptial gifts, and territory boundaries with behavior formerly described as 'displacement activity'.
[21] As long as the food source remains available, visiting ants will continuously renew the pheromone trail.
[26] These species include the yeast Saccharomyces cerevisiae, the filamentous fungi Neurospora crassa and Mucor mucedo, the water mold Achlya ambisexualis, the aquatic fungus Allomyces macrogynus, the slime mold Dictyostelium discoideum, the ciliate protozoan Blepharisma japonicum and the multicellular green algae Volvox carteri.
[27] Many well-studied insect species, such as the ant Leptothorax acervorum, the moths Helicoverpa zea and Agrotis ipsilon, the bee Xylocopa sonorina, the frog Pseudophryne bibronii, and the butterfly Edith's checkerspot release sex pheromones to attract a mate, and some lepidopterans (moths and butterflies) can detect a potential mate from as far away as 10 km (6.2 mi).
In addition, Colias eurytheme butterflies release pheromones, an olfactory cue important for mate selection.
[31] In mealworm beetles, Tenebrio molitor, the female preference of pheromones is dependent on the nutritional condition of the males.
[33] With regard to the Bombus hyperboreus species, males, otherwise known as drones, patrol circuits of scent marks (pheromones) to find queens.
[39] In humans and other animals, TAARs in the olfactory epithelium function as olfactory receptors that detect volatile amine odorants, including certain pheromones;[39][40] these TAARs putatively function as a class of pheromone receptors involved in the olfactive detection of social cues.
[39][40] A review of studies involving non-human animals indicated that TAARs in the olfactory epithelium can mediate attractive or aversive behavioral responses to a receptor agonist.
[42] While the VNO is present in most amphibia, reptiles, and non-primate mammals,[43] it is absent in birds, adult catarrhine monkeys (downward facing nostrils, as opposed to sideways), and apes.
[44] An active role for the human VNO in the detection of pheromones is disputed; while it is clearly present in the fetus it appears to be atrophied, shrunk or completely absent in adults.
[citation needed] It has been suggested that it serves survival by generating appropriate behavioral responses to the signals of threat, sex and dominance status among members of the same species.
[46] Some authors assume that approach-avoidance reactions in animals, elicited by chemical cues, form the phylogenetic basis for the experience of emotions in humans.
While humans are highly dependent upon visual cues, when in close proximity smells also play a role in sociosexual behaviors.
[52] Though various researchers have investigated the possibility of their existence, no pheromonal substance has ever been demonstrated to directly influence human behavior in a peer reviewed study.
[57] Several axillary steroids have been described as possible human pheromones: androstadienol, androstadienone, androstenol, androstenone, and androsterone.
Research in this field has suffered from small sample sizes, publication bias, false positives, and poor methodology.
Milinski and colleagues found that the artificial odors that people chose are determined in part by their major histocompatibility complexes (MHC) combination.
[71] 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.
[52] Claus Wedekind and colleagues found that both men and women prefer the axillary odors of people whose MHC is different from their own.
Despite these claims, no pheromonal substance has ever been demonstrated to directly influence human behavior in a peer reviewed study.
