Pheromones in humans

Pheromones have been defined as substances released by an individual into the external environment which precipitate a particular reaction in a conspecific (Karlson and Liischer 1959). Pheromones are used by species in a variety of phyla (see e.g. McClintock, Jacob, Zelano and Hayreh 2001), and there exist many examples of pheromone-mediated behaviour in a wide range of mammals, particularly in relation to mating behaviour and maturation (see e.g. Vandenbergh 1983). In humans however, the question of whether pheromones influence behaviour was recently listed by Science magazine as one of the top 100 outstanding questions (Anon 2005). A recent review of behavioural and anatomical studies relating to the function of pheromones in human interactions concluded that while a small number were unambiguously supportive , none seemed ultimately conclusive (Hays 2003). 

Pause, B. M. (2004) Are androgen steroids acting as pheromones in humans Physiol. Behav. 83, 21-29. 

There is also evidence for signal pheromones in humans. For example, soon after birth, infants can recognize their mothers by smell alone. The converse is also true mothers can identify their children by smell alone. Finally, newborn babies can recognize the smell of a lactating woman. 

Pheromones play roles such as the time-tested topics menstrual synchrony and mother-infant olfactory communication, as well as the more controversial topics of the role of pheromones in human mate choice and the existence or non-existence of a vomeronasal organ in humans and Old World primates, Especially fascinating is a table published by Wyatt [8] detailing odours associated with various human illnesses (i.e. patients with gout or schizophrenia have differing, distinct odours to their sweat), and another table listing various commercial products, both past and present, that contain pheromones. 

No support for a releaser pheromone in humans (Black Biron, 1982)... 

Found in various plant sources inch cassava, rice, Cannabis sativa. Also found in cider, stale beer and wood ant secretions. Acts as an insect pheromone and may also be a pheromone in humans. Perfumery ingredient. Liq. with sharp, pleasant odour. Bp 190-192°, Bp22 91-92°. Polymerises readily with H2SO4. Oxidised fairly rapidly in air. 

Rodriguez I., Greer C., Mok M. and Mombaerts P. (2000). A putative pheromone receptor gene expressed in human olfactory mucosa. Nature Genet 26, 18-19. 

Claims of commercial manufacturers notwithstanding, it is evident that pheromones do not function as behavioural releasers in humans in the same way as they do in other species. Instead of searching for specific reactions to purported human pheromones, it may be that these chemicals are better described as modulators (Jacob and McClintock 2000) which influence psychological states and, thereby, also influence behaviour in a variety of fashions depending on the situation in which they are experienced, or the accompanying cues. The co-occurrence of different cues can affect their interpretation (Rowe 1999). In humans, we know that odour cues provide non-redundant information about potential mates because, while both visual and olfactory cues may be used to gauge physical attractiveness, the information in each is not equivalent (Roberts, Little, Gosling, Jones, Perrett, Carter and Petrie 2005). 

Male sand flies release this sex pheromone to attract females for mating. The males attractant is more potent when mingled with odors from a host that can furnish a blood meal, so that a male sand fly is a more efficient lure for females when he is on an appropriate host. This host attractant in humans is some component of skin odor, but its chemical nature is still obscure. Experiments with human volunteers have revealed that individuals have widely differing levels of attraction for sand flies and that a single individual s attractiveness fluctuates over time. Male sand flies respond to these host odors just as females do, even though they do not feed on blood. In this way, flies can meet and mate on a host, and the mated female can proceed to take a blood meal at once in preparation for laying her eggs. 

Understandably, there is a lot of general and also commercial interest in research aimed at the identification and evaluation of human pheromones. In as much as humans can motivate their responses to test compounds, it should be simpler to work with humans than with other mammals. However, although much has already been accomplished in this field, pheromone communication in humans, by and large, still remains an enigma. 

Molecular recognition underlies chemical communication, including the phenomena of taste and smell. Pheromones are chemical communicators between individuals, usually members of the same species. Pheromone action has been demonstrated in a number of mammalian species. Several of these affect reproduction. It seems likely that there are human pheromones. The role of these in human behavior is not clear. 

A subset of all odorants is pheromones, about which much more follows later. Basically, pheromones transmit chemical messages among members of the same species. Bombykol is a pheromone for the silkworm moth the scent of lilacs as perceived by a human being is not. Although the question of human pheromones is difficult, that for many mammals is not. The pheromones in mammals are not detected... 

Despite the difficulties, there is substantial additional reason to believe in human pheromones, although their role in shaping our lives is far from clear. The evidence just summarized from the 1971 McClintock study of menstrual synchrony in women provides an example of a primer pheromone at work in humans. Others have replicated McClintock s pioneering study. A 1980 study suggesting that underarm secretions might mediate menstrual synchrony,has been followed up by a more detailed study, also by McClintock, together with her coworker Kathleen Stem. " Here it is. 

It seems likely that there are human pheromones. The role of these in human behavior is not clear. 

Throughout history, mankind has always been interested in naturally occurring compounds from prebiotic, microbial, plants and animals sources. Various extracts of flowers, plants and insects have been used for isolating compounds whose task, color and odor could be used for various purposes. Many natural products, such as plant hormones, have a regulatory role, while others function as chemical defense against pests. The role of certain compounds is to act as chemical messengers, such as sex-attractants (pheromones) in insects, terrestrial and marine animals and humans. What is the origin of natural products ... 

Chemical signals are indispensable for the survival of many organisms which use chemoreceptors to find their way, to hunt for and inspect food, to detect enemies and harmful objects, and to find members of the opposite sex (pheromones). These functions are no longer vitally important for humans. The importance of flavor and fragrance substances in humans has evolved to become quantitatively and qualitatively different from that in other mammals this is because humans depend to a greater extent on acoustic and optical signals for orientation. However, humans have retained the ability to detect odors and human behavior can undoubtedly be affected by fragrances and aromas. 

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