Pheromones: The Smell of Beauty Pheromones: The Smell of Beauty by Yoshihiro Kobayashi Larry R. Fisher, Instructor International English Center University of Colorado December 16, 1997 Outline Thesis: All animals emit pheromones to communicate with each other; even humans seem to have responses to certain chemicals that are produced in human bodies. I. Introduction 1. History 2. Definitions II. Insect pheromones III. Non-human mammal pheromones A. Rodents B. Primates IV. Human pheromones A. Menstrual cycle synchrony B. Infants and mothers C. Effect of pheromone-like substances V. Conclusion For years, humans have used perfumes to cover up natural body odor and to put on attractive pleasant scents. To make attractive-smelling perfumes, humans have tried using animal sex pheromones, such as musk, ambergris, and civet. These pheromones are chemicals that affect such special behaviors as communication, sexual activity, and reproduction in animals and insects with differing chemical structures from species to species. Therefore, pheromones from other species may or may not affect humans in the same way they affect the particular species. Instead of relying on other animal scents to create sexual attraction, humans have become curious about their own olfactory systems managed by a romantic cupid. The importance of pheromones differs from species to species. For insects, pheromones are indispensable for life and for maintaining their societies; consequently, insects have more highly developed chemical communication systems than other species. Moreover, all of non-human species emit and detect
pheromones; however, Cowley and Springen say that the existence of human pheromones is still unclear, but in human sweat there are some chemicals that act like pheromones (67). For the lower mammals, such as rodents, pheromones are still important for communication; however, the more animals develop, the less they rely on pheromones for communication. The reason for this may be that more highly developed animals can communicate with each other by making sounds, or expressing feelings with their faces. For this reason, it seems as if higher mammals have lost or reduced their pheromone-receiving senses, though it is clear that they still have pheromone receptors in their nasal cavities. Even humans have pheromone receptors, but it is not apparent whether they are functional or not. It is important to find out if the receptors work in order to prove the existence of human pheromones. The study of pheromones does not have a long history. The first person who recognized the importance of smell was a French entomologist, Henri Fable (1823-1915). He found that male moths could detect a chemical that is emitted by female moths even if they were surrounded by other strong smells (http://www.microscopy-uk.org.uk/mag/art97/pherom.htm). The first scientific research about pheromones was done in 1959. Monmaney says those researchers collected some samples of chemicals that insects emit in order to communicate, and by the middle of the 1970s interest in human pheromones increased, and Russell showed the existence of those pheromone-like chemicals in his research (54). The word "pheromone" first appeared in the 1950s from the Greek words "pherein" and "hormone," meaning "excitement carrier" (http://www.microscopy-uk.org.uk/mag/art97/pherom.htm). Monmaney defines pheromones as "a substance that is produced by an organism and that elicits a specific and unlearned response in another member of the same species" (54). Therefore, pheromones are used as intraspecific communication mediums by most animals and insects. For insects, pheromones are very important and have many roles. The following are some examples indicating the effects of pheromones. In bee societies, worker bees are all female and cannot reproduce. The reason for this phenomenon, Cowley and Springen say, is that worker bee sexual development is stopped by the queen bee's pheromones (67). An article from a web site shows that in ant societies pheromones are used to alarm, attract, lay trails, groom other ants, help molting, exchange food (between worker ants and feeding larvae), recognize nestmates, control reproduction, and make territorial signals
(http://www.mil.ufl. edu/eel5840/classes/class11/sld012.htm). Furthermore, one well-known fact is that female moths emit pheromones to attract male moths. A certain kind of moth can detect pheromones at the distance of five kilometers by using their antennae. Each antenna has lots of sensory hair, and all of the hair is tuned to the female pheromones (http://www.microscopy-uk.org.uk/mag/art97/pherom.htm). Pheromones for insects are well known, synthesized, and used as behavior controlling chemicals to prevent harvests from being eaten by such insects. By using this method people can control insects to make them gather outside farms. This method is very efficient and harmless to other species and the environment. In contrast to insects, the importance of pheromones decreases dramatically because mammals have more complicated and advanced ways to communicate, such as facial expressions, body gestures, and languages. Every non-human mammal emits pheromones. Non-human mammals have many special glands to secrete special pheromones outside their bodies, in order to mark their scents. They often mark their scents to send territorial signals or in order to attract other opposite sex members in the group. However, in order to detect pheromones, unlike insects, vertebrates do not have antennae, so they have developed another organ in their nasal cavity that is called the "vomeronasal organ (VNO)" (http://www.microscopy-uk.org.uk/mag/art97/pherom.htm). This organ works as a "pheromone receptor," not as a smell detector. The VNO is more sensitive than olfaction; it can detect very small amounts of molecules (http://neuro.fsu.edu/research/vomer.htm). Rodents are considered the lowest mammals with a higher reliance on pheromones than other mammals. According to one web site, in rodents, pheromonal communication among the same groups can cause sensational effects such as reproductive and physiological behaviors. The chemical signals from female mice repress other females' sexual signals. Also the chemical signals from male mice accelerate female puberty. These effects are brought by chemosensory signals from VNO, so removal of VNO prevents responses to these signals (http://neuro.fsu.edu/research/vomer.htm). According to Brown, for rodents, the most important social behaviors, such as "mate selection," reproduction, and "parent-offspring interactions," can be affected by pheromones (245). Monmaney says that, when golden hamsters have their olfaction part of their brains removed, they give up mating completely (48). Epple says that chemical communication in primates, especially apes, is less
known than rodents (739). According to Marler, this is because, compared to other mammalian species, primates have more intricate communication systems, such as "variable calls," postures, and facial expressions (qtd. in Epple 739). Epple says, although visual and vocal signals have been intensively investigated, our knowledge of chemical communication systems among primates is limited (739). However, the evidence for using chemical signals in primates has been collected recently. He pointed out that some species not only sniff and lick, but also ingest excretions and secretions. This observation supports the belief that primates use chemical communication systems in their societies (740). According to Epple, the role of chemical communications in the well-developed primates is less powerful than other groups of monkeys (764). The existence of human pheromones is not apparent; however, some scientists report that some chemicals affect the human body like pheromones. In other animals, pheromones are detected by VNO. Therefore, some scientists conducted research on human VNO and its responses to certain chemicals. The existence of human VNO, in fetuses, has been known for a long time; however, in adults, the existence of the VNO has been reported rarely since the eighteenth century. In the middle of the1980s, the existence of the VNO in human adults was disclosed, although the location of VNO and the system were different from other mammals. Unlike other mammals, human VNO does not have an obvious thick sensory quality; however, there are cells that may be VNO receptor neurons (http://neuro.fsu.edu/research/vomer. htm). Monmaney says that menstrual cycle synchrony may be the strongest case for the existence of human pheromones (54). McClintock was one of the first to report about menstrual cycle synchrony in a college dormitory. So this phenomenon is widely known as the McClintock effect. On the other hand, Monmaney also introduces the opinions of skeptics, that menstrual synchrony is brought about because those women eat, study, wash, talk, and stay up all night together, share stress and joys, and therefore regulate their cycles, but not by chemical messages. Russell shows the same effect by using scientific methods. In his research, he used female underarm sweat and applied its alcohol solution to the upper lips of an experimental group. The underarm sweat was collected from a female whose menstrual cycle had been regular. To compare those females' reactions, he applied only alcohol to the lips of the control group. The result was that the members of experimental group synchronized their menstrual cycles. Russell concludes "this experiment supports the theory that odor is a communicative
element in human menstrual synchrony, and that olfactory control of the hormonal system in humans occurs in a similar fashion to other mammals" (138). The existence of VNO in human fetuses is clear, so the odorous relationship between infants and their mothers was examined. MacFarlane examined whether infants can detect the odors of their mothers' breasts (qtd. in Doty 823). He concluded that an infant could distinguish between the smell of a clean breast pad and a breast pad that had been used by his or her mother (qtd. in Doty 823). Russell also examined infants' responses to their mothers' odors and showed that most infants were obviously attracted to their mothers' scents and often repulsed by strangers' (qtd. in Monmaney 54). Russell concludes, "the existence of olfactory maternal attraction suggests that humans have a pheromonal system and that it operates at a very early age" (qtd. in Monmaney 54). However, Monmaney says in the opinions of critics what Russell called "olfactory maternal attraction" was simply from the memory of their mothers' scents; in other words, "olfactory maternal attraction" is not caused by pheromones but by learning their mothers' scents (54). Pool also says that the existence of human pheromones is not clear, but the human body produces "sex-specific chemicals" (14). Some researchers examined the effect of different pheromone-like substances. Those substances are usually in a group of steroids secreted from glands in the human body. Many researchers chose androstenone, a pig pheromone contained in human male urine and in female urine during a certain period, to examine. Other researchers used a human male hormone androsterone. Recently, one of the researchers examined another substance that is called androstandienone. In addition, some researchers conducted research on the responses of human VNO to certain other pheromone-like chemicals. Furlow says that the human body emits pheromone-like odorous chemicals that start to be produced in puberty. However, human reaction to these odors is not always predictable. Also he writes that the World Smell Survey that was organized by the National Geographic Society in 1986 examined whether people from different cultures perceive odor in the same way. They examined over a million smells, including androsterone. The results were unexpected. Most people from different cultures rated steroids the second to the last in pleasantness. Furlow also referred to Karl Grammer's opinion, one of the members of the Austria Institute for Human Biology. Grammer studied the reaction of females to a pheromone-like chemical. He expected that women would feel pleasant if they were in ovulation stage, when their olfaction would be more sensitive. However, the result was not in the manner he expected. Women were not attracted to the substance, but reported indifference. Human sex-attractant pheromones might be
expected to have pleasant smell, but this result shows that pheromone-like substances in the human body do not lead to pleasantness. The notion that pleasant smells lead to sexual attraction may be inaccurate, potentially causing stress in the perfume industry. Research on the VNO by Jennings-White also examined what responses pheromone-like substances produced in the VNO. According to his research, the most active pheromone-like chemicals for humans are estratetraenol and androstandienone. In his research, he also examined the effectiveness of commercial perfumes that contain pheromone-like substances by using scientific measuring methods. In addition, he found that these pheromone-like chemicals are gender-specific, i.e., females are sensitive to androstandienone, and males are sensitive to estratetraenol. Furthermore, he says that these substances are also species-specific, so androstenone, the pig pheromone, does not give remarkable activity for humans (http://www.erox.com/sixth sense/storyone.html). Many scientists are currently doing research on human pheromones, but most of the research is on pheromones as attractants between the sexes, not on the other possible effects of pheromones. Probably, the existence of human pheromones and the performance of human VNO will be definitively proven in the future. However, in the case of sex-attractant pheromones, the effect of those substances seems to be less than expected because human kinds have more developed visual senses of beauty than other species. In other words, beauty as seen through the eyes is more attractive than beauty perceived through the nose. If this hypothesis were incorrect and human VNO performed effectively, sex-attractant human pheromones would be used in not only the perfume industry but also other kinds of industries to make consumers purchase their products. If the existence of sex-attractant human pheromones were proven, interests in other kinds of human pheromones, such as alerting and reproduction-repression, would increase. Probably, the human reproduction-repressive pheromones would be used as a most efficient and harmless contraception method. Then humans could enjoy romantic times more sensually than ever without worrying about the consequences. Bruce, Anne. Chemicals that cause excitement. http://www.microscopy-uk.org.uk/mag/art97/pherom.htm. Comfort, A. "Liklihood of Human Pheromones." {Nature} 230 (1971): 432-33. Cowley, Geoffrey, and Karen Springen. "Is There a Sixth Sense?"
{Newsweek} Oct. 1997: 67. Elements Of Machine Intelligence Pheromones & Behavior. http://www.mil.ufl.edu/eel5840/classes/class11/sld912.htm. Epple, Gisela. "The Primates I: Order Anthropoidea." {Social Odours in Mammals Volume 2}. Ed. Richard E. Brown and David W. Macdonald. Oxford: Clarendon Press, 1985. 739-69. Furlow, F. Bryant. "The Smell of Love." {Psychology Today} Mar. 1996: 13. Jennings-White, Clive. Perfumery and the Sixth Sense. http://www.erox.com/sixthsense/storyone.html. Monmaney, Terence. "Are We Led by the Nose?" {Discover} September (1987): 48-54. Pool, Hannah. "Sixth Sense." {The Guardian} 7 Oct. 1997: 14. Russell, Michael J., Genevieve M. Switz, and Kate Thompson. "Olfactory Influences on the Human Menstrual Cycle." {Pharmacology Biochemistry & Behavior} 13 (1980): 737-38. The Vomeronasal Organ. http://neuro.fsu.edu/research/vomer.htm.