Ravi K. Puri
                  

 “Our sexual behavior comes dangerously close to that of animals and it is therefore necessary to make it taboo in order to keep the essential distinction that separates us from them.”                    Bernard Acard

Pheromones in animals and insects have been known for a long time. These are the primary communication system for animals used to sense danger, food and mating. In fact animals rely on pheromones for their survival.

Human pheromones may be defined as natural chemicals produced by an individual and transferred by air that affects the sexual physiology of another individual. They are believed to send out subconscious scent signals to the opposite sex that trigger very powerful responses.

The word pheromone is derived from the Greek word "pherein"- to carry, and "hormon"- to excite. Karlson and Luscher (1959) coined the term pheromone for the first time. Pheromones are called ectohormones, meaning chemical messengers that are transported outside the body and have the capability to trigger responses like physiological and behavior changes. Human pheromone detection has also been proposed to be the reason of instant attraction or dislike when first meeting someone.

Currently, human pheromones remained ambiguous bioactive compounds, as only a few have been identified. Standard bioassays have suggested that they are nonvolatile, activate vomeronasal sensory neurons and regulate innate social behavior and neuroendocrine release. Recent discoveries of potential pheromones reveal that they may be more structurally and functionally diverse than previously defined (Stowers and Morton 2005).

There are overwhelming advertisements on the Internet, newspapers, magazines and TV shows that claim the effectiveness of human pheromones as sexual attractants and aphrodisiacs. According to these advertisers, concept of seduction in a bottle is no longer a myth rather becoming a reality these days. Love at first sight is well-known. However, love at first smell is also being recognized. Seduction, sexual attraction, lust, sexual drive lovemaking and falling in love are being attributed to human pheromones.

Advertisers claim that human pheromones make a person irresistible to the opposite sex. When added to a favorite perfume they are believed to enhance pheromone power into ones romantic life. Do they really work? Can these costly sex drops in a tiny bottle find the person of our choice and stimulate the sex desire or it is all in the head.

Present paper purports to review the latest research conducted on human pheromones and would throw some light on their merits and demerits.

Human sex pheromones have been well advertised. There are lots of pheromone websites on the Internet that make wild claims about their products. Exotic advertisements with emphatic claims about their products can lure any person with low libido to buy these products. Some commercially available human pheromones are being advertised using claims that these products contain sexual pheromones and can act as aphrodisiacs. Nevertheless, newspapers and magazine add fuel to the fire with emphatic news and articles about human pheromones. From time to time, there have been stories about human pheromones on 20/20, Dateline ABC, and television programs. Newspapers, medical journals, and many popular magazines have featured stories about the astonishing discovery of human pheromones as follow-

"Pheromones can improve one's sex life, pheromones send out subconscious signals to the opposite sex that naturally trigger romantic feelings." (Willis, 2002)

"Scientific studies have actually shown that subjects who used synthesized pheromones had sex more often." (Knowlton,1994)

"The power of smell is undeniable humans are influenced by airborne chemicals undetectable as odors, called pheromones. Researchers at the University of Chicago say they have the first proof that humans produce and react to pheromones.” (Rowland, 1998)

“Secret perfume ingredients that may boost your love life.” (Utton, 2002)

In spite of all these news and propaganda, human pheromones often lack faith due to marketing by unsolicited e-mail and lack of consistent scientific data. Contradictory scientific reports cause doubts about their efficacy.

There are some people out there who want to know if human pheromones really work - and if so, which pheromone products are the best on the market. Do they really act as aphrodisiacs? To know the reality about human pheromones, it is very pertinent to understand the definition, occurrence, function, chemistry, and mechanism of their action (detection) as sex attractants or stimulants.

Occurrence:
The apocrine (sweat) glands of human secrete pheromones. They carry characteristic odor. Freshly produced apocrine secretion has no odor. The microbial conversion causes the odor (Zeng et al. 1992).

They are chemically similar to hormone dehydroepiandrosterone and are secreted by endocrine glands, apocrine glands occur in the armpits, face, nipples, and anal and genital regions of both sexes. The apocrine glands become functional after reaching puberty, which some believe, could contribute to people developing a sexual attraction for others at that time (Cohn 1994).

Cutler et al. (1986) conducted the first controlled scientific studies to reveal the existence of pheromones in humans. Prior to their landmark research there were no conclusive indications that humans excreted pheromones. A few well-controlled scientific studies have been published demonstrating the possibility of pheromones in humans. The best-studied case involves the synchronization of menstrual cycles among women based on unconscious odor cues, the so called McClintock effect, named after the first investigator (McClintock 1971). In the later stages, a similar synchrony was observed between mothers and daughters living in the same house. They also have the menses at the same time. Study by Stern and Mclintock (1998) states that human female axillae release two types of pheromones. One, produced prior to ovulation, shortens the ovarian cycle, and the second, produced just at ovulation, and lengthens the ovarian cycle.

Pheromone production starts to decline with the level of declining of sex hormones. That means the production is inversely proportional to age. This links between apocrine gland function and puberty reflects that function is closely related to level of sex steroid hormones in human.  

Function
It is assumed that human pheromones when inhaled may cause sexual attraction, relaxation, excitement, euphoria and regulation of menses. Pheromones may affect women and men differently. Every man and woman produces pheromones. Every person has an odor print as unique as his or her fingerprint. Odorprints depend upon diet, gender, heredity, health, medication, occupation and mood. Human pheromones can be used in menstrual regulation. It can be used in marriage therapy to improve interpersonal relationship. Its use can protect people from the sex offenders and rapist using a characteristic odor that may dispel the offenders.

Detection
Human pheromones are detected by vomeronasal organ (VNO) unlike fragrances, which are detected by the olfactory glands in the nose and are a special part of the olfactory system. The VNO is located in the nasal pit directly under the nose. When the VNO receives a pheromone signal, it sends a message to the brain going to hypothalamus, which is the center in the brain that control one’s basic drives and emotions. The signal stimulates the body and creates a subconscious increase in sexual desire in opposite sex; women get attracted to men and men to women (Monti-Bloch et al. 1991; 1994). However, so far there is no concrete evidence that the human VNO is connected to a functional accessory olfactory system. This has caused significant controversy among the scientists, even about the presence of pheromones in human (Martinez-Macros 2001; Regelson 2002).

Berliner et al. (1996) tried to prove that humans have a functional VNO. They measured electrical activity in VNO tissue in response to chemical stimulation, which may indicate that the cells are transmitting signals. However, cells that generate electrical activity are not necessarily transmitting signals to the brain, says Wysocki, neuroscientist at the Monell Chemical Senses Center, Philadelphia. There must be chemical communication among humans. Infants respond to breast pads worn by their mothers but not those worn by other women and a mother can identify the T-shirt worn by her infant from a pile of T-shirts. “We know its chemical, but is the information being transferred pheromonal” asks Wysocki. “No one knows.” Other researchers found Berliner et al. result intriguing, but not conclusive. “Clearly there’s something present in humans but it is quite different than in animals,” says Meredith, Professor, Department of Neurobiology at Florida State University, Tallahassee, Florida (Ettienne 2002; Wyoscki and Preti 2000)

Monti-Bloch et al. (1994) purified several potential pheromones found in sweat and other human secretions. One secretion—purified from the skin of men—seems to affect mood in women. In one study, Monti-Bloch applied either the secretion or a placebo directly to the VNO of 40 women. The women exposed to the secretion displayed a statistically significant decrease in negative affect. Although VNO is often regarded as only pheromones detector, evidence is emerging that suggests it might respond to a much broader variety of chemosignals (Brennan and Keverne 2004).

Chemistry
As discussed above, human pheromones are largely produced by the skin's apocrine sebaceous glands, which develop during puberty. They are usually associated with sweat glands, other glandular secretion and to skin flora present in moist area of the body. The substances produced by these glands are imperceptible by the human nose; because these are not the fresh glandular secretions of the skin but rather the bacterial breakdown products of these glandular secretions. The sebaceous secretions themselves comprise mostly of lipids such as squalene and other esters. After degradation by bacteria present on human skin it give rise to free fatty acids including hircine which is very unpleasant. The most prominent examples of these hircine fatty acids are butyric acid, caproic acid and caprylic acid. Chemically, the active constituents of human pheromones are similar to DHEA (dehydroepiandrosterone).

The most commonly known are: • Androstenone (5 alpha-androst-16-en-4-one) • Androstenol (3 alpha- androst-16-en-3-ol) • Androsterone (3 alpha hydroxy-5 alpha-androstan-17-one) • Androstadienone (delta 4,16-androstadien-3-one) • Androstadienol (delta 4,16-androstadien-3-ol) • Copulins (C2-C5 aliphatic acids) • Estratetraenol (estra-1,3,5(10), 16-tetraen-3-ol) Androstenone, androstenol, androsterone, androstadienone, and estratetraenol are shown in Figure 1.

These have been identified as the male pheromone that increases the luteinizing hormone (LH) in women. Presence of testosterone and estrogens has also been shown in the pheromone secretions. Estratetraenol (Fig. 1) is supposedly the female equivalent to androstadienone. It stimulates the VNO and act as mood elevator.

Female pheromones are known as Copulins. Copulins do behave like pheromones but chemically dissimilar to any other compound that is considered as pheromone. These are found in human vaginal secretion and are secreted into the vagina during ovulation. Copulins believed to increase male testosterone levels that directly linked to increased sexual drive. Chemically copulins are volatile C2-C5 aliphatic acids (Michael et al. 1974). Huggins and Preti (1976) studied the chemical Composition of copulins in 12 patients for 44 ovulatory cycles by means of gas chromatography tandem with mass spectroscopy to identify organic volatile components. These vaginal secretions contain mixture of aliphatic acids, alcohol, hydroxy ketones and aromatic compounds. Some manufacturers use oil base for human pheromones and claim that drop of alcohol can completely destroy pheromones (Pheromonesheromones.com), whereas the others recommend the use of alcohol as base. They believe that alcohol keep the solution sterile and increases shelf life. It kills bacteria on the skin where the pheromones are applied. Skin bacteria are capable of breaking down pheromones fairly quickly, which destroys their effectiveness (pherone.com). The company further states that alcohol do not change the chemical nature of synthetic pheromones. However, there is no evidence or supportive studies in both the cases. Mostly human pheromones are steroids in chemical nature and are soluble in organic solvents. These compounds are lipohilic and like nonpolar solvents. Some of the manufacturers are selling pheromones in the form of shave lotion or cologne with additive perfumes. Some believed that deodorants and antiperspirants often destroy the natural human pheromones that humans do produce.

Classification of Human Pheromones
During the past twenty-five years, there has been significant increase in the number of studies conducted on human pheromones.

The scientific literature recognizes four classes of human pheromones:

a. Olfactory recognition (Mother-infant recognizer)

b. Primer (Menstrual synchrony)

c. Modulators (Human sex-attractant pheromones)

d. Releaser (Behavioral effect)

Recognizer pheromones provide information such as mother- infant recognizer. Infant can smell her own mother’s pheromones through the air. Mother can also recognize the shirt of her infant from a pile of shirts. Pheromones that affect endocrine glands are primers. These can influence long term changes in hormones levels such as menstrual cycles, puberty and pregnancy. Pheromones that modify emotions or moods are known as modulator such as sex attractants. These pheromones elevate the mood and alleviate stress.

Finally those that effect behavioral releaser responses are known as releaser. However, according to Wysocki and Preti (2004) there is no good evidence for releaser effects in adult humans. They further emphasized that no bioassay-guided study has lead to the isolation of true human pheromones, a step that will elucidate specific functions to chemical signals.

Role of Human Pheromones

a. Regulating menstrual cycle:
Grammer and Jutte (1997) suggested that male pheromones androstenol/ androstenonone from male sweat have a direct impact on female menstrual cycle and ovulation.

Cutler et al. (1999) showed that Pheromones in men's bodies can cause their female sex partners to be more fertile, have more regular menstrual cycles and milder menopause. Women who have sex with men at least once a week are benefited the most from these chemicals. They have regular menstrual cycles and fewer fertility and menopause problems, apparently because of exposure to pheromones. Cutler’s studies show that women are affected by pheromones from men. Women with unusually long or short menstrual cycles get closer-to-average cycles after regularly inhaling male essence, described as a compound of male sweat, hormones and natural body odors.

b. Synchronizing menstrual cycle:
 Preti et al. (1986) confirmed a long-observed phenomenon (Mclintock 1971) that women exposed to another woman's "female essence" menstruated at the same time after a few months that women who live together menstruate at the same time. However, according to Trevathan et al. (1993) this synchronization was not observed among lesbian couples. Morofushi et al. (2000) found that women whose menstrual cycles synchronized with roommates had higher olfactory activity for androstenol.

c. Increase sex attraction:
Scientific studies have actually shown that people who used synthesized human pheromone had sex more often. Researchers at the University of Chicago said, “The power of scent is undeniable, humans are influenced by airborne chemicals undetectable as odors, called pheromones” (Gorner 2000).

Human pheromones also act as sexual attractants. The secretion of pheromones by humans is believed to significantly increase the desirability and sexual attractiveness in both male and female have been suggested by Thorne et al. (2002) and Grammer et al. (2005).

Willis (2002) reported that scientists at San Francisco State University found that women who had pheromone added to their perfume reported a more than 50% increase in sexual attention from men. The study, which was conducted by McCoy and Pitino (2002), found that 74% of the women saw an overall increase in 3 or more of the following socio-sexual behaviors: frequency of dates, kissing, heavy petting and affection, sexual intercourse, and sleeping closer to their partner.

Copeland and Link (2001) published the findings of an Australian organization, Bennett Research, which conducted a survey of 306 men using human pheromones. Their findings showed that use of pheromones had increased attractiveness to women. They reported an increase in various socio-sexual behaviors, as follows: Making conversation - 61%; starting up a conversation - 52%; expressing an interest in the man - 43%; being responsive to him - 40%; paying unsolicited compliments - 36%; and overt flirting - 34%.

Sobel and Brown (2001) reported that men and women's brains respond to two putative pheromones-related to testosterone and estrogen, when men smelled a compound similar to estrogen, increased blood flow to the hypothalamus was documented. In turn, female participants experienced increased blood flow to the hypothalamus when exposed to the testosterone-like compound. These researchers found that the testosterone-like compound existed in men's sweat at levels 20 times that of women's. They monitored the results using sophisticated brain imaging techniques.

d. Human pheromones and other related attractions:
Men are strongly attracted to women with large breast, thinner waist and broad hips has been attributed to female pheromones (Kohl 2002). Likewise, women prefer tall and handsome man. Their selection is linked to an increase in male pheromone production (Kohl 2002).

Countless similar studies have since been conducted and the results have always been stunning. Pheromones appear to have the ability to dramatically increase sexual attraction between men and women. No doubt these studies have ignited hopes in people who are assiduously buying them.

e. Send specific signals to potential mates:
Human pheromones may play a big role in selecting a mate according to a new study conducted by researchers at the Monell Chemical Senses Center, Philadelphia. They found that your preference for another person's body odor is influenced by the gender and sexual orientation of that person as well as your own gender and sexual orientation. (Martins et al. 2005)

"Our findings support the contention that gender preference has a biological component that is reflected in both the production of different body odors and in the perception of and response to body odors," says Charles Wysocki, neuroscientist at the Monell Chemical Senses Center.

f. Regulate ovulation time:
Stern and McClintock (1998) found that odorless compounds from the armpits of women in the late follicular phase of their menstrual cycles accelerated the preovulatory surge of luteinizing hormone of recipient women and shortened their menstrual cycles. Axillary (underarm) compounds from the same donors that were collected later in the menstrual cycle (at ovulation) had the opposite effect: they delayed the luteinizing-hormone surge of the recipients and lengthened their menstrual cycles. By showing in a fully controlled experiment that the timing of ovulation can be manipulated, this study provides definitive evidence of human pheromones.

Preti et al. (2003) studied the effect of male axillary extracts containing pheromones. Human under arm secretion when applied to women recipient, it altered the length and timing of menstrual cycle, reduced tension and increased relaxation. These results demonstrate that male axillary secretions contain one or more pheromones that can act as primer (endocrine affect) and modulator pheromones.

It is now evident that human pheromones, a type of social chemosignal, modulate endocrine function by regulating the timing of ovulation. In animals, pheromones not only regulate ovulation but also female reproductive motivation and behavior. There is no extant evidence that humans produce social chemosignals that affect human sexual motivation or reproductive behavior as occurs in other mammals. 

Spencer et al. (2004) demonstrated that natural compounds collected from lactating women and their breastfeeding infants increased the sexual motivation of other women, measured as sexual desire and fantasies. Moreover, the manifestation of increased sexual motivation was different in women with a regular sexual partner. Those with a partner experienced enhanced sexual desire, whereas those without one had more sexual fantasies. These results are consistent with previous pheromonal effects on endocrine function, and require further study of these social chemosignals as candidates for pheromonal processes.

g. In postmenopausal women:
In the past twenty years hundreds of peer-reviewed studies have provided significant information to guide women during and after their menopause phase. One of the guideline is hormonal replacement therapy. It is a successful treatment in majority of the cases. However, hormonal replacement therapy does not work for everybody.

Some other regimens for menopause have the potential to produce disease, especially over-the-counter remedies like dehydroepiandrosterone and the formulas that contain estrogen. All sex hormones influence physiologic systems including the cardiovascular system, bones metabolism, cognitive function, sexual response, and sexual attractiveness. Menopause is an extremely complex phase. During this period, some women increase their estrogen levels to new lifetime highs; others start an unequivocal decline, and still others vary from month to month. In addition to estrogen, changes in progesterone and androgen secretion by the ovary also occur. Many women show increases in circulating androgens while many others show deficiencies. Both the adrenal and the ovarian sources of these hormones show age-related changes that alter a woman's capacity to attract sexual attention through both her physical appearance and her pheromonal excretions. Menopause phase differs from woman to woman. The phenomena is complex and very complicated and most of the time difficult to understand. In most of the cases, hysterectomy is suggested. There is no guarantee that hysterectomy works. Estrogen, progesterone, and androgens all tend to be compromised by hysterectomy; all should be considered for replacement. Hormonal regimens can be prescribed to enhance the quality of life; the review of the available research on pheromones can allow the medical art to greatly benefit mature women. Avoidance of hysterectomy helps prevent its side effects such as sexual deficiencies, acceleration of cardiovascular disease and more rapid aging. Cutler and Genovese-Stone (1998) concluded that human hormones if prescribed appropriately, best serve the menopause patient. They suggested that regular exposure to human pheromones from both sexes can provide health benefits that include better endocrine secretion, healthy estrogens level and a reduced risk of developing osteoporosis and heart diseases.

Cutler and Genovese-Stone (2002) further reviewed pheromones, and their effects, with a special emphasis on their potential contribution to sexual attractiveness in the menopause. Key topics included were biological functions of pheromones in humans and the source of pheromones in humans. The axillary extract studies that led to the independent synthesis of pheromones, olfactory mechanisms for mediating pheromones, aging, attractiveness and sexual dysfunction. Physical attractiveness is important for a better quality of life. Three separate, double-blind, placebo-controlled investigations, using the same protocol, demonstrated that a synthesized human pheromone, topically applied, increased sexual attractiveness. If partners are available, sexual attractiveness can increase affectionate intimate behavior, which, in turn, increases well-being and quality of life. However, more research is needed to address ways in which postmenopausal women can benefit from these pheromones.

h. In Socio-sexual behavior:
Friebely and Rako (2004) studied the pheromonal influences on socio behavior in postmenopausal women to determine whether a putative human sex-attractant pheromone increases specific sociosexual behaviors of postmenopausal women. They tested a chemically synthesized formula derived from research with underarm secretions from heterosexually active, fertile women that was recently tested on young women. Participants (n=44, mean age 57) were postmenopausal women who volunteered for a double-blind placebo-controlled study designed, to test an odorless pheromone, added to their preferred fragrance, to learn if it might increase the romance in their life. During the experimental 6-week period, a significantly greater proportion of participants using the pheromone formula (40.9%) than placebo (13.6%) recorded an increase over their own weekly average baseline frequency of petting, kissing, and affection. More pheromone (68.26%) than placebo (40.9%) users experienced an increase in at least one of the four intimate sociosexual behaviors. These results suggest that the human pheromone formulation worn with perfume for a period of 6 weeks have sex-attractant effects for postmenopausal women.

To find the influences of human pheromones on sociosexual behavior in young women a double blind, placebo-controlled study of a synthesized putative female pheromone was conducted by McCoy and Pitino (2002) with regularly menstruating, university women (N=36, mean age=27.8). The pheromone formula was derived from their earlier work investigating the underarm secretions of fertile, sexually active, heterosexual women. A vial of either synthesized human pheromone or placebo was selected blindly and added to a subject's perfume. Subjects recorded seven sociosexual behaviors and reported them weekly across three menstrual cycles. Beginning with day 8 of each cycle, the first cycle contained a 2-week baseline period followed by an experimental period of as many as 3 weeks each from the next two cycles for a maximum of 6 weeks. The 19 pheromone and 17 placebo subjects did not differ significantly in age, weight, body mass index, dating status or ethnicity or in reported accuracy, back-filling data, and perception of a positive effect or perfume use. Placebo subjects were significantly taller than pheromone subjects. Except for male approaches, subjects did not differ significantly at baseline in average weekly sociosexual behaviors. A significantly greater proportion of pheromone users compared with placebo users increased over baseline in frequency of sexual intercourse, sleeping next to a partner, formal dates and petting/affection/kissing but not in frequency of male approaches, informal dates or masturbation. Three or more sociosexual behaviors increased over baseline for 74% of pheromone users compared with 23% of placebo users. They conclude that this synthesized human pheromone formula acted as a sex attractant pheromone and increased the sexual attractiveness of women to men.

Cutler et al. (1998) also studied the influence of human pheromones on sociosexual behavior in men. This study tested whether synthesized human male pheromones increase the sociosexual behavior of men. Thirty-eight heterosexual men, ages 26-42, completed a 2-week baseline period and 6-week placebo-controlled, double-blind trial testing a pheromone "designed to improve the romance in their lives." Each subject kept daily behavioral records for 6 sociosexual behaviors: petting/affection/kissing, formal dates, informal dates, sleeping next to a romantic partner, sexual intercourse, and self-stimulation to ejaculation (masturbation). Significantly more pheromone than placebo users increased above baseline in sexual intercourse and sleeping with a romantic partner. There was a tendency for more pheromone than placebo users to increase above baseline in petting/affection/kissing, and informal dates, but not in self-stimulation to ejaculation or in formal dates. A significantly larger proportion of pheromone than placebo users increased in sociosexual behaviors involving a female partner. Thus, there was a significant increase in male sociosexual behaviors in which a woman's sexual interest and cooperation plays a role. These initial data need replication but suggest that human male pheromones affected the sexual attractiveness of men to women.

i. In homo and heterosexuality:
Using a brain imaging technique, Swedish researchers at the Karolinska institute in Stockholm, Sweden, have shown that homosexual and heterosexual men respond differently to two odors that may be involved in sexual arousal, and that the gay men respond in the same way as women. Lesbian women and heterosexual women respond differently to the scent of human pheromones. This research suggests a possible role for human pheromones in the biological basis of sexual orientation. That means heterosexuality and homosexuality is determined by one’s preference for a specific odor or pheromones that of a man or woman (Berglund et al. 2006; Hitti 2006; Kohl 2006; Martins et al. 2005).

 Most Commonly Known Human Pheromones
A number of human pheromones have been isolated and studied. Some of them have been found effective for attracting members of the opposite sex. These are androstenone, androstenol, androsterone, androstadienone and copulins.

Androstenone appears to be the essence of male aggression and dominance. Women are attracted to men who naturally secret large quantity of these pheromones. However, it has been shown that female find the odor of andrstenol to be attractive or the perception of this odor of androstenol results in stimulating female sexual arousal while androstenone induce negative emotions particularly when they are menstruating or close to that period. (McCollough, et al.1981). Commonly available preparations containing androstenone are Scent of Eros (Men’s Version), Perception, Alter Ego (Men’s and women’s versions), and Perfect 10.

 Androstenol is produced from the start of puberty until the early twenties, after that it starts declining. Androstenol has been considered to alter people’s impressions of a man attractiveness, intelligence and confidence. Cowley and Brooksbank (1991) reported in their findings that females exposed to androstenol engage in sex more, longer duration and deeper interaction with men. Androstenol is known as the friendly pheromone. It tends to make the person nice and friendly. On the other Shinohora et al (2000) reported that androstenol retarded the growth and maturation of ovarian follicles and consequently delayed the timing of ovulation. Preparation containing androstenol are Scent of Eros (Men’s version), Alter Ego (Men’s and women’s versions), Perception, Perfect 10 (Men and Women’s versions), Chikara, Passion Pheromone Attractan (Women’s version).

Androsterone is known as mood elevator. It is assumed that men with large ratio of androsterone are more masculine and dominant. When women wear this pheromone, it elevates their mood.

Preparation contain androsterone are Scent of Eros, Alter Ego, Perfect 10 and Perception.

Androstadienone is a very popular pheromone that has a very specific effect on the brain activity of women. It is considered to affect attention and social cognition areas of the brain. It can elevates a woman’s mood and even alleviate PMS (Premenstrual Symptoms) stress. It has been known to increase intimacy and caring feelings of women and thus is known as “Love Pheromone.” Preparation comprising androstadienone are Pheromax (Men’s version), and Realm (women’s version). Grosser et al. (2000) observed that administration of androstadienone results in a significant reduction of nervousness, tension and other negative feelings in women. Bensafi et al. (2004) reported that sniffing androstadienone elevates the mood and autonomic arousal in women. Wyart et al. (2007) revealed that smelling androstadienone found in the sweat of man increase the cortisol level in women. Villemure and Bushnell (2007) studied the effects of the steroid androstadienone on the mood and pain perception of men and women. They found that it diminished pain and elevated the mood of men and women.

Today there are many companies that are selling different kind of pheromone products. These products contain one or all of the human pheromones such as androsterone, andrstenol, androstenone and copulins. Copulins are found in the products designed to lure men.

 Copulins
Copulins are found exclusively in human vaginal secretions as discussed earlier (Waltman et al. 1973, Michael et al.1974, 1975). It is assumed that once a man smells copulins on a woman she is deemed to be more attractive. Secretions, quality and quantity of copulins vary with menstrual cycle phase of an individual. The odor of copulins and its behavioral effect also vary with the menstrual cycle. Sokolov et al. (1976) isolated short chain fatty acids from the fractionation of human vaginal secretion by chromatographic techniques and confirmed that there is a possible correlation of the rise and fall of hormone level during the female menstrual cycle. These acids were found predominant at midcycle and during the luteal phase (Huggins and Preti 1976). Female pheromones copulins, influence male perception of females and induce hormonal changes in male (Grammer and Jutte 1997). The preparation comprising copulins are being sold as female pheromones to lure males. Most common pheromone products that contain copulins are as follow:

• Essence of Woman (EW)
• Primal Instict (PI)
• Passion Copulins Concentrate (PCC)
• Passion Pheromone Attractant (PPA)
• Perfect 10 (P10- Women’s version)
• Scent of Eros (SOE- Women’s version)
• Pheromax (PMAX- women’s version)
• Realm (contains Estratetraenol- Men’s version)

Toxicity of Pheromones
Adverse reaction: Higher concentration may cause aversive effect. Contraindication: none so far
Side effects: none known
Toxic effects: These could cause skin reaction or can be allergic to hypersensitive person. An overdose may lead to headaches, impression of weakness.
Shelf life: Not very well studied. However shelf life depends upon the purity, concentration and conditions of storage of the finished products. If the product is devoid of microflora, it may last longer as compared with that of the microflora.

Products on the Market
There are three kinds of pheromone products in the Market:

A. Pheromone colognes.
B. Pheromone sprays
C. Pheromone releaser

Products are sold in various forms as concentrates pheromones or diluted in some base or sometimes these products have perfume additives. However, these perfume additives do not enhance their action as revealed by Winman (2004). These products are called pheromones perfumes.

There are number of manufacturers who produced pheromones products and pheromones perfumes. Search of any engine on the Internet will give you lots of information about these preparations. Each manufacturer claims the inclusion of human pheromones in his products. The first is Realm Corporation formerly known as Erox Corporation claims that their products are designed to enhance sexual attraction, confidence and feeling of well being in both the sexes. They promote pheromones perfumes such as Realm Perfume, Pherose and Realm Cologne for male and females. Similarly Estee Lauder (NY) a famous perfume manufacturers is also launching pheromone perfumes. Likewise, Athena Institute of Chester Springs, Pennsylvania founded by Dr Winnifred Cutler, co discoverer of pheromones in human has also produced products like Athena pheromone 10X for men and Athena pheromone 10-13 for women. These products are in the form of shave lotion or cologne or cosmetics and supposed to enhance sex appeal and romance in life. Another company, Health Freedom Nutrition, Santa Rosa, California has produced a pheromone containing product for men and women known as Eroscent. Erosscent is placed on the upper lip so that it directly affects the VNO (Vomeronasal organ). The same product works for both the sexes. It contains the pheromone derived from dehydroe-piandrosterone (DHEA). They claim that just one drop of Eroscent applied to the upper lip of either sex imparts mood improvement, social relaxation, improves ones self-image, self-esteem, feel sexually confident and attract the opposite sex. Another company known as Pherone, Wilson, North Carolina sells pheromone products such as Pherone formula M-11, Pherone formula M-15, and Pherone formula W-1 for men and women. The company claims that their preparations are very effective to enhance sexual interactions, attractions and create a light euphoria.

Pheromone preparations are very expensive and range from $50 to $110 for a small quantity (10ml). It is very difficult to find the right product that suits to an individual chemistry. There are thousands of brands and formulations of pheromones available on the market in the USA with different concentrations and ingredients. Only a few meet high standards in quality, research and product knowledge (Regelson 2002).
 
Conclusion:
 During recent years, there have been lots of speculations on human pheromones. They are considered as sex attractants, mood elevators, and aphrodisiacs. The fundamental question arises in mind. Are pheromones in humans a myth or reality? At this point, it is very difficult to answer this question. It can be myth as well as reality. The field is its rudimentary stage. Contradictory findings make the question difficult to answer. Some researchers demonstrate the existence of human pheromones, other refute their existence. Moreover, majority of the work in this field is qualitative and without adequate controlled studies and statistical data. Majorities of the earlier studies have been criticized on the methodology, insufficient sample size, inadequate control groups, and lack of ecological validity and double blind studies. Moreover, Human response is variable from person to person. The results vary from one lab to the other. That means there are too many uncontrolled variables.

It is a very well recognized fact that pheromones play a significant role in the life span of animals. Ever since scientist discovered pheromones 30 years ago, they have found pheromones communication in hundred of species. They depend upon them for their food, mating, and signals of danger and survival. There is no doubt; this invisible and undetectable force runs their life. Animal action after sensing the pheromones is without reasoning. They can be lured by them. How about human beings? Are we lured by such unambiguous signals? Human behaves in a similar manner does not make any sense. He has intellect, emotions that govern by physical attraction. He makes his move on the basis of physical, intellectual and spiritual data instead of sniffing. Sexual identity, preference, performance depends upon the stimulation of sexual awareness through body appearance, body odor, vision, hearing and emotions. It is a complicated phenomenon and does not depend on a single factor i.e. sniffing.

Scientists have been researching for years the same latent force in human that can draw to some one. They have been successful to some extent in isolating and characterizing human pheromones that can attract opposite sex. However, some of the scientific data are controversial (Wysocki and Preti 2004). After two decades of research, the field pheromone is still in infancy stage. More scientific evidences are required to support this hypothesis. The idea of applying few drops of human pheromone formulation by an individual to lure the opposite sex sounds funny. It is difficult to accept the tall claims of the advertisers. However, people are buying them.

Chemistry of love is a complicated phenomenon and depends upon lots of factors in addition to these sex attractants. Love is natural not synthetic. One cannot be in love just sniffing the other person. It is a blend of physical attraction, emotions and the right chemistry between the two persons. Pheromones industry does not care for that. They have sufficient raw data to their advantage to support the production and marketing of synthetic version of these human pheromones as perfumes or colognes. In spite of the lack of consistent clinical data, these pheromone products are being sold like hot cakes. Love at first sight is known forever. But love at first sniff sounds weird.

It is hard to admit that pheromones act as aphrodisiacs. Do they stimulate the sexual desire or low libido? However, manufacturers claim that pheromones increase sexual desire and name them as olfactory aphrodisiacs. How much these products help to stimulate low libido. Nobody knows. They may be acting as sex attractant or mood elevators when added in a perfume. It is further not clear whether the perfume is luring the opposite sex or the pheromones. Testimonials given by the people vary from person to person. Men and women react to aromas like perfume cologne and pungent footwear and armpits sweat very differently. Same goes with the pheromones preparations.

Human pheromone products may alleviate the mood or sense of well being in some person depending upon their liking and prejudices. The multi-billion dollar perfume industry indicates that the power of smell is undeniable. That is the reason people are buying them assiduously. However, buyer should be aware of the fact that FDA does not control these pheromone products either. Moreover, there is no way to determine the genuineness of claims of the advertisers or toxic side effects of these products. Future of human pheromones is bright; many commercial enterprises are in hot pursuit of sexual fragrances. In old age physical and sexual attractions diminish with the decline of hormones. Quality of the odor of human pheromones and copulins also changed at this age and rejuvenation of the entire body is required. Pheromones or perfume industry should take advantage of this fact and imbibe youthful spirit by the help of suitable pheromone preparations in aging men and women. Women particularly during and after menopause have low libido and sexual interest. Instead of HTR (Hormone Treatment Therapy) pheromones preparations should take their place. If they motivate the emotions, hormones can be motivated since hormones and emotions go hand in hand. Preliminary studies with human pheromones have shown some encouraging results in postmenopausal hormonal therapy as discussed earlier. The pheromones can be used alternative or complimentary treatment to HRT.

At present the number of good studies available on human pheromones and their role in human reproduction is very limited. Active research can be conducted to isolate specific pheromones from men and women that could be used as fertility agents for couple who wish to conceive and as contraceptive who do not want to conceive. Human pheromones can be used as mood regulator and could help to control depression. Human pheromone treatment could control prostate activity in men to reduce the risk of cancer since prostate gland is highly hormone dependent and sexual activity play a significant role in determining the prostrate cancer risk.

Field of human pheromones needs more research and consistent clinical data. The field is still in an elementary stage and studies are contradictory. It needs to be completely explored. There is a possibility of finding an intriguing sexual mystery that the researchers are just beginning to unravel. History reveals that scientific data can turn myth into reality. Without the concrete scientific evidences pheromone preparations will stay as myth.

Androstenone,  Androstenol, Androsterone, Androstadienone, Estratetraenol Fig. 1 HUMAN PHEROMONES 

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