the functional dualism of pheromones

The Functional Dualism of Pheromones


Myrna D. Washington

PSY 350: Physiological Psychology

Instructor: Candice Ward

October 13, 2008

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Like many of us, the quest for purpose in this life has motivated many

of my academic pursuits. What I have found is that the purpose of life is “to

live”. If this is so, then the purpose of all species-typical behaviors is

the perpetuation of the species and the procreation of life. In this respect,

sexual behaviors (which ensure the survival of our species to reproduce and

live again) become the most important of the so-called four F’s: “fighting,

feeding, fleeing, and mating” (Carlson, 2008, p. 79). The sexual behaviors of

both males and females (dimorphic behaviors, “which include courting, mating,

parental behavior, and most forms of aggressive behaviors” [p. 258]), are

controlled by the organizational and activational effects of hormones (i.e.,

the androgens in males and progesterone and estradiol in females) that are

present both before and after birth. Not only do these hormones communicate

messages from one part of the body to another, they also control our sexual

physiology and behaviors.

What are pheromones?

In the same manner that hormones communicate within our bodies, chemicals

called pheromones communicate between bodies (i.e., male-female and female-

female), interacting with hormones and influencing “proceptivity, receptivity,

and attractiveness” (p. 277). These interactions combine with olfactory and

visual cues to make human sexuality the most complex of all mammalian sexual

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behaviors. Although we humans prefer to think of ourselves as “evolved” visual

creatures, who determine our mate selections based upon visual stimulation and

cognitive assessments, when it comes to why we choose who we choose, we are,

nevertheless, under the influence of the mysterious, undetectable,

unconscious, underappreciated effect of pheromones.

How are pheromones detected?

In humans (and in most mammals) pheromones produce odors that are

detected by olfaction. If you have ever found yourself declaring that someone

“smells funny”, “reeks”, “stinks”, or “smells fishy” when justifying your feelings of

uneasiness about that individual, then what you are describing is your

detection of sub- and unconscious human pheromones. Perhaps the negative

inference of this description is proof of man’s pride in his visual and

cognitive acuity. You see, through natural selection in the evolutionary

process, we humans have chosen to develop our visual acuity while allowing our

olfactory acuity and specificity to deteriorate. We have become ‘microsmatic’

(worse smellers – with only 10 million olfactory receptor cells) instead of

‘macrosmatic’ (better smellers, like dogs, who have approximately 230 million

olfactory receptors) (Kohl et al, 2001, para. 1). We have chosen to rely on

what we ‘see’ and ‘hear’, which is processed cognitively, rather than the more

primitive assessment of what we ‘smell’ (as most mammals do), which often

bypasses our conscious detections and interpretations and influences the

neuroendocrinology of our memories and emotions.

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Recent empirical evidence suggests that our olfactory sense is more

acute than we consciously realize. In fact, despite historical scientific

controversy, these recent findings have proven that our bodies are actually

equipped with glands (“apocrine glands that develop in the embryo, but become

functional only with the onset of puberty” [Kohl et al, 2001, para. 15]) that

secrete odors and pheromones that directly affect the physiology and behavior

of others.

The purpose of this project is to explore the function of human

pheromones, “the chemical messengers that are transported outside the body (of

one animal) that have the potential to evoke certain responses, such as

physiological (e.g., hormonal) or behavioral changes in a conspecific (another

animal)” (Kohl et. al., 2001, para. 9). We accomplish this by reviewing two

scholarly articles, each of which explores the function of human pheromones

from opposing views; one examining pheromones from the ‘popular’ (traditional)

perspective (as stimulators, acting to attract and encourage human sexual

behavior) and the other taking a novel approach, exploring pheromones as

inhibitory signals that act to discourage reproduction (anti-breeding

signals). Since the scientific community continues to take a speculative

perspective on the existence of pheromones and a human vomeronasal organ

(VNO), most of the information contained in both of these articles reveals new

and controversial ideas and empirical evidence regarding pheromones. The

information presented in both articles allows us to understand how we humans

signal each other of our availability (or unavailability) to procreate and

perpetuate our species and to discover the criterion that we use as the basis

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for the selection of our mates. Finally, we will realize that human sexuality

really does have an odor and this odor acts to control the development,

physiology, and behavior of everyone within our environment.

My interest in the subject of pheromones began after observing the fact

that the teenage girls in my adopted daughter’s class looked more mature than

both my oldest son’s teenage peers (who are now 38 years old) and my own

teenage peers. After observing this, I began to notice that teenage girls

everywhere, especially in the media, were developing at younger ages than they

were even 25 years ago. As I began to ponder this phenomenon, my studies

revealed that empirical evidence has shown that females are now entering

puberty and developing at much earlier ages; the age of puberty has declined

from 15- and 16-years of age over the last fifty years to the current 11- or

12-years of age. My suspicions were that this ‘early physiological and sexual

maturity’ was related to pheromones (nature’s own barrier), the rising divorce

rate, and family structure. After all, my own daughter is being raised in a

home in a large metropolitan area (she was a “city mouse”), with a non-

biological father, step-brothers, and no sisters. And after contemplating my

own delayed development (menarche at eighteen years old), I surmised that this

was due to my own family structure (the consistent presence and influence of

my biological father), my birth order (number seven in a family of ten), and

the presence of five sisters (four of whom were older). As we will see from

the evidence presented in these two articles, I was correct in my assumptions:

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Pheromones do more than attract sexual development and behavior; they also act

to inhibit and discourage physiological and sexual behavior, as well.

Pheromones as Stimulatory/Enhancing Reproduction

Kohl, J. V., Alzmueller, M., Fink, B., & Grammer, K. (2001). Human pheromones:

Integrating neuroendocrinology & ethnology. Neuroendocrinology Letters. 22,

309-321. Retrieved October 4, 2008, from http://love-

scent.freeservers.com/unprotectednel.pdf

According to Kohl et al, (2001),”Human pheromones have more potential

than any other social environmental sensory stimuli to influence physiology

and, therefore, behavior” (para. 48). In their exploration of the

controversial and complex influence of pheromones on human physiology and

behavior, the authors present a well-written, detailed, and thorough

discussion of the existence and function of pheromones as ‘human magnets’.

They reveal novel empirical evidence that greatly enhances what is currently

known (and believed) about the existence of pheromones. However, the

professional, specific, scientific vernacular of this article suggests that

the target population of this article consists of psychologists, educators and

professionals interested in human ethnology, pheromones, odor, olfaction,

human sexuality, sexual selection and mate choice.

In this article, the authors explore how human life and interactions

are influenced by pheromones outside conscious and cognitive awareness; the

biological basis for the development of physical “attraction” based on

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http://love-scent.freeservers.com/unprotectednel.pdf



pheromones. They accomplish this insurmountable task by conducting a meta-

analysis of over fifty empirical studies exploring how human reproductive

biology and human behavior are affected by olfaction, the existence of a

human vomeronasal organ (VNO), the history of pheromones, how human pheromones

are produced and detected, how they influence human behavior, and how

pheromones influence mate selection.

According to Kohl et al. (2001), pheromones are detected by the human

VNO, which “directly translates olfactory cues into neuroendocrine responses”

(para. 8). These olfactory cues are detected by the olfactory region of the

nasal mucosa (found on both sides of the nasal septum in the upper nasal

conchae), which contains the sensory cells that endow humans with the superior

cognitive power to “discern between many different odors” (para. 2). When

pheromoneal odors are initially detected, their molecules dock with receptor

proteins in the membrane of the olfactory ciliae. From there, ‘the axons of

the sensory cells enter the olfactory bulb, are projected via the olfactory

tract into the olfactory love of the brain, and are then projected into the

thalamus to the neocortex and to the limbic system’ (para. 2).

Because they occur in the limbic system (without any cognitive or

cortical assessment), these non-verbal chemical signals evoke positive and

negative affective reactions (emotional reactions which occur without extensive

perceptual and cognitive encoding) that “allow humans to select for, and to

mate for, traits of reproductive fitness that cannot be assessed simply from

visual cues” (Kohl et al., 2001, para. 4). The authors call this the

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‘affective primacy hypothesis’ (para. 3). This pathway links “the affect of

pheromones on our emotions to the effect of pheromones on the hormones of the

hypothalamic-pituitary-gonadal axis – an unconscious affect” (para. 5).

Visual cues then combine with pheromoneal cues to produce the conditioned

response of the male luteinizing hormone (LH) release, an increase in male

testosterone (T), and an increase in the production of female estradiol (E).

Thus, these chemosignals “modulate psychological state without being consciously

discernible as an odor” (para. 7).

Kohl et al. (2001) refer to pheromones as “ecto-hormones” (para. 9) and

examine the two classes of pheromones: 1) signals - “which cause short-term

changes, such as the release of neurotransmitters that can directly modify the

recipient’s behavior” (para. 10); and 2) primers - “which influence the entire

hypothalamic-pituitary-gonadal axis and influence behavior by altering

neuroanatomy and neurotransmission” (para. 11). In further elucidating how

human pheromones elicit changes in the physiology and behavior of a

conspecific, the authors give a detailed explanation of the production of

pheromoneal ‘odors’ by the apocrine glands, which are “found in areas that

include the genital area, around the naval, on the chest, breast, and areola,

and are concentrated in the axillae” (para. 15). Humans tend to produce

relatively high amounts of apocrine secretions, which, although initially

odorless, are transformed by microoganisms into odorous products that elicit

both conscious and aversive hedonic behaviors. “The link between aprocrine

gland function and puberty reflects that function is closely linked to levels

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of sex steroid hormones that increase with the onset of adrenarche and

puberty” (Para. 15).

Although there are many different human pheromones, the authors focus

their discussion on two of the 16-androstenes, which develop with the

metabolism of the male sexual hormone, testosterone: 1) androstenol, which has a

musk-like odor, induces female attraction to males, and oxidizes to

androstenone; and 2) androstenone, which has a urinous odor and induces

negative emotions toward males. Although the authors present numerous studies

exploring how olfactory acuity, sensitivity, and specificity are modulated by

the female hormonal status (i.e., ovulation or the menstrual cycle), nearly

all the studies found that androstenone is rated negatively independent of the

female cycle.

Kohl et al. (2001) then turn their exploration of pheromones to the

Parental Investment Theory, which “predicts that females who look for long-term

relationships should seek out and choose males who are ready to invest

resources in their offspring” (para. 28); the old adage that ‘females should

spread their seed wisely and males should spread their seed widely.’ According

to this theory, females and males develop and use cognitions in mate selection

that include biological constraints such as: 1) concealed ovulation - evolved

because “the female’s ability to secure paternal care is affected by

mechanisms that increase temporal aspects of the pair bond and enhance male

confidence in paternity” (para. 29); suggesting that females need to trick

makes into forming a bond; 2) the evolution of the androstenone-androstenol signaling system

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- an “ovulation-radar” (para. 35) - evolved as a male counter strategy

designed to detect concealed ovulation; and 3) the existence of copulins –

“ovulatory fatty acids that stimulate male androgen secretion and change the

discriminatory cognitive capacities of males with regard to female

attractiveness, making them less discriminating” (para. 37). These copulins

“act as putative human pheromones and provide beautifully balanced ‘strategic

weapons’ in the ‘battle of the sexes’ and the ‘war of signals’” resulting from

sex differences in the parental investment theory” (para. 37). Incidentally,

the afore-mentioned behaviors are the behaviors that combine to define human

sexual behavior as the most complex of all mammalian sexual behavior.

Finally, Kohl et al. (2001) conclude their exploration with a discussion

of pehromones as ‘honest signals in mate selection’ (para. 40). This

discussion includes four other cues that signal reproductive fitness: 1) the

effect of facial and bodily symmetry – which “signals developmental stability, an

individual’s ability to cope with genetic and environmental perturbations

during early development” (para. 40); 2) the link between body odor and attractiveness

- with both males and females preferring the scent of “non-self odors” (para.

43); 3) the testosterone-immunocompetence-developmental stability link (para. 42); 4) genetic

diversity – with both males and females preferring mates who are similar, but

not too similar to themselves (para. 43); 5) hormone-mediated facial

attraction – with symmetry being preferred over asymmetry (para. 44); and 6)

the waist-to-hip ratio (WHR) - with “high levels of LH, FSH (follicle

stimulating hormone), and estradiol levels being linked to lower WHR and to

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the earlier pubertal endocrine activity of females” (para. 45). Simply put,

“we (humans) think about what we see and decide whether or not it is

attractive” (para. 46.) These considerations facilitate ‘rapid responses and

accurate choices in mate selection that do not require cognition; unconscious

odor cues that link genetic diversity and all aspects of hormone-mediated mate

choice’ (para. 47).

Finally, when Kohl et al., (2001) look at how pheromones influence human

behavior, they conclude that “the influence of human pheromones on social

behavior may pale by comparison to the influence that pheromones may have on

human reproduction” (para. 22). According to McClintock (as cited in Kohl et

al, 2001), “pheromones influence the human menstrual cycle (i.e. ovulatory

synchronicity)” (para. 22). In addition, “Maiworm (as cited in Kohl et al.,

2001, para. 26) found that at different periods in the menstrual cycle,

androstenone and androstenol had different effects” (para. 26). In essence,

“effects are greatest during the first period of the menstrual cycle and both

pleasant and less pleasant in the final period of the cycle” (para. 26).

Moreover, the authors hint that “female infidelity peaks at ovulation” (para.

31), which produces a “female-induced sperm competition” (para. 31).

Throughout this article, Kohl et al. (2001) “addressed several aspects

of what is consciously perceived to be visual attraction both from an

ethological and neuroendocrinological approach” (para. 47). They provided

empirical evidence that suggests that “the olfactory link among hormones,

pheromones, and a conspecific’s hormones and behavior … readily establish(es)

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that visually perceived facial attractiveness, bodily symmetry, attractive

WHRs, and genetically determined HLA attractiveness, are due to the

neuroendocrinological conditioning of visual responsivity to olfactory

stimuli” (para. 47).

The authors conclude their meta-analysis with their projections of

future research on pheromones:

Predictably, we will soon address other aspects of human attraction, and

social confounds such as the paraphillias – and even sexual orientation

in future discourse. Finally, we might even address the obvious

question of how our everyday social lives and future human reproductive

success will be affected by the modern striving for cleanliness and

reduction of natural body odor.

Pheromones as Inhibitory/Anti-inbreeding

Matchock, R. L. & Susman, E. J. (2006, July-Aug). Family composition and

menarcheal age: Anti-inbreeding strategies. American Journal of Human Biology,

18(4), 481-491

Matchock & Susman (2006) take the theoretical perspective of pheromones

as “inhibitory/anti-inbreeding” chomesensory signals. This study began with

the study of how the absence of a father is associated with pubertal timing in

women and the physiopsychosocial influences of sexual maturation and concludes

by unveiling the existence of ‘natural boundaries’ between parents and their

offspring.. “The primary aim of this report is to investigate the link

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between social environment and reproductive status, as defined by age of

menarche, to further the understanding of human socioendocrinology” (para.

10). This is done by exploring how the contextual social environment (i.e.,

the presence or absence of a father, family composition, and sibship) is

correlated with pubertal timing (menarche) in females.

The authors support their study, which argues that “the father

absence/early menarche link is an evolutionary strategy to prevent inbreeding”

(para. 2), with the empirical research of several early pioneers. This

research includes: 1) Whiting, “who (in 1965) first reported that the absence

of the biological mother in infancy was associated with earlier menarche in

women” (para. 1); ) Later, Jones et al., “who (in 1972) found that father-

absent girls were more likely to have earlier menarche than father-present

girls” (para. 1); 3) Draper and Harpending, “who (in 1982) hypothesized that

the absence of a father causes females to express earlier sexual interest and

sexual activity” (para. 1); 4) Belsky et. Al, “who (in 1991) proposed that an

early stressful rearing environment, characterized by family conflict,

divorce, father absence, untrustworthy pair-bonds, and insecure attachments

led to an internalization of problems, changes in metabolism and body fat, and

thus early menarche” (para. 1); and 5) Ellis, “who (in 2004) postulated that

high levels of familial interpersonal stress cause girls to orient toward

early pubertal maturation” (para. 2).

To further strengthen their perspective that pheromones “convey

important information about the socioendocrinological milieu and its

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coduciveness to successful breeding” ( Matchock & Susman, 2006, para. 2), the

authors collected retrospective data on menarcheal age and family composition

from a sample of approximately 1,938 college students at Pennsylvania State

University during 1998-2001. The average year of birth for the sample

population was 1980, with a range from 1947-1986 (para. 11) and the

demographics were divided as follows: 86.5% “Caucasian” (N = 1,650); 4.3%

“African-Americans” (N = 82); 3.0% “Asian” (N = 58); 2.6% “Hispanic” (N= 50);

0.8% “Native American” (N = 15); and 2.8% who described themselves as “Other”

(N = 53) (para. 11).

Between-subjects analyses of the variance (ANOVAs) were used, as

appropriate, to distinguish differences in the dependent measures of

menarcheal age and the age of first sexual intercourse, which are both

reported in years. Bonferroni multiple comparisons were used to adjust

for multiple comparisons. A best-subject regression analysis and

multiple linear regressions were also used to determine major predictors

of menarcheal age. Father-absence was operationalized as the absence of

the biological father in the household prior to the onset of the

daughter’s menarche and was measured through the menarche questionnaire.

The most striking findings of Matchock & Susman’s (2006) article are:

1) “Participants whose fathers had at least a 4-year degree (M = 12.86)

had a later age of menarche than participants whose fathers had less than a 4-

year degree (M = 12.72), F (1, 1,899) = 4.87, P < 0.027” (para. 13);

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2) Father-absent women (M = 12.47, N = 326) have an earlier menarcheal

age than father-present women (M = 12.86, N = 1,570), F(1, 1894) = 22.15, P <

0.0001 (para. 14);

3) When the father left is significant, “with the absence of the father

occurring very early in life for most participants (M = 1.8 years)” (para.

14). “An analysis of participants whose fathers left before age 1 year (M =

12.39, N = 218) revealed a marginally significant earlier age of menarche than

participants whose fathers left after age 1 year (M = 12.65, N = 102), F(1,

318) = 295, P < 0.087” (para. 15). In addition, “the menarcheal age of girls

whose fathers left the home before 10 years of age was 10 months earlier than

if the father left after age 10” (para. 25).

4) Participants with 1+ older sisters (M = 12.91) have an earlier

menarche than participants with no older sisters (M = 12.73) and participants

with no younger sisters (M = 12.75), F(1, 1916) = 6.72, P < 0.01 (para. 17);

5) In multiple-sibling families, later-born women have earlier menarche

than earlier-born women. “A 4 (birth order: 1, 2, 3, or 4) X 4 (total

siblings: 0, 1, 2, or 3) ANOVA was performed; the main effect of birth order

(P < 0.881), sibship size (P < 0.720), and their interaction (P < 0.444) was

not significant” (para. 18);

6) “Women living with half- and step-brothers (M = 12.47, N = 67) had an

earlier age of menarche than those without half- or step- brothers (M = 12.89,

N – 1087), F(1, 1,154) = 4.87, P < 0.028” (para. 19); and

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7) Women raised in urban environments (M = 12.37) had significantly

earlier ages of menarche than both women living in suburban environments (M =

12.82) and rural environments (M = 12.88), F(2, 1906) = 10.95, P < 0.0001

(para. 20).

In addition, “the correlation between age of menarche and age of first

sexual intercourse was significant, at r = 0.165, P < 0.0001” (Matchock &

Susman, 2006, para. 23); “Father-absent girls also had first sexual

intercourse (M = 16.87) earlier than father-present girls (M = 17.47), F(1,

1,289) = 24.48, P < 0.0001” (para. 23). While the authors noted that African-

American participants had both earlier menarcheal ages (M = 12.11) and earlier

ages of first sexual intercourse (M = 16.55), the contextual social

environments, familial compositions and sibships of these participants were

not correlated in this observation. It is this author’s supposition that the

entire population base of this study (irrespective of race) consist of college

students from upper-middle-class families who resided in urban areas.

The findings of Matchock & Susman (2006) are consistent with past

research in that they successfully demonstrate how “pheromoneal cues modulate

sexual maturity so as to enhance mating and prevent inbreeding” (para. 35). In

fact, “the prevention of inbreeding is so paramount to the successful

propagation of healthy genes that anti-inbreeding behaviors and changes in

reproductive physiology appear to be highly conserved across species; that is,

parents suppress reproduction of their offspring” (para. 35).

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“A limitation of (this study) is that it used a retrospective design

where college-age women were asked to recall a menarcheal experience that

happened, on average, more than 6 years earlier” (Matchock & Susman, 2006,

para. 35). While menarche is considered to be a “salient experience” (para.

35), the retrospective design of this study has been criticized as being

“susceptible to retroactive and proactive interference” (para. 35). In

addition, the authors noted that future investigations of within-species,

socially-mediated adjustments should “examine other aspects of reproductive

life, such as number of children or spacing between births” (para. 35).

Discussion

My critical opinion of these articles is that Koch et al.’s article is a

quantitative study that implicates the stimulatory and magnetic effects of

pheromones in sexual reproduction and Matchock & Susman’s article is an eclectic

blend (of both qualitative and quantitative measures) that emphasizes the

inhibitory and anti-breeding effects of pheromones within the familial structure.

Both articles support my suspicions regarding the existence of pheromones and

their effects on the early menarcheal ages of my daughter and her peers and my

own delayed menarcheal age. A parsimonious explanation might be that “the

acceleration of female sexual maturation occurs in the presence of any

appropriate male (i.e., a genetically unrelated, adult fertile male)”

(Matchock & Susman, 2006, para. 27). [An even shorter explanation is that we

humans affect one another; and those affects have effects on our sexual behaviors.]

From the perspective of an emerging psychology professional, each article was

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extremely well-organized and well-written, ‘jam-packed’ with startling new

ideas and findings surrounding the pheromone/VNO controversy and

physiological/sexual maturity. At times, each article appears to be ‘over the

heads’ of the above-average reader. However, keeping a dictionary and

physiological psychology nearby, makes the material more palatable and more

readily understood.

The overall findings of these two articles provide the informed reader

with well-documented evidence of the dual functions of pheromones that is

above and beyond the discussion presented by Carlson (2008) on the effects of

pheromones (p. 269). Carlson (2008), however, does deliver a concise

presentation of the four effects of pheromones (observed in mice): 1) The

Lee-Boot effect - “the slowing and eventual cessation of estrous cycles in

groups of female animals that are housed together, caused by a pheromone in

the animals’ urine” (p. 269); 2) The Whitten effect – “the synchronization of

the menstrual or estrous cycles of a group of females, which occurs only in

the presence of a pheromone in a male’s urine” (p. 269); 3) The Vandenbergh

effect – “ the earlier onset of puberty seen in female animals that are housed

with males; caused by a pheromone in the male’s urine” (p. 269); and 4) The

Bruce effect – “the termination of pregnancy caused by the odor of a pheromone

in the urine of a male other than the one that impregnated the female” (p.

269). Matchock & Susman (2006) cite data consistent with the Vandenberg

effect in their observation that “the presence of half- and step-brothers in

the household (is) associated with earlier age of menarche” (para. 28). In

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addition, without defining them as such, Koch et al. (2001) demonstrate all

four effects in their exploration of the androstinol-androstenone signaling

system (paras. 33–38).

While his presentation of pheromones is somewhat unilateral, Carlson

(2008) briefly defines pheromones as “chemicals released by one animal (that)

directly affect the physiology or behavior of another” (p. 269). His

description of the Lee-Boot effect, the Whitten effect, the Vandenbergh

effect, and the Bruce effect give a brief and general (but interesting)

description of how pheromones affect sexual and reproductive behavior in mice.

In addition, Carlson (2008) briefly discusses the existence of a hamster VNO

and asserts that ‘the detection of odors (in humans) is accomplished by the

olfactory bulbs” (p. 269). In addition, he briefly points out amidst his

presentation on intellect and emotions) that the presence of the sensory input

of odors and pheromones is received by the medial nucleus and relayed to the

medial basal forebrain and to the hypothalamus (p. 291). This area of the

brain is “the single most important part of the brain for the expression of

emotional responses provoked by aversive stimuli” ( p. 292), such as

androstenone.

Carlson (2008) also suggests that, while ‘we are not generally conscious

of the familiar odor of a sex partner, we can identify other people on the

basis of olfactory cues’ (p. 271). He concludes his section on pheromones by

stating that: “Human reproductive physiology is clearly affected by

pheromones, but it appears that these chemical signals are detected by the

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‘standard’ olfactory system – the receptor cells in the olfactory epithelium –

and not by the cells in the VNO” (p. 271). This implies the speculative

nature of Carlson’s stance on the existence of pheromones (congruent with a

large percentage of the scientific community) and the belief that a human VNO

no longer exists.

Conclusion

As we have seen, pheromones have a dual effect on sexual behavior:

stimulatory (magnetic) and inhibitory (anti-breeding). Whether we are

consciously aware of them or not, their effects are obvious. Aside from our

nuclear families, in which pheromones act to inhibit and discourage sexual

behavior between parents and their offspring, most of us have no idea why we

choose the special people in our lives. If we take a moment to reflect, we

will see that we have all experienced the four pheromonal effects presented by

Carlson (the Lee-Boot, the Whitten, the Vandenbergh, and the Bruce effects) in

our everyday lives. In deference to Carlon’s (2008) description of the human

VNO as a “vestigial organ like the human appendix” (p. 271), the articles of

Kohl et al. (2001) and Matchock & Susman (2006) have finally provided us with

irrefutable empirical evidence suggesting that the human VNO actually exists

and that it detects the powerful chemicals produced by the human apocrine

glands, pheromones. Like melatonin (produced by the pineal gland, which is

said to have once been the size of a plum in ancient man, but is now the size

of a shriveled pea), pheromones have a powerful, dualistic influence on the

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sexual and reproductive behaviors within every species of the animal kingdom –

including (and especially) humans.

References

Carlson, N. R. (2008). Foundations of physiological psychology (7th ed.). Boston: Pearson-Allyn-Bacon.

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Kohl, J. V., Alzmueller, M., Fink, B., & Grammer, K. (2001). Human pheromones:

Integrating neuroendocrinology & ethnology. Neuroendocrinology Letters. 22,

309-321. Retrieved October 4, 2008, from http://love-

scent.freeservers.com/unprotectednel.pdf

Matchock, R. L. & Susman, E. J. (2006, July-Aug). Family composition and

menarcheal age: Anti-inbreeding strategies. American Journal of Human Biology,

18(4), 481-491.

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The Functional Dualism of Pheromones 23

the functional dualism of pheromones

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