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Review Article
Pheromones: Does humans emit sex scent signals
Shrikant L Patil
Assistant Professor, Department of Physiology, K. S. Hegde Medical Academy, Nitte University, Deralakatte, Mangalore-575018, Karnataka,
INDIA.
Email: shrikantlpatil@gmail.com
Abstract
The invisible, colourless chemical scent emitted by human beings is known as Pheromones, these chemical signalling
molecules are volatile, odorous substances, triggering some sort of physiological reaction. The physiological reactions
can manifest themselves in a variety of different ways: some pheromones affect aggression, some modulate sexual
activity and other pheromones have similarly diverse effects on the target animal. Pheromones have been known to
perform main role in number of organisms ranging from amoebas to fish to mammals, including primates. However, the
question of whether does humans emit sex scents signals? Do human olfactory signals for pheromones exist? Has been a
question of much debate with few definite conclusions. In this paper I will look at some possible examples of odour
signalling in humans.
Key Words: Pheromones, vomeronasl organ, sex, odour, behaviour.
Address for Correspondence:
Dr. Shrikant L. Patil, Assistant Professor, Department of Physiology, K. S. Hegde Medical Academy, Nitte University, Deralakatte,
Mangalore-575018, Karnataka, INDIA.
Email: shrikantlpatil@gmail.com
Received Date: 09/04/2017 Revised Date: 10/05/2017 Accepted Date: 22/06/2017
INTRODUCTION
Pheromones are chemicals secreted by a particular animal
which can alters/changes the behaviour of the another
animal belongs to the same species. Many scientists have
described pheromones are one of those behaviour-altering
agents, which can trigger different behavioural changes
apart from the sexual behaviour in the animal belongs to
the same species. Pheromones are known as
ectohormones – i.e. they act outside of the individuals
body who secrets them – they alter the behaviour of
another individual. In case of hormones which only can
affect the individuals body functions that secrets them
1-3
.
It is well documented that males and females of many
species can emits or can communicate through chemical
signals (chemotaxis) known as pheromones, but there
remains the same question as to whether humans can also
secrets these chemical signalling molecules called as
pheromones
4-6
. Researchers from Sweden used brain
imaging procedures which have found the evidence those
men and women can in fact release and receive the
subconscious odour signals, both of them, responds to
theses odour signals differently
7-10
. The airborne chemical
messengers released from human body (i.e. urine and
sweat) are known as human pheromones which haves
direct impact on physical and emotional changes on
another fellow humans. Most of the animals including
humans can detect, smell these pheormoens with the help
of half-moon shaped specialized structure located inside
the nose called the vomeronasl organ (VMO). On the
other hand, non-pheromone scents such as the smell of
food or flowers are sensitized by another part of nose
called as olfactory epithelium. Pheromonal signals sensed
by VMO then relayed through olfactory nerves to
olfactory cortex, then some part of information send to an
area of the brain called hypothalamus, which is known for
its activity to alter the hormonal changes, emotion, sexual
and reproduction behaviour
11,12
. A Signature Scent: As
the search for human pheromones continues, scientists
have also investigated other potential explanations for the
subtle effects of smells. Consider, for example, the
finding that human infants will crawl toward the odour of
their mother’s breast. Baby rabbits are known to begin
nursing when exposed to a specific pheromone from a
lactating mother rabbit. Yet the human infants might
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simply be attracted to a mother’s so-called odour print, or
unique personal scent. Odour prints are influenced by
diet, environment, health and genetics. They consist of far
too many compounds to be described as pheromones
themselves
4,5,11
.
PROOF ABOUT HUMAN PHEROMONES
Gustav Jäger a German doctor and hygienist is thought to
be the first scientist to put forward the idea of human
pheromones. He called them anthropines and said that
they were lipophilic compounds associated with skin and
follicles that mark the individual signature of human
odours. Lipophilic compounds are those that tend to
combine with, or are capable of dissolving in lipids
13-15
.
In 1998, the path-breaking discovery carried out by Dr.
Martha McLkintock in human pheromones field
described that those women stay in hostel together, stay
in a group in home like accommodation their physiology
shows that there is synchronization of menstrual cycle; it
is probably because of the chemical scents released
through sweat from those menstruating women body
16-
20,25
. In recent advances in the field of human
pheromones, scientists used scanning technique such as
PET (Positron Emission Tomography) scan to study the
brain functions of selected 24 men and women while they
are exposed the odour emanating chemicals which are
almost identical to the human sex hormones such as
testosterone and oestrogen. The expert scientist from the
field of chemical signalling Dr. David Berliner analysed
these PET scan findings and concluded that women has a
ability to communicate with men and vice versa, these
findings also support that the human pheromones do
exist. This opinion is based on the important observation
that the human sex hormones like chemicals activate
specific areas of the brain which controls human
behaviour
11,12,14
. Another scientist group form Karolinska
Institute under the leadership of Dr. Ivanka Savic, found
out that the hormone-like scents activates and turn on the
human brain’s specific area called as “hypothalamus”,
which regular odours are not able to activates. They also
observed that the brains of women and men respond very
differently to the different sex hormones
27-29
. When men
are allowed to smell the chemical similar to estrogen,
their brain’s hypothalamus became “turn on” but not
during smelling of testosterone-like chemicals, whereas
women’s hypothalamus has the exactly opposite
response: their hypothalamus was turned on only by the
testosterone-like chemicals and not the estrogen-like one.
They have also observed the sexual disparity among the
specific sub-regions of the hypothalamus after the
activation to specific smell stimuli
23,24,26
. Scientists
believe that human behaviours are geneder-specific, this
may be because of the way we chemically perceive the
opposite sex is very different than the way we perceive
members of the same sex
11,12
. A Swedish study found
that lesbians react differently to AND
(progesterone derivative 4,16-androstadien-3-one)
compared with heterosexual women. AND is ten times
more abundant in human male sweat than female sweat
8
.
A study, published in Respirology in January 2016,
showed that AND caused swelling in the erectile tissue of
female noses. This was taken as evidence that AND
might be a functioning pheromone
1
. Another contender
for the role of human pheromone is androstadienone.
There is some evidence that androstadienone, a
component of male sweat, increases attraction, affects
mood and cortisol levels and activates brain areas linked
to social cognition. One study found that and
rostadienone increased cooperative behavior in males
31
.
Androstenone, secreted only by males, has also been
tested for its potential role as a pheromone. According to
some studies, androstenone increases a woman's mood,
especially if she is presented with it close to the time of
ovulation. Overall, evidence for the existence of
pheromones in humans is weak but it cannot be ruled out
entirely. If human pheromones are ever found, the
likelihood is that their effects are incredibly subtle
30,32,33
.
Types of Pheromone: There are four principal kinds of
pheromones
33,34
:
1. Releaser pheromones - They elicit an
immediate response, the response is rapid and
reliable. They are usually linked to sexual
attraction.
2. Primer Pheromones - These take longer to get a
response. They can, for example, influence the
development or reproduction physiology,
including menstrual cycles in females, puberty,
and the success or failure of pregnancy. They can
alter hormone levels. In some mammals,
scientists found that females who had become
pregnant and were exposed to primer
pheromones from another male, could
spontaneously abort the fetus.
3. Signaler Pheromones - These provide
information. They may help the mother to
recognize her newborn by scent (fathers cannot
usually do this). Signaler pheromones give out
our genetic odor print.
4. Modulator Pheromones - They can either alter
or synchronize bodily functions. Usually found
in sweat. In animal experiments, scientists found
that when placed on the upper lip of females,
they became less tense and more relaxed.
Modulator hormones may also affect a female's
monthly cycle.
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Can Pheromones Make Us More Sexually
Attractive? - If these pheromones turn on areas of
the brain that control mood, hormones and sexual
behavior, one might then ask: "Can these chemicals
make us more attractive?" The answer is: Maybe.
Researchers at the University of Chicago and
University of Utah have found that the same sex
hormone-like chemicals used in the Swedish study
can in fact have a pheromone effect by producing
changes in mood, heart rate, breathing, and body
temperature. However, there is currently no
indication these chemicals can actually increase
sexual arousal or attraction
35,36
. Many perfume
companies have tried to capitalize on the potential
sex-specific effects of these chemicals by adding
them to their fragrances. But most of these companies
add hormones from animals such as pigs and deer, so
they probably don't work. Pheromones are generally
species-specific, so a perfume enhanced with pig
pheromones is really only useful for other pigs
35-37
.
The promotions of one company that adds human
hormones to its fragrances claim the additives will
"put you and your partner at ease, boost your
confidence, and contribute to a feeling of well being."
The general idea is that pheromone perfume can
replace our naturally produced pheromones that have
been washed off through bathing and hidden by
layers of clothing. If these claims are true,
pheromones may make us more attractive to potential
mates by bringing out our best qualities and allowing
us to appear more self-assured and relaxed. That
"feeling of well being" may also make us a lot more
pleasant to be around
37-39
. Pheromones as
Therapeutics: The ability of these sex hormone-like
chemicals to activate areas of the brain that control
hormones indicates they may have more broad-
ranging therapeutic value as well. For example,
Pherin Pharmaceuticals is currently developing
numerous synthetic pheromones that it hopes will be
effective in decreasing symptoms of anxiety
disorders, premenstrual syndrome in women, and
prostate enlargement in men.
CONCLUSION
The previously discussed studies have suggested that
pheromones can communicate information about genetic
compatibility, sexual orientation and gender by affecting
humans unconsciously and physically. Reproduction is
the most important aspect when it comes to being a
successful species, comparable only, perhaps, to survival.
Of course it makes sense, then, that there are mechanisms
beyond our control that urge us not only to procreate, but
with mates that will result in the most successful
offspring. I urge those of you who are not yet die-hard
determinists not to view the effect of pheromones on mate
choice as a loss of agency, but as a gain of sensory
ability, enabling us to make a more informed decision.
Pheromones are just another way we can communicate.
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Source of Support: None Declared
Conflict of Interest: None Declared
