524
J. Cosmet. Sci., 75.5, 524–528 (September/October 2024)
*Address all correspondence to Paolo Giacomoni, paologiac@gmail.com.
This is an excerpt from a paper published on Relata Tecnica, Issue 2023, 3 under the title “The Importance
of Personal Scent.”
The Role of Personal Scent
PAOLO U. GIACOMONI AND VINCENZO P.M. RIALDI
L-Raphael, Geneva, Switzerland (P.G.)
Vevy Europe, Genova, Italy (V.R.)
Accepted for publication August 8, 2024.
INTRODUCTION
Olfactory signals are often considered a nuisance. We notice bad odors, try to remove
them or mask them and do not consider the possibility that olfactory signals might play
important roles in our life. And yet, fragrances can affect our mood, stimulate our focus,
reduce our mental confusion, increase vigor, decrease anger and anxiety. Their effect
is mediated by the binding of the fragrant molecule to a receptor and the neurological
transmission of a signal that provokes a cerebral response via the release of neuropepetides.
As much as many acoustic signals, such as ultrasounds that are not detected by our ears,
some olfactory signals are not odoriferous (we call them subliminal) and consist of molecules
that, while undetected by our sense of smell, bind to receptors in our olfactory organs
and provoke a variety of physiological effects. We release subliminal olfactory signals that
can vary with our physiological status, and we receive subliminal signals with behavioral
consequences that depend on our physiological status.
OLFACTORY SIGNALS IN HUMANS
It is known that androstenol (5α-androst-16-en-3-ol) is a natural steroid with 19 carbon
atoms, synthetized in the human testicles. It is found at a high concentration in human
urine, armpits, sweat, and saliva. It is also known that copuline is a complex mixture of
aliphatic acids normally contained in vaginal secretory products of young healthy women
with regular, hormone-controlled menstrual cycles.
When asked to smell the T-shirts of a large cohort of college male students, female students
preferred (or found less repugnant) the odor of T-shirts from males whose MHC (Major
Histo-compatibility Complex) was complementary to their, as if the scent could direct
women to choose a mate such that the offspring would have an optimal immune response.1
Conversely, females are more attractive when they are fertile than when they are not. It was

525 THE ROLE OF PERSONAL SCENT
found that fertile, regularly cycling lap dancers made about $20 more in tips per hour than
when nonfertile, and about $35 more in tips per hour than when menstruating!2 There are
numerous studies that tell us that men find women more attractive when they are fertile,
for instance.3 Juette and Grammer asked a group of men to rate pictures of females for
attractiveness while having them exposed to female pheromones or to a nonpheromone
control.4 While unknowingly being exposed to vaginal pheromones, the men rated the
same females as being more attractive than they felt when they were not exposed to the
pheromones.
It might be of interest to learn that women who are using the contraceptive pill choose
men with immunity genes similar to their own, as opposed to naturally cycling women,
who choose men with immunity genes different from their own (and mating with an
individual with different immunity genes is evolutionarily beneficial). In addition, the
use of hormonal contraceptives reduces the production of copulin and its fluctuations. As
we said above, copulin is a blend of aliphatic acids (acetic, propionic, butyric, isovaleric,
isocaproic) usually present in vaginal fluids of healthy women.5
One study even proposed that this phenomenon could have downstream effects on the
health of future children6 and lap dancers who were using hormonal contraceptives
received in tips about $80 dollars less per shift than dancers that did not use oral hormonal
contraceptives.2 This supports what we know about how the human olfactory system picks
up on pheromones and subconsciously uses them to interpret attractiveness.
POSSIBLE APPLICATION OF THE RESULTS OF THIS RESEARCH
The conclusion is that Homo sapiens is an efficient receiver and sender of chemical signals
like all species with an active olfactory communication system.7 From these studies it can
be inferred that it is important to maintain the release of the molecules that constitute
the chemical signature of fertility and immune response, that might well be weakened
or altered by the use of hormonal contraception in females and by the use of deodorants
fragrances and the excessive cleaning of one’s skin in males.
It appears therefore possible to add to fragrances or other personal care products, molecules
able to mimic the ones released by fertile women to maintain their attractiveness or the
ones released by males that are recognized as stimulating by women even when they are
using hormonal contraception.
Experiments in this sense have been performed, for instance by Friebely and Rako.8 They
reported that the addition of female pheromones to common perfume increased the sexual
attraction of postmenopausal women. This effect was assessed by documenting behavioral
changes in their contemporary partners. Other experiments have shown that adult males
exposed to a female pheromone-mimetic substance do produce more testosterone than
unexposed controls, and this effect is amplified by physical exercise.9
Male and female pheromones can be synthesized following routine chemical reactions.
Since in cosmetics the use of hormones is prohibited or controversial, two molecules of a
nonhormonal nature were studied. These molecules were selected because they reproduce
respectively the typical effects of female pheromones as well as of male pheromones.
Originally, both molecules were synthesized in 1978 as osmostenicizing steroids, that is,
steroids which can enhance olfactory stimuli. They were later reconstituted with specific