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PHEROMONES – Scientific Research

Since the 20th-century hygiene revolution and the rise of the personal-care industry, however, companies have pitched deodorants, perfumes, and colognes to consumers as the epitome of sex appeal. But instead of furthering our quest to find the perfect mate, such products may actually derail it, say researchers, by masking our true scent and making it difficult for prospects to assess compatibility. "Humans abuse body smell signals by hiding them, masking them, putting on deodorant," says Devendra Singh, a psychologist at the University of Texas. "The noise-to-signal ratio was much better in primitive society."
Miller argues that modern hygiene may be such an impediment to sexual signaling that it could explain why so many people in our culture get so physical so fast. "Hunter-gatherers didn't have to do a lot of kissing, because they could smell each other pretty clearly from a few feet away," Miller says. "With all the showering, scents, and soap, we have to get our noses and mouths really up close to people to get a good idea of their biochemistry. People are more motivated to do a lot more kissing and petting, to do that assessment before they have sex." In other words, the need to smell our mates—and the comparative difficulty of doing so in today's environment of perfumes and colognes—may actually be driving the sexual disinhibition of modern society.

All it takes is a few molecules of a certain chemical to enable mammals
to smell their own species up to a half-mile away, says Milos Novotny,
Distinguished Professor of chemistry and director of the Institute for
Pheromone Research.

The chemicals, called pheromones, are detected by the vomeronasal
organ (VNO) in the animal's nose. Unlike the part of the nose that detects
ordinary smells, this super-sensitive organ is connected directly to the
mid-brain.

Professor Novotny current emphasis is on the neurochemistry of neurons
in the VNO and OE. He is the leader of interdisciplinary studies that
bridge the physical sciences, life sciences and social sciences, including
chemistry, neurobiology, psychobiology, biochemistry, wildlife ecology,
medical sciences, and animal physiology and behavior.

Ever notice how male dogs come from the other side of the
neighborhood when a female dog is in heat?

In a paper published July 12 in the journal Nature, Novotny and
co-workers at Harvard Medical School in Boston headed by Linda
Buck reported that the vomeronasal organ can actually detect both
odorants and pheromones. The VNO detected odorants classified as
animalic, camphoraceous, citrus, floral, fruity, green/minty, musky, sweet
or woody. Like pheromones, these odorants were detected at extremely
small concentrations.

"This suggests that in mammals, as in insects, odorous compounds
released from plants or other animal species may act as
'semiochemicals' -- signaling molecules that elicit behaviors that are
advantageous to the sender or the receiver," Novotny said.

Compared with many other creatures, human women and men simply
don't rely too heavily on their noses for sniffing out a  partner. But new
studies suggest that our sense of smell may be more important than was
previously assumed. In fact, says Alan Hirsch, neurological director at the
Smell & Taste Treatment Research Foundation in Chicago, people
can lose sexual function if they lose their sense of smell.

Some researchers think olfactory research in animals may help explain
human behaviors. Let's start with mice. Claus Wedekind, a zoologist at
Bern University in Switzerland, says female mice sniff for mating partners
with DNA that's different from their own, to help their offspring resist a
wider range of diseases. Specifically, Wedekind says, female mice look
for a mate with a different MHC (major histocompatibility complex), a
protein complex that lets the immune system know when disease is
present, spurring killer T cells into action. Similarly, researchers say,
human females are more likely to be attracted by a man's body odor if he
has different MHC.

Even if a woman turns up her nose at first, researchers have learned, a
relationship may flower later, when her body is more receptive. In studies
at the Ludwig-Bolzman-Institut in Vienna, 290 young women who were
ordinarily turned off by androsterone (a key component in men's sweat)
were less so by it while they were ovulating. Androsterone, it seems, may
act as a pheromone that attracts women, increasing the likelihood of
fertilization

Scientists at the University of Pennsylvania and the
Monell Chemical Senses Center in Philadelphia have found that
exposure to male perspiration has marked psychological and
physiological effects on women: It can brighten women's moods,
reducing tension and increasing relaxation, and also has a direct effect
on the release of luteinizing hormone, which affects the length and timing
of the menstrual cycle.

The results will be published in June in the journal Biology of
Reproduction and currently appear on the journal's Web site.

"It has long been recognized that female pheromones can affect the
menstrual cycles of other women," said George Preti, a member of the
Monell Center and adjunct professor of dermatology in Penn's School of
Medicine. "These findings are the first to document mood and
neuroendocrine effects of male pheromones on females."

In a study led by Preti and colleague Charles J. Wysocki, extracts from
the underarms of male volunteers were applied to the upper lip of 18
women ages 25 to 45. During the six hours of exposure to the compound,
the women were asked to rate their mood using a fixed scale.

"Much to our surprise, the women reported feeling less tense and more
relaxed during exposure to the male extract," said Wysocki, a member of
the Monell Center and adjunct professor of animal biology in Penn's
School of Veterinary Medicine. "This suggests that there may be much
more going on in social settings like singles bars than meets the eye."

After the women's exposure to the underarm extract, further testing
revealed a shift in blood levels of luteinizing hormone. Levels of this
reproductive hormone, produced in pulses by the pituitary gland, typically
surge right before ovulation but also experience hundreds of smaller
peaks throughout the menstrual cycle.

Preti and Wysocki found that application of male underarm secretions
hastened onset of these smaller pulses. Duration to the next pulse of
luteinizing hormone was shortened by an average 20 percent, from 59 to
47 minutes.

Preti and Wysocki are now looking at the several dozen individual
compounds that make up male perspiration to determine which may be
responsible for the effects they observed. They also plan to study whether
female pheromones can affect men's moods or physiological functions.

"This may open the door to pharmacological approaches to manage
onset of ovulation or the effects of premenstrual syndrome or even natural
products to aid relaxation," Wysocki said. "By determining how
pheromones impact mood and endocrine response, we might be able to
build a better male odor: molecules that more effectively manipulate the
effects we observed."

The underarm extracts used in the study came from men who bathed with
fragrance-free soap and refrained from deodorant use for four weeks.
The extracts were blended to avoid reactions to individual men's odors.
None of the women involved in the study discerned that male sweat had
been applied right under their noses; some believed they were involved
in a study of alcohol, perfume or even lemon floor wax.

Half the women received three applications of the male secretions during
a six-hour period, followed three controlled exposures to ethanol, used as
a control substance, over a six-hour period. For the other half, the
regimen was reversed. The women did not report feeling any more or
less energetic, sensuous, tired, calm, sexy, anxious, fatigued or active
after exposure to male perspiration.

Research on human putative pheromones has
recently focused on the effects of exposure to
4,16-androstadien-3-one (androstadienone). This
steroid has been observed in the skin, axillary hair,
and blood plasma, primarily in males. In addition to
effects of the steroid on measures of physiological
arousal and brain blood flow, positive mood effects
have also been reported. The current study further
investigated mood effects of androstadienone
exposure (250 M) in women in two experiments.
Through psychophysical testing of each individual
we controlled for whether any observed mood
effects could be related to sensory detection of the
steroid. In both experiments, we observed positive
changes of women's feeling of being focused,
which could not be related to sensory detection of
the steroid. Overall, the patterns of results were
significantly correlated between the two
experiments. In conclusion, this study corroborates
earlier findings suggesting that androstadienone
exposure yields effects on women's mood; the
feeling of being focused. The mood effects were
not dependent on menstrual cycle phase. Further,
these effects are replicable and occur also when
androstadienone detection is rigorously controlled
for across variation in menstrual cycle.

We examined the physiological and
psychological effects of nanomolar
amounts of steroids applied directly
under the nose (Delta4,16-
androstadien-3-one and 1,3,5,(10),16-
estratetraen-3-ol). These potential
human chemosignals were not
consciously discernible in a strong-odor
carrier (clove oil and propylene glycol). In
a double-blind, within-subject, repeated-
measures experiment with 65 subjects,
we demonstrated that both steroids
produced sustained changes in digit skin
temperature and palmar skin
conductance (an indicator of sympathetic
nervous system tone) while the subjects
were completing psychological
questionnaires or reading. These effects,
however, did not follow the sex-
stereotyped pattern predicted by a sex
attractant function. Both
androstadienone and estratetraenol
raised the skin temperature of men's
hands and lowered it in women. Likewise,
each steroid increased skin
conductance, with a significantly greater
effect on women than men. Women's
responses were observed only in the
sessions run by the male tester, an effect
that may or may not be solely attributable
to tester sex. Men's responses, in
contrast, were not affected by this
difference in socioexperimental condition.
Similarly, women experienced an
immediate increase in positive mood only
in the presence of the male tester, while
men's responses were unaffected by this
socioexperimental context. One source of
this sex difference may be the fact that
the majority of women were in the late
follicular phase of their menstrual cycle.
Although it is premature to classify these
steroids as pheromones, our data
suggest that they function as
chemosignals that modulate autonomic
nervous system tone as well as
psychological state.

For laboratory certified human pheromone products see …

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