belgareth
06-20-2006, 05:03 AM
The Sexy, Healthy Scent of
a Man
By Robert Roy
Britt
LiveScience Senior Writer
posted: 04 November 2004
The scent of a man, at least among mice, can reveal the state of his health and determine whether a female
gets pregnant, a new study shows.
The research suggests that other
animals, perhaps even you, choose mates in part based on the strength of their immune
systems.
Previous research had shown mice prefer to breed with mates
whose immune-system genes -- which produce chemicals that help the body fight invading cells -- are different from
their own. Such selective sex leads to healthier offspring.
The new
study shows how the selection occurs.
Researchers at the University of
Maryland examined molecules known as peptides that come from the immune system and end up in urine. Each mouse's
disease-fighting peptides are unique, like fingerprints. A female records and remembers the scent of a mate's
peptides using its vomeronasal organ, inside the nose.
"Exposure,
during a critical period, to urine odor from another male, will prevent embryo implantation, leading to loss of
pregnancy, while exposure to the familiar odor will not," said Frank Zufall of the university's School of Medicine.
Spiking the punch
"We can
trick this odor memory and the outcome of the pregnancy-block test by adding peptides to urine," Zufall told
LiveScience. "In other words, we can switch an unfamiliar urine odor to a familiar one (and vice versa) by spiking
the urine with only a few peptides."
Other studies have shown that
vomeronasal organs in many animals detect pheromones and other molecules that pack information on sexual and social
status. Pheromones were first discovered in the 1950s to be sex attractants in
insects.
"We believe that detection of [immune system] peptides via the
nose may be of general significance for social behaviors in all vertebrates," Zufall
said.
The study was led by Trese Leinders-Zufall and will be detailed
in the Nov. 5 issue of the journal Science.
Picky,
picky
Similar peptides exist in human immune systems. But our
vomeronasal organ has apparently been rendered defunct by evolution, many scientists believe, though there's some
uncertainty about this. In fact the question of how and whether scent affects a woman has been widely debated in
recent years.
Since discovering powerful sex pheremones in silkworms
decades ago, scientists have been hot to learn whether humans could be similarly stimulated. The investigation has
proved frustrating.
"Compared to insects, whose behavior is stereotyped
and highly predictable, mammals are independent, ornery, complex creatures," notes writer Maya Pines of the Howard
Hughes Medical Institute.
Like any animal, we humans are picky. And
that provides a line of investigation.
Stinky
T-shirts
In 1996, Claus Wedekind, a zoologist at Bern University in
Switzerland, conducted what's become known as the stinky T-shirt study. Wedekind had 44 men each wear a t-shirt for
two nights straight, then tested how women reacted to the smelly shirts.
Like mice, women preferred the scent of men whose immune systems were unlike their own. If a man's immune
system was similar, a woman tended to describe his T-shirt as smelling like her father or
brother.
Since then, companies have developed pheremone-based perfumes
and cologns, with promises of increased sexual attraction. Researchers don't agree on their effectiveness.
More research is needed to figure out how and to what extent a
woman's nose leads her to sex, and how adept she is at picking a healthy partner.
"We cannot rule out that other parts of the human nose are able to detect the peptides," Frank Zufall
said. "We can now ask whether these peptides are present in human secretions such as sweat and saliva, whether they
can be detected by the human nose, and if so, whether they have any influence on our own social behavior."
The article and further
info can be found here:
http://www.livescience.com/humanbiology/041
104_sex_and_smell.html (http://www.livescience.com/humanbiology/041104_sex_and_smell.html)
a Man
By Robert Roy
Britt
LiveScience Senior Writer
posted: 04 November 2004
The scent of a man, at least among mice, can reveal the state of his health and determine whether a female
gets pregnant, a new study shows.
The research suggests that other
animals, perhaps even you, choose mates in part based on the strength of their immune
systems.
Previous research had shown mice prefer to breed with mates
whose immune-system genes -- which produce chemicals that help the body fight invading cells -- are different from
their own. Such selective sex leads to healthier offspring.
The new
study shows how the selection occurs.
Researchers at the University of
Maryland examined molecules known as peptides that come from the immune system and end up in urine. Each mouse's
disease-fighting peptides are unique, like fingerprints. A female records and remembers the scent of a mate's
peptides using its vomeronasal organ, inside the nose.
"Exposure,
during a critical period, to urine odor from another male, will prevent embryo implantation, leading to loss of
pregnancy, while exposure to the familiar odor will not," said Frank Zufall of the university's School of Medicine.
Spiking the punch
"We can
trick this odor memory and the outcome of the pregnancy-block test by adding peptides to urine," Zufall told
LiveScience. "In other words, we can switch an unfamiliar urine odor to a familiar one (and vice versa) by spiking
the urine with only a few peptides."
Other studies have shown that
vomeronasal organs in many animals detect pheromones and other molecules that pack information on sexual and social
status. Pheromones were first discovered in the 1950s to be sex attractants in
insects.
"We believe that detection of [immune system] peptides via the
nose may be of general significance for social behaviors in all vertebrates," Zufall
said.
The study was led by Trese Leinders-Zufall and will be detailed
in the Nov. 5 issue of the journal Science.
Picky,
picky
Similar peptides exist in human immune systems. But our
vomeronasal organ has apparently been rendered defunct by evolution, many scientists believe, though there's some
uncertainty about this. In fact the question of how and whether scent affects a woman has been widely debated in
recent years.
Since discovering powerful sex pheremones in silkworms
decades ago, scientists have been hot to learn whether humans could be similarly stimulated. The investigation has
proved frustrating.
"Compared to insects, whose behavior is stereotyped
and highly predictable, mammals are independent, ornery, complex creatures," notes writer Maya Pines of the Howard
Hughes Medical Institute.
Like any animal, we humans are picky. And
that provides a line of investigation.
Stinky
T-shirts
In 1996, Claus Wedekind, a zoologist at Bern University in
Switzerland, conducted what's become known as the stinky T-shirt study. Wedekind had 44 men each wear a t-shirt for
two nights straight, then tested how women reacted to the smelly shirts.
Like mice, women preferred the scent of men whose immune systems were unlike their own. If a man's immune
system was similar, a woman tended to describe his T-shirt as smelling like her father or
brother.
Since then, companies have developed pheremone-based perfumes
and cologns, with promises of increased sexual attraction. Researchers don't agree on their effectiveness.
More research is needed to figure out how and to what extent a
woman's nose leads her to sex, and how adept she is at picking a healthy partner.
"We cannot rule out that other parts of the human nose are able to detect the peptides," Frank Zufall
said. "We can now ask whether these peptides are present in human secretions such as sweat and saliva, whether they
can be detected by the human nose, and if so, whether they have any influence on our own social behavior."
The article and further
info can be found here:
http://www.livescience.com/humanbiology/041
104_sex_and_smell.html (http://www.livescience.com/humanbiology/041104_sex_and_smell.html)