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Mice and Men…or when humans and mice share something … When
mice choose mates, experience counts
Choosing a mate is a big decision. And, at least for mice,
it's one that is best made with input from one's peers.
In a series of experiments designed help scientists
understand the brain chemicals that guide mate selection, Pfaff and
his colleagues exposed female mice to odors of either a male mouse
alone or a male mouse with a female. The females consistently
preferred the scent of males linked to other females.
"Our data suggest that female mice may use, or even copy, the
interests of other females based on olfactory cues," says
Pfaff, who is head of the Laboratory of Neurobiology and
Behavior. "It could also be seen as a female trusting the
mate choice of another female."
That one female's choice of mate could influence the choices
of other females is well documented in birds and fish, but had not
been documented for any mammalian species. Pfaff says that the
female mice's mate preference was so strong that they even preferred
the combined male/female scent when it was tainted with the scent of
infectious parasites, opting for that over the scent of a healthy
lone male.
"Male odors can provide female mice with information on their
quality, condition, health and suitability as a potential mate,"
says Pfaff. "This type of 'public information' uses cues
inadvertently provided by an individual, such as odor, which others
observe use to make decisions such as mate choice, food location, or
presence of danger. Specifically in birds and fish, 'public
information' has been shown play a role in when and what to eat and
with whom to mate with, but its use in mate choice has not been seen
in mammals."
Pfaff, who is interested in how brain chemicals affect
behavior, says the decisions made by the female mice hinge on the
presence of oxytocin, a neurotransmitter associated, in humans, with
bonding, trust and sexual attraction. When the gene for oxytocin was
missing, female mice no longer preferentially chose male odors
paired with other female odors, and they did not avoid the odors of
infected males, though other tests showed that their olfactory
system was perfectly intact.
"Our research shows that the oxytocin gene is involved in the
processing and integration of inadvertent social information used in
directing mate choice of female mice," says Pfaff. "Of course, we
don't know if it works the same way in humans. But many have
speculated that social influences do play a role in how we choose
our friends and partners."
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