Scientists discover female mice consistently choose mated males over unexperienced single males.

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 to help scientists understand the
brain chemicals that guide mate selection, Don Pfaff and his colleagues
exposed female mice to the odor 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 and use to make
decisions such as mate choice, food location or presence of danger.
Specifically in birds and fish, ‘public information’ has been shown to
play a role in when and what to eat and 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 hinged 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 in 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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