Go for it, baby
New Scientist, 27 April 2002
smell really can change the way people around you behave—and it has
nothing to do with bad BO. Breastfeeding women and newborns give off
odours that boost the sexual desire of other women.
adds to the growing body of evidence suggesting that our natural smell
influences other people on an unconscious level, and strengthens the
argument that human pheromones exist and still exert a subtle influence
In the study, smells associated with breastfeeding
increased feelings of sexual intimacy in childless women volunteers.
Why this should be so is a mystery, but the researchers suggest it may
be a way that women signal to each other that the environment is a good
one in which to reproduce.
Julie Mennella of the Monell Chemical
Senses Center in Philadelphia and a team at the University of Chicago
asked 26 nursing mothers to wear absorbent pads in their bras and under
their armpits. The odours collected on the pads probably came from both
the mother and the feeding baby.
Another 45 women, who had never
given birth, then spent the next three months undertakng a "sniff
challenge". For a month, all the women sniffed control pads with a
phosphate buffer on them four times a day. For the final two months,
some women were randomly chosen to sniff pads with the breastfeeding
compounds, while others continued with the control scent. Each day the
volunteers measured their temperature, took a urine sample and recorded
Last year, Mennella's group showed that
exposure to breastfeeding odours disrupted the menstrual cycles of
volunteers: longer cycles got longer and shorter ones got shorter.
new study reveals a more subtle effect. While the women smelling the
breastfeeding compounds did not report increased sexual activity—this
behaviour was most obviously influenced by the absence or presence of a
partner—they did report significantly heightened and more enduring
sexual desire and fantasies. "The data are pretty striking," says
Mennella, who presents her evidence this week to a meeting of the
Association for Chemoreception Sciences in Sarasota, Florida.
concludes that the chemicals encourage other women to reproduce, and
that they may have evolved as a signal that the environment is suitable
for raising young. In many cultures, newly-wed young women are
encouraged to spend time around new mothers to increase their own
chances of having children, she says. "I wonder if these cultures have
tapped into something." She is eager to find out if the breastfeeding
smell has any impact on fertility.
Richard Brown, a psychologist
at Dalhousie University in Halifax, Nova Scotia, notes that these are
only preliminary findings. But he points out that breastfeeding women
have higher than normal progesterone levels. "Maybe the high
progesterone acts like an androgen," he speculates. "Maybe it's the
weirdest of possible things and they're producing male-like odours."