Prefer Men Who Smell Like Dad.
(HealthScoutNews) -- Women prefer men who smell like Dad.
That's the translation of a scientific T-shirt-sniffing study
that found a woman is attracted to the smell of a man who has
immune genes similar to those she inherited from her father.
The research, which appears in the February issue of Nature
Genetics, is the first to propose that humans can have such
preferences based on a parent's genetic contribution.
But one expert cautions that the study used an artificial experimental
design, and that more studies are needed.
The findings grew out of research suggesting that women prefer
the scent of men with human leukocyte antigen, or HLA, genes,
that differ from their own.
At the time, researchers suggested women use these scent signals
to find a mate whose immune genes differ from their own. Theoretically,
this would give any children produced by that couple the ability
to fight off a greater number of bacteria and viruses than children
whose parents have similar immune genes.
HLAs are proteins found on the surface of white blood cells that
play an important role in the body's immune response. Everyone
inherits a pair of these HLA genes from each parent, yet the millions
of combinations of HLA genes vary from person to person.
"This would be a way that genetic information could get
out into the environment and be shared," says investigator
Martha K. McClintock, a professor of psychology at the University
The latest study looked at scent preferences among 49 unmarried
women with an average age of 25 from an isolated German-Austrian
community in which the HLA genes are known over two generations.
The women had never been pregnant, and were not using any kind
of hormonal contraception.
McClintock and her colleagues asked a group of men from diverse
ethnic backgrounds to wear cotton T-shirts for two consecutive
nights. At the same time, the men were asked to abstain from certain
aromatic foods, scented toiletries and sex.
Some of the men had HLA genes similar to those in the isolated
community, while others were completely foreign.
The researchers placed sections of the T-shirts in foil-lined
cardboard boxes with holes through which the women could smell
but not see the shirts.
The women, who were not told the source of the odors, were asked
to smell each T-shirt and rate its smell by familiarity, intensity,
pleasantness and spiciness. As controls, the women rated sections
from unworn T-shirts and those scented with "household smells"
of bleach and clove oil. The researchers weren't interested in
which smells the women found sexy, only which smells they wouldn't
mind being exposed to 24 hours a day.
McClintock found that each woman's most preferred T-shirt came
from a donor with significantly more HLA genes that matched her
But more importantly, each woman preferred scents from donors
who had an average of 1.39 HLA genes matching those she had inherited
from her father; her least preferred scents matched only 0.55
genes from her father. There was no significant association with
any of the mothers' HLA genes.
While previous studies had pointed to preference for mates who
are genetically different, these findings suggest there may be
some advantage to a degree of similarity, says McClintock.
And although choosing a mate who is genetically different would
avoid inbreeding, she says, "there's a cost to outbreeding."
For example, she says, it would be problematic for a female Chihuahua
to mate with a male Great Dane.
"What we've shown is that what seems to be chosen is an
intermediate number of [genetic] matches," says McClintock.
"Not zero matches, and not 100 percent
dangers at both ends."
Wayne K. Potts, an associate professor of biology at the University
of Utah in Salt Lake City, says the findings are compelling but
"The idea is that these mating preferences function to produce
offspring that are more disease-resistant," says Potts. "The
mating preferences themselves could also be functioning to avoid
inbreeding, and they could also be used to do other kin-biased
However, Potts points out it may be more accurate to study HLA
preference based on marriage patterns, rather than by studying
brief exposure to boxes containing unknown scents.
And he points out that only 19 percent of the women described
the smells as being related to humans.
McClintock says these findings could apply beyond mate choice,
extending to a broad range of social relationships.
"I think it has implications for interactions between friends
and acquaintances, and in family structure," she says.
What To Do
You can read about mate choice and parenting from the
How Humans Evolved Web book, or look through this
Society for Neuroscience brain briefing on smell and the olfactory
Curious about humans and pheremones? Check out this article from
JunkScience, which discusses previous research by McClintock.
Reference Source 101