Genetic Test Could Reveal a Cheating Heart
By
Jeanna
Bryner
LiveScience Staff Writer
Relationship
quizzes in magazines are fun, but a test
for genetic compatibility might be the
better way to go to see if your wife or
girlfriend will cheat on you.
A
new study reveals that a cluster of genes,
involved in immune
function among other things,
could predict how sexually attracted
a person is to a partner and how likely
a woman is be faithful to her mate.
Couples
in which the individuals had dissimilar
versions of so-called major histocompatibility
complex (MHC) genes had the greatest sexual
compatibility.
"There's
this idea of romantic chemistry, but until
now we haven't been able to pinpoint anything
that predicts it," said lead researcher
Christine Garver-Apgar, a psychologist
at the University of New Mexico.
"These
are some of the first findings that I
know of that get at this idea of romantic
chemistry and what it is exactly that
makes two people just so compatible and
attracted to each other," said Garver-Apgar,
whose husband is related to Virginia Apgar-who
developed in 1952 the Apgar score used
today in hospitals to rate a newborn's
health.
The
MHC genes direct the production of certain
protein receptors that coat the outer
surfaces of cells. The protein receptors
signal to the body's immune
system whether a cell is a
native resident or a foreign
invader. With more MHC variations,
the immune system can recognize a broader
range of foreign cells, making associated
offspring more fit.
All
you need is DNA .
Garver-Apgar
and her colleagues studied 48 romantically
involved couples, ranging from 18 to 35
years old. For genetic
material, they scraped cells
from the inner cheeks of subjects.
The
couples completed surveys at the start
of the study, when the female partner
was at the fertile part of her menstrual
cycle and during her infertile period.
Questions gauged a person's overall satisfaction
with the current romantic relationship,
contentment with in-couple sex, number
of sex
partners and attitude toward
sex
in general.
A
measure of female subjects' luteinizing
hormone, which regulates egg
production, indicated the stage of menstrual
cycle and level of fertility.
It
turned out that opposites did attract,
particularly when women were most fertile.
"As the [MHC] similarity increases,
women are more turned off toward the guy
sexually and more likely to be fantasizing
about other men, specifically when she's
at the fertile point in her cycle,"
said study team member Randy Thornhill,
a biologist at the University of New Mexico.
Not
only did they fantasize, but women in
similar-MHC relationships reported more
sexual
encounters outside with other
men.
"This
speaks to the possibility that women do
seek sex outside of the relationship for
a particular reason and it's to possibly
obtain genetic benefits, whether those
are good genes or compatible genes,"
Garver-Apgar told LiveScience.
Men
showed no discrimination when it came
to sexual
desire toward their partners.
That supports the idea that men
don't put as much energy into reproduction.
They just copulate
when the opportunity arises.
Sexual
chemistry
Humans
might be able to sniff
out a mate's genes to discern
this immunological compatibility. Past
studies have shown that some species of
mice, birds, fish and lizards can identify
a potential mate's MHC type through smell.
Somehow
MHC genes could set in motion the formation
and release of scent molecules through
a person's glands on their skin, the researchers
suggest in the October issue of the journal
Psychological Science.
Whether
an MHC test could truly be more predictive
of mate compatibility than magazine
quizzes is outside of scientists' realm.
But cheek-scraping for DNA material is
simple.
"All
you need is some DNA,"
Thornhill said, "because the DNA
is going to contain the chemistry of that
person's genes