Penn University
— In the Vienna of 1924, Sigmund Freud wrote,
"Anatomy is destiny." Fast-forward to the 21st century
culture of genome-mapping, Web-surfing and
gender-bending. How well, we might ask, is Freud's famous
dictum holding up? When it comes to gender research,
science has discovered gray areas where Freud saw black
and white.
Psychology professor
Sheri Berenbaum has an unusual window on the issue of
genetics and sex roles. As director of the
longest-running behavioral study on children with
congenital adrenal hyperplasia (CAH) <http://www.congenitaladrenalhyperplasia.org/>,
Berenbaum does research that gives her an understanding
of gender -- with all its subtleties and complexities --
that is sometimes missed by the majority.
CAH is a relatively rare
enzyme deficiency (affecting one in 15,000 newborns) that
begins in gestation and causes the adrenal glands to
overproduce masculinizing sex hormones, androgens. The
typically virilized genitals -- enlarged clitoris and
fused labia -- of female infants with CAH can even create
confusion about their sex at delivery.
This unusual anatomy is
not their destiny for long: Nearly all girls with CAH
have corrective surgery in infancy, along with daily (and
lifelong) hydrocortisone medication that regulates
androgen levels. Since most grow up with a normal female
appearance, can we assume that they will make typically
"feminine" choices throughout their lives? More broadly,
is there evidence that any human behaviors are
"male-typical" or "female-typical?"
Decades of studies have
generally answered that question in the affirmative,
explained Berenbaum. From a young age, girls and boys are
apt to choose different kinds of toys, splitting
stereotypically into the "truck" and "Barbie doll" camps.
Boys tend toward more active and aggressive play than
girls, and fare better than girls in tests of spatial,
navigational and mathematical abilities.
Female strengths usually
include better verbal skills, precision manual dexterity,
emotion decoding and "landmark memory," defined as the
ability to recall objects and their locations within a
confined space. (Yes, there's research backing up the
cliche about men staring into the fridge, asking "Honey,
where’s the ketchup?")
If you believe that
socialization -- the molding power of our environment --
is the main cause of gender differences, consider this:
Berenbaum's data on girls with CAH point to the power of
sex hormones, particularly those we're exposed to
prenatally, in shaping our choices and aptitudes as
children.
As a group, the girls in
Berenbaum's study tend to prefer toys more typical for
boys, show more interests in sports, have better spatial
ability, and show less interest in infants and dolls than
girls without CAH. Despite the hormone-balancing
medication they've received since birth, exposure to high
androgen levels during brain development in-utero seems
to have a lasting masculinizing effect.
"The question is 'How
does that happen?'" asked Berenbaum. "It's very complex.
Despite some of my own data, I certainly wouldn't make a
direct equation that hormones cause you to like trucks."
And, she added, laughing, there's no dishwashing
gene.
"Yes, there's evidence
that biology does influence behavior that shows sex
differences," said Berenbaum. "It's also true that, for
all behaviors studied, the distributions for males and
females overlap on a continuum. Nevertheless, the
differences are observed consistently."
Don't rule out the impact
of socialization on gender though, cautioned Berenbaum.
"What happens to most people is that we start out with
small biological differences which send us off on
different environmental trajectories. Socialization then
magnifies the differences until they become bigger over
time."
"Let's take interest in
babies, for instance," she added. "Say as a girl you have
a slightly increased predisposition to be interested in
babies. So you hang around babies. You get comfortable
with babies. You get lots of rewards for hanging around
babies -- getting paid and praised for babysitting -- so
after a while, a slight preference becomes a strong
interest because it's magnified by the experiences you
have."
That close dance between
nature and nurture may be what "makes it hard to answer
this question" as Berenbaum put it. A self-described
feminist who believed, as a grad student in the 1970s,
that gender differences would be leveled by changing
social norms, Berenbaum is quick to point out that genes
-- like anatomy -- are not necessarily
destiny.
"I think that some people
are afraid to think that genes influence behavior because
it therefore means we can't change it, but that's not
correct. I would argue that if we know the genes that
influence a certain behavior, it might be easier to
change them with an environmental intervention because we
would know what we'd be targeting."
With training and
support, we can strengthen cognitive and behavioral
skills across the gender divide, said Berenbaum. "No
matter what the cause of the difference, you can change
it by the right intervention. You can teach men to be
more emotionally sensitive. You can teach women to have
better spatial abilities."
Conversely, negative
social messages have an undermining effect. "If, before
giving a math test to women, you tell them, 'Women don't
do as well on this test as men do,' they don't do as well
compared to when you don't give them that message. So it
seems that when you set up negative expectations, it
lowers their performance."
Why are people so
fascinated by gender differences in the first place?
"Part of the reason we care about whether women are in
math and science careers," hypothesized Berenbaum, "is
because those careers pay more money and have more
prestige than typically female careers. If we valued
women's careers more maybe this would not be such an
issue."
"While I think the
differences are real," she concluded, "what we should
work on is saying it's OK to be whatever you are.
Differences still matter because we still value males and
females differently.
Sheri Berenbaum,
professor of psychology, has directed behavioral studies
of children and adults exposed to high prenatal levels of
androgens since 1985. She can be reached at
sberenbaum@psu.edu
