~ S P E C I A L ~
F E A T U R E
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An Excerpt
From
Why
Men Never Remember and Women Never
Forget
by Marianne J. Legato, MD, FACP, and
Laura Tucker
September 2005 -
Rodale
What
We Know -- And What We
Don't
I'd like to present you with an
overview of the science as we currently
understand it, via true-or-false
statements that come from questions I've
been asked at lectures and by my patients.
As you read, I'd like to remind you that
while there do seem to be gender-specific
ways of thinking, remembering, and
experiencing emotion, those differences do
not necessarily connote superiority. Dr.
Eric Kandel's groundbreaking research on
learning assures us that our brains aren't
set in stone, even if our sex is. If we
learn from each other, then these
differences become opportunities, not
divisions.
True
or False: Sex is determined by our
biology.
True and false. Although our sex
is determined at the moment of our
conception, and we stay that sex for the
rest of our lives, we actually become more
or less female or male over the course of
our lives. Let's take a look at how this
happens.
The sex chromosome contributed by our
fathers pushes us to form male or female
sex organs. Those organs, in turn, release
hormones that cause dramatic and
sex-specific changes to every organ and
tissue in our bodies -- including the
brain -- and program them to respond in
sex-specific ways down the line. Varying
levels of hormones over the course of our
lives continue the process of sexing
us.
In other words, our genes set us up for
the sex we'll be, and our hormones salt
the stew. The complex interaction between
these two factors -- especially during
specific windows when their levels drop or
surge as they do during puberty and
menopause -- make the two sexes different
and each of us different from one another
as well.
Nature is only part of the explanation
for the differences between us. In fact,
one of the thorniest challenges faced by
those of us who study gender differences
is teasing out which differences are due
to the genetic and hormonal components of
our biology and which are the result of
"nurture," or how we're conditioned and
shaped by our environment.
Society certainly believes men and
women are different and expects
sex-specific behavior from us. Even when
children are young, parents encourage sons
and daughters to do quite different kinds
of activities, and in fact, boys and girls
seem to enjoy quite different
things.
These very disparate paradigms of what
it means to be male or female provoke
important questions about the difference
between the sexes. How many of the
differences between us are the result of
the gender roles that the society of the
time imposes? Are our sex-specific
talents, temperament, and world view
inescapably hardwired into our central
nervous system? Or is our sexually
stereotyped behavior choreographed by our
culture's expectations of us?
Some of the differences between men and
women are hardwired. But as soon as we're
born, the environment works in powerful
ways to interact with, and even change,
our hardwiring to shape the way we act and
interface with others. The idea that our
experiences can change our brains means
that the strands of conditioning and
biology are more closely intertwined than
we'd even thought. Treating your daughter
like she's a girl may make her more so.
The brain is never "done," but continues
to grow and change as long as we provide
it with inspiration.
True
or False: There are significant
differences between the brains of men and
women.
True. It seems self-evident that
men and women would have different brains
-- after all, what could be more
fundamental about us than whether we're
male or female? And yet, for most of
medical history, doctors and scientists
assumed that all the organs of men and
women were the same, except for those
directly involved in reproduction.
Research suggesting otherwise is very new:
Scientists first made the observation that
there were differences in the physical
structure of the brains of female and male
rats a little more than three decades ago.
It has now been confirmed that this is
true not only in other species with two
sexes, like songbirds and monkeys, but in
our own as well: The anatomy of the brain
and how it works are different in men and
women.
True
or False: The brain has a sex at
birth.
True. Our sex is fixed and
immutable -- and not just at birth, but
from the very moment of conception. That
sex has implications for all the systems
in our bodies, including our
brains.
But in a sense, this is a trick
question, because while we are undeniably
and indelibly male or female from the very
beginning, there are a variety of factors
that contribute to the process by which we
acquire our sex over the course of our
lives. So, although you're always male or
female, other factors are working on you
at specific stages throughout your life to
make you more or less that way.
What are those factors? Our genes are
the unique cellular blueprint that makes
us who we are, including our sex: The sex
chromosome we get from our fathers at
conception determines which sex organs
we'll develop. An X chromosome from Dad
means the baby will have two Xs and
develop into a female. A Y chromosome
means that there will be an XY complement,
creating a boy. The sex organs we develop,
in turn, release sex-specific hormones,
which continue the process not only in the
uterus but also during certain windows of
time throughout life -- puberty and
menopause, for example -- when hormone
levels change precipitously. Those
hormones also turn certain genes on or
off, which further influences the
sex-specific functions of our tissues,
which is why more than one teenage girl
has cursed her mother for the size (large
or small) of her new breasts.
These genes are also why hormone levels
vary from person to person. Those hormone
levels affect our behavior. Individuals
with high testosterone levels, for
instance, are bolder, more aggressive, and
more focused on a single goal. They smile
less, have a higher libido, and are more
likely to engage in extramarital
sex.
There's one more factor influencing our
sex -- our experiences. A striking example
of this is the conduct of some of the
female soldiers at Abu Ghraib, the
American-run prison in Iraq. Many of us
were shocked -- not just by the
brutalities these women meted out, but at
the discovery that women were just as
capable of acts of humiliation and
savagery as men. Clearly, experience is an
important factor in modifying
behavior.
True
or False: Men's brains are
bigger.
True. Whenever I lecture on this
subject, nothing gets a more outraged
response than this simple biological
truth: Men's brains are bigger than those
of women and weigh 10 percent
more.
But size isn't everything. Women have
more gray matter in certain parts of their
brains and more intricate and extensive
communications between brain cells than
men, particularly in the frontal cortex.
This is the area involved in judgment and
decision making: the "executive center" of
the brain. Some scientists think that this
relatively more intricate system of
neuronal interconnections explains why
women's brains have a higher rate of blood
flow. In fact, smaller brains may be more
efficient. Ounce for ounce, women get more
brain bang for the buck, possibly because
of the greater degree of connectivity
between cells.
And while it is true that male fetuses
have more brain cells than female ones do,
this may be the reason boys have more
developmental defects than girls; it may
require more energy to keep these larger
brains in tip-top shape. It takes a lot of
energy to drive a brain, especially a
baby's brain, which has twice the number
of working connections between cells as an
adult's does. Boys, with their bigger
brains, have significantly lower heart
rates and lower body temperatures than
girls; just when they need the energy to
support their bigger brains, they fall
behind! A higher number of boys have
developmental disorders that become
apparent in early childhood, such as
mental retardation, expressive and
receptive language disorders, stuttering,
and autism; the energy deficit may explain
why.
True
or False: Women are better at
multitasking, while men are better when
concentrating on a single task from
beginning to completion.
True. Ruben Gur, PhD, and Raquel
Gur, MD, PhD, at the University of
Pennsylvania in Philadelphia, measured
blood flow and activity in men's and
women's brains, and they found repeatedly
that women use more parts of their brains
when given a wide variety of verbal and
spatial tasks. They believe that this may
contribute to women's ability to focus on
a number of different things at one
time.
A new study has raised an important
question: Women may be better at
multitasking, but is multitasking really
the most efficient way to work? Newer
research shows that switching back and
forth from one task to another takes
precious seconds of reevaluation, and
those seconds add up. As the researchers
point out, in the best-case scenario, this
makes you only slightly less efficient --
but in the case of someone talking on a
cell phone and driving, that fraction of a
second may make the difference between
life and death.
The conclusion I personally have come
to is this: Multitasking is certainly
helpful when you don't have any options,
when your assistant is out sick or when
you're trying to put dinner on the table
while at the same time making sure your
children are entertained and safe. But I
find that when I need to concentrate on
writing, it's helpful for me to turn off
my phone and my e-mail program, with its
constant "new mail" alerts, so that I can
better and more purely concentrate on the
task at hand.
True
or False: The effects of our sex hormones
(such as estrogen and testosterone) are
restricted to the reproductive
system.
False. There are two interesting
things about hormones. The first is how
many hormones play a role in sexing us --
not just the sex hormones, as you might
think, but others, like the ones we
release when we're under stress.
The second is how many systems these
hormones affect. Yes, estrogen is
responsible for menstrual periods, but did
you know that it also has a profound
effect on the way women learn, think, and
remember? For instance, estrogen may be
one of the keys to the earlier questions
about the differences between
schizophrenia in men and women. Here's a
more pedestrian example: I tell patients
with young girls to keep an eye on their
daughters' sneakers. The hormonal changes
that announce puberty and bring on a
girl's first menstrual period will cause a
sudden surge in her growth and a leap in
her shoe size as well.
All of the hormones in the body have
far-reaching effects, which is why it's so
important to take note when differing
levels of them are found in men and
women.
True
or False: Boys and girls develop on
different schedules.
True. One of the most important
ways in which our brains are shaped is not
through growth, but the programmed death
of a large number -- about half -- of the
neurons originally produced as the brain
forms. This pruning process goes on from
the final month of pregnancy and continues
long after birth. Synapses, or connections
between cells, that don't get reinforced
by stimulation from the outside world
atrophy and eventually disappear. The
connections that are stimulated grow
stronger and become permanent. You have to
use it, or you lose it, and practice makes
perfect.
It's a mysteriously wasteful process.
Why don't we simply make what we need to
begin with? I like to think that we're
choosing the neurons that function
optimally, like choosing the prettiest and
healthiest flowers out of a bunch for a
bouquet.
This brain tailoring process is part of
what makes us unique: Our experiences --
the stimulation we're exposed to, or
protected from -- have a very real impact
on who we become. If we don't have
appropriate input during these times, the
systems can be impaired forever, and there
are all too many examples of abused and
neglected children who are cut off from
interaction during crucial developmental
windows and will never develop normal
language skills as a result. Less
tragically, it's what makes the
differences between siblings and even
identical twins who carry the same genetic
information.
New information also tells us that how
and when this brain tailoring occurs
between the ages of 6 and 17 is different
for boys and girls. There are major
differences in when boys and girls prune
and expand the connections in their
brains, and in which areas they tend, as
well as in the numbers of connections
between the two halves of the brain in
boys and girls. The hormones that surge
during puberty (testosterone in boys,
estrogen in girls) play a major role in
these processes, as they have very
different effects on brain function. These
hormonal differences may be the reason for
the different pace of development in
pubescent boys and girls.
True
or False: We treat boys and girls
differently.
True. Of course, the society and
culture in which we raise boys and girls
has a tremendous impact on their outcomes.
A landmark study done in the seventies
showed that women tended to coo at babies
dressed in pink jumpsuits, while men
tossed those in blue up into the air.
People tend to talk to girls, while they
encourage boys to play with mechanical
toys and objects, often from a very young
age. In fact, this research leaves us
unable to tell what comes first. Do the
sex-specific innate areas of the brain
make one sex function differently from the
other? Or is it the impact of
gender-specific behavior, induced by the
societal roles we are asked to play?
Gender bias may be even more important
than we once thought, if the structure of
our brains is in play.
About the Author: Marianne
J. Legato, MD, FACP, is a professor of
clinical medicine at Columbia University,
where she founded and heads the
Partnership for Gender-Specific Medicine.
One of the world's foremost experts on
gender medicine and winner of many awards
for her work, she is the author of The
Female Heart, What Women Need to Know,
and Eve's Rib.
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Dr. Dolhenty's Review of This
Book
Copyright © 2005 Marianne J.
Legato, MD, FACP and Laura Tucker:
Reprinted from: Why Men Never Remember
and Women Never Forget, by Marianne J.
Legato, MD, FACP, and Laura Tucker. ©
2005 Rodale Inc. Permission granted by
Rodale, Inc., Emmaus, PA 18098.
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