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The Aggressive Sex
In every culture on this planet, boys are
more aggressive than girls. That is the conclusion of researchers
Eleanor Maccoby and Carol Jacklin.
In a study of elementary and junior high
school classes, boys were found to be eight times more likely
to call out answers than girls. In a three-year study, Sexism
in the Schoolroom of the 80s, it was found that boys
participate and are called on in class more than girls
significantly more and that the teachers didnt
Teachers were shown a film of a classroom
discussion. When it was over, they were asked who was talking
more. Most of the teachers said the girls were. Then they went
back through carefully coding and counting who was talking and
they discovered that the boys were outtalking the girls at a
ratio of three to one.
Boys get more attention in grade school.
Maybe this explains why they do better on tests in high school.
Why do they get more attention? Because theyre more aggressive
calling out answers, piping up with questions, etc. Im
using the term aggressive in the scientific sense.
In everyday talk, we usually say someone is aggressive if they
are hostile, selfish or picking a fight. But anything someone
does that isnt passive is aggressive. Saying I love
you to someone is aggressive in the scientific sense. It
is reaching, acting, approaching, initiating trying to
cause an effect. Interrupting someone who is talking is aggressive
act of communication.
The opposite of aggression is being passive,
receptive or responsive. A boy who has a crush on a girl is being
aggressive if he asks her out on a date. He is being passive
if he only fantasizes about it or tries to look attractive in
the hopes shell ask him out.
Trini Johannesen, a teacher in Stockbridge,
Michigan and vice president of the Michigan Education Association,
took the advice of researchers and videotaped her own classroom
to be able to observe dispassionately. Johannesen noticed girls
take more time to think through their answers. Boys tended to
simply shout out and appeared less concerned if their answer
was right. She noticed some girls were having similar difficulties
with classroom material as some boys, but the boys received more
help because they were more noticeable. Says Johannesen, The
girls were simply less overt.
Psychology professor Aletha Houston (University
of Kansas in Lawrence) conducted experiments at several preschools
and found girls more likely to do activities that were supervised
by an adult. Boys were more likely to play independently.
Studies of young children show boys like
hostile humor more than girls. Boys are more likely than girls
to find aggressive cartoons funnier. Boys tend to initiate more
aggression when playing. Part of the way aggression shows itself,
and part of the cause of aggression is competition. There
is a strong element of competition among men. We are, after all,
larger than women, an indication that at some time in our past,
there was competition between men for mates. In any species where
an individual mates with several others of the opposite sex,
there is competition, and the competing sex grows larger or more
beautiful than the noncompeting sex. We must have taken the larger
Genes acting on male brains with
male hormones make males bigger, more competitive and
more aggressive. Boys tease more than girls and use forbidden
words more often. As adults, polls have shown men far more likely
than women to favor military intervention in other countries.
Animals exposed to testosterone in utero
display markedly more aggression as adults.
Girls who were exposed to male hormones
in the womb are found to be tomboys they liked
outdoor roughhousing and were more physically active. The parents
werent trying to teach these girls to be more active. In
fact, parents concerned about their daughters boy-like
behavior is what brought them to the doctor. Thats how
most of these accidental exposures to male hormones were discovered.
At one time, male hormones were given to
pregnant mothers who had toxemia. The hormones made the mothers
feel better, but those who were pregnant with daughters found
the girls behaved like boys: not interested in playing with dolls,
more active, enjoyed roughhousing, and more aggressive.
The researcher June Reinisch found the
same thing at the Kinsey Institute for Research in Sex, Gender
and Reproduction at Indiana University. The assessment of aggression
was based on interviews with the girls mothers, questionnaires
given to the girls themselves, and independent ratings by the
Reinisch gave multiple-choice tests to
pairs of brothers and pairs of sisters (ages 6 to 18). The respondents
were to answer how they would respond to different kinds of stressful
situations. On average, the males gave more aggressive and belligerent
answers than the girls did. But boys who were exposed to extra
male hormones in the womb were even more aggressive than
their unexposed brothers, and the girls exposed to extra male
hormones were measurably more aggressive than their normal sisters.
Melissa Hines at UCLA and a colleague watched
CAH girls, ranging from two and a half years old to eight years
old, at play. CAH is a condition that produces an excessive amount
of male hormones in girls (because of a lack of two key enzymes).
Sometimes they are born with a clitoris so large they are thought
to be boys. The researchers put the CAH girls in a room with
toys of all kinds (kitchen supplies, books, dolls, board games,
trucks, construction toys, etc.), and made careful notes of what
they played with and for how long. They did the same thing with
the girls brothers and sisters for comparison. The CAH
girls played more with masculine toys than did their
unaffected sisters. They played with the same toys as the boys
did, played with them in the same ways, and spent the same amount
of time playing with them, on average, as the boys.
A hormone is a powerful thing. It can not
only change the way the body is built, but can also change what
were interested in. Hines is perplexed by the findings.
Why, she asks, would you evolve to want to
play with a truck? There is good reason to expect that
some of the CAH girls mothers would try to discourage masculine
interests in their CAH daughters, or at least to not encourage
it. But whether discouraged or not, the hormonally-influenced
Hormones affect us whether we want them
to or not. We are animals, no matter how much you cover us with
clothes and the trappings of modern civilization. A mans
beard grows faster when he is exposed to female pheromones (a
particular molecule produced by certain glands in a woman).
When researchers sprayed male pheromones
on half a doctors waiting-room seats, women sat in the
sprayed seats, and men did not, even though when asked, none
of them smelled anything or had any inkling their behavior was
being influenced by anything but their own conscious decision.
Pheromones have no odor. They effect special nerve endings in
the nose that send messages to certain parts of the brain.
The testosterone levels of men rise and
fall, not only in regular rhythms during the day, but in seasonal
rhythms too. Levels of testosterone are highest during the months
of the most sunlight in summer and early fall. And since
testosterone is responsible for sex-drives, the rate of intercourse
frequency peaks in the month of July, during the longest and
sunniest days of the year. Fertility rates, contraceptive sales
and outbreaks of venereal disease all peak in summer and early
fall. Is it a coincidence that in a more primitive setting, our
young are more likely to survive when born in the spring? Keep
in mind that the infant-mortality rate of all hunter-gather societies
is very high. Any adaptations that improved the rate of infant
survival have been genetically bequeathed to you and me.
Certain kinds of activities can raise a
mans testosterone level: Fighting, watching violence on
TV, an intense emotional expression, winning or succeeding at
something, and thinking about or engaging in sex.
Both men and women in positions of power
have higher testosterone levels than people in lower ranks of
a hierarchy. This is true for monkeys too. And when you give
a small, weak male monkey at the bottom of the hierarchy a big
dose of testosterone, he gets so aggressive, hell fight
his way to the top of the hierarchy by sheer feistiness!
Testosterone makes animals more prone to
extreme forms of aggression: violence. Men have 10 to 20 times
more testosterone than women. The higher the testosterone level
in humans, the more prone to antisocial behavior, fighting, arrests,
drug use, and divorce. A study matching relationship histories
and testosterone levels of over four thousand men showed that
men with higher testosterone levels are less likely to marry
and more likely to divorce.
In Europe, the reoffense rate for brutal
rapists and child molesters is normally around 70 percent. But
in some places they use an unusual method for handling them this
problem: castration. And it works extremely well. It drops the
reoffense rate from 70 percent down to 3 percent! They either
do the castration surgically or they use drugs that neutralize
the male hormones in the blood. Both methods work equally well.
In a placebo-controlled study by the National
Institute of Mental Health, researchers found that anabolic steroids
(artificial male hormones) caused anger, violent feelings, sexual
arousal, a higher energy level and more self-confidence.
Could it be that 90% of the children diagnosed
as hyperactive are boys because testosterone produces a high
energy level and estrogen has a calming influence?
Rhesus monkeys have a nervous system similar
to humans. The male monkeys play rougher and mount other monkeys
more often than the females do. Yet when pregnant mothers are
injected with male hormones, the female offspring behave like
males. Depending on when the hormone is injected, they display
specific male behaviors. Give the shot at a certain stage in
the pregnancy for example, and the female will play rough, but
not mount other monkeys. Give the shot at another time, and she
will mount other monkeys but not play rough. The same has been
found in experiments on rats. Apparently, the different parts
of their brains (and ours) develop at different stages in the
womb, and depending on the presence or absence of male hormones,
those parts of the brain form a male design or a female design.
Remember, the female design is what forms in the absence of male
At McGill University, a researcher by the
name of Michael Meaney found that one of the male hormones (dihydrotestosterone)
directly activates a brain structure (the amygdala) and produces
play-fighting in juvenile male rodents.
You know they can teach rats to learn a
maze by giving them a reward at the end, right? Well, theyve
found that male rats will learn the maze even if the only reward
at the end is the opportunity to fight with another male rat.
In adult male mice, the more testosterone
they have, the faster they will attack a strange male in their
territory. Castrate them and they become less aggressive and
In the hypothalamus, there is a small cluster
of cells called the SDN (sexually dimorphic nucleus). We know
that in animals, the SDN is responsible for mating behavior,
sexual response, and territorial marking. In humans, the SDN
is two and a half times bigger in men than in women.
In rats, the male SDN is also bigger than
in females. But give a female a prolonged dose of male hormones
in the womb and her SDN grows just as big as a males. Castrate
a male just after birth and half his SDN neurons die within 24
The point is, different parts of the brain
are different sizes in males and females, and that these different
sizes are caused by different levels of hormones while the fetus
is developing. And further, that these differences in brains
show up as differences in interests and behavior. We may not
like it, but that doesnt mean it isnt so. Men are
more aggressive than women. Thats a fact. Testosterone
makes men more aggressive, and estrogen makes women less aggressive.
I could go on and on. The amount of research
on mens aggression is even more extensive than research
on womens ability to communicate. Men are more aggressive
To some people, this is a count against
men. But aggression is only bad in certain contexts.
And it is good (useful, advantageous, more effective)
in others. Its safe to say the human race would not exist
today without a sizable aggressive capacity.
Aggression helps get things done. Sure,
a lot of what gets accomplished is destructive. But that doesnt
mean aggression is bad. Aggression is only a power, like hydrogen.
You can use hydrogen to get the space shuttle into orbit, or
you can use it to make a hydrogen bomb. The power itself is not
good or bad; it depends on what you do with it.
Aggression needs to be channelled into
constructive, productive, life-enhancing projects. There is plenty
that needs to be done on this Earth. Lets harness the power
of aggression and put it to work.
We've looked at trivial differences
and important differences in the sexes and some of the evidence
that shows these differences are not learned but inborn. In the
final section (part four), we will explore what this all means
and what we can do with this information.