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Brain Rule #11
Male and female brains are different.
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The X chromosome that males have one of and females have two of—
though one acts as a backup—is a cognitive “hot spot,” carrying an
unusually large percentage of genes involved in brain manufacture.
•
Women are genetically more complex, because the active X
chromosomes in their cells are a mix of Mom’s and Dad’s. Men’s X
chromosomes all come from Mom, and their Y chromosome carries less
than 100 genes, compared with about 1,500 for the X chromosome.
•
Men’s and women’s brains are different structurally and biochemically—
men have a bigger amygdala and produce serotonin faster, for example—
but we don’t know if those differences have significance.
•
Men and women respond differently to acute stress: Women activate the
left hemisphere’s amygdala and remember the emotional details. Men
activate the right hemisphere’s amygdala and get the gist.
exploration
Brain Rule #12
We are powerful and natural explorers.
MY DEAR SON JOSH got a painful beesting at the tender age of 2, and he
almost deserved it.
It was a warm, sunny afternoon. We were playing the “pointing game,”
a simple exercise where he would point at something, and I would look.
Then we’d both laugh. Josh had been told not to touch bumblebees because
they could sting him; we used the word “danger” whenever he approached
one. There, in a patch of clover, he spotted a big, furry, buzzing temptress.
As he reached for it, I calmly said, “Danger,” and he obediently withdrew
his hand. He pointed at a distant bush, continuing our game.
As I looked toward the bush, I suddenly heard a 110-decibel yelp. While
I was looking away, Josh reached for the bee, which promptly stung him.
Josh had used the pointing game as a diversion, and I was outwitted by a 2-
year-old.
“DANGER!” he sobbed as I held him close.
“Danger,” I repeated sadly, hugging him, getting some ice, and
wondering what puberty would be like in 10 years or so.
This incident was Dad’s inauguration into a behavioral suite often called
the terrible twos. It was a rough baptism for me and the little guy. Yet it also
made me smile. The mental faculties kids use to distract their dads are the
same they will use as grown-ups to discover the composition of distant suns
or the next alternative energy. We are natural explorers, even if the habit
sometimes stings us. The tendency is so strong, it is capable of turning us
into lifelong learners. But you can see it best in our youngest citizens, often
when they seem at their worst.
Babies give researchers a clear view, unobstructed by years of
contaminating experiences, of how humans naturally acquire information.
Preloaded with lots of information-processing software, infants acquire
information using surprisingly specific strategies, many of which are
preserved into adulthood. In part, understanding how humans learn at this
age means understanding how humans learn at any age.
We didn’t always think that way. If you had said something about preset
brain wiring to researchers 40 years ago, their response would have been an
indignant, “What are you smoking?” or, less politely, “Get out of my
laboratory.” This is because researchers for decades thought that babies
were a blank slate—a tabula rasa. They thought that everything a baby
knew was learned by interactions with its environments, primarily with
adults. This perspective undoubtedly was formulated by overworked
scientists who never had any children. We know better now. Amazing
strides have been made in understanding the cognitive world of the infant.
Indeed, the research world now looks to babies to show how humans,
including adults, think about practically everything.
Babies test everything—including you
Babies are born with a deep desire to understand the world around them and
an incessant curiosity that compels them to aggressively explore it. This
need for explanation is so powerfully stitched into their experience that
some scientists describe it as a drive, just as hunger and thirst and sex are
drives.
All babies gather information by actively testing their environment,
much as a scientist would. They make a sensory observation, form a
hypothesis about what is going on, design an experiment capable of testing
the hypothesis, and then draw conclusions from the findings. They use a
series of increasingly self-corrected ideas to figure out how the world
works.
42 minutes old: Newborns can imitate
In 1979, Andy Meltzoff rocked the world of infant psychology by
sticking out his tongue at a newborn and being polite enough to wait for a
reply. What he found astonished him. The baby stuck her tongue back out at
him! He reliably measured this imitative behavior with infants only 42
minutes old. The baby had never seen a tongue before, not Meltzoff’s and
not her own, yet the baby knew she had a tongue, knew Meltzoff had a
tongue, and somehow intuited the idea of mirroring. Further, the baby’s
brain knew that if it stimulated a series of nerves in a certain sequence, she
could also stick her tongue out. That’s definitely not consistent with the
notion of tabula rasa.
I tried this with my son Noah. He and I started our relationship in life by
sticking our tongues out at each other. In his first 30 minutes of life, we had
struck up an imitative conversation. By the end of his first week, we were
well entrenched in dialogue: Every time I came into his crib room, we
greeted each other with tongue protrusions. It was purely delightful on my
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