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My subject today is learning.And in that spirit, I want to spring on you all a pop
quiz.Ready?When does learning begin?Now as you ponder that question,maybe you're
thinking about the first day of preschoolor kindergarten,the first time that kids are
in a classroom with a teacher.Or maybe you've called to mind the toddler phasewhen
children are learning how to walk and talkand use a fork.Maybe you've encountered the
Zero-to-Three movement,which asserts that the most important years for learningare
the earliest ones.And so your answer to my question would be:Learning begins at
birth. Well today I want to present to youan idea
that may be surprisingand may even seem implausible,but which is supported by the
latest evidencefrom psychology and biology.And that is that some of the most important learning
we ever dohappens before we're born,while we're still in the womb.Now I'm a science
reporter.I write books and magazine articles.And I'm also a mother.And those two roles came
together for mein a book that I wrote called "Origins.""Origins" is a report from the
front linesof an exciting new fieldcalled fetal origins.Fetal origins is a scientific
disciplinethat emerged just about two decades ago,and it's based on the theorythat
our health and well-being throughout our livesis crucially affectedby the nine months we
spend in the womb.Now this theory was of more than just intellectual interest to me.I
was myself pregnantwhile I was doing the research for the book.And one of the most
fascinating insightsI took from this workis that we're all learning about the worldeven
before we enter it. When we hold our babies for the first time,we
might imagine that they're clean slates,unmarked by life,when in fact, they've already been
shaped by usand by the particular world we live in.Today I want to share with you
some of the amazing thingsthat scientists are discoveringabout what fetuses learnwhile
they're still in their mothers' bellies. First of all,they learn the sound of their
mothers' voices.Because sounds from the outside worldhave to travel through the mother's
abdominal tissueand through the amniotic fluid that surrounds the fetus,the voices
fetuses hear,starting around the fourth month of gestation,are muted and muffled.One
researcher saysthat they probably sound a lot like the the voice of Charlie Brown's
teacherin the old "Peanuts" cartoon.But the pregnant woman's own voicereverberates
through her body,reaching the fetus much more readily.And because the fetus is with
her all the time,it hears her voice a lot.Once the baby's born, it recognizes her voiceand
it prefers listening to her voiceover anyone else's.
How can we know this?Newborn babies can't do much,but one thing they're really good
at is sucking.Researchers take advantage of this factby rigging up two rubber nipples,so
that if a baby sucks on one,it hears a recording of its mother's voiceon a pair
of headphones,and if it sucks on the other nipple,it hears a recording of a female
stranger's voice.Babies quickly show their preferenceby choosing the first one.Scientists
also take advantage of the factthat babies will slow down their suckingwhen something
interests themand resume their fast suckingwhen they get bored.This is how researchers discoveredthat,
after women repeatedly read alouda section of Dr. Seuss' "The Cat in the Hat" while they
were pregnant,their newborn babies recognized that passagewhen they hear it outside the
womb.My favorite experiment of this kindis the one that showed that the babiesof women
who watched a certain soap operaevery day during pregnancyrecognized the theme song
of that showonce they were born.So fetuses are even learningabout the particular language
that's spokenin the world that they'll be born into.
A study published last yearfound that from birth, from the moment of birth,babies
cry in the accentof their mother's native language.French babies cry on a rising
notewhile German babies end on a falling note,imitating the melodic contoursof
those languages.Now why would this kind of fetal learningbe useful?It may have
evolved to aid the baby's survival.From the moment of birth,the baby responds most
to the voiceof the person who is most likely to care for it --its mother.It even
makes its criessound like the mother's language,which may further endear the baby
to the mother,and which may give the baby a head startin the critical taskof learning
how to understand and speakits native language. But it's not just soundsthat fetuses are
learning about in utero.It's also tastes and smells.By seven months of gestation,the
fetus' taste buds are fully developed,and its olfactory receptors, which allow it to
smell,are functioning.The flavors of the food a pregnant woman eatsfind their
way into the amniotic fluid,which is continuously swallowedby the fetus.Babies seem to
remember and prefer these tastesonce they're out in the world.In one experiment, a group
of pregnant womenwas asked to drink a lot of carrot juiceduring their third trimester
of pregnancy,while another group of pregnant womendrank only water.Six months later,
the women's infantswere offered cereal mixed with carrot juice,and their facial
expressions were observed while they ate it.The offspring of the carrot juice drinking womenate
more carrot-flavored cereal,and from the looks of it,they seemed to enjoy it more.
A sort of French version of this experimentwas carried out in Dijon, Francewhere researchers
foundthat mothers who consumed food and drinkflavored with licorice-flavored anise
during pregnancyshowed a preference for aniseon their first day of life,and
again, when they were tested later,on their fourth day of life.Babies whose mothers
did not eat anise during pregnancyshowed a reaction that translated roughly as "yuck."What
this meansis that fetuses are effectively being taught by their mothersabout what
is safe and good to eat.Fetuses are also being taughtabout the particular culture
that they'll be joiningthrough one of culture's most powerful expressions,which is food.They're
being introduced to the characteristic flavors and spicesof their culture's cuisineeven
before birth. Now it turns out that fetuses are learning
even bigger lessons.But before I get to that,I want to address something that you
may be wondering about.The notion of fetal learningmay conjure up for you attempts
to enrich the fetus --like playing Mozart through headphonesplaced on a pregnant
belly.But actually, the nine-month-long processof molding and shaping that goes
on in the wombis a lot more visceral and consequential than that.Much of what a
pregnant woman encounters in her daily life --the air she breathes,the food and
drink she consumes,the chemicals she's exposed to,even the emotions she feels
--are shared in some fashion with her fetus.They make up a mix of influencesas individual
and idiosyncraticas the woman herself.The fetus incorporates these offeringsinto
its own body,makes them part of its flesh and blood.And often it does something more.It
treats these maternal contributionsas information,as what I like to call biological postcardsfrom
the world outside. So what a fetus is learning about in uterois
not Mozart's "Magic Flute"but answers to questions much more critical to its survival.Will
it be born into a world of abundanceor scarcity?Will it be safe and protected,or
will it face constant dangers and threats?Will it live a long, fruitful lifeor a short,
harried one?The pregnant woman's diet and stress level in particularprovide important
clues to prevailing conditionslike a finger lifted to the wind.The resulting tuning and
tweakingof a fetus' brain and other organsare part of what give us humansour enormous flexibility,our
ability to thrivein a huge variety of environments,from the country to the city,from the tundra
to the desert. To conclude, I want to tell you two storiesabout
how mothers teach their children about the worldeven before they're born.In the
autumn of 1944,the darkest days of World War II,German troops blockaded Western
Holland,turning away all shipments of food.The opening of the Nazi's siegewas followed by
one of the harshest winters in decades --so cold the water in the canals froze solid.Soon
food became scarce,with many Dutch surviving on just 500 calories a day --a quarter
of what they consumed before the war.As weeks of deprivation stretched into months,some
resorted to eating tulip bulbs.By the beginning of May,the nation's carefully rationed
food reservewas completely exhausted.The specter of mass starvation loomed.And then
on May 5th, 1945,the siege came to a sudden endwhen Holland was liberatedby the
Allies. The "Hunger Winter," as it came to be known,killed
some 10,000 peopleand weakened thousands more.But there was another population that
was affected --the 40,000 fetusesin utero during the siege.Some of the effects
of malnutrition during pregnancywere immediately apparentin higher rates of stillbirths,birth
defects, low birth weightsand infant mortality.But others wouldn't be discovered for many years.Decades
after the "Hunger Winter,"researchers documentedthat people whose mothers were pregnant during
the siegehave more obesity, more diabetesand more heart disease in later lifethan individuals
who were gestated under normal conditions.These individuals' prenatal experience of starvationseems
to have changed their bodiesin myriad ways.They have higher blood pressure,poorer cholesterol
profilesand reduced glucose tolerance --a precursor of diabetes.
Why would undernutrition in the wombresult in disease later?One explanationis that
fetuses are making the best of a bad situation.When food is scarce,they divert nutrients towards
the really critical organ, the brain,and away from other organslike the heart and
liver.This keeps the fetus alive in the short-term,but the bill comes due later
on in lifewhen those other organs, deprived early on,become more susceptible to disease.
But that may not be all that's going on.It seems that fetuses are taking cuesfrom
the interuterine environmentand tailoring their physiology accordingly.They're preparing
themselvesfor the kind of world they will encounteron the other side of the womb.The
fetus adjusts its metabolismand other physiological processesin anticipation of the environment
that awaits it.And the basis of the fetus' predictionis what its mother eats.The
meals a pregnant woman consumesconstitute a kind of story,a fairy tale of abundanceor
a grim chronicle of deprivation.This story imparts informationthat the fetus usesto
organize its body and its systems --an adaptation to prevailing circumstancesthat facilitates
its future survival.Faced with severely limited resources,a smaller-sized child
with reduced energy requirementswill, in fact, have a better chanceof living to
adulthood. The real trouble comeswhen pregnant women
are, in a sense, unreliable narrators,when fetuses are ledto expect a world of scarcityand
are born instead into a world of plenty.This is what happened to the children of the Dutch
"Hunger Winter."And their higher rates of obesity,diabetes and heart diseaseare
the result.Bodies that were built to hang onto every caloriefound themselves swimming
in the superfluous caloriesof the post-war Western diet.The world they had learned
about while in uterowas not the sameas the world into which they were born.
Here's another story.At 8:46 a.m. on September 11th, 2001,there were tens of thousands
of peoplein the vicinity of the World Trade Centerin New York --commuters spilling
off trains,waitresses setting tables for the morning rush,brokers already working
the phones on Wall Street.1,700 of these people were pregnant women.When the planes
struck and the towers collapsed,many of these women experienced the same horrorsinflicted
on other survivors of the disaster --the overwhelming chaos and confusion,the rolling
cloudsof potentially toxic dust and debris,the heart-pounding fear for their lives.
About a year after 9/11,researchers examined a group of womenwho were pregnantwhen
they were exposed to the World Trade Center attack.In the babies of those womenwho
developed post-traumatic stress syndrome, or PTSD,following their ordeal,researchers
discovered a biological markerof susceptibility to PTSD --an effect that was most pronouncedin
infants whose mothers experienced the catastrophein their third trimester.In other words,the
mothers with post-traumatic stress syndromehad passed on a vulnerability to the conditionto
their children while they were still in utero. Now consider this:post-traumatic stress
syndromeappears to be a reaction to stress gone very wrong,causing its victims tremendous
unnecessary suffering.But there's another way of thinking about PTSD.What looks like
pathology to usmay actually be a useful adaptationin some circumstances.In a
particularly dangerous environment,the characteristic manifestations of PTSD --a
hyper-awareness of one's surroundings,a quick-trigger response to danger --could
save someone's life.The notion that the prenatal transmission of PTSD risk is adaptiveis
still speculative,but I find it rather poignant.It would mean that, even before
birth,mothers are warning their childrenthat it's a wild world out there,telling them,
"Be careful." Let me be clear.Fetal origins research
is not about blaming womenfor what happens during pregnancy.It's about discovering
how best to promotethe health and well-being of the next generation.That important effort
must include a focuson what fetuses learnduring the nine months they spend in the womb.Learning
is one of life's most essential activities,and it begins much earlierthan we ever imagined.
Thank you. (Applause)