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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 insightsI 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 alouda 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)

My subject today is learning.And in that spirit, I want to spring on you all a pop

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Ted.com talk - What babies learn before they're born

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    Halu Hsieh posted on 2013/09/07
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